3-Phase PM Synchronous Motor Control with Quadrature Encoder
Contents
1. Motorola DSP TN ai and Features 2 Motorola DSP Advantages and Features The Motorola DSP56F80x family is well suited for digital motor control combining the DSP s Digital Signal Processor calculation capability with the MCU s Micro Controller Unit features on a single chip These DSPs offer many dedicated peripherals like a Pulse Width Modulation PWM module an Analog to Digital Converter ADC Timers communication peripherals SCI SPI CAN on board Flash and RAM Generally all family members are well suited for various motor controls A typical member of the family the DSP56F805 provides the following peripheral blocks e Two Pulse Width Modulator modules PWMA amp PWMB each with six PWM outputs three Current Sense inputs and four Fault inputs fault tolerant design with deadtime insertion supporting both center and edge aligned modes e 12 bit Analog to Digital Converters ADCs supporting two simultaneous conversions with dual 4 pin multiplexed inputs the ADC can be synchronized to the PWM modules e Two Quadrature Decoders Quad DecO amp Quad Dec1 each with four inputs or two additional Quad Timers A amp B e Two dedicated General Purpose Quad Timers totaling six pins Timer C with two pins and Timer D with four pins e A CAN 2 0 A B Module with a 2 pin port used to transmit and receive e Two Serial Communication Interfaces SCIO amp SCI1 each with two pins or four additional G2. 1 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 0 215 and the most positive long word is 7FFFFFFF or 1 0 gar The following equation shows the relationship between real and fractional representations PSE a Real Value Fractional Value eee ees eee Quantity Range EQ 6 2 18 3 Phase PMSM Control with Quadrature Encoder MOTOROLA For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 Implementation Notes where Fractional Value is a fractional representation of the real value Frac16 Real Value is the real value of the quantity V A RPM etc Real Quantity Range is the maximum range of the quantity defined in the application V A RPM etc 6 1 1 DC Bus Voltage Scaling The DC Bus voltage sense is defined by the following equation VDC_BUS MAX 32767 u_dc_bus Where u_dc_bus variable of DC Bus voltage Vpc_gyus measured DC Bus voltage Vmax max measurable DC Bus voltage Vmax 16V for the EVM Motor Board 6 1 2 PI Controller Parameters The P constant was chosen as 0 2 26214 217 and the I constant was chosen as 0 3 31457 2 20 or 0 12 31457 27 8 To get better response to error speed the I constant is changed according the actua
3. Controller This process compares the required and actual speed and calculates the duty cycle of the PWM output signals For detailed information see Section 3 1 4 Speed Control 5 1 4 3 phase Sinewave generation The process 3 phase Sinewave Generation calculates the PWM output from the actual rotor position and the required sinewave amplitude The output is written to the PWM module This process is performed within the PWM Reload interrupt 5 2 Software Implementation The general software diagram shows the Main routine entered from Reset and the interrupt states see Figure 5 2 MOTOROLA 3 Phase PMSM Control with Quadrature Encoder 15 For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 Software Design The Main routine initializes both the DSP and the application then enters into an infinite background loop This loop contains an application State Machine The following interrupt service routines are utilized e PWM Reload ISR services signals generated by the Quadrature Encoder and generates the 3 phase sinewave output e Input Capture ISR TimerA1 services period measurement for speed calculation e Timer ISR services the speed controller and LED diode blinking e Push Button Up ISR and Push Button Down ISR service the Up and Down push buttons e SCIISR services communication with the PC master soft
4. On This Product Go to www freescale com 9 2005 C9 Lo INC X O L T D le Semiconductors Inanc 2005 System Concept DSP56F80xEVM DSP56F80x PC Master Control SW Amplitude PI Controller Rotor Position START STOP Required Speed UP Figure 4 1 System Concept The control process is as follows The state of the user interface is periodically scanned while the speed of the motor is measured on each new coming edge from the Quadrature Encoder only one phase is used for speed measurement According to the state of the control signals Start Stop switch speed up down buttons the speed command is calculated The comparison between the actual speed command and the measured speed generates a speed error The speed error is brought to the speed PI controller that generates a new corrected amplitude of the sinewave output The rotor position is also periodically scanned together with sinewave generation The sinewave generation generates 3 phase sinewaves shifted by 120 electrical degrees according to actual rotor position and the required amplitude The output of sinewave generation defines directly the duty cycle of the PWM output signals for the power stage In the case of under voltage the PWM outputs are disabled and the fault state is displayed by an on board LED 4 3 Hardware Implementation 12 As already stated the applicatio
5. PM Synchronous motor is a rotating electric machine where the stator is a classic three phase stator like that of an induction motor and 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 PM Synchronous Motor Cross Section In this respect the PM Synchronous motor is equivalent to an induction motor where the air gap magnetic field is produced by a permanent magnet It means that the rotor magnetic field is constant PM Synchronous motors provide a set of advantages for designing modern motion control systems The use of a permanent magnet to generate a substantial air gap magnetic flux makes it possible to design highly efficient PM motors The PM Synchronous motor is described by the following equations dV EQ 3 1 Ug Teg Ys Es ist Wu EQ 3 2 T is Ws sin lt is Y5 is Yu sin lt is Yy EQ 3 3 where us is the space phasor of stator voltage is is the space phasor of stator current rs is the stator phase resistance 4 3 Phase PMSM Control with Quadrature Encoder MOTOROLA For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 Target Motor Theory Ys is the space phasor of stator magnetic flux Yu is the space phasor of rotor magnetic flux evoked by the permanent magnet T is the electrical t
6. Semiconductor Inc 2005 Target Motor Theory To avoid the current measurement there is one of possible solution which aligns the vector of the applied voltage to be orthogonal to the rotor position see Figure 3 6 b As can be seen the angle between the stator and rotor flux is not exactly 90 electric degrees because the voltage drop on the stator inductance is not compensated The real angle is lower than 90 electric degrees and depends on the load For low cost applications such a solution is fully sufficient For high end applications the current measurement and the stator flux need to be evaluated see 16 JOL sig JOLgI Rei Us a b Figure 3 6 PM Synchronous Motor Phasor Diagram 3 1 2 Position Sensing The rotor position is obtained from a Quadrature Encoder mounted on the rotor shaft The encoder transfers the rotational movement into signal pulses corresponding to the position The Quadrature Encoder output signals are connected to the on chip Quadrature Decoder input The signals go through a digital filter to the Quad Timer The Quad Timer is set to count in quadrature mode During alignment the Quad Timer is preset to a value which represents a shift of the rotor position by 90 electrical degrees Thus the applied voltage is aligned with Back EMF according to Figure 3 6 b 3 1 3 Position Alignment Since the Quadrature Encoder doesn t give the absolute position we need to know exactly the rotor pos
7. and installs all necessary services The default baud rate of the SCI communication is 9600Bd It is set automatically by the PC master software driver and can be changed if needed A detailed description of PC master software is provided by the dedicated User s Manual 12 The 3 phase PM Synchronous motor control application utilizes PC master software for remote control from the PC It enables the user to e Start stop control e Set the motor speed Variables read by the PC master software and displayed to the user are e Required and actual motor speed e Application operational mode e Start stop status e DC Bus voltage The PC master software Control Page is illustrated in Figure 7 1 The profiles of the required and actual speeds can be seen in the Speed Scope window 3 Phase PMSM Control with Quadrature Encoder MOTOROLA For More Information On This Product Go to www freescale com arcikveeseale Semiconductor Ines 2005 DSP Usage PHL en De re irix Ls i ame ube dav bow Lae Emra Sa a if oe Sed ed Tene 1 A lel la e Fal ee ee a Joh ee le E3 sns rrp En Aky MOTOROLA PM Synchro Motor Demo with Quadrature Decoder Anipliludn Speed Application mode aede ae aa ee eres S ppicater Made W aning EMU WHE TOF Sar Stats EWJ LHA W Ba valage LAY 4mpiruce Be Actual Speed 4 KHI Teymi Spel sa aamin simie reman semas rane ea ee Figure 7 1 PC Control Window 8 DSP Usage
8. www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 Motorola DSP Advantages and Features Features of complementary channel operation Deadtime 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 the PWM pins Write protectable registers The 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 deadtime The PWM block generates three sinewave outputs mutually shifted by 120 degrees The Quad Timer is an extremely flexible module providing all required services related to time events It has the following features Each timer module consists of four 16 bit counters timers Count up down Counters are cascadable Programmable count modulo Max count rate equals peripheral clock 2 when counting external events Max count rate equals peripheral clock when using internal clocks Count once or repeatedly Counters are preloadable Counters can share available input pins Each counter has a separate presc
9. DUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 SDK Implementation 7 4 Interrupts The SDK serves the interrupt routine calls and automatically clears interrupt flags The user defines the callback functions called during interrupts The callback functions are assigned during driver initialization open Callback function assignment is defined as one item of the initialization structure which is used as a parameter of the function open Some drivers define the callback function in the appconfig h file 7 5 PC Master Software 22 PC master software was designed to provide an application debugging diagnostic and demonstration tool for the development of algorithms and applications It runs on a PC connected to the DSP EVM via an RS232 serial cable A small program resident in the DSP communicates with the PC master software to parse commands return status information to the PC and process control information from the PC PC master software executing on a PC uses part of Microsoft Internet Explorer as the user interface PC master software is part of the Motorola Embedded SDK and may be selectively installed during SDK installation To enable PC master software operation on the DSP target board application the following lines must be added to the appconfig h file define INCLUDE_SCI SCI support define INCLUDE_PCMASTER PC master software support This automatically includes the SCI driver
10. Freescale Semiconductor Inc MOTOROLA Order by AN1917 D Motorola Order Number Rev 0 9 02 ANNE ZUUD R INC CHIVED BY F 3 Phase PM Synchronous Contents M oto r Co nt rol with 1 Introduction of Application Quadrature Encoder Using BGM Git cess esse ssccepevscaccsessusteteiees 1 DSP56F80x ee ni Design of a Motor Control Application Based 3 Target Motor Theory 4 on Motorola Software Development Kit 3 1 Digital Control of a PM Synchronous MOtor nannan 5 Paver Gres Cine 4 System Concept ee 10 4 1 System Outline ee 10 1 1 1 4 2 Application Description 11 l Introduction of Application 4 3 Hardware epee E 12 Benefit 5 Software Design 14 This Application Note describes the design of a 3 phase PM 5 1 Data Mow sissiiissssececitivde 14 Permanent Magnet Synchronous motor drive based on 5 2 Software Implementation 15 Motorola s DSP56F80x dedicated motor control device The software design takes advantage of the SDK Software 6 Implementation Notes 18 Development Kit developed by Motorola 6 1 Scaling of Quantities sevessesseseees 18 6 2 Motor Constant Calculation 19 PM Synchronous motors are very popular in a wide range of applications Compared with DC motors PM Synchronous 7 SDK Implementation 21 motors are without a commutator so they are more reliable 7 1 Drivers and Library Functi
11. PIO lines e A Serial Peripheral Interface SPI with a configurable 4 pin port or four additional GPIO lines e A Computer Operating Properly COP timer e Two dedicated external interrupt pins e Fourteen dedicated General Purpose I O GPIO pins 18 multiplexed GPIO pins e An external reset pin for hardware reset e JTAG On Chip Emulation OnCE e asoftware programmable Phase Lock Loop based frequency synthesizer for the DSP core ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 clock Table 2 1 Memory Configuration DSP56F801 DSP56F803 DSP56F805 DSP56F807 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 Aside from to the fast Analog to Digital converter and the 16 bit Quad Timers the most interesting peripheral from the PM Synchronous motor control point of view is the Pulse Width Modulation PWM module The PWM module offers a high degree of freedom in its configuration permitting efficient control of the PM Synchronous motor The PWM has the following features e Three complementary PWM signal pairs or six independent PWM signals 3 Phase PMSM Control with Quadrature Encoder MOTOROLA For More Information On This Product Go to
12. Table 8 1 shows how much memory is needed to run the 3 phase PM Synchronous drive in a speed closed loop using the Quadrature Encoder A majority of the DSP s memory is still available for other tasks Table 8 1 RAM and FLASH Memory Usage for SDK2 4 and CW5 01 Freescale Semiconductor Inc ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 l Memory Available Available Used Used in 16 bit Words DSP56F803 DSP56F807 Application Application without PC DSP56F805 master software SCI Program FLASH 32K 60K 8791 4926 Data FLASH 4k 8K 217 217 Program RAM 512 2K 101 101 Data RAM 2K 4K 903 568 MOTOROLA 3 Phase PMSM Control with Quadrature Encoder 23 For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 9 arcikveeseale Semiconductor Inc 2005 References 1 Brushless DC Motor Control using the MC68HC708MC4 John Deatherage and Jeff Hunsinger AN1702 D Motorola 2 DSP56F80x MC PWM Module in Motor Control Applications Leos Chalupa AN1927 D Motorola 3 Design of Brushless Permanent magnet Motors J R Hendershot JR and T J E Miller Magna Physics Publishing and Clarendon Press 1994 4 CodeWarrior for Motorola DSP56800 Embedded Systems CWDSP56800 Metrowerks 2001 5 DSP56F800 16 bit Digital Signal Processor Family Manual DSP56F800FM D Motorola 2001 6 DSP56F80x 16 bit Digital Signal Processor User s Manual DSP56F801 7UM D Motor
13. aler Each counter has capture and compare capability The PM Synchronous motor application utilizes one channel of the Quad Timer module counting in quadrature mode It enables sensing of the rotor position using the Quadrature Encoder The second channel of the Quad Timer module is set to generate a time base for a speed controller 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 Logic to decode quadrature signals Configurable digital filter for inputs 32 bit position counter 16 bit position difference counter Maximum count frequency equals the peripheral clock rate Position counter can be initialized by software or external events Preloadable 16 bit revolution counter Inputs can be connected to a general purpose timer to aid low speed velocity MOTOROLA 3 Phase PMSM Control with Quadrature Encoder 3 For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Ines 2005 Target Motor Theory The PM Synchronous motor application utilizes the Quadrature Decoder connected to Quad Timer module A It uses the Decoder s digital input filter to filter the Encoder s signals but does not make use of its decoding functions so the decoder s digital processing capabilities are free to be used by another application 3 Target Motor Theory The
14. ctions SPEED SETTING by BUTTONS omega_required_mech E omega_desired_mech Amplitude Software Block C Hardware Block 14 Speed Controller PI Controller SCI Communication POSITION SENSOR Quadrature Decoder gee Period Measuring MeasuredTime 7 DirectionSpinning RotorPosition Velocity a Calculation omega_actual_mech 3 Phase Sinewave Generation PWM GENERATION Figure 5 1 Main Data Flow 3 Phase PMSM Control with Quadrature Encoder For More Information On This Product Go to www freescale com Read Latest Position DC Bus Voltage A D Converter u_de_bus MOTOROLA ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 Software Design The main data flow can be divided to four parts e Speed control e Velocity calculation e 3 phase sinewave generation e DC Bus voltage measurement Speed control starts with the required speed omega_required_mech This variable is set by user buttons or remotely by the PC within allowed limits The variable omega_required_mech is copied to omega_desired_mech at a defined moment This variable is used as a shadow variable to avoid change of the required speed from the PC at any time The variable omega_desired_mech is input to the speed PI controller as a reference value MeasuredTime incorporates a time period of one phase of the Quadrature Encoder The time peri
15. cy to Repeatedly set Count Length to Past Compare set Count Direction to Up set Capture Mode RisingEdges associate Callback On Input Edge to CallbackOnNewEdge associate CallbackOnOverflow to CallbackOnOverload Sets up I O ports brake switch push buttons Brake LED switch on GPIO Push buttons on interrupts IRQO IRQ1 Initializes the Analog to Digital Converter ADC set for sequential sampling single conversion Channel 0 DC Bus voltage Initializes control algorithm speed controller control algorithm parameters Enables interrupts Starts ADC conversion 5 2 2 Interrupts The interrupt handlers have the following functions PWM Reload reads the actual rotor position calculates the 3 phase sinewave output and spin direction and updates PWM Value Registers Input Capture Interrupt Handler Timer A1 reads the time between the two subsequent IC edges one phase of the Quadrature Encoder which is used for speed calculation POSIX Timer Interrupt Handler generates the time base 1ms The routine called within this time base blinks the green LED diode reads the result of the ADC conversion calculates the speed and provides the speed controller Push Button Interrupt Handler takes care of the push button service The UpButton Interrupt Handler increments the desired speed the DownButton Interrupt Handler decrements the desired speed PC and SCI Interrupt Handlers provide SCI communicati
16. d calculation can be calculated SIN_TABLE MUTIPLIER ee x 256 16794 20 3 Phase PMSM Control with Quadrature Encoder MOTOROLA For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcifveeseale Semiconductor Inc 2005 Implementation 7 SDK Implementation The Motorola Embedded SDK is a collection of APIs libraries services rules and guidelines This software infrastructure is designed to let DSP5680x software developers create high level efficient and portable code The application code is available in the SDK This chapter describes how the PM Synchronous motor control application is written under the SDK 7 1 Drivers and Library Functions The PM Synchronous motor control application uses the following drivers e ADC driver e Timer driver e Quad Timer driver e Quadrature Decoder driver e PWM driver e LED driver e Switch driver e Button driver All drivers except the Timer driver are included in the bsp lib library The Timer driver is included in the sys lib library The PM Synchronous motor control application uses the following library functions e megen3PhWaveSinelntp 3 phase sinewave generation mcfunc lib library e controllerPItypel standard PI controller mcfunc lib library e switchcontrol switch control mcfunc lib library 7 2 Appconfig h File The purpose of the appconfig h file is to provide a mechanism for overwriting the default con
17. figuration settings which are defined in the config h file There are two appconfig h files The first appconfig h file is dedicated to External RAM ConfigExtRam directory and the second one is dedicated to FLASH memory ConfigFlash directory In the case of the PM Synchronous motor control application both files are identical The appconfig h file can be divided into two sections The first section defines which components of the SDK libraries are included in the application the second part overwrites the standard settings of the components during their initialization 7 3 Initialization of Drivers Each peripheral on the DSP chip or on the EVM board is accessible through a driver The driver initialization of each peripheral used is described in this chapter For a detailed description of drivers see the document Embedded SDK Targeting Motorola DSP5680x Platform The following steps are required to use the driver e Include driver support in the appconfig h file e Fill the configuration structure in the application code for specific drivers depends on driver type e Initialize the configuration setting in appconfig h for specific drivers depends on driver type e Call the open create function Access to individual driver functions is provided by the ioctl function call MOTOROLA 3 Phase PMSM Control with Quadrature Encoder 21 For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICON
18. ged by the PWM technique The required speed is controlled by a speed controller The speed controller is implemented as a conventional PI controller The PI controller compares the actual and required speeds The difference between the actual and required speed is input to the PI controller and based on this difference The PI controller calculates the duty cycle which corresponds to the voltage amplitude required to keep the required speed Power Stage Sinewave Amplitude 0 PWM Generator Speed Controller Sinewave Generation Oactual Rotor Position Figure 3 8 Speed Controller MOTOROLA 3 Phase PMSM Control with Quadrature Encoder 9 For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 System Concept The speed controller calculates a Proportional Integral PI algorithm according to the equations below u t Kfe Ff ecoa EQ 3 4 Ty 0 After transformation to a discrete time domain using an integral approximation by a Backward Euler method we get the following equations for the numerical PI controller calculation u k up k u k EQ 3 5 up k K e k EQ 3 6 uj k u k 1 kT e k EQ 3 7 where e t e t is the input error in time t T e k is the input error in step k w k is the desired value in step k m k is the measured value in step k u k is the controller o
19. he same power stage is used for AC induction and BLDC motors Such a power stage for 3 phase PM Synchronous motors is illustrated in Figure 3 4 The power stage utilizes six power transistors with independent switching The power transistors are switched in the complementary mode The sinewave output is generated using a PWM technique Unce Q5 PWM_Q1 gt PWM_Q3 gt PWM_Q5 gt Q6 PWM_ 2 gt PWM_Q4 gt PWM_Q6 gt a Phase A Phase B Phase _C Figure 3 4 3 Phase Power Stage 6 3 Phase PMSM Control with Quadrature Encoder MOTOROLA For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 Target Motor Theory 3 1 1 Control Technique The presented control algorithm demonstrates the principle of PM Synchronous motor control and use of the DSP56F80x peripheral It means that this algorithm can be used as starting point for more sophisticated algorithms As is well known the PM Synchronous Permanent Magnet motor is very similar to a Brushless DC motor The PM Synchronous motors differ in three respects e sinusoidal distribution of magnet flux in the air gap e sinusoidal current waveforms e sinusoidal distribution of stator conductors Using a six step control technique we get six flux vectors This technique is commonly used for BLDC motors see 14 15 In the case of sinusoidal voltage output we are able to generate
20. ition before the motor is started One possible and very easy implementable method is the rotor alignment to a predefined position The motor is powered by a selected static voltage pattern usually the zero position in the sinewave table and the rotor aligns to the predefined position The alignment is done only once during first motor start Figure 3 7 shows the position of the aligned rotor After alignment the position counter is set to 90 electric degrees from alignment position in order to preset the angle between stator and rotor flux 8 3 Phase PMSM Control with Quadrature Encoder MOTOROLA For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 Target Motor Theory VDCB 2 1 sin0 S Phase A Actual Counter Value C After Alignment Next Flux Vector According to Direction of Rotation Zero Aligned Rotor Position VDCB 2 1 sin120 z s PhaseB Phase C ga y j DR ee K VDCB 2 1 sin240 Figure 3 7 Alignment of Rotor Position 3 1 4 Speed Control The correct shift between the rotor and stator flux ensures that the PM Synchronous motor generates a torque The torque amplitude depends on the amplitude of the applied voltage It means that the motor speed is also controlled by the amplitude of the applied voltage The amplitude of the applied voltage is chan
21. l speed The I constant equals 0 3 from 50 to 200 RPM Over 200 RPM the I constant equals 0 12 The controller parameters were experimentally tuned 6 1 3 Velocity Calculation The constant OMEGA_ACTUAL_MECH_CONST is defined by the following equations position difference 1 500 rev given by each rising edge of one phase of Quadrature Encoder and two pole pairs motor max period time 0 008 s chosen according to required min speed Vmin 00 position difference max period time 15 RPM Vmax 100 V nin 1500 RPM chosen according to required max speed OMEGA_ACTUAL_MECH_CONST 32767 Vyyin Vmax 327 6 2 Motor Constant Calculation The PM Synchronous motor control application uses the constants which depend on a motor type number of pole pairs and on a Quadrature Encoder type number of pulses per revolution The depended constants are e PULSES_PER_REVOLUTION e VOLTAGE_SHIFT e SIN_TABLE_ MULTIPLIER The following paragraphs explain the constant calculations The range for all constants is unsigned integer MOTOROLA 3 Phase PMSM Control with Quadrature Encoder 19 For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 Implementation Notes 6 2 1 Constant PULSES_PER_REVOLUTION The constant PULSES_PER_REVOLUTION defines the number of pulses of the Quadrature Encoder per electrical revolution Since the Quadrature E
22. level system status PC master software Speed Scope observes actual amp desired speeds e DC Bus under voltage fault protection The introduced PM Synchronous drive is designed to power a low voltage PM Synchronous motor equipped with a Quadrature Encoder which is supplied with the EVM Motor Board The motor has the following specifications Table 4 1 Specifications of the 3 Phase BLDC Motor Motor Type 3 Phase BLDC Motor 4 Poles Motor Specification Speed Range lt 5000 RPM Line Voltage 60V Phase Current 2A Sensor 1 Type 3 Phase Hall Sensors Position Sensor Specification Quadrature Encoder a TYPE 500 Pulses Per Revolution Note The EMV Motor kit includes the 3 phase BLDC motor Since the BLDC motor has very similar behaviors as PM Synchronous motor see Section 3 1 the BLDC motor may be used for this application instead of the PM Synchronous motor 4 2 Application Description A standard system concept is chosen for the drive see Figure 4 1 The system incorporates the following hardware boards e Power Supply 12V DC 4Amps e EVM Motor Board e BLDC Motor IB23810 with Quadrature Encoder e Evaluation Board DSP56F803 DSP56F805 or DSP56F807 The DSP runs the main control algorithm According to the user interface and feedback signals it generates 3 phase PWM output signals for the AC BLDC inverter MOTOROLA 3 Phase PMSM Control with Quadrature Encoder 11 For More Information
23. may be provided in Motorola 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 Motorola does not convey any license under its patent rights nor the rights of others Motorola 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 Motorola product could create a situation where personal injury or death may occur Should Buyer purchase or use Motorola products for any such unintended or unauthorized application Buyer shall indemnify and hold Motorola 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 Motorola was negligent regarding the design or manufacture of the part Motorola and the Stylized M Logo are registered trademarks of Motorola Inc Motorola Inc is an Equal Opportunity Affirmative Action Employer MOTOROLA and the Stylized M Logo are registered in the US Patent amp Trademark Office All other pr
24. n runs on Motorola motor control DSPs using the DSP EVM Boards and a dedicated 3 phase AC BLDC platform The application can be controlled by the following Motorola motor control DSPs e DSP56F803 e DSPS6F805 e DSP56F807 The application can run on an EVM motor board 3 Phase PMSM Control with Quadrature Encoder MOTOROLA For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcihveeseale Semiconductor Inc 2005 ystem Concept The application HW setup is shown in Figure 4 2 The system hardware setup for a particular DSP varies only by the EVM board used The application software is identical for all DSPs The EVM and the chip differences are handled by the SDK off chip drivers for the particular DSP EVM board Detailed application HW setup can be found in the document Targeting_DSP5680x_Platform that is part of the SDK documentation Dedicated User s Manuals describe the individual boards in detail The User s Manual incorporates a schematic of the board a description of individual function blocks and a bill of materials for the board Individual boards can be ordered from Motorola as standard products Descriptions of all the mentioned boards and documents can be found at http Avww motorola com 40w Flat U2 Ribbon U1 Cable 12 GND Controller Board DSP5680xEVM Evaluation Motor Board 12VDC Hall Sensor Co
25. ncoder counts both rising and falling edges the value is multiplied by four The resultant value must be an integer 4 x number of pulses per mech revolution PULSES_PER_REVOLUTION 1 number of pole pairs EQ 6 3 In the case of presented application the constant is equal PULSES_PER_REVOLUTION 1 999 4 x 500 2 Note In case that the constant is not an integer it is necessary to set the constant PULSES_PER_REVOLUTION to a value which is equal to the number of pulses per mechanical revolution minus one Then the actual rotor position has to be recalculated from the mechanical to electrical revolution 6 2 2 Constant VOLTAGE SHIFT The constant VOLTAGE_SHIFT defines the shift of applied voltage by 90 el degree and is calculated as _ PULSES_PER_REVOLUTION 1 4 EQ 6 4 VOLTAGE_SHIFT Then for the presented application the constant is equal to VOLTAGE_SHIFT oun 250 6 2 3 Constant SIN_TABLE_MULTIPLIER The constant SIN_TABLE_MULTIPLIER rescales the rotor position which is defined in pulses per electrical revolution to the sinewave table which is scaled from 1 to 1 lt 1 1 Detailed information about sinewave generation can be found in the SDK documentation 11 The constant is calculated as 65535 SIN_TABLE_ MUTIPLIER X 256 PULSES PER REVOLUTION EQ 6 5 For the presente
26. nn Table Controller DSP56F803 DSP56F805 DSP56F807 Controller DSP56F803 Encoder Cable DSP56F805 DSP56F807 M1 1B23810 Figure 4 2 Low Voltage Evaluation Motor HW System Configuration All the system parts are supplied and documented according the following references e M1 1B23810 Motor supplied in kit ECMTREVAL Evaluation Motor Board Kit e U2EVM Motor Board supplied in kit with IB23810 Motor ECMTREVAL Evaluation Motor Board Kit described in Evaluation Motor Board User s Manual e Ul CONTROLLER BOARD for DSP56F803 supplied as DSP56803EVM described in DSP Evaluation Module Hardware User s Manual e or Ul CONTROLLER BOARD for DSP56F805 supplied as DSP56805EVM described in DSP Evaluation Module Hardware User s Manual e orUl CONTROLLER BOARD for DSP56F807 supplied as DSP56807EVM described in DSP Evaluation Module Hardware User s Manual MOTOROLA 3 Phase PMSM Control with Quadrature Encoder 13 For More Information On This Product Go to www freescale com Freescale Semiconductor InG 2005 Software Design l 5 Software Design This section describes the design of the software blocks of the drive The software will be described in terms of e Control Algorithm Data Flow e Software Implementation 5 1 Data Flow The control algorithm of a close loop PM Synchronous drive is described in Figure 5 1 The individual processes are described in the following se
27. od is used for speed calculation Calculated speed onega_actual_mech is input to the speed PI controller as a secondary input The PI controller output determines the amplitude of the generated sinusoidal output signals For the rotor position scanning the Timer AO set as a quadrature counter is used The Timer AO gives the actual rotor position shifted by 90 electrical degrees after initialization This rotor position RotorPosition is input to the 3 phase sinewave modulation together with required amplitude Amplitude The result of the sinewave modulation is written directly to the PWM block The rotor position scanning with sinewave modulation is performed by an interrupt routine which is called each PWM reload 16 kHz The next task which is provided by an interrupt routine is the calculation of the spin direction The result Direct ionSpinning is used for the speed calculation The variable u_dc_bus contains the actual DC Bus voltage The value is used for an under voltage detection 5 1 1 Read Latest Position The process Read Latest Position is executed with each PWM Reload interrupt 16 kHz The process reads the actual rotor position and calculates the direction of spinning 5 1 2 Period Measuring and Velocity Calculation The processes Period Measuring and Velocity Calculation read the time between the adjacent edges of one phase of the Quadrature Encoder and calculates the actual motor speed omega_actual_mech 5 1 3 Speed
28. oduct or service names are the property of their respective owners Motorola Inc 2002 How to reach us USA EUROPE Locations Not Listed Motorola Literature Distribution P O Box 5405 Denver Colorado 80217 1 303 675 2140 or 1 800 441 2447 JAPAN Motorola Japan Ltd SPS Technical Information Center 3 20 1 Minami Azabu Minato ku Tokyo 106 8573 Japan 81 3 3440 3569 ASIA PACIFIC Motorola Semiconductors H K Ltd Silicon Harbour Centre 2 Dai King Street Tai Po Industrial Estate Tai Po N T Hong Kong 852 26668334 Technical Information Center 1 800 521 6274 HOME PAGE http www motorola com semiconductors MOTOROLA AN1917 D For More Information On This Product Go to www freescale com
29. ola 2001 7 8 9 atr DSP56F803 Evaluation Module Hardware User s Manual DSP56F803EVMUM D Motorola 2001 DSP56F805 Evaluation Module Hardware User s Manual DSP56F805EVMUM D Motorola 2001 DSP56F807 Evaluation Module Hardware User s Manual DSP56F807EVMUM D Motorola 2001 10 Evaluation Motor Board User s Manual MEMCEVMBUM D Motorola 11 Embedded Software Development Kit for 56800 56800E MSW3SDKOO0AA available on Motorola SPS web page Motorola 2001 a 12 User Manual for PC master software included in the SDK documentation Motorola 2001 13 Motorola SPS web page http www motorola com 14 3 Phase BLDC Motor Control with Hall Sensors Using DSP56F80x Pavel Grasblum AN1916 D Motorola 2001 15 3 Phase BLDC Motor Control with Quadrature Encoder Using DSP56F80x Pavel Grasblum AN1915 D Motorola 2001 16 3 Phase PM synchronous Motor Vector Control using DSP56F80x Libor Prokop and Pavel Grasblum AN1931 D Motorola 2001 Motorola reserves the right to make changes without further notice to any products herein Motorola makes no warranty representation or guarantee regarding the suitability of its products for any particular purpose nor does Motorola 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 which
30. on and service routines for the PC master software These routines are fully independent of the motor control tasks MOTOROLA 3 Phase PMSM Control with Quadrature Encoder 17 For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 Implementation Notes 5 2 3 Drive State Machine The drive can be in any of the states shown in Figure 5 3 which shows the transition conditions between the drive states The user is able to recognize the current state by a blinking green LED diode In the case of the init and stop state the green LED diode blinks at a frequency of 2 Hz In the fault state the green LED diode blinks at a frequency of 8 Hz During the running state the green LED diode is continuously turned on Reset SwitchState RUN u_dc_bus gt MIN DC BUS VOLTAGE SwitchState STOP u_dc_bus lt MIN DC BUS VOLTAGE Stopped State SwitchState STOP SwitchState RUN r Running State Figure 5 3 Drive State Machine Transitions 6 Implementation Notes 6 1 Scaling of Quantities The PM Synchronous motor 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 IN 1 1 0 lt SF lt 1 0 2 EQ 6
31. ons 21 than DC motors Also in comparison to AC induction T Z A ppcontig APIE i seguri a 7 3 Initialization of Drivers 21 motors PM Synchronous motors have advantages PM TA Interrupt 0 0 0 ccceeseeeseseeeseeeeeeees 22 Synchronous motors generate the rotor magnetic flux with 7 5 PC Master Software rotor magnets so that PM Synchronous motors are highly efficient Therefore PM Synchronous motors are used in 8 DSP Usage ceceecseceeeceeree 23 high end white goods refrigerators washing machines dishwashers etc high end pumps fans and in other 9 References eee 24 appliances which require high reliability and efficiency The concept of this application is a speed closed loop PM Synchronous drive using a Quadrature Encoder It serves as an example of a PM Synchronous motor control system design using a Motorola DSP with SDK support It also illustrates the usage of dedicated motor control libraries that are included in the SDK s 25 9 62 Ow o Os o Q o QS lt O A oD This Application Note includes the basic motor theory system design concept hardware implementation and software design including the PC master software visualization tool le rj E s s YW ra 0 Motorola Inc 2002 All rights reserved MOTOROLA digital dna intelligence everywhere For More Information On This Product Go to www freescale com reescale Semiconductor Incr 2005
32. orque As can be seen from equation EQ 3 3 optimal torque is generated when the stator current vector is placed 90 relative to the rotor permanent magnet flux space vector This situation is shown in Figure 3 2 JOLsig Rsis Us Figure 3 2 Torque Optimal Control of PM Synchronous Motor where Rs is the stator resistance Ls is the stator inductance e is the Back EMF voltage Y resultant magnetic flux 3 1 Digital Control of a PM Synchronous Motor A PM Synchronous motor is driven by sinewave voltage coupled with the given rotor position The generated stator flux together with the rotor flux which is generated by a rotor magnet defines the torque and thus speed of the motor The sinevawe voltage output have to be applied to the 3 phase winding system in a way that angle between the stator flux and the rotor flux is kept close to 90 to get the maximum generated torque To meet this criterion the motor requires electronic control for proper operation MOTOROLA 3 Phase PMSM Control with Quadrature Encoder 5 For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Ines 2005 Target Motor Theory Output Voltage Phase A Phase B Phase C B60 Electrical Angle Figure 3 3 Sinewave Voltage Output Applied onto a PM Synchronous Motor For a common 3 phase PM Synchronous motor a standard 3 phase power stage is used T
33. the stator flux in any position The resultant flux is calculated as the sum of flux vectors of Phase A Phase B and Phase C see Figure 3 5 If the phase voltage changes sinusoidally over time a fluent rotational flux field is generated As a result a PM Synchronous motor runs smother and quiter than a BLDC motor VDCB 2 1 sin0 d gt Phase A a J Actual flux vector lt an Ph B Phase C p b 3 i ad W ya One p l VDCB 2 1 sin240 VDCB 2 1 sin120 Figure 3 5 Stator Flux Generation The motor runs with optimal torque generation when the angle between the stator and rotor flux is 90 electric degrees see Figure 3 6 a To ensure the angle between rotor and stator flux equals to 90 electric degrees it is necessary to know the position of the rotor and stator flux The position of the rotor flux is bound to the rotor position Thus by measuring rotor position we can get the exact position of the rotor flux The position of stator flux is bound to the vector of the stator current To know the exact position of the stator flux it requires measurement of the phase currents and the calculation of the stator current vector Since the presented application does not measure current there is no way to obtain the position of current vector MOTOROLA 3 Phase PMSM Control with Quadrature Encoder 7 For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale
34. utput in step k up k is the proportional output portion in step k uj k is the integral output portion in step k uj k 1 is the integral output portion in step k 1 Ty is the integral time constant is the sampling time K is the controller gain LT is the time p is the Laplace variable 4 System Concept 4 1 System Outline The system is designed to drive a 3 phase PM Synchronous motor The application meets the following performance specification e Voltage control of PM Synchronous motor using Quadrature Encoder e Targeted for DSP56F803EVM DSP56F805EVM DSP56F807EVM e Running on a 3 phase EVM Motor Board 10 3 Phase PMSM Control with Quadrature Encoder MOTOROLA For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 System Concept e Control technique incorporates Voltage PM Synchronous motor control with speed closed loop Both directions of rotation Motoring mode Start from any motor position without rotor alignment Minimum speed 50 RPM Maximum speed 1000 RPM limited by power supply e Manual interface Start Stop switch Up Down push button control Led indication e PC master software control interface motor start stop speed set up e PC master software monitor PC master software graphical Control Page required speed actual motor speed start stop status DC Bus voltage
35. ware Reset Initialization Main loop State Machine Figure 5 2 State Diagram General Overview 5 2 1 Initialization 16 The Main Routine provides initialization of the DSP e Disables Interrupts e Initializes DSP PLL e Disables COP and LVI e Initializes the POSIX Timer for time base reference 1 ms e Initializes the LED e Initializes the PWM module Center aligned complementary PWM mode positive polarity PWM modulus defines PWM frequency PWM deadtime defines PWM deadtime Disable faults e Initializes Quadrature Decoder Sets on chip digital filter of the Quadrature Decoder inputs Connects Quadrature Decoder signals to QuadTimerA e Initializes QuadTimerA channel AO 3 Phase PMSM Control with Quadrature Encoder MOTOROLA For More Information On This Product Go to www freescale com ARCHIVED BY FREESCALE SEMICONDUCTOR INC 2005 arcikveeseale Semiconductor Inc 2005 Software Design set Count Mode to Quadrature Count set Input Source to Input 0 set Input Polarity to Normal set Secondary Input Source to Input 1 set Count Frequency to Repeatedly set Count Length to Until Compare set Count Direction to Down disable Capture Mode Initializes QuadTimerA channel Al set Count Mode to Count set Input Source to Bus Clock 128 set Input Polarity to Normal set Secondary Input Source to Input 1 set Count Frequen
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