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3-Phase PM Synchronous Motor Vector Control Using

1. fBEMFShft u_SDQ q_axis coefBEMF oe on omega_actual_mech u_SDQ_lin q_axis EQ 6 1 u_SDQ d_axis u_SDQ lin d_axis EQ 6 2 The u_SDOQ voltages are transformed into u_SAlphaBeta see Section 3 3 3 by the Voltage Transformation process The Scaling DCBus Ripple Compensation block scales u_SAlphaBeta according u_dc_bus_filt to u_Salpha_RipElim described in the svmlimDcBusRip function in the Motor Control Library The space vector modulation process generates duty cycle pwmABC and svmSector according to u_Salpha_RipElim The u_LimitF 16 is a voltage limit for current controllers The u_OverMax constant is used to increase the limitation of u_SDO voltages over maximum SVM_INV_INDEX 2 u_dc_bus_filt determined by the DCBus voltage and space vector modulation Although the pwmABC will be limited by the space vector modulation process functions the reserve is used for field weakening controller dynamics In the stable state the u_SDOQ voltages vector will not exceed u_S_max_FWLimit see Section 6 2 5 4 6 2 5 2 Speed Ramp This process generates angular speed omega_desired_mech from angular speed omega_required_mech with a linear ramp The speed ramp is implemented so as not to saturate the speed regulator during acceleration 6 2 5 3 Speed Alignment Control Process The process controls the i_SDQ_desired q_axis current according to the PMSM Control Process Status For Alignment status it sets i_SDO_desired d_axis to i_Sd_Alignm
2. As explained in Section 4 2 a widely used speed control with inner current closed loop was chosen where the rotor flux is controlled by a field weakening controller In this method the field generating and torque generating parts of the stator current must be broken down in order to be able to separately control the magnetic flux and the torque In accomplish this it s necessary to set up the rotary coordinate system connected to the rotor magnetic field this system is generally called a d q coordinate system Very high CPU performance is needed to perform the transformation from rotary to stationary coordinate systems Therefore Freescale s 56F80x or 56F8300 devices are very well suited for use in a vector control algorithm All transformations needed for Vector Control will be described in the next section 3 3 2 Block Diagram of Vector Control Figure 3 6 shows the basic structure of PMSM vector control To perform vector control follow these steps e Measure the motor quantities phase voltages and currents e Transform the quantities into a 2 phase system 0 8 using Clarke transformation e Calculate the rotor flux space vector magnitude and position angle Transform stator currents into the d q coordinate system using Park transformation The stator current torque i and flux i producing components are separately controlled by the controllers The output stator voltage space vector is calculated using the
3. Quad Dec0 and Quad Dec1 each with four inputs or two additional Quad Timers A and B Two dedicated general purpose Quad Timers totaling six pins Timer C with two pins and Timer D with four pins CAN 2 0 B compatible module with 2 pin ports used to transmit and receive Two Serial Communication Interfaces SCIO and SCI1 each with two pins or four additional GPIO lines Serial Peripheral Interface SPI with configurable 4 pin port or four additional GPIO lines Computer Operating Properly COP Watchdog timer Two dedicated external interrupt pins Fourteen dedicated General Purpose I O GPIO pins 18 multiplexed GPIO pins External reset pin for hardware reset JTAG On Chip Emulation OnCE Software programmable Phase Lock Loop based frequency synthesizer for the hybrid controller core clock Table 2 1 Memory Configuration for 56F80x Devices 56F801 56F803 56F805 56F807 Program Flash 8188 x 16 bit 32252 x 16 bit 32252 x 16 bit 61436 x 16 bit Data Flash 2K x 16 bit 4K x 16 bit 4K x 16 bit 8K x 16 bit Program RAM 1K x 16 bit 512 x 16 bit 512 x 16 bit 2K x 16 bit Data RAM 1K x 16 bit 2K x 16 bit 2K x 16 bit 4K x 16 bit Boot Flash 2K x 16 bit 2K x 16 bit 2K x16 bit 2K x 16 bit 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 56F8346 56800E Core Family 2 2 56F8346 56800E Core Family The 56F8346 provides the following peripheral blocks Two Pulse Width Modul
4. Rev 3 Freescale Semiconductor 63 Preliminary How to Reach Us Home Page www freescale com E mail support freescale com USA Europe or Locations Not Listed Freescale Semiconductor Technical Information Center CH370 1300 N Alma School Road Chandler Arizona 85224 1 800 521 6274 or 1 480 768 2130 support freescale com Europe Middle East and Africa Freescale Halbleiter Deutschland GmbH Technical Information Center Schatzbogen 7 81829 Muenchen Germany 44 1296 380 456 English 46 8 52200080 English 49 89 92103 559 German 33 1 69 35 48 48 French support freescale com Japan Freescale Semiconductor Japan Ltd Headquarters ARCO Tower 15F 1 8 1 Shimo Meguro Meguro ku Tokyo 153 0064 Japan 0120 191014 or 81 3 5437 9125 support japan freescale com Asia Pacific Freescale Semiconductor Hong Kong Ltd Technical Information Center 2 Dai King Street Tai Po Industrial Estate Tai Po N T Hong Kong 800 2666 8080 support asia freescale com For Literature Requests Only Freescale Semiconductor Literature Distribution Center P O Box 5405 Denver Colorado 80217 1 800 441 2447 or 303 675 2140 Fax 303 675 2150 LDCForFreescaleSemiconductor hibbertgroup com Information in this document is provided solely to enable system and software implementers to use Freescale Semiconductor products There are no express or implied copyright licenses granted hereunder to design or fabricate
5. The rotor position in o f coordinate system EQ 3 9 through EQ 3 13 represent the model of PMSM in the stationary frame a B fixed to the stator Besides the stationary reference frame attached to the stator motor model voltage space vector equations can be formulated in a general reference frame which rotates at a general speed If a general reference frame is used with direct and quadrature axes x y rotating at a general instantaneous speed W d0 d as shown in Figure 3 3 where 0 is the angle between the direct axis of the stationary reference frame 0 attached to the stator and the real axis x of the general reference frame then EQ 3 14 defines the stator current space vector in general reference frame _ 0 i te Sil EQ 3 14 sy y p l sa Figure 3 3 Application of the General Reference Frame The stator voltage and flux linkage space vectors can be similarly obtained in the general reference frame Similar considerations hold for the space vectors of the rotor voltages currents and flux linkages The real axis ra of the reference frame attached to the rotor is displaced from the direct axis of the stator reference frame by the rotor angle 6 Since it can be seen that the angle between the real axis x of the general reference frame and the real axis of the reference frame rotating with the rotor ra is 6 0 in the general reference frame the space vector of the rotor currents can be expressed as pe
6. k The transformation constant chosen as k 2 3 Figure 3 2 shows the stator current space vector projection 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 7 Preliminary Target Motor Theory Phase B a Phase A Phase C Figure 3 2 Stator Current Space Vector and Its Projection The space vector defined by EQ 3 2 can be expressed utilizing two axis theory The real part of the space vector is equal to the instantaneous value of the direct axis stator current component isg and whose imaginary part is equal to the quadrature axis stator current component i g Thus the stator current space vector in the stationary reference frame attached to the stator can be expressed as i ia digg EQ 3 3 S In symmetrical 3 phase machines the direct and quadrature axis stator currents i q and i g are fictitious quadrature phase 2 phase current components which are related to the actual 3 phase stator currents as follows gt i 1 1 EO 3 4 lsa T sa 5 sb 5 sc Q 3 j Ba ae EQ 3 5 lsp F lsb sc a Where k 2 3 isa transformation constant 3 Phase PMSM Motor Vector Control Rev 3 8 Freescale Semiconductor Preliminary Mathematical Description of PM Synchronous Motor The space vectors of other motor quantities voltages currents magnetic fluxes etc can be defined in the same way as the stator current space vector For a description of the PM synchronous motor consider t
7. see Figure 4 7 and Figure 4 8 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 27 Preliminary System Concept Q1 Q3 Q5 SKB04N60 SKB04N60 SKB04N60 Gate_AT gt Gate_BT r Gate_CT Phase_A j Phase_B a Phase_C T Q2 Q4 Q6 SKBO4N60 SKBO4N60 SKBO4N60 Gate_AB Gate_BB 7 Gate_CB Source_AB 3i Source_BB Source_CB 5 l_sense_A1 x sense R1 l_sense_B1 g sense R2 l_sense_C1 sense R3 0 11 0 11 0 11 l_sense_A2 sense l_sense_B2 amp sense _sense_C2 sense Figure 4 7 Current Shunt Resistors R318 75k 1 R320 10k 1 6 1 65V 1 65V Imax _sense_C1 Ei 7 5 l_sense_C l_sense_C2 C R321 10k 1 R322 U301B R323 390 75k 1 MC33502D 3 3V_A O 1 65V ref R324 C307 C306 100k 1 100nF 3 3uF 10V LM285M U304 R325 33k 1 GNDA SA GNDA Figure 4 8 Current Amplifier As shown in Figure 4 7 the currents can only be measured in certain circumstances For example the current flows through Phase A and shunt resistor R1 only if transistor Q2 is switched on Likewise the current in Phase B can be measured if transistor Q4 is switched on and the current in Phase C can be measured if transistor Q6 is switched on A voltage shape analysis must be performed to get a moment of current sensing The voltage shapes of two different PWM periods are shown in Figure 4 11 The voltage shapes correspond to center aligned PWM sinewave modulation As shown the best moment of current samplin
8. 1 Beans and Library Functions 57 8 2 Beans Initialization 0 0 0 cece 57 83 Interrupts s sccsctesscasecbestseacessess penne sstensaes 57 8 4 PC Master Software eects 58 9 Hybrid Controller Memory Use 60 10 References asin ciicedeineeeuieeeeiinee 60 4 freescale semiconductor Advantages and Features of Freescale s Hybrid Controller 2 Advantages and Features of Freescale s Hybrid Controller The Freescale 56F80x 56800 core and 56F8300 56800E core families are well suited for digital motor control combining the DSP s calculation capability with the MCU s controller features on a single chip These hybrid controllers offer many dedicated peripherals such as Pulse Width Modulation PWM unit s an Analog to Digital Converter ADC Timers communication peripherals SCI SPI CAN on board Flash and RAM The following sectins use a specific device to describe the family s features 2 1 56F805 56800 Core Family The 56F805 provides the following peripheral blocks Two Pulse Width Modulator modules PWMA and PWMB each with six PWM outputs three Current Sense inputs and four Fault inputs fault tolerant design with dead time insertion supporting both center aligned and edge aligned modes Twelve bit Analog to Digital Converters ADCs supporting two simultaneous conversions with dual 4 pin multiplexed inputs the ADC can be synchronized by PWM modules Two Quadrature Decoders
9. Brake Control process is dedicated to the brake transistor control which maintains the DCBus voltage level It is called from Main see Figure 6 1 The UP DOWN Button and Switch Control processes are subprocesses of Application Control and are described in Section 7 4 The Up Down Button processes are split into Button Processing Interrupt called from Quadrature Timer DO Interrupt see Figure 6 3 Button Processing Background called from ApplicationControlProcessing 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 35 Preliminary Software Design C Reset D Hybrid Controller Initialization 2 Fault Control Background if faultCtriStatus AnalogFaultEnbl check Undervoltage Overheating faults if Position sensing Overvoltage Overcurrent faults set appFaultStatus trigger beginning of Fault State Application Control Processing according to appOpMode control check switch set omega_required_mech according to appState trigger appState Run Stop Init set PMSM Control Run Stop set Fault Control status set Brake Control Run Stop set LED Indication i Brake Control Processing if u_dc_bus_filt gt U_DCB_ON_BRAKE_SYSU Brake On if u_dc_bus_filt lt U_DCB_OFF_BRAKE_SYSU Brake Off Figure 6 1 Software Flow Chart General Overview e The Switch process is split into Switch Filter
10. Processing called from Quad Timer DO Interrupt see Figure 6 3 Switch Get State called from Application Control processing which handles Manual switch control Switch Get State PC master software in PC master application operating mode 3 Phase PMSM Motor Vector Control Rev 3 36 Freescale Semiconductor Preliminary Main Software Flow Chart Interrupt ADC Complete Y Interrupt PWM B Fault Analog Sensing Processing Fault Control PWM Fault ISR part according to anSensingCtriStatus if Overcurrent or Overvoltage sensing initialization set appFaultStatus Overvoltage sense Temperature Overcurrent calculate Filtered Temperature triggers beginning of Fault State disable PWM sense correct 2 Phase Currents calculate 3 Phase Currents y sense Voltage d Return 3 correct Voltage calculate Filtered Voltage PMSM Control Current Processing proceeds according to pmsmCtrlStatus sin cos generation get position from Position Mea surement sin theta_actual_el cos theta_actual_el Current Control Currents Transformation a b c to d q Field Weakening Controller Current d Regulator Current q Regulator Voltages Transformation d q to a DCBus Ripple Compensation Space Vector Module sets pwmABC PWM set duty cycles to pwmABC Y Analog Sensing ADC Phase Set set ADC converter phase current samples two easily measured ph
11. The EVM boards do not resolve button contact bouncing which may occur while pushing and releasing the button so this issue must be resolved by software The reading of buttons is masked by software methods The following algorithm is used to check the state of the desired GPIO pins The level of a GPIO may be LOW or HIGH When the button is pressed the logical level LOW is applied on the GPIO pin and the scanning routine detects the low level and sets the corresponding buttonStatus bit see Figure 7 1 Due to contact bounces the routine disables the scanning process and sets the debounce counter to a predefined value just after the low level is detected The variable buttonStatus represents the interrupt flag Using the 56F83xx s software timer the ButtonProcessingInterrupt function is periodically called as shown in Figure 7 1 The function ButtonProcessingInterrupt decrements the debounce counter and if the counter is 0 the reading of GPIO pins is again enabled The button press is checked by the ButtonEdge function see Figure 7 2 When the variable buttonStatus is set the ButtonEdge function returns 1 and clears buttonStatus When the variable buttonStatus is not set the ButtonEdge function returns 0 According to the ButtonProcessing calling period the value of the debounce counter should be set close to 180ms This value is sufficient to prevent multiple sets of buttonStatus bits due to contact bounces 3 Phase PMSM Motor
12. Vector Control Rev 3 Freescale Semiconductor 55 Preliminary Implementation Notes ButtonProcessing Background debouncecounter 0 ButtonProcessing Interrupt debouncecounter gt 0 Yes Yes Read data from Decrement debounce GPIO pin counter Data from GPIO Low Yes y Set buttonStatus y debounceCounter DEBOUNCE_VALUE al Laat Return Figure 7 1 Button Control ButtonProcessingBackground and ButtonProcessing nterrupt ButtonEdge buttonStatus 1 Yes Clear buttonStatus Figure 7 2 Button Control ButtonEdge 3 Phase PMSM Motor Vector Control Rev 3 56 Freescale Semiconductor Preliminary Interrupts 8 Processor Expert PE Implementation PE is a collection of beans APIs libraries services rules and guidelines This software infrastructure is designed to let a 56F80x or 56F8300 software developer create high level efficient portable code This chapter describes how the PMSM Vector Control application is written under PE 8 1 Beans and Library Functions The PMSM Vector Control application uses the following beans e e ADC bean Quad Timer bean Quadrature Decoder bean PWM bean PC master software bean The PMSM Vector Control application uses the following motor control functions cptrfmClarke Clarke transformation MC_ClarkePark bean cptrfmPark Park transfo
13. and software design including the PC master software visualization tool Freescale Semiconductor Inc 2005 All rights reserved AN1931 Rev 3 1 2005 PRELIMINARY Contents 1 Introduction sesser 1 2 Advantages and Features of Freescale s Hybrid Controller eeeeeeseeeeees 2 2 1 56F805 56800 Core Family 2 2 2 56F8346 56800E Core Family 3 2 3 Peripheral Description 0 eee 4 3 Target Motor Theory ssec 6 3 1 Permanent Magnet Synchronous Motor PMS csccssessocesscssersipienstsicenestaretentatead 6 3 2 Mathematical Description of PM Synchronous Motor s s s 7 3 3 Digital Control of PM Synchronous MO tO oye esvenestes cn thadveseertesstver scsenvecvens 11 4 System Concept cc eeeceescesceeeteeeneeeeees 19 4 1 System Specification eee eee 19 4 2 Vector Control Drive Concept 20 4 3 System Blocks Concept ieee 22 5 Hardware Implementation eee 32 5 1 Hardware Set Up 0 cece eeeeeeseeteeeees 32 6 Software Design ccccceceseeseeteeeeeees 34 6 1 Main Software Flow Chart 34 6 2 Data FOW ssetsca ciostaisinneuiin 39 6 3 State Diagram ose eeeeeseeeeeeeeees 46 7 Implementation Notes cccceseeees 51 7 1 Scaling of Quantities occ 51 7 2 PI Controller Tuning cece 54 7 3 Subprocesses Relation and State Transition S ensisi orena 55 7 4 RUN STOP Switch and Button Controlan 55 8 Processor Expert PE Implementation 57 8
14. clock 4 Not used Secondary source Figure 4 3 Quad Timer B Configuration 4 3 1 1 Position Sensing The position and speed sensing algorithm uses all of the timers in module B and an additional timer as a time base Timers BO and B1 are used for position sensing Timer BO permits connection of three input signals to the Quad Timer B1 even if Timer B1 has only two inputs primary and secondary accomplished by using Timer BO as a Quadrature Decoder only It is set to count in the quadrature mode count to zero and then reinitialize This timer setting is used to decode quadrature signals only Timer B1 is connected to Timer BO in cascade mode in which the information about counting up or down is connected internally to Timer B1 freeing the secondary input of Timer B1 to be used for the index pulse Counter B1 is set to count to 4 number of pulses per revolution 1 and reinitialize after compare The value of Timer B1 corresponds to the rotor position 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 23 Preliminary System Concept The position of the index pulse is sensed to avoid the loss of some pulses under the influence of noise during extended motor operation which can result in incorrect rotor position sensing If some pulses are lost a different position of the index pulse is detected and a position sensing error is signaled If a check of the index pulse is not required Timer B1 can be removed
15. designed to provide a debugging diagnostic and demonstration tool for development of algorithms and applications It consists of components running on PCs and components running on the target hybrid controller connected by an RS 232 serial port A small program is resident in the hybrid controller that communicates with the PC master software to parse commands return status information to the PC and process control information from the PC The PC master software executing on a PC uses Microsoft Internet Explorer as a user interface to the PC To enable the PC master software operation on the hybrid controller target board application add the PC_Master bean to the application The PC_Master bean is located under CPU External Devices gt Display in PE s Bean Selector The PC master bean automatically includes the SCI driver and installs all necessary services This means there is no need to install SCI driver because the PC_Master bean encapsulates its own SCI driver The default baud rate of the SCI communication is 9600 and is set automatically by the PC master software driver A detailed PC master software description is provided in the PE documentation The 3 Phase PMSM Vector Control utilizes PC master software for remote control from a PC It enables the user to e Control the PC master software e Control the motor s Start stop Set motor speed Variables read by the PC master software as a default and displayed to the user ar
16. duration are set The alignment is provided by setting desired current for d_axis to i_Sd_Alignment and for q_axis to 0 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 49 Preliminary Software Design The alignment state provides current control and time out search When alignment time out occurs End Alignment is entered In that state the Position Sensing Zero Position is set so the position sensor is aligned with the real vector of the rotor flux When the End Alignment state ends the PMSM Control enters a regular Run state where the motor is running at the required speed If the Application Control state is set to Begin Stop or Begin Fault the PMSM Control enters the Begin Stop or Fault then the Stop or Fault state 6 3 4 Fault Control State Diagram The state diagram of the Fault Control subprocess is illustrated in Figure 6 11 After the initialization the fault conditions are searched If any fault occurs the appFaultStatus variable is set according to detected error PWM is switched on PWMEN bit 0 the Fault state is entered This state also causes Application Control Fault state If the faults are successfully cleared this is signaled to the Application Control process The Fault state is left when the Application Control Init state is entered Application Control Init Reset Fault Control Hybrid Controller Initialization Fault Control Application Initialization clea
17. first order filters Reset Analog Sensing Hyb d Controller Initialization Application Control Begin Init Analog Sensing Begin Init clear variables clear InitDoneFlag Analog Sensing Init Proceed sense and sum samples count samples samples counter analog sensing init samples Application Control Begin Init Analog Sensing Init Finished samples average set current offsets set InitDoneFlag Analog Sensing Init Done normal operation Figure 6 12 State Diagram Analog Sensing 7 Implementation Notes This section explains implementation notes for targeting a 56F83xxEVM 7 1 Scaling of Quantities The PMSM Vector Control application uses a fractional representation for all real quantities except time The N bit signed fractional format is represented using 1 N 1 format 1 sign bit N 1 fractional bits Signed fractional numbers SF lie in the following range 10 lt sr lt sH02 EQ 7 1 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 51 Preliminary Implementation Notes For words and long word signed fractions the most negative number that can be represented is 1 0 whose internal representation is 8000 and 80000000 respectively The most positive word is 7FFF or 1 0 aA and the most positive long word is 7FFFFFFF or 1 0 27 The following equation shows the relationship between the real and fractional representation
18. on the basis of a motor mechanical constant Thus EQ 4 2 calculates the minimum speed as 16 3rpm The maximum speed can be expressed as 60 Og ANT on EQ 4 3 clkT3 Where Omax Maximum obtainable speed rpm N Number of pulses per revolution 1 rev TelkT3 Period of input clock to Timer B3 s 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 25 Preliminary System Concept Substitution in EQ 4 3 for N and 7 73 Timer B3 input clock system clock 30MHz 2 yields a maximum speed of 219726rpm As demonstrated the algorithm can measure speed across a wide range Because such high speed is not practical the maximum speed can be reduced to a required range by the constant k in EQ 4 1 The constant k can be calculated as pa 60 ANT 1K 73 Onax EQ 4 4 Where k Scaling constant in EQ 4 1 Omax Maximum of the speed range rpm N Number of pulses per revolution 1 rev TelkT3 Period of input clock toTimer B3 s In this application the maximum measurable speed is limited to 6000rpm Notes To ensure an accurate speed calculation you must choose the input clock of Timer B3 so that the calculation period of speed processing in this case 900s is represented in Timer B3 as a value lower than 0x7FFFH 900 10 T 79 lt 0X7FFFH 4 3 1 3 Position Reset with Rotor Alignment After reset the rotor position is unknown because a Quadrature Encoder does not give an absolute position u
19. signals Supports complementary channel operation Dead time insertion Separate top and bottom pulse width correction via current status inputs or software Separate top and bottom polarity control Edge aligned or center aligned PWM signals 15 bits of resolution Half cycle reload capability Integral reload rates from 1 to 16 Individual software controlled PWM outputs Mask and swap of PWM outputs Programmable fault protection Polarity control 20mA current sink capability on PWM pins Write protectable registers PM synchronous motor control utilizes the PWM block set in the complementary PWM mode permitting generation of control signals for all switches of the power stage with inserted dead time The PWM block generates three sinewave outputs mutually shifted by 120 degrees 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor Preliminary Peripheral Description The Analog to Digital Converter ADC consists of a digital control module and two analog Sample and Hold S H circuits ADC features include e 12 bit resolution Maximum ADC clock frequency is 5MHz with 200ns period Single conversion time of 8 5 ADC clock cycles 8 5 x 200ns 1 74s Additional conversion time of 6 ADC clock cycles 6 x 200ns 1 2us Eight conversions in 26 5 ADC clock cycles 26 5 x 200ns 5 3us using simultaneous mode ADC can be synchronized to the PWM via the sync signal Simultaneous or sequential sampling Internal mult
20. the d axis see Section 4 3 1 3 Therefore using a Quadrature Decoder to decode the encoder s signal requires either the calculation of an offset which aligns the Quadrature Decoder position counter with the aligned rotor position zero position or the coupling of the zero rotor position with the index pulse of a Quadrature Encoder To avoid the calculation of the rotor position offset the Quadrature Decoder is not used in this application The decoder s digital processing capabilities are then free to be used by another application In addition to the Quadrature Decoder the input signals Phase A Phase B and Index are connected to Quad Timer B The Quad Timer module consists of four Quad Timers Due to the wide variability of Quad Timer modules it is possible to use this module to decode Quadrature Encoder signals sense position and speed A configuration of the Quad Timer module is shown in Figure 4 3 3 Phase PMSM Motor Vector Control Rev 3 22 Freescale Semiconductor Preliminary System Blocks Concept Quadrature Decoder Primary source QTimer BO Secondary source Position Counter Primary source QTimer B1 Secondary source Phase A Phase B Index Internal digital filter Cascade mode Impulses Counter Sease Primary source QTimer B2 Secondary source Period Timer Primary source QTimer B3 System clock 4 Secondary source Time Base Primary source QTimer DO System
21. u_sdq_max with some reserve for regulation Since the DCBus voltage determines the 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor Preliminary System Specification u_sdq_max limit the u_S_max_FWLimit is set according to the DCBus The u_S_max_FWLimit can be a constant or it can be calculated from a measured DCBus voltage The Field Weakening controller is described in Section 6 2 5 4 4 System Concept 4 1 System Specification The motor control system is designed to drive a 3 phase PM Synchronous Motor PMSM in a speed closed loop The application meets the following performance specifications Vector control of PMSM using the Quadrature Encoder as a position sensor Targeted for a 56F80xEVM or 56F83xxEVM plus Legacy Motor Daughter Card LMDC Runs on a 3 phase PMSM control development platform at a variable line voltage 110 230V AC Control technique incorporates Vector control with speed closed loop and field weakening Rotation in both directions Motoring and generator mode with brake Start from any motor position with rotor alignment Minimum speed of 50rpm Maximum speed of 3000rpm at input power line 230V AC Maximum speed of 1500rpm at input power line 115V AC Manual interface RUN STOP switch UP DOWN push button control LED indicator PC master software control interface Motor start stop Speed set up PC master software remote monit
22. 6 bit 4K x 16 bit 4K x 16 bit Program RAM 2K x 16 bit 2K x 16 bit 2K x 16 bit 2K x 16 bit 2K x 16 bit Data RAM 4K x 16 bit 4K x 16 bit 4K x 16 bit 4K x 16 bit 2K x 16 bit Boot Flash 4K x 16 bit 4K x 16 bit 4K x 16 bit 4K x 16 bit 4K x16 bit 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 3 Preliminary Advantages and Features of Freescale s Hybrid Controller Table 2 2 Memory Configuration for 56F8300 Devices Continued 56F8355 56F8356 56F8357 56F8365 56F8366 56F8367 Program Flash 128K x 16 bit 128K x 16 bit 128K x 16 bit 256K x 16 bit 128K x 16 bit 128K x 16 bit Data Flash 4K x 16 bit AK x 16 bit 4K x 16 bit 16K x 16 bit 4K x 16 bit 4K x 16 bit Program RAM 2K x 16 bit 2K x 116 bit 2K x 16 bit 2K x 16 bit 2K x 16 bit 2K x 16 bit Data RAM 8K x 16 bit 8K x 16 bit 8K x 16 bit 16K x 16 bit 4K x 16 bit 8K x 16 bit Boot Flash 4K x 16 bit 8K x 16 bit 8K x 16 bit 16K x 16 bit 8K x 16 bit 8K x 16 bit 2 3 Peripheral Description In addition to the fast Analog to Digital converter and the 16 bit Quadrature Timers the most interesting peripheral for PMSM control is the Pulse Width Modulation PWM unit The PWM module offers a high degree of freedom in its configuration allowing efficient control of the PM synchronous motor The PWM has the following features Three complementary PWM signal pairs or six independent PWM
23. AN1702 Freescale Semiconductor Inc 3 56F80x Evaluation Module Hardware User s Manual DSPS6F80xEVMUM Freescale Semiconductor Inc 4 3 Phase AC BLDC High Voltage Power Stage User s Manual MEMC3PBLDCPSUM D Freescale Semiconductor Inc 56800 Family Manual DSP56F800FM Freescale Semiconductor Inc DSP56F800 User Manual DSP56F801 7UM Freescale Semiconductor Inc 56F8300 Peripheral User Manual MC56F8300UM Freescale Semiconductor Inc 56F805 Evaluation Module Hardware User s Manual DSP56F805EVMUM Freescale Semiconductor Inc 5 6 7 8 9 56F83xx Evaluation Module Hardware User s Manual for the specific device being implemented MC56F83xxEVMUM Freescale Semiconductor Inc 10 Evaluation Motor Board User s Manual MEMCEVMBUM D Freescale 11 User Manual for PC master software see PE documentation 12 Sensorless Vector and Direct Torque Control P Vas 1998 Oxford University Press ISBN 0 19 856465 1 New York 13 Elektricke pohony Caha Z Cerny M 1990 SNTL ISBN 80 03 00417 7 Praha 14 Freescale web page www freescale com 3 Phase PMSM Motor Vector Control Rev 3 60 Freescale Semiconductor Preliminary PC Master Software 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 61 Preliminary References 3 Phase PMSM Motor Vector Control Rev 3 62 Freescale Semiconductor Preliminary PC Master Software 3 Phase PMSM Motor Vector Control
24. Designed By EMS Current Regulators Freescale Czech Systems Laboratories Roznov p Radh Czech Republic 4 DQ Recorder 4 u_s_DQ EME Speed Regulators 88 u_s_Q 45 Speed Scope aH aw 3 ph PM Synchronous Motor Vector Control on MC56F8346 3 000 rpm 0 rpm No fault 3 000 rpm T T Ie Done R5232 COM1 jspeed 9600 I Psrort O a S BA JH pmaster BB Metrowerks CodeWarrior EA Adobe FrameMaker E inbox Microsoft Outlook E 3ph_pmsm_vector EM 3 OBS HAD 14 06 Figure 8 1 PC Control Window 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 59 Preliminary Hybrid Controller Memory Use 9 Hybrid Controller Memory Use Table 9 1 shows how much memory is needed to run the 3 phase PMSM Vector Control drive using the Quadrature Encoder A part of the hybrid controller memory is still available for other tasks Table 9 1 RAM and FLASH Memory Use by PE 2 94 and CodeWarrior 6 1 2 Memory Available for 56F8300 Application Used Stack Application Used without in 16 bit Words Hybrid Controller PC Master Software SCI Program Flash 64K 9009 4546 Data Flash 4K 4373 4360 Program RAM 2K 0 0 Data RAM 4K 2580 512 stack 396 512 stack 10 References 1 Design of Brushless Permanent magnet Motors J R Hendershot JR and T J E Miller Magna Physics Publishing and Clarendon Press 1994 2 Brushless DC Motor Control using the MC68HC708MC4
25. Figure 3 5 Pulse Width Modulation 3 Phase PMSM Motor Vector Control Rev 3 12 Freescale Semiconductor Preliminary Digital Control of PM Synchronous Motor The most popular power devices for motor control applications are Power MOSFETs and IGBTs A Power MOSFET is a voltage controlled transistor It is designed for high frequency operation and has a low voltage drop thus it has low power losses However the saturation temperature sensitivity limits the MOSFET application in high power applications An Insulated Gate Bipolar Transistor IGBT is a bipolar transistor controlled by a MOSFET on its base The IGBT requires low drive current has fast switching time and is suitable for high switching frequencies The disadvantage is the higher voltage drop of a bipolar transistor which causes higher conduction losses 3 3 1 Vector Control of PM Synchronous Motor Vector control is an elegant method to control a PMSM where field oriented theory is used to control space vectors of magnetic flux current and voltage It is possible to set up the coordinate system to decompose the vectors into a magnetic field generating part and a torque generating part The structure of the motor controller Vector Control Controller is then almost the same as for a separately excited DC motor which simplifies the control of a PMSM This vector control technique was developed specifically to achieve a similarly dynamic performance in PM synchronous motors
26. Freescale Semiconductor Application Note 3 Phase PM Synchronous Motor Vector Control Using a 56F 80x 56F8100 or 56F8300 Device Design of Motor Control Application Libor Prokop Pavel Grasblum Note The PC master software referenced in this document is also known as Free Master software 1 Introduction This application note describes the design of a 3 phase Permanent Magnet Synchronous Motor PMSM drive based on Freescale s 56F80x or 56F8300 dedicated motor control device The software design takes advantage of Processor Expert PE software PM synchronous motors are very popular in a wide application area The PMSM lacks a commutator and is therefore more reliable than the DC motor The PM synchronous motor also has advantages when compared to an AC induction motor Because a PMSM achieves higher efficiency by generating the rotor magnetic flux with rotor magnets a PMSM is used in high end white goods such as refrigerators washing machines dishwashers high end pumps fans and in other appliances which require high reliability and efficiency This application creates a speed closed loop PM synchronous drive using a vector control technique It serves as an example of a PMSM control design using a Freescale hybrid controller with PE support It also illustrates the use of the PE s dedicated motor control libraries This application note includes basic motor theory system design concept hardware implementation
27. In most cases the 3 phase system is symmetrical which means that the sum of the phase quantities is always Zero a K a tb 4c a b c 0 b Reg EQ 3 23 2 2 2 The constant K can be freely chosen equalizing the a quantity and Phase A quantity is recommended Then asa gt K 5 EQ 3 24 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 15 Preliminary Target Motor Theory EQ 3 25 fully defines the Park Clarke transformation BAB 3 3 3 2 Transformation from a B to d q Coordinates and Backwards 2 1 1 af 3 3 S atbt e 0 B OES al 0 jja 1 b EQ 3 25 c Ww Vector control is performed entirely in the d q coordinate system to make the control of PM synchronous motors elegant and easy see Section 3 3 2 This process requires transformation in both directions and the control action must be transformed back to the motor side First establish the d q coordinate system 2 2 Pu NY vat mg y MB sin p Field Yua cos Pua Field Yua Then transform from a P to d q coordinates _ COs ried SM Frijeld H q sin Field COS fieral L Figure 3 8 illustrates this transformation 3 Phase PMSM Motor Vector Control Rev 3 EQ 3 26 EQ 3 27 EQ 3 28 Freescale Semiconductor Preliminary Digital Control of PM Synchronous Motor Pug Figure 3 8 Establishing the d q Coordinate System Park Transformation The backward Inv
28. In this case the output voltages are divided into six sectors as shown in Figure 4 11 The current calculation is then made according to the actual sector value Sectors 1 and 6 EQ 4 6 3 Phase PMSM Motor Vector Control Rev 3 30 Freescale Semiconductor Preliminary System Blocks Concept Sectors 2 and 3 ba 1yg ip EQ 4 7 Sectors 4 and 5 ic 1p 1s EQ 4 8 Notes The sector value is used for current calculation only and has no other meaning in the sinewave modulation But if we use any type of space vector modulation we can get the sector value as part of space vector calculation 4 3 3 Voltage Sensing The DCBus voltage sensor is represented by a simple voltage divider The DCBus voltage does not change rapidly It is nearly constant with the ripple given by the power supply structure If a bridge rectifier is used for rectification of the AC line voltage the ripple frequency is twice the AC line frequency If the power stage is designed correctly the ripple amplitude should not exceed 10 of the nominal DCBus value The measured DCBus voltage must be filtered to eliminate noise One of the easiest and fastest techniques is the first order filter which calculates the average filtered value recursively from the last two samples and coefficient C UnceusFil 1 Cupcpusrin 1 Cupcpusrin Upcpusrink EQ 4 9 To speed up the initialization of the voltage sensing the filter has exponential depend
29. O Frac Fractional representation of speed quantities OReal Real speed quantities in physical units rpm OMEGA_RANGE_MAX Defined speed range maximum used for scaling in physical units rpm In the application the OMEGA_RANGE_MAX value is defined as OMEGA_RANGE_MAX 6000rpm Other speed variables omega_reqPCM_mech omega_desired_mech omega_required_mech omega_reqMAX_mech omega_reqMIN_mech omega_actual_mech are scaled in the same way The relation between speed scaling and speed measurement with encoder is described in Section 4 3 1 2 In the final software the constant OMEGA_SCALE is identical with the scaling constant k in equations EQ 4 1 and EQ 4 4 and OMEGA_RANGE_MAX is Omax 7 1 4 Position Scaling Position Scaling is described in Section 4 3 1 1 7 1 5 Temperature Scaling As shown in Section 4 3 4 the temperature variable does not have a linear dependency 7 2 PI Controller Tuning The application consists of four PI controllers Two controllers are used for the J and Z currents one for speed control and the other for field weakening The controller s constants are given by simulation in Matlab and were experimentally specified A detailed description of controller tuning is beyond the scope of this application note 3 Phase PMSM Motor Vector Control Rev 3 54 Freescale Semiconductor Preliminary RUN STOP Switch and Button Control 7 3 Subprocesses Relation and State Transitions As shown in S
30. Status brakeCtrlStatus 1 CtrlStat appFaultStatus omega_required_mech pmsmCtrlStatus i_Sa Sb i Sc anSensingCtriStatus d _bus temperature PHASEA PHASEB INDEX y temperature_filt Analog Sensing Temperature DCBus volt PC Master Position Speed Phase Currents a b c Software Measurement XU u_dc_bus omega_actual_mech theta_actual_el theta_align_el_C LO OO _ e 0adSWtmrSpeedControl a pwmABC i_Sabc_comp svmSector u_dc_bus_filt i_Sd_Alignment _SDQ_MAX SVM_INV_INDEX u_Reserve_FW reloadSWtmrAlignment SVM_INV_INDEX u_OverMax PWM Generation coefBEMF coefBEMFShift Sm PWM Outputs Pwm_AT Pwm_AB Pwm_BT Pwm_BB Pwm_CT Pwm_CB Figure 6 4 Data Flow Part 1 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 39 Preliminary Software Design pe ee eee PWM Faults TEMPERATURE_MAX_F16 Overvoltage Overcurrent temperature_filt i_Sabc_comp u_dc_bus_min_fault_C Check Index Position u_dc_bus_filt faultCtrlStatus u_dc_bus_on_brake appFaultStatus pmsmCtrlStatus Control Os PWMEN bit N ak PC u_dc_bus_off_brake Master Software brakeCtrlStatus PWM Generation A Pwm_AT Pwm_AB Pwm_BT Pwm_BB Pwm_CT Pwm_CB PWM Outputs a AE IO_BRAKE Figu
31. _max 2 The absolute value of the stator current i should be maintained below a limit of _ SDQ_MAX given by the maximum current rating In the normal operating range the current torque producing component i can be set up to Z SDO_MAX since ig 0 sq Due to the voltage limitation the maximum speed in the normal motor operating range is limited for i q 0 to a nominal motor speed as shown in Figure 3 9 and EQ 3 30 Nominal Speed Stator Voltage u I Normal Operating Range Stator Current i Figure 3 9 Normal Operation and Field Weakening 3 3 4 2 Control in Field Weakening Range The field weakening technique must be used where a higher maximum motor speed is required which is provided by maintaining the flux producing current component i in the field weakening range as shown in Figure 3 9 Due to the limitation of absolute current value the current torque producing component i must be maintained below a limited value ie LSDQ_MAX 72 EQ 3 31 One possibility to maintain the flux producing current component isq for field weakening is to use a look up table A more progressive method uses a Field Weakening Controller which generates a negative current flux producing component i whenever the absolute value of stator voltage exceeds u_S_max_F WLimit The field weakening limit u_S_max_FWLimit is set to be close to the maximum voltage limit of the 3 phase power inverter
32. a Flow PMSM Control 6 2 5 1 Current Control Process The data flow inside the Current Control process is detailed in Figure 6 7 The measured phase currents i_Sabc_comp are transformed into i_SDQ_lin using sinCos_theta_el see Section 3 3 3 Both d and q components are regulated by independent Proportional Integrational PI regulators to i_SDQ_desired values The outputs of the regulators are u_SDQ_lin 3 Phase PMSM Motor Vector Control Rev 3 42 Freescale Semiconductor Preliminary Data Flow i_Sabc_comp sinCos_theta_el Current Transformation a b c gt d q i_SDQ_desired gq_axis i_SDQ q_axis i_SDQ d_axis i_SDQ_desired d_axis u_LimitF16 s y D ON Current q Regulator omega_actual_mech _ SDQ_MAX_F16 Current d Regulator ae ae u_SDQ_lin d_axis u_SDQ_lin q_axis Feed Forward coefBEMF coefBEMFShift pmsmCtrlStatus sinCos_theta_el u_LimitF16 X oltage Transformation d q gt alpha beta SVM_INV_INDEX 2 u_dc_bus_filt u_OverMax u_SAlphaBeta Scaling DCBus Ripple Compensatio u_dc_bus_filt SVM_INV_INDEX So u_OverMax u_Salpha_RipElim Space Vector Modulation pwmABC svmSector Figure 6 7 Data Flow PMSM Control Current Control 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 43 Preliminary Software Design The Feed Forward process provides the following calculations
33. and Timer BO set as the position counter B1 The resulting value of Timer B1 is scaled to range lt 1 1 which corresponds to lt 7 7 4 3 1 2 Speed Sensing There are two common ways to measure speed The first method measures the time between two following edges of the Quadrature Encoder and the second method measures a position difference a number of pulses per constant period The first method is used at low speed When the measured period is so short that the speed calculation is not precise the speed calculation algorithm switches to the second method The proposed algorithm combines both methods The algorithm simultaneously measures the number of Quadrature Encoder pulses per constant period and an accurate time interval between the first and last pulse is counted during that constant period The speed can then be expressed as _k N speed F EQ 4 1 where speed Calculated speed k Scaling constant N Number of pulses per constant period T Accurate period of N pulses The algorithm requires two timers for counting pulses and measuring their period and a third timer as a time base see Figure 4 3 Timer B2 counts the pulses of the Quadrature Encoder and Timer B3 counts a system clock divided by 4 system clock 4 The values in both timers can be captured by each edge of the Phase A signal The time base is provided by timer DO which is set to call the speed processing algorithm every 900us An explanation of how th
34. annot be measured from one voltage shape The PWM period II illustrated in Figure 4 11 shows a moment when the bottom transistor of Phase A is switched on for a very short time If the time on is shorter than a critical time the current can not be accurately measured The critical time is given by hardware configuration transistor commutation times response delays of the processing electronics etc Therefore only two currents are measured and a third current is calculated from the following equation 0 i tigtic 3 Phase PMSM Motor Vector Control Rev 3 EQ 4 5 Freescale Semiconductor Preliminary 29 System Concept l II PWM PERIOD PWM RELOAD PHASE_A PHASE_B PHASE_C gt 4 critical pulse width ADC sampling point Figure 4 10 Voltage Shapes of Two Different PWM Periods IL L 1 F u 0 8 T 9 0 6 S 0 4 gt o i Phase A za 0 2 Phase B Phase C 0 kN 0 60 120 180 240 300 360 angle Sector 1 Sector 2 Sector 3 Sector 4 Sector 5 Sector 6 Figure 4 11 3 Phase Sinewave Voltages and Corresponding Sector Value A decision must now be made about which phase current should be calculated The simplest technique is to calculate the current of the most positive voltage phase For example Phase A generates the most positive voltage within section 0 to 60 Phase B within section 60 to 120 and so on see Figure 4 11
35. any integrated circuits or integrated circuits based on the information in this document Freescale Semiconductor reserves the right to make changes without further notice to any products herein Freescale Semiconductor makes no warranty representation or guarantee regarding the suitability of its products for any particular purpose nor does Freescale Semiconductor assume any liability arising out of the application or use of any product or circuit and specifically disclaims any and all liability including without limitation consequential or incidental damages Typical parameters that may be provided in Freescale Semiconductor data sheets and or specifications can and do vary in different applications and actual performance may vary over time All operating parameters including Typicals must be validated for each customer application by customer s technical experts Freescale Semiconductor does not convey any license under its patent rights nor the rights of others Freescale Semiconductor products are not designed intended or authorized for use as components in systems intended for surgical implant into the body or other applications intended to support or sustain life or for any other application in which the failure of the Freescale Semiconductor product could create a situation where personal injury or death may occur Should Buyer purchase or use Freescale Semiconductor products for any such unintended or unauthorized applica
36. ases Y C Return gt Figure 6 2 Software Flow Chart General Overview II 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 37 Preliminary Software Design Interrupt DO QTimer Speed Measurement Processing PMSM Control Speed Alignment Processing proceeds according to its status get speed from Speed Measurement pmsmCtrlStatus AlignFlag RunFlag others Alignment Speed Control Software Timer Software Timer if Timeout if Timeout PMSM Control End Alignment Field Weakening Controller Speed Regulator Speed Ramp gt lt a y LED Indication Processing Switch Filter Processing Button Processing Interrupt part decrements debounceCounterUp Down C Retum Figure 6 3 S W Flow Chart General Overview III 3 Phase PMSM Motor Vector Control Rev 3 38 Freescale Semiconductor Preliminary Data Flow 6 2 Data Flow The PMSM Vector Control Drive Control Algorithm is described in the data flow charts shown in Figure 6 4 and Figure 6 5 The variables and constants described should be clear from their names UP DOWN ern ae Green LED RUN STOP Switch Buttons ASISI 9 ee omega_reqPCM_mech appOpMode appState appPcmCtrlStatus Application Control LED Indication faultCtrl
37. ative e U3 3 phase AC BLDC High Voltage Power Stage Supplied in a kit with the In Line Optoisolation Box Freescale Part ECINLHIVACBLDC Described in the 3 Phase AC BLDC High Voltage Power Stage User s Manual e U4 In Line Optoisolation Box Supplied in a kit with the 3 Phase AC BLDC High Voltage Power Stage Freescale Part H ECINLHIVACBLDC Or Supplied by itself Freescale Part H ECOPTINL Described in the In Line Optoisolation Box Manual WARNING To avoid potential damage to the development equipment the use of an In line Optoisolation Box is strongly recommended during development 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor Preliminary 33 Software Design e MB1 Motor Brake SM40V SG40N Notes The application software is targeted for a PM Synchronous Motor with sinewave Back EMF shape In this demonstration application a BLDC motor is used instead due to the availability of the BLDC motor MB1 Although the Back EMF shape of this motor is not an ideal sinewave it can be controlled by the application software The drive parameters will be ideal with a PMSM motor with an exact sinewave Back EMF shape A detailed description of the individual board can be found in the appropriate 56F80x Evaluation Module User s Manual or 56F83xx Evaluation Module User Manual or on the Freescale web site www freescale com The Users Manual includes the schematic of the board descr
38. ator modules PWMA and PWMB each with six PWM outputs three Current Sense inputs and three Fault inputs for PWMA PWMB fault tolerant design with dead time insertion supporting both center aligned and edge aligned modes Two 12 bit Analog to Digital Converters ADCs supporting two simultaneous conversions with dual 4 pin multiplexed inputs the ADC can be synchronized by PWM modules Two Quadrature Decoders Quad Dec0 and Quad Dec1 each with four inputs or two additional Quad Timers A and B Two dedicated general purpose Quad Timers totaling three pins Timer C with one pin and Timer D with two pins CAN 2 0 B compatible module with 2 pin ports used to transmit and receive Two Serial Communication Interfaces SCIO and SCI1 each with two pins or four additional GPIO lines Serial Peripheral Interface SPI with configurable 4 pin port or four additional GPIO lines Computer Operating Properly COP Watchdog timer Two dedicated external interrupt pins 61 multiplexed General Purpose I O GPIO pins External reset pin for hardware reset JTAG On Chip Emulation OnCE Software programmable Phase Lock Loop based frequency synthesizer for the hybrid controller core clock Temperature Sensor system Table 2 2 Memory Configuration for 56F8300 Devices 56F8322 56F8323 56F8345 56F8346 56F8347 Program Flash 16K x 16 bit 16K x 16 bit 64K x 16 bit 64K x 16 bit 64 x 16 bit Data Flash 4K x 16 bit 4K x 16 bit 4K x 1
39. decoupling block e The stator voltage space vector is transformed back from the d q coordinate system into the two phase system and fixed with the stator by inverse Park transformation e Using sinewave modulation the output 3 phase voltage is generated 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 13 Preliminary Target Motor Theory Speed Line Input Command 3 phase Power Stage PMSM Position Position Speed sensor Figure 3 6 Block Diagram of PM Synchronous Motor Vector Control 3 3 3 Vector Control Transformations Transforming a PMSM into a DC motor is based on selection of coordinates As shown in Section 3 3 2 a coordinate transformation is required The following transformations are involved in vector control Transformations from a 3 phase to a 2 phase system Clarke transformation e Rotation of orthogonal system f to d q Park transformation d q to o f Inverse Park transformation 3 3 3 1 Clarke Transformation Figure 3 7 shows how a 3 phase system is transformed into a 2 phase system 3 Phase PMSM Motor Vector Control Rev 3 14 Freescale Semiconductor Preliminary Digital Control of PM Synchronous Motor Phase B Isp measured a Phase A isc calculated Phase C Figure 3 7 Clarke Transformation To transfer the graphical representation into mathematical language 7 1 a a J K a o2 b EQ 3 22 Bo la BA 2 2
40. e e Required motor speed e Actual motor speed e Application status Init Stop Run Fault e DCBus voltage level e Identified line voltage e Fault Status No_Fault Overvoltage Overcurrent Undervoltage Overheating The profiles of required and actual speeds together with the desired 7 4 and 7 currents can be seen in the Speed Scope window 3 Phase PMSM Motor Vector Control Rev 3 58 Freescale Semiconductor Preliminary T PC Master Software The course of quickly changing variables can be observed in the Recorder windows displayed by the PC master s Speed Scope The Recorder can only be used when the application is running from External RAM due to the limited on chip memory The length of the recorded window may be set in Recorder Properties gt bookmark Main gt Recorded Samples The dedicated memory space is defined in the appconfig h file of the ExtRAM target The recorder samples are taken every 125usec The following records can be captured e Required speed e Actual speed e Desired J current e Desired q current The PC master software Control Page is illustrated in Figure 8 1 The profiles of the required and actual speeds can be seen in the Speed Scope window F 3ph_pmsm_vector_control pmp FreeMaster File Edit View Explorer Item Project Tools Help suom a eal 2 eee fin EFI 3 ph PM Synchro Motor Vector Contro EMS Interesting Variables 448 phase currents
41. e 8 _ lpg L Lex ji EQ 3 15 3 Phase PMSM Motor Vector Control Rev 3 10 Freescale Semiconductor Preliminary Digital Control of PM Synchronous Motor i The space vector of the rotor current in the rotor reference frame The space vectors of the rotor voltages and rotor flux linkages in the general reference frame can be similarly expressed The motor model voltage equations in the general reference frame can be expressed by utilizing introduced transformations of the motor quantities from one reference frame to the general reference frame The PMSM model is often used in vector control algorithms The aim of vector control is to implement control schemes which produce high dynamic performance and are similar to those used to control DC machines To achieve this the reference frames may be aligned with the stator flux linkage space vector the rotor flux linkage space vector or the magnetizing space vector The most popular reference frame is the reference frame attached to the rotor flux linkage space vector with direct axis d and quadrature axis q After transformation into d q coordinates the motor model as follows u g Rsisat Vary EQ 3 16 us Rigg S EQ 3 17 Ysa Lsisat Yu EQ 3 18 Olly EQ 3 19 ETP Ysaisg Ysgisa Te EQ 3 20 Below base speed i 4 0 EQ 3 20 can be reduced to the following form d _ p 3 From EQ 3 21 it can be seen that the torque is dependent and can be direct
42. e speed processing algorithm works follows First the new captured values of both timers are read The difference in the number of pulses and their accurate time interval are calculated from actual and previous values The new values are then saved for the next period and the capture register is enabled From that moment the first edge of Phase A signal captures the values of both Timer B2 and Timer B3 and the capture register is disabled This process is repeated on each call of the speed processing algorithm see Figure 4 4 3 Phase PMSM Motor Vector Control Rev 3 24 Freescale Semiconductor Preliminary System Blocks Concept New values captured Phase A j Phase B Timer B2 z E Timer B3 System Clock 4 E Timer DO Speed processing i Accurate time period if im Figure 4 4 Speed Processing 4 3 1 2 1 Minimum and Maximum Speed Calculation The minimum speed is calculated with the following equation ane 60 min NT oale EQ 4 2 Where Onin Minimum obtainable speed rpm N Number of pulses per revolution 1 rev Teale Period of speed measurement calculation period s In the application the Quadrature Encoder has 1024 pulses per revolution and a calculation period of 900us was chosen
43. ect the drive from overvoltage undervoltage overcurrent and overheating Undervoltage and overheating protection is performed by software while the overcurrent and overvoltage fault signals utilize a fault input of the hybrid controller If any of the previously mentioned faults occur the motor control PWM outputs are disabled in order to protect the drive and the fault state of the system is displayed by the on board LED 4 3 System Blocks Concept This section explains the system block concept for targeting the 56F83xxEVM 4 3 1 Position and Speed Sensing All members of Freescale s 56F8300 family have a Quadrature Decoder This peripheral is commonly used for position and speed sensing The Quadrature Decoder position counter counts each edge of Phase A and Phase B signals up or down according to its order On each revolution the position counter is cleared by an index pulse see Figure 4 2 TOOTN TOON oe Position Counter Values Phase A eaten ae Phase B i PELES Index One Revolution m Figure 4 2 Quadrature Encoder Signals Because the position counter is cleared on each revolution by an index pulse the zero position is linked with the index pulse but vector control requires the zero position where the rotor is aligned to
44. ection 6 2 and Section 6 3 the software is split into subprocesses according to functionality The application code is designed to be able to extract individual processes such as Analog Sensing and use them for customer applications The C language functions dedicated for each process are located in one place in the software so they can be easily used for other applications Function naming usually starts with the name of the process for example AnalogSensingInitProceed As Section 6 3 shows the processes or subprocesses state transients have some mutual relations For example Application Control Begin Initialization is a condition for transient of the Analog Sensing process Init Done to Begin Init state In the code the interface between processes is provided via trigger functions The naming convention for these functions is lt ProcessName gt lt State gt Trig The functionality is explained in following example The trigger function Process1StateTrig is called from process1 The transient functions of process2 process3 etc which must be triggered by Process 1State are put inside Process 1StateTrig 7 4 RUN STOP Switch and Button Control The RUN STOP switch is connected to the GPIOES pin The state of the RUN STOP switch can be read directly from the GPIO Data Register User buttons are also connected to GPIO pins The state of buttons are read periodically from the GPIO Data Register
45. eed controller 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 5 Preliminary Target Motor Theory The Quadrature Decoder is a module providing decoding of position signals from a Quadrature Encoder mounted on a motor shaft It has the following features e Includes logic to decode quadrature signals e Configurable digital filter for inputs e 32 bit position counter e 16 bit position difference counter e Maximum count frequency equals the peripheral clock rate e Position counter can be initialized by software or external events e Preloadable 16 bit revolution counter Inputs can be connected to a general purpose timer to aid low speed velocity The PM synchronous motor vector control application utilizes the Quadrature Decoder connected to Quad Timer module B It uses the decoder s digital input filter to filter the encoder s signals but does not make use of its decoding functions freeing the decoder s digital processing capabilities to be used by another application 3 Target Motor Theory 3 1 Permanent Magnet Synchronous Motor PMSM The PMSM is a rotating electric machine with a classic 3 phase stator like that of an induction motor the rotor has surface mounted permanent magnets see Figure 3 1 Stator Stator winding in slots Shaft Rotor Air gap Permanent magnets Figure 3 1 Cross Section of a PM Synchronous Motor In this respect the PMSM is equivalent to an induct
46. ency with constant of 1 N samples the moving average filter which calculates the average value from the last N samples can be used for initialization N UDCBusFilt yy 1 DCBus EQ 4 10 4 3 4 Power Module Temperature Sensing The power module temperature measured is used for thermal protection The hardware realization is shown in Figure 4 12 The circuit consists of four diodes connected in series a bias resistor and a noise suppression capacitor The four diodes have a combined temperature coefficient of 8 8mV C The resulting signal Temp_sense is fed back to an A D input where software can be used to set safe operating limits In this application the temperature in Celsius is calculated according to the conversion equation Temp_sense b temp oa a EQ 4 11 Where temp Power module temperature in centigrade Temp_sense Voltage drop on the diodes which is measured by ADC V a Diodes dependent conversion constant a 0 0073738 b Diodes dependent conversion constant b 2 4596 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 31 Preliminary Hardware Implementation 3 3V_A R1 2 2k 1 gt gt Temp_sense BAV99LT1 BAV99LT1 c1 100nF Figure 4 12 Temperature Sensing 5 Hardware Implementation 5 1 Hardware Set Up This section explains the hardware set up for targeting a 56F83xxEVM The application can run on Freescale s motor control hybrid contro
47. ent and i_SDQ_desired q_axis to 0 For Run status it controls the omega_actual_mech speed to omega_desired_mech by calculation of the PI regulator with i_SDQ_desired q_axis output 6 2 5 4 Field Weakening Process The Field Weakening process provides control of i_SDQ_desired d_axis in order to achieve higher motor speeds by the field weakening technique The control algorithm is shown in Figure 6 8 The u_S_max_FWLimit is computed from u_dc_bus_filt To maintain voltage reserve the u_Reserve_FW is subtracted from the maximum SVM_INV_INDEX 2 u_dc_bus_filt determined by DCBus voltage and space vector modulation The reserve is used for field weakening controller dynamics in the stable state the u_SDQ voltages vector will not exceed u_S_max_FWLimit This process also provides voltage limitation i_SDOQ_desired d_axis i_SDQ_desired q_axis lt I_SDO_MAX_F16 by setting PIRegParams_omega_mech PositivePILimit J I SDQ MAX He i SDQ darddan EQ 6 3 PIRegParams_omega_mech NegativePILimit hi SDQ_MAX Fie SDQ_desired d sae EQ 6 4 3 Phase PMSM Motor Vector Control Rev 3 44 Freescale Semiconductor Preliminary Data Flow u_dc_bus_filt SVM_INV_INDEX u_Reserve_FW y Y Y SVM_INV_INDEX 2 u_dc_bus_filt u_Reserve_FW 0 1_SDQ_MAX_F16 u_S_max_FWLimit u_SD d_axis ii maximum minimum R a ai axis 2 4 limit limit i_SDQ_desired d_axis u_SD q_axis E gt PI regulato
48. erse Park transformation from d q to a B is al _ CSPpi1q SN Fiejal d EQ 3 29 B SIND rieig CSU req Z 3 3 4 PMSM Vector Control and Field Weakening Controller This section describes the control regarding the required stator current vectors icq isq There are two speed ranges shown in Figure 3 9 which differ by controlled current vector e Control in Normal Operating Range control mode used when a speed is required below nominal motor speed e Control in Field Weakening Range control mode used when a speed is required above nominal motor speed 3 3 4 1 Control in Normal Operating Range Assume an ideal PMSM with constant stator reluctance L constant EQ 3 17 EQ 3 18 and EQ 3 19 can then be written as d usg Rsisg Lsgpsa Op Lgisg t Py EQ 3 30 As demonstrated from the PMSM equations the maximum efficiency of the ideal PMSM is obtained when maintaining the current flux producing component i j at zero Therefore in the drive from Figure 3 6 the Field Weakening Controller sets i 0 in the normal operating range The speed regulator controls the current torque producing component i 4 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 17 Preliminary Target Motor Theory A real 3 phase power inverter has voltage and current rating limitations 1 The absolute value of stator voltage u is physically limited according to DCBus voltage to a limit of u_sdq
49. g is in the middle of the PWM period where all bottom transistors are switched on To set the exact moment of sampling the 56F8300 family offers the ability to synchronize ADC and PWM modules via the SYNC signal This exceptional hardware feature patented by Freescale is used for current sensing The PWM outputs a synchronization pulse which is connected as an input to the synchronization module TC3 Quad Timer C counter timer 3 A high true pulse occurs for each reload of the PWM regardless of the state of the LDOK bit The intended purpose of TC3 is to provide a user selectable delay between the PWM SYNC signal and the updating of the ADC values A conversion process can be initiated by the SYNC input which is an output of TC3 The time diagram of the automatic synchronization between PWM and ADC is shown in Figure 4 9 3 Phase PMSM Motor Vector Control Rev 3 28 Freescale Semiconductor Preliminary PWM COUNTER PWM SYNC PWM GENERATOR OUTPUTS 0 1 PWM PINS 0 1 POWER STAGE VOLTAGE TC3 COUNTER TC3 OUTPUT ADC CONVERSION ADC ISR Figure 4 9 Time Diagram of PWM and ADC Synchronization System Blocks Concept Dead Time 2 Dead Time 2 Ay Dead Time T Dead Time PESEE Sar are E a t2 SD However all three currents c
50. he Overvoltage and Overcurrent faults are set in the PWMA Fault interrupt 6 3 State Diagram The software can be split into the processes shown in Section 6 2 These processes are described in the following sections Hybrid Controller Initialization Application Control State Diagram PMSM Control State Diagram Fault Control State Diagram Analog Sensing State Diagram All processes start with the Hybrid Controller Initialization state after Reset 6 3 1 Hybrid Controller Initialization The hybrid controller Initialization state Initializes PWM Application control PM Synchronous Motor PMSM Control Analog sensing Brake control Fault control LED indication Button control Sets manual application operating mode Enables masked interrupts Sets Application Control Initialization Triggers which sets all affected processes to the Begin Application Initialization state 6 3 2 Application Control State Diagram The Application Control process is detailed in Figure 6 9 3 Phase PMSM Motor Vector Control Rev 3 46 Freescale Semiconductor Preliminary State Diagram Reset Hybrid Controller Initialization done Application Control Init Initializations proceeding appState APP_INIT Init Fault Control pcb identification set appOpMode switchState Stop amp Fault Control faults cleared appPcmCtrlStatus switchState Stop amp RequestC
51. he symmetrical 3 phase smooth air gap machine with sinusoidally distributed windings The voltage equations of stator in the instantaneous form can then be expressed as d ig Rsisa t FM sa EQ 3 6 Rj 44 usg Rsisg t Ji TY sg EQ 3 7 Risc t 4 EQ 3 8 Usc Astsc ag sc Q 3 Where Us4 Uspandusc The instantaneous values of stator voltages in phase SA SB and SC ig4 isp and isc The instantaneous values of stator currents in phase SA SB and SC Ws4 Ysg Ysc The instantaneous values of stator flux linkages in phase SA SB and SC Due to the large number of equations in the instantaneous form including EQ 3 6 EQ 3 7 and EQ 3 8 it is more practical to rewrite the instantaneous equations using the two axis theory Clarke transformation The PM synchronous motor can be expressed as _ d usa Rsisa A sa EQ 3 9 Roicg gd y Ysa Lsisa Yycos EQ 3 11 Fsg Lsisg Pysin O EQ 3 12 do a F 5P CY soisg Y 56 so Tr EQ 3 13 Where a The stator orthogonal coordinate system Usa g The stator voltage Isab The stator current Y oa B The stator magnetic flux Fy The rotor magnetic flux R S The stator phase resistance 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 9 Preliminary Target Motor Theory Ls The stator phase inductance The electrical rotor speed fields speed p The number of poles per phase J The inertia Tr The load torque
52. ion motor where the air gap magnetic field is produced by a permanent magnet so the rotor magnetic field is constant PM synchronous motors offer a number of advantages in designing modern motion control systems The use of a permanent magnet to generate substantial air gap magnetic flux makes it possible to design highly efficient PM motors 3 Phase PMSM Motor Vector Control Rev 3 6 Freescale Semiconductor Preliminary Mathematical Description of PM Synchronous Motor 3 2 Mathematical Description of PM Synchronous Motor The model used for vector control design can be understood by using space vector theory The 3 phase motor quantities such as voltages currents magnetic flux etc are expressed in terms of complex space vectors Such a model is valid for any instantaneous variation of voltage and current and adequately describes the performance of the machine under both steady state and transient operation The complex space vectors can be described using only two orthogonal axes The motor can be considered a 2 phase machine Using a 2 phase motor model reduces the number of equations and simplifies the control design 3 2 1 Space Vector Definition Assume isa isp isc are the instantaneous balanced three phase stator currents ing t ign t igg 0 EQ 3 1 S It is then possible to define the stator current space vector as follows i K i aig isc EQ 3 2 Where a and a The spatial operators E 20 3 of 403
53. iplexer to select two of eight inputs Ability to sequentially scan and store up to eight measurements Ability to simultaneously sample and hold two inputs Optional interrupts at end of scan if an out of range limit is exceeded or at zero crossing Optional sample correction by subtracting a preprogrammed offset value Signed or unsigned result Single ended or differential inputs The application utilizes the ADC block in simultaneous mode and sequential scan It is synchronized with PWM pulses This configuration allows the simultaneous conversion within the required time of required analog values all phase currents voltage and temperature The Quad Timer is an extremely flexible module providing all required services relating to time events and offers the following features Each timer module consists of four 16 bit counters timers Counts up down Counters are cascadable Programmable count modulo Maximum count rate equals peripheral clock 2 when counting external events Maximum count rate equals peripheral clock when using internal clocks Counts once or repeatedly Counters are preloadable Counters can share available input pins Each counter has a separate prescaler Each counter has capture and compare capability The PMSM vector control application utilizes four channels of the Quad Timer module for position and speed sensing A fifth channel of the Quad Timer module is set to generate a time base for speed sensing and a sp
54. iption of individual function blocks and a bill of materials The individual boards can be ordered from Freescale as standard products 6 Software Design This section explains the software design for targeting a 5 6F83xxEVM and describes the design of the drive s software blocks The software description comprises these topics e Main software flow chart e Data flow e State diagram For more information on the system blocks used refer to Section 4 3 6 1 Main Software Flow Chart The main software flow chart incorporates the Main routine entered from Reset see Figure 6 1 and Interrupt states see Figure 6 2 and Figure 6 3 The Main routine includes the initialization of the hybrid controller and the main loop The software consist of processes The Application Control process is the highest software level and precedes settings for other software levels Inputs for this level are the RUN STOP switch UP DOWN buttons for manual control and PC master software via the registers shown in Section 6 2 This process is handled by Application Control Processing called from Main see Figure 6 1 The PM Synchronous Motor PMSM Control process provides most of the motor control functionality It is split into Current Processing which is called from ADC Complete Interrupt see Figure 6 2 once per two PWM reloads with a period 125us It can also be set to each PWM reload 62 5us but the PC master software recorder pc
55. llers using the 56F83xxEVM Freescale s 3 Phase AC BLDC high voltage power stage and the BLDC high voltage motor with a Quadrature Encoder and integrated brake All components are an integral part of Freescale s embedded motion control development tools Application hardware set up is shown in Figure 5 1 The system hardware set up for a particular hybrid controller varies only by the EVM used The application level of the software is identical for all hybrid controllers The EVM and chip differences are handled by the off chip software drivers for the particular hybrid controller EVM Detailed application hardware set up can be found in the Targeting Freescale 56F83xx Platform manual for the specific device being implemented 3 Phase PMSM Motor Vector Control Rev 3 32 Freescale Semiconductor Preliminary 100 240VAC 49 61Hz 3 phase N AC BLDC High Voltage Power Stage Motor Brake 40w flat ribbon cable Hardware Set Up 56F83xxEVM ECINLHIVACBLDC ECMTRHIVBLDC Optoisolation Box Figure 5 1 High Voltage Hardware System Configuration All system parts are supplied and documented in these references e Ul Controller Board for 56F83xx Supplied as 56F83xxEVM Described in the 56F83xx Evaluation Module Hardware User s Manual for the specific device being implemented e U2 Legacy Motor Daughter Card LMDC Supplies limited please contact your Freescale represent
56. ly controlled by the current i only 3 3 Digital Control of PM Synchronous Motor In adjustable speed applications the PM synchronous motors are powered by inverters The inverter converts DC power to AC power at the required frequency and amplitude A typical 3 phase inverter is illustrated in Figure 3 4 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 11 Preliminary Target Motor Theory Phase_A Phase_B Phase_C Figure 3 4 3 Phase Inverter The inverter consists of three half bridge units where the upper and lower switches are controlled complimentarily meaning when the upper one is turned on the lower one must be turned off and vice versa Because the power device s turn off time is longer than its turn on time some dead time must be inserted between turning off one transistor of the half bridge and turning on its complementary device The output voltage is mostly created by a Pulse Width Modulation PWM technique where an isosceles triangle carrier wave is compared with a fundamental frequency sine modulating wave and the natural points of intersection determine the switching points of the power devices of a half bridge inverter This technique is shown in Figure 3 5 The 3 phase voltage waves are shifted 120 to one another and thus a 3 phase motor can be supplied Generated PWM Carrier Sine Wave Wave W e a U E E Pe i feee Aa D E e CH E A ot ot
57. masterdrvRecorder must be removed from the code Speed Processing which is called from the Quadrature Timer DO Interrupt see Figure 6 3 with the period PER_TMR_POS_SPEED_US 900us The advantage of splitting the current and the speed control processes is that current control can be executed with a high priority and frequency of calls while the execution of the speed control is not that highly prioritized The Analog Sensing process handles sensing filtering and correction of analog variables phase currents temperature DCBus voltage It is provided by Analog Sensing Processing see Figure 6 2 3 Phase PMSM Motor Vector Control Rev 3 34 Freescale Semiconductor Preliminary Main Software Flow Chart and Analog Sensing ADC Phase Set split from Analog Sensing Processing because it sets ADC according to the svmSector variable calculated after PMSM Control Current Processing Position and Speed Measurement processes are provided by hardware Timer modules and the functions giving the actual speed and position see Section 4 3 1 LED Indication processing is called from Quadrature Timer DO Interrupt which provides the time base for the LEDs flashing The Fault Control process is split into Background see Figure 6 1 which checks the Overheating Undervoltage and Position Sensing Faults PWM Fault ISR see Figure 6 2 takes care of Overvoltage and Overcurrent Faults which cause a PWM B Fault interrupt The
58. nd Speed Measurement Process The Position and Speed Measurement process gives e Mechanical angular speed omega_actual_mech e Electrical position theta_actual_el 6 2 5 PM Synchronous Motor PMSM Control Process The PMSM Control process provides most of the motor control functionality Figure 6 6 shows the data flow inside the PMSM Control process including essential subprocesses e Sine e Cosine Transformations e Current Control e Speed e Alignment Control e Field Weakening 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 41 Preliminary Software Design The Sine and Cosine Transformations generate sinCos_theta_el with the components sine cosine according to electrical position theta_actual_el It is provided in a look up table omega_required_mech Speed Ramp Control reloadSWtmrAlignment reloadSWtmrSpeedControl omega_actual_mech omega_desired_mech i_Sd_Alignment I_SDQ_MAX SVM_INV_INDEX _ _ _ u_Reserve_FW ry a a FA PIRegParams_omega_mech theta_align_el_C 2 Speed Align ee OSE a Control Field Weakening theta_actual_el u_SDQ i_SDQ_desired i_SDQ_desired q_axis d_axis Sin Cos Transformation pmsmCtrlStatus u_dc_bus_filt sinCos_theta_el a coefBEMF coefBEMFShift Current u_S_max_FWLimit Control eS i_Sabc_comp svmSector SVM_INV_INDEX SDQ_MAX_F16 pwmABC u_OverMax Figure 6 6 Dat
59. nguage macro 7 1 1 Voltage Scaling Voltage scaling results from the sensing circuits of the hardware used for details see the 3 Phase AC BLDC High Voltage Power Stage User s Manual 3 Phase PMSM Motor Vector Control Rev 3 52 Freescale Semiconductor Preliminary Scaling of Quantities Voltage quantities are scaled to the maximum measurable voltage which is dependent on the hardware The relationship between real and fractional representations of voltage quantities is u ee ee EQ 7 6 Prac VOLT_RANGE_MAX l Where U Frac Fractional representation of voltage quantities UReal Real voltage quantities in physical units V VOLT_RANGE_MAX Defined voltage range maximum used for scaling in physical units V In the application the VOLT_RANGE_MAX value is the maximum measurable DCBus voltage VOLT_RANGE_MAX 407V All application voltage variables u_dc_bus u_dc_bus_filt u_SAlphaBeta u_SDQ u_SAlphaBeta and so on are scaled in the same way 7 1 2 Current Scaling Current scaling also results from the sensing circuits of the hardware used for details see the 3 Phase AC BLDC High Voltage Power Stage User s Manual The relationship between real and fractional representation of current quantities is zt I Real lirga ea ee EQ 7 7 CURR_RANGE_MAX Where Frac Fractional representation of current quantities Real Real current quantities in physical units A CURR_RANGE_MAX Defined current
60. ntil the index pulse arrives As shown in Figure 4 5 the rotor position must be aligned with the d axis of the d q coordinate system before a motor begins running The alignment algorithm is shown in Figure 4 6 First the position is set to zero independent of the actual rotor position The value of the Quadrature Encoder does not affect this setting Then the J current is set to alignment current The rotor is now aligned to the required position After rotor stabilization the encoder is reset to the zero position then the 74 current is set back to zero and alignment is finished The alignment is executed only once during the first transition from the Stop to the Run state of the RUN STOP switch 3 Phase PMSM Motor Vector Control Rev 3 26 Freescale Semiconductor Preliminary System Blocks Concept Unknown Rotor Position not aligned Zero Rotor Position aligned riea 9 1 d oO Figure 4 5 Rotor Alignment Alignment as Reset encoder Set fixed position 0 position lq 0 lq4 0 la lAlignment l4 0 Wait for rotor Set position from stabilization encoder Figure 4 6 Rotor Alignment Flow Chart 4 3 2 Current Sensing Phase currents are measured by a shunt resistor in each phase A voltage drop on the shunt resistor is amplified by an operational amplifier and shifted up by 1 65V The resulting voltage is converted by an A D converter
61. o the UP DOWN push buttons or PC master software commands The required speed proceeds through an acceleration deceleration ramp and a reference command is put to the speed controller The actual speed is calculated from the pulses of the Quadrature Encoder The comparison between the required speed command and the actual measured speed generates a speed error Based on the error the speed controller generates a current s_qgReq which corresponds to torque A second part of stator current s_dReq which corresponds to flux is given by the Field Weakening Controller Simultaneously the stator currents s_a Is_b and Is_c are measured and transformed from instantaneous values into the stationary reference frame a B and consecutively into the rotary reference frame d q Park Clarke transformation Based on the errors between required and actual currents in the rotary reference frame the current controllers generate output voltages Us_g and Us_d in the rotary reference frame d q The voltages Us_g and Us_d are transformed back into the stationary reference frame a B and after DCBus ripple elimination are recalculated to the 3 phase voltage system which is applied to the motor 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 21 Preliminary System Concept In addition to the main control loop the DCBus voltage DCBus current and power stage temperature are measured during the control process They are used to prot
62. or Power stage board identification Fault protection against Overvoltage Undervoltage Overcurrent Overheating 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor Preliminary 19 System Concept The PM synchronous drive introduced here is designed to power a high voltage PM synchronous motor with a Quadrature Encoder Specifications are detailed in Table 4 1 Table 4 1 High Voltage Hardware Set Specifications Motor Characteristics Motor Type Six poles 3 phase star connected BLDC motor Speed Range 2500rpm at 310V DCBus Maximum Electrical Power 150W Phase Voltage 3 220V Phase Current 0 55A Drive Characteristics Speed Range lt 3000rpm Input Voltage 310V DC Maximum DCBus Voltage 380V Control Algorithm Speed Closed Loop Control Optoisolation Required 4 2 Vector Control Drive Concept A standard system concept is used with this drive see Figure 4 1 The system incorporates the following hardware parts e Three phase PMSM high voltage development platform e Feedback sensors for Position Quadrature Encoder DCBus voltage Phase currents DCBus overcurrent detection Temperature e Evaluation Modules 56F80xEVM 56800 Core 56F83xxEVM 56800E Core The drive can be controlled in two operating modes In the Manual operating mode the required speed is set by the RUN STOP switch and the UP DOWN
63. push buttons e Inthe PC master software operating mode the required speed and RUN STOP switch are set by the PC 3 Phase PMSM Motor Vector Control Rev 3 20 Freescale Semiconductor Preliminary Vector Control Drive Concept 3 phase BLDC Power Stage Line AC oe UP DOWN START Software STOP ayy TL semper Quadrature Encoder Isa lsb Isc AA SCI SCI Driver 7 GPIO Driver z j 5 SEID PWM Driver Sk PWM Driver ADAD l Application Fault Protection Control Buty ou Duty Cycle C Omega_Req Waveform Modulation Chaney Ray ee ees Position Current q s 5 inte OOR 3 mame Pl Contro Speed Controller 25 Sensing g P Inverse Park amp Us_q 50 T i S ae ransformation De Usd 9 s 23 _ gt a 3 BGO Current d x 8 Ox Lp PI 8 a Lgo Controller a z0 x S Is_q Is_beta Is_a_comp VVVVY Forward Park Forward Clark Is_b_comp Current ld Transformation s_alpha Transformation Sensing Us_q Us_d 5 alpha beta gt d qa b c gt alpha beta lt Is c comp Processing Omega_actual_mech 56F80x 56F8300 plus LMDC Figure 4 1 Drive Concept The control process follows When the Start command is accepted using the RUN STOP Switch or PC master software command the required speed is calculated according t
64. r Figure 6 8 Field Weakening Controller 6 2 6 Brake Control Process The Brake Control process maintains DCBus voltage level via the IO_BRAKE driver which controls the brake switch The voltage comparison levels are e u_dc_bus_on_brake which is initialized according to mains voltage with either U_DCB_ON_BRAKE_MAINS230_F16 U_DCB_ON_BRAKE_MAINS115_F16 e u_dc_bus_off_brake initialized with either U_DCB_OFF_BRAKE_MAINS230_F16 U_DCB_OFF_BRAKE_MAINS115_F16 6 2 7 PWM Generation Process The PWM Generation process controls the generation of PWM signals driving the 3 phase inverter The input is pwmABC with three PWM components scaled to the range lt 0 1 gt of type Fracl6 The scaling according to PWM module setting and the PWM module control on the hybrid controller is provided by the PWM driver 6 2 8 Fault Control Process The Fault Control process checks these faults e Overheating e Undervoltage e Overvoltage e Overcurrent e Position Sensing 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 45 Preliminary Software Design Overheating and Undervoltage are checked by the comparisons temperature_filt lt TEMPERATURE_MAX_F16 u_dc_bus_filt lt u_dc_bus_min_fault_C where u_dc_bus_min_fault_C is initialized with U_DCB_MIN_FAULT_MAINS230_F 16 or ULDCB_MIN_FAULT_MAINS115_F 16 The Position Sensing fault is checked with the Check Index Position process T
65. r appFaultStatus pcb identification Fault Control No Fault searching faults Fault Undervoltage filtered Overheating filtered Overcurrent fault pin Overvoltage fault pin Position Sensing fault Fault Control Begin Fault Application Control Begin Fault setting of appFaultStatus PWMEN bit 0 Fault Control Fault clear test faults Figure 6 11 State Diagram Fault Control 3 Phase PMSM Motor Vector Control Rev 3 50 Freescale Semiconductor Preliminary Scaling of Quantities 6 3 5 Analog Sensing State Diagram The state diagram of the Analog Sensing subprocess is shown in Figure 6 12 The Hybrid Controller Initialization state initializes hardware modules such as ADC synchronization with PWM etc In Begin Init Initialization is started so the variables for initialization sum and the InitDoneFlag are cleared In the Init Proceed state the temperature DCBus voltage and phase current samples are sensed and summed After required analog sensing Init samples are sensed and the Jnit Finished state is entered The samples average is calculated from the sum divided by the number of analog sensing Init samples According to the phase currents average value the phase current offsets are initialized All variable sensing is initialized and the state Init Done is entered so the variables from analog sensing are valid for other processes In this state temperature and DCBus voltage are filtered in
66. range maximum used for scaling in physical units A In the application the CURR_RANGE_MAX value is the maximum measurable current CURR_RANGE_MAX 5 86A All application current variables components of i_Sabc_comp i_SAlphaBeta i_SDQ i_SDQO_desired i_Sd_Alignment and so forth are scaled in the same way Notes As shown in 3 Phase AC BLDC High Voltage Power Stage User s Manual the current sensing circuit provides measurement of the current in the range from CURR_MIN 2 93A to CURR_MAX 2 93A giving the voltage for the ADC input ranges from 0 to 3 3V with 1 65V offset The 56F80x s ADC converter is able to automatically cancel subtract the offset The fractional representation of the measured current is then in the range lt 0 5 0 5 while the possible 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 53 Preliminary Implementation Notes representation of a fractional value is lt 1 1 as shown in EQ 7 3 Therefore CURR_RANGE_MAX is calculated according to the following equation CURR_RANGE_MAX CURR_MAX CURR_MIN 2 CURR_MAX EQ 7 8 7 1 3 Speed Scaling Speed quantities are scaled to the defined speed range maximum which should be set lower than all speed variables in the application so it was set higher than the maximum mechanical speed of the drive The relationship between real and fractional representation of speed quantities is O Rea EQ 7 9 Frac QMEGA_RANGE_MAX l where
67. re 6 5 Data Flow Part 2 The data flows consist of the processes described in the following sections 6 2 1 Application Control Process The Application Control process is the highest software level which precedes settings for other software levels The process state is determined by the variable appState The application can be controlled either e Manually e From PC master software The Manual or PC master application operating mode is determined by the setting of appOpMode For Manual control the input of this process is the RUN STOP switch and UP DOWN buttons 3 Phase PMSM Motor Vector Control Rev 3 40 Freescale Semiconductor Preliminary Data Flow The PC master software communicates via omega_regPCM_mech which is the required angular speed from PC master software e appPcmCtrlStatus which consists of the flags StartStopCtrl for START STOP e RequestCtrl for changing the application s operating mode appOpMode to Manual or PC control e appFaultStatus which indicates faults The other processes are controlled by setting pmsmCtrlStatus omega_required_mech e appPcmCtrlStatus e brakeCtrlStatus faultCtrlStatus 6 2 2 LED Indication Process This process controls the LEDs flashing according to appState 6 2 3 Analog Sensing Process The Analog Sensing process handles Sensing e Filtering e Correction of analog variables Phase currents Temperature DCBus voltage 6 2 4 Position a
68. rmation MC_ClarkePark bean cptrfmParkInv Inverse Park transformation MC_ClarkePark bean mcElimDcBusRip DC bus ripple elimination MC_SpaceVectorMod bean mcPwmict 3 phase sinewave modulation MC_SpaceVectorMod bean rampGetValue ramp generation MC_Ramp library controllerPItype1_asmSc PI controller MC_Controller bean 8 2 Beans Initialization Each peripheral on the hybrid controller or on the EVM board is accessible through a bean This section describes the bean initialization of all peripherals used For a more detailed description of drivers see the Targeting Freescale MC56F83xx Platform manual To use a bean follow these steps e Add the required bean Right click Beans under the Processor Expert tab in the project window and select Add Beans When PE s Bean Selector window opens select the desired bean Configure the added bean Call the bean s init function or use PE initialization by selecting Call init in the CPU init code Access to individual driver functions is provided from PESL support by the ioctl or PESL function call To enable access to these functions PESL support should be enabled in the CPU bean used 8 3 Interrupts When configuring a bean in PE the user defines the callback functions called during interrupts 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 57 Preliminary Processor Expert PE Implementation 8 4 PC Master Software PC master software was
69. s Real Value Fractional Value R al Ouantity Rance Max EQ 7 2 Where Fractional Value The fractional representation of the real value Frac16 Real Value The real value of the quantity V A RPM etc Real Quantity The maximum of the quantity range defined in the application V A RPM etc Range Max The C language standard does not have any fractional variable type defined Therefore fractional operations are provided by CodeWarrior intrinsics functions e g mult_r As a substitution for the fractional type variables the application uses types Fracl6 and Frac32 These are in fact defined as integer 16 bit signed variables and integer 32 bit signed variables The difference between Frac16 and pure integer variables is that Frac16 and Frac32 declared variables should only be used with fractional operations intrinsics functions A recalculation from real to a fractional form and Frac16 Frac32 value is made with the following equations Real Value Fracl6 Value 32768 ____ ___ 7 sa men Real Quantity Range Max POTA for Fracl16 16 bit signed value and 31 Real Value Frac32 Value X ____ ____ EQ 7 4 oe aoe Real Quantity Range Max Q for Frac32 32 bit signed value Real Value Fractional Value ee eg ee Vices Real Quantity Range Max PUTA Fractional form a conversion from Fraction Value to Fracl6 and Frac32 Value can be provided by the C la
70. tialization clear AlignInitDoneFlag Application Control Begin Running done pmsmCtrlStatus AligninitDoneFlag No PMSM Control Stop or Fault PMSM Control Begin Alignment set Alignment current set Alignment timeout set AlignFlag PMSM Control Begin Stop or Fault clear RunFlag clear AlignFlag Begin Running AligninitDoneFlag 1 done PMSM Control Alignment timeout search Current ramp Application Control Begin Stop Fault PMSM Control Begin Run set RunFlag PMSM Control Alignment Timeout Run PMSM Control End Alignment Set Zero Position set AligninitDoneFlag clear AlignFlag Figure 6 10 State Diagram PMSM Control When Application Control initializes the PMSM Control subprocess initialization state is entered The AlignInitDoneFlag is cleared which means that alignment can proceed e The next PMSM Control state is Begin Stop or Fault e RunFlag and AlignFlag are cleared and the Stop or Fault state is entered e When Application Control equals Begin Run the PMSM Control subprocess enters the Begin Alignment or Begin Run state depending on whether or not the alignment initialization has already proceeded flagged by AlignInitDoneFlag The alignment state is necessary for setting the zero position of position sensing see Section 4 3 1 3 In the state Begin Alignment The Alignment current and
71. tion Buyer shall indemnify and hold Freescale Semiconductor and its officers employees subsidiaries affiliates and distributors harmless against all claims costs damages and expenses and reasonable attorney fees arising out of directly or indirectly any claim of personal injury or death associated with such unintended or unauthorized use even if such claim alleges that Freescale Semiconductor was negligent regarding the design or manufacture of the part P C4 2 freescale semiconductor Freescale and the Freescale logo are trademarks of Freescale Semiconductor Inc All other product or service names are the property of their respective owners This product incorporates SuperFlash technology licensed from SST Freescale Semiconductor Inc 2005 All rights reserved AN1931 Rev 3 1 2005
72. topCtrl depending on the application s operating mode 3 Phase PMSM Motor Vector Control Rev 3 Freescale Semiconductor 47 Preliminary Software Design In the Stop state appState APP_STOP e The PWM is disabled so no voltage is applied on motor phases When switchState Run the Begin Run state is processed If there is a request to change application operating mode appPcmCtrlStatus RequestCtrl 1 the application Jnit is entered and the application operating mode request can only be accepted in the nit or Stop state by transition to the Jnit state In the Begin Run state all the processes provide settings to the Run state In the Run state e The PWM is enabled so voltage is applied on motor phases e The motor is running according to the state of all subprocesses If switchState Stop the Stop state is entered If a fault is detected the Begin Fault state is entered which is a subprocess of Fault control e It sets appState APP_FAULT e The PWM is disabled The subprocess PMSM Control is set to Stop The Fault state can only move onto the Init state when switchState Stop and the Fault Control subprocess has successfully cleared all faults 6 3 3 PMSM Control State Diagram A state diagram of the PMSM Control process is illustrated in Figure 6 10 3 Phase PMSM Motor Vector Control Rev 3 48 Freescale Semiconductor Preliminary State Diagram Application Control Init PMSM Control Ini
73. trl 1 initializations finished Application Control Fault Fault Control Begin Fault switchState Run done Application Control Stop appState APP_STOP Application Control Fault Begin clear pmsmCtrlStatus RunFlag clear pmsmCtrlStatus AlignFlag set appState APP_FAULT Application Control Begin Run set appState APP_RUN Application Control Begin Stop set appState APP_STOP Application Control Run appState APP_RUN Fault Control Begin Fault ewiChoite Step Figure 6 9 State Diagram Application Control After reset the Hybrid Controller Initialization state is entered The peripherals and variables are initialized in this state and the application operating mode appOpMode is set to Manual Control When the state is finished the Application Control Init state follows As shown in Figure 6 9 appState APP_INIT e All subprocesses requiring initialization are proceeding e PCB identification is provided e The PWM is disabled so no voltage is applied on motor phases If the appPcmCtrlStatus RequestCtrl flag is set from PC master software the application operating mode appOpMode is toggled and the application operating mode can only be changed in this state If the switchState Stop Application Control enters the Stop state The switchState is set according to the manual switch on the EVM or PC master software register AppPcmCtrlStatus StartS

3-Phase PM Synchronous Motor Vector Control Using

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