Battery Management System User's Manual
Contents
1. DIMENSIONS 136 E oa O ee 56 18 a Ey 165 s i 3 i 2 z 0D ta V i an a S O 7 of 29 5 4 5 5 5 6 5 7 5 TRITIUM USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 CONNECTORS OVERVIEW The following illustration shows the connections and indicators on the CMU CMU CAN Bus 10 way IDC ribbon Cell Voltage amp Temperature Sense 12 way single row MicroFit Green Status LED ISOLATION The CMU is isolated from the CMU CAN bus and therefore from the vehicle chassis and other CMUs with an isolation barrier rated for 1000V DC This allows the HV battery pack to be fully floating from the vehicle chassis as is required by most EV construction standards eg NCOP14 in Australia This isolation barrier rating is only valid if the correct insulation material is installed between the CMU and the surface it is mounted on As the CMU CAN bus operates relative to the vehicle chassis the CMU CAN ribbon cable should be kept isolated from the cells and cell sense wiring with a rating of at least the full voltage of the battery pack VOLTAGE RATING The CMU voltage sense inputs are rated for a maximum of 5V per cell Therefore there must not be any breaks in the main battery string from contactors fuses or service links among the set of up to eight cells that are measured by a CMU as a high voltage2. 25 Refer to TRI67 018 BMU Wiring Digram PDF for details of the BMU wiring HV contactor and fuse layout Refer to TRI67 006 Assembly Procedure PDF for CMU wiring harness construction guidelines and recommended part numbers Refer to TRI67 010 BMU Communications Protocol for CAN packet format and specifications REVISION RECORD REV DATE CHANGE 1 1 August 2012 Document creation JMK Website release 2 7 July 2013 Updated for new v7 BMU hardware added SOC reporting Added command line parameters for BMS_Viewer 29 of 29
3. Battery Management System TRI67 011 ver 2 7 July 2013 VEHICLE CAN BUS CAN NETWORK TOPOLOGY The CAN bus is structured as a linear network with short stubs branching from T connectors on the main bus backbone to each device The CAN bus data lines must be terminated at each end of the main bus with 120 ohm resistors between the CAN H and CAN L signals In the range of Tritium EV products including the WaveSculptor 200 EV Driver Controls and BMU the CAN connections are implemented with an in and an out connector therefore placing the T on the device resulting in a very short fixed length stub on the circuit board of each device This is ideal from a signal integrity and network performance point of view Driver Controls Battery Management WaveSculptor CAN High Termination CAN Low Resistor The BMU uses the vehicle CAN bus to receive operating and configuration commands and transmit telemetry as well as a source of low voltage DC power to operate the electronics CAN WIRING The CAN data lines CAN H and CAN L must be implemented with twisted pair wire for proper data integrity The wire should have a characteristic impedance of 120 ohms Power should also be provided along the CAN cable ideally with another twisted pair to minimise noise pickup An overall shield can also be advantageous The optimal choice of cable is 7mm Devicenet CANbus thin cable with 24AWG data 22AWG power twist
4. Use of an insulation material layer may allow a lower profile mounting This distance will be determined by the maximum operating voltage of the pack required isolation voltage rating and regulatory creepage and clearance distances All connections to the BMU are along one edge simplifying wire routing inside your battery enclosure Wiring should be appropriately strain relieved to withstand the vibration typically found in an automotive environment do not support the weight of the wiring loom solely from the connectors on the BMU DIMENSIONS The BMU PCB size and mounting holes des below Dimensions in mm e O CT j S a 200 0 0001 is lo Nera agouti of NUL LaLa lt y E 5 65 56 65 10 of 29 USER S MANUAL Battery Management System TRI67 011 ver 2 5 TRITIUM 7 July 2013 7 3 CONNECTORS OVERVIEW The following illustration shows the connections on the BMU CMU CAN Bus Relay Output 10 way IDC ribbon 6 way MiniFit Jr Contactor Outputs Vehicle CAN Bus 3x 4 way MiniFit Jr HV Sense 2x 6 way MicroFit 10 way MiniFit Jr Fan Pump Outputs Contactor 12V Input 2x 3 way KK 2 wav MiniFit Ir Refer to the relevant sections of this document for more details on the pinout and wiring for each connector 7 4 ISOLATION The HV Sense connection is isolated from the remainder of the BMU with an isolation barrier rated for 10
5. C Pack mV PackmA Balance Balance CMU Count Sys Status N8 C603293 N12 C4 3316 N7 24 9 N8 25 4 0 20 3610 3600 14 Fan Spd rpm SOC BAL Ah SOC BAL Prechg Status IDLE 0 0 00 Flags CMUPWROK 0 0 00 CMU Telemetry Serial PCB C Cell C CellOmV Celll mV Cell2mV Cell3mV Cell4mV CellSmV Cell6mV Cell7 mV cmu1 8343 26 6 25 3307 3306 3305 3308 3304 3316 3298 3311 cmu2 8322 268 25 2 3308 3308 3306 3311 3298 3312 3298 3312 cmu3 8340 26 6 25 3307 3308 3303 3308 3300 3305 3307 3303 cMU4 8341 275 25 2 3308 3308 3303 3306 3310 3307 3303 3308 cmu5 8319 263 25 2 3306 3310 3307 3302 3298 3307 3308 3302 cmu 8321 26 8 253 3304 3308 3299 3307 3305 3304 3303 3308 cmu7 8320 27 249 3306 3311 3303 3302 3313 3306 3304 3307 cmMus 8323 26 7 254 3306 3307 3305 3307 3307 3305 3293 3315 cmMu9 8324 26 4 25 2 3305 3307 3307 3305 3305 3307 3304 3303 cMu10 8339 27 2 25 3306 3309 3305 3309 3303 3304 3304 3305 CMU11 8372 258 25 2 3306 3307 3307 3300 3306 3303 3299 3314 cMmu12 8378 263 253 3307 3307 3303 3300 3316 3301 3310 3296 cmu13 8342 274 25 3307 3307 3311 3304 3306 3298 3314 3305 cmu14 8344 269 249 3308 3308 3304 3307 3304 3305 3301 3305 The top section shows data from the BMU while the lower section shows CMU data one row per CMU BMU DATA The top row of BMU data presents the following information left to right e Minimum voltage cell in the pack and its voltage The example shows Node CMU 8 Cell 6 is mini
6. a professional and competent manner to function as designed Attention should also be paid to the larger system that the vehicle is part of especially the systems associated with charging and the infrastructure to support it As well as using the BMS to protect the pack additional systems should be provided as backup as part of the charging infrastructure for instance fitting of smoke detectors overcurrent and RCD protection in the AC supply regular physical checks of charge cabling and connections regular review of telemetry data for abnormal readings This list is not exhaustive and it is the responsibility of the system designer installer to conduct their own failure mode analysis and determine what is required Working around batteries is DANGEROUS Not only are lethal high voltages present but individual cells can also put out thousands of amps when shorted for example with a stray wire or dropped tool throwing out arcs and molten metal Check the legal requirements in your jurisdiction for using licensed technicians for this type of work Wear eye protection Use insulated tools Take extreme caution Go slow Think through every step before doing it 4 TERMINOLOGY Cell A single physical unit or permanently connected parallel group of units A parallel group functions electrically as a larger capacity single unit Battery A series connected group of cells 6 of 29 5 2 5 3 5 TRITIUM USER
7. hU d O a a aa E EEE a a a a A A aiaiai k tAE Sa 13 Contactor Drive Sensei 14 Contactor 12V Supply CoOnnectol 0 cece eee eee eee eee eee ee eae eee nee ee need 14 Contactor Output CONNECTOIMS ccc ree ee eee eee eee reer eee AE aA 15 PreCharg Gi iii ee 15 CONCE PEs O E 15 AN a 15 Seguente zpide a e a a a aE i a aaa o aaa AAAA 16 Precharge Resistor SelectiON oooooonccconcccnocnconcnnonacnnnnrnnonnnnonnnnonarnnnnnnnnrnnnnnnrnnnnnnnns 16 ES AE a aaa al 17 Trusted MeasuremenNtS ccocccccoccocononoconnananronnnnanrnnnn nn rra nr rana 18 13 14 15 15 1 15 2 15 3 15 4 15 5 15 6 16 17 17 1 17 2 17 3 17 4 17 5 17 6 18 19 20 20 1 21 21 1 22 22 1 22 2 22 3 22 4 22 5 22 6 22 7 23 23 1 23 2 23 3 24 25 5 TRITIUM Contactor Selection Operating Thresholds Over Voltage Threshold Balance Threshold Balance Threshold Hysteresis Zero SOC Threshold Under Voltage Threshold Over Temperature Threshold Charger Control State of Charge SOC reporting Pack Isolation Detection Fan Pump Control Fan Pump Connectors Relay Output Relay Output Connector Vehicle CAN Bus CAN Network Topology Vehicle CAN Bus Connectors CAN Shielding CAN Termination Communications Power Supply Telemetry Viewing Software Command line Options Additional Documentation Revision Record USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 3 of 29 USER S MANUAL T
8. may be seen across this break when it is open and destroy the CMU Any breaks must be located between CMUs INDICATORS The green LED on the CMU flashes to indicate that the CMU has power via the CMU CAN bus and the microcontroller is operating The red LED illuminates when any of the eight cells are balancing This LED illuminating is not a fault condition 8 of 29 5 8 5 TRITIUM USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 CELL VOLTAGE amp TEMPERATURE SENSE CONNECTOR The connector used for the Cell Voltage Sense is a 12 way single row 3mm pitch Molex MicroFit connector The pinout is shown below as viewed from the wire side as you would look at it while inserting crimps The colours shown match those used in the recommended cable RED ORANGE YELLOW GREEN BLUE PURPLE GREY WHITE BLACK BROWN BROWN CELL CELL CELL CELL ca ll e A G i 7 E i Please refer to the associated Assembly Procedure document TRI67 006 for detailed procedures on making the cell sense wiring harness CMU CAN BUS The CMUs and BMU communicate via CAN bus at a fixed 125kbit s rate running over standard 1 27mm pitch 10 way IDC ribbon cable The BMU supplies 12V power to the CMUs along this cable As a CAN bus this cable requires termination of the CAN H and CAN L signals together at both ends of the network Use the supplied CMU CAN termination boards to d
9. parameters e Individual cell voltages Group cell temperatures CMU temperatures e Total pack voltage Total DC bus voltage e Total pack current e Isolation from chassis e 12V supply voltages and currents e Contactor status Fan Pump speeds To achieve management over the cells and pack it controls e Individual cell bypass shunt balance resistors e Pack contactors including precharging HV loads e Battery pack fan pump e Battery charger charging current setpoint Individual cell voltages are the most critical measurement taken by the system and in the Tritium BMS are measured using two separate redundant circuits each with it s own analog circuitry A D converter and reference All measurements are cross checked and any fault in the system can be identified and reported This system not only gives reliable and accurate cell voltage measurements it gives trusted measurements The Tritium BMS reports if any measurements are not trustworthy and this information can be acted on by a higher level system in the vehicle for instance by notifying the driver that the vehicle requires servicing 5 of 29 USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 5 TRITIUM 3 WARNINGS A properly designed BMS system will protect a battery pack from being operated outside of acceptable limits However a poorly implemented system may not provide the expected protection the Tritium BMS must be installed in
10. the system A professional design will use all three contactors The contactors are energised in sequence 1 3 2 during precharge and de energised when shutting down the system both under user command and due to a fault being detected by the BMS The BMU operates the contactors to protect the cells above all other priorities Each contactor output connector also has pins for feedback from contactors with auxilliary sense contacts These can be used by the BMU to detect failed contactors both failed open or welded shut Do not connect these pins to anything other than auxilliary contact output terminals they are not rated for anything more than the 12V supplied by the BMU Refer to the BMS datasheet for continuous and peak current and voltage ratings of the contactor drive outputs Contactors without integrated electronics must have a diode fitted across their coil terminals to limit flyback voltage at turn off 10 1 CONTACTOR 12V SUPPLY CONNECTOR The connector used for the Contactor 12V supply input is a 2 way 4 2mm pitch Molex MiniFit Jr connector The pinout is shown below as viewed from the wire side as you would look at it while inserting crimps GROUND This connection should be wired to the vehicle 12V DC supply via the emergency stop switch if fitted the G force impact switch an optional HV disable switch and a fuse It requires a low impedance connection to the vehicle battery since most contact
11. value for the 25mV shunt The Ah is then also calculated to a percentage based on the user set value for total pack capacity Ah are set to zero when the first cell reaches the balance threshold while charging for the first time It then counts up to indicate Ah drawn from the pack It will count back down towards zero when the pack is recharged 22 of 29 TRI67 011 ver 2 7 July 2013 USER S MANUAL 5 TRI TIUM Battery Management System A second telemetry value is also reported the Balance SOC This value begins counting when the first cell reaches the balance threshold during charging and continues to count until the last cell has reached the balance threshold This gives an accurate value for the amount of imbalance in the battery pack that was corrected during this charging session Logging this value in a higher level system controller and looking for changes over time will give an indication of potential problems with the pack 19 PACK ISOLATION DETECTION The BMU contains hardware that is capable of sensing if the HV battery pack connections both and and any point along the pack are isolated from the chassis This test is run during each startup sequence and a failed test will report as an isolation fault in the configuration software A failed pack isolation test will not prevent operation of the system but should be flagged by the user interface for the system eg dashboard display and indicate to the user to seek s
12. voltage measurements A pack isolation test is performed at this point 3 The capacitors in the devices in the vehicle precharge through the precharge resistor that is in parallel with Contactor 2 4 When the pack voltage and the DC bus voltage are within tolerance then Contactor 2 is energised to complete the high current circuit 5 The BMU is now in Run mode and does the following e reports this fact on the CAN bus e activates the status relay output which can be used to enable the DC DC converter e turns on the pack fan outputs PRECHARGE RESISTOR SELECTION Selection of the external precharge resistor is critical for correct and long term reliable operation of the precharge circuit A judgement must be made by the designer of the vehicle power system to the tradeoff between resistor size cost and weight and expected precharge time A slower time can use a smaller cheaper resistor but taking too long to precharge will be annoying to the end user of the vehicle An aluminium cased wirewound resistor is the most commonly chosen type of resistor As an example the calculations for a typical EV system are shown as follows System battery voltage maximum 450V Motor controller Tritium Wavesculptor 200 capacitance 800uF Chosen precharge current 1A Therefore the minimum resistance fastest precharge will be 450V 1A 450 Ohms Choose 470 Ohms as the next highest common value Peak power dissipation in the resist
13. 00V DC This allows the HV battery pack to be fully floating from the vehicle chassis as is required by most EV construction standards eg NCOP14 in Australia The remainder of the BMU operates relative to the GND supplied along the vehicle CAN bus connection and this must be tied to the vehicle chassis at some point in the system 7 5 INDICATORS The output status of the three contactor drives fan outputs and CMU CAN bus power are all indicated with green LEDs at the edge of the BMU adjacent to the relevant connector Other indications and faults can be observed using the Windows PC software via the CAN Ethernet bridge or by any other device on the CAN bus that is programmed to receive status messages from the BMS 11 of 29 8 8 1 USER S MANUAL 5 TR I TIUM Battery Management System TRI67 011 ver 2 7 July 2013 HV SENSE The HV Sense connector allows the BMU to measure the total pack voltage pack side of the contactors total DC bus voltage vehicle side of the contactors and total pack current flow This information is used to control precharge and pack safety and to calculate pack Ah usage and SOC The HV Sense connector and associated electronics are isolated from the remainder of the BMU Take care when routing wiring around this connector to maintain good isolation between it and the rest of the vehicle system Wire the Vehicle HV and Battery HV sense wires to their respective sides of Contactor 2 in the po
14. A 50mV shunt The value of the shunt can be set in the user interface software STATE OF CHARGE REPORTING The BMU takes readings of the shunt current using a high accuracy front end circuit and 24 bit A D converter It integrates these readings to accumulate an Ah consumption for the pack The Ah accumulation is used in conjunction with the user settable pack capacity value to calculate a SOC in percent Both Ah and percent are reported on the CAN bus The SOC reading is reset to full when the first bypass shunt has activated during a charge cycle At this point the Balance SOC telemetry value begins incrementing halting when all bypass shunts are active This Balance SOC telemetry value therefore shows the amount of imbalance between cells that has been corrected during the current charging session OVERCURRENT SHUTDOWN The BMU has the capability to shut down the pack by opening the contactors if the pack current exceeds a fixed threshold This function is not currently implemented in the default firmware but will be added at a later date 13 of 29 USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 5 TRITIUM 10 CONTACTOR DRIVE SENSE The BMU provides three outputs for driving HV contactors with 12V coils Ata minimum Contactors 1 amp 2 are required for pack safety although this option still presents a shock hazard via the precharge resistor in a single fault situation to the rest of
15. D This voltage is the target setpoint for the charging control algorithm and will be the voltage that the cells are charged to in normal operation It should be chosen to be part way up the knee in the voltage charge curve so that the cells can be easily seen to be at different SOC and therefore balanced accurately Choosing this number to be higher closer towards the Over Voltage Threshold will give a slightly increased useable capacity of the pack but will make it more likely that sudden regen braking will push a cell above the Over Voltage Threshold and shut down the system without warning Pushing the usual charge voltage to the maximum rating of the cell may also reduce cell cycle life refer to the cell datasheet for specific information on this aspect as it is highly dependant on cell chemistry and manufacturing techniques When any cell exceeds this voltage the cell balance shunt resistor for that cell is switched on and begins to discharge that cell at approximately 250mA The shunt resistor remains switched on until the cell falls below the Balance 19 of 29 15 3 15 4 15 5 15 6 16 5 TRITIUM USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 Threshold by the Balance Threshold Hysteresis value BALANCE THRESHOLD HYSTERESIS This voltage determines the hysteresis used to control the balance resistors If using CMUs made after January 2013 it should be set to around 5mV as the
16. RITIUM Battery Management System TRI67 011 ver 2 7 July 2013 1 INTRODUCTION This document describes the interface installation and usage requirements for the Tritium Battery Management System BMS The BMS provides an easy way to monitor and control an Electric Vehicle battery pack and can work seamlessly with Tritium s WaveSculptor motor controllers It is a mature design with five previous product generations of real world experience with various types of cells form factors and vehicles The BMS consists of two components multiple Cell Management Units CMU which measure and control the individual cells in the battery pack and a single BMS Master Unit BMU which interfaces between the CMUs and the vehicle controls precharge and other safety systems and provides total pack telemetry 4 of 29 USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 5 TRITIUM 2 BMS FUNCTION The function of the BMS is threefold in order of priority e Monitor cell voltages and temperatures and act on this information to protect the pack against being operated outside acceptable limits Manage the cells to keep them at equal state of charge SOC Report telemetry to the other systems in the vehicle to allow a graceful reduction in vehicle performance as the battery approaches its limits The BMS performs these functions by measuring the following
17. S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 CELL MANAGEMENT UNIT FORM FACTOR The Cell Management Unit CMU is supplied as a 1 6mm thickness Printed Circuit Board PCB conformally coated without an enclosure It is designed to be installed inside the battery box in a weather sealed area along with the cells themselves This means that all connections to the cells remain inside the battery pack enclosure simplifying fusing and wiring installation requirements INSTALLATION The CMU should be mounted to a flat surface using at least four M3 fasteners with the supplied piece of insulation material between the CMU and the surface The CMU will operate at a much lower temperature when balancing if the mounting surface is a thermally conductive material such as aluminium or steel and it is strongly recommended to install the CMUs on a surface such as this CMUs should not be stacked together as they will overheat For a professional installation press fit M3 studs eg PEM FHS M3 10 can be installed in the wall of the box prior to fitting the CMUs The insulating sheet and CMU are then installed over the studs and retained in place with Nyloc nuts Wiring should be appropriately strain relieved to withstand the vibration typically found in an automotive environment do not support the weight of the wiring loom solely from the connectors on the CMU
18. USER S MANUAL TRI67 011 ver 2 7 July 2013 Battery Management System User s Manual 7 July 2013 2013 Tritium Pty Ltd Brisbane Australia http www tritium com au 1 of 29 10 1 10 2 11 11 1 11 2 11 3 11 4 11 5 12 5 TRITIUM USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 TABLE OF CONTENTS Introduction 4 BMS FUNCION ic a a tees 5 Warning S iia reer reer Cert reer Creer TPeereeerere ere ree tr eer errr rere eT TT 6 Ter MinolO0Qy coccccnccconnnconnnnnnncnnnnrannnrnnncnnnnrnnnnrrnnannnrrnnnnnnrranannnanennanaannes 6 Cell Management UNit cccconncconncconcccnncccnnnranncrannnrnnncrnnnnnranannnnnrnnanaannnans 7 Form Facto eeiam i anana a a vind Hd bebo nduabeadi tela warned davesd Meta ae a ds 7 DS easels E HAE ae ee oe a e acted ees 7 DIMENSIONS 2 355055 A ehchiaee ieee Sn anda das 7 CONNE COS A e de 8 SO a a td Daeg aah 8 Voltage RAIN A A is 8 INAICA LO Said A A O e A 8 Cell Voltage Temperature sense CONNECtOTF ooccccnccccnncccnncnnnnancnccnnnnnncnnnnnnnnnannnns 9 CMU CAN BUS ici wa sateen a a a aa aaa haee Eaa E 9 BMS Master Unit rinsa aa aa aa a evn a aaa A E 10 Form FaCtOk acti in it a A ES ide a 10 DIMENSION Sit A A a Dare EEN 10 Connectors DIV di 11 A E 11 Ad Sd E 11 HV SeNSe arranca A a 12 HV SENSE CONO tios 12 HVSeNse EEE E A E A E ET 13 Pack Current Sensei ds 13 SHUNT Select oa e 13 State Of Charge reporting trn siea naa E eae a AE i Ea oti Ea 13 OVErcUrrent S
19. cause components to fail Precharging the capacitors in the various devices solves these problems This can be done by first connecting the loads to the battery through a resistor so that the current into the capacitors is limited to a few amps The voltage on the capacitors will then rise in a controlled manner and when it is close to the battery voltage the main contactor can be closed to directly connect everything together ACTION The BMU initiates a precharge sequence when commanded to do so from the EV Driver Controls There are two conditions that begin precharge the ignition key moving to the start position from the run position and the fuel door being opened for charging Either closing the fuel door or moving the key to no longer be in Ignition run position will shut down the system and open the contactors to make the system safe 15 of 29 11 3 11 4 5 TRITIUM USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 The BMU can also be set to run in Standalone Operation mode where it will precharge as soon as it measures an acceptable voltage on the 12V contactor power input This mode would normally be used in remote area power installations and similar applications not in vehicles SEQUENCE The precharge sequence is as follows 1 Contactor 1 energises to connect Pack to the vehicle 2 Contactor 3 energises to connect Pack to the precharge resistor and allow the BMU to take pack
20. e required 120 Ohm termination resistor at each end of the CAN bus plug a connector into the unused CAN connector on the last device at each end of the network with a resistor crimped into the appropriate locations COMMUNICATIONS The CAN standard does not specify high level message protocols Tritium devices use a custom protocol outlined in the communication specification document for each device By default each device operates at 500 kbits second and comes programmed from the factory with a CAN base address that will allow it to work in unison with other Tritium devices The CAN bit rate and base address can be set with the Windows BMS configuration software POWER SUPPLY The BMS electronics operate from 12V supplied on the CAN bus connector which is switched on by the Tritium EV Driver Controls when it is in accessories or run key switch positions A second high current 12V supply connection is present for contactor and fan operating power refer to the precharge section of this document for more details The CAN Ground and Contactor Supply Ground must be both tied to the vehicle chassis at some point in the system 26 of 29 23 23 1 USER S MANUAL 5 TRI TIUM Battery Management System TRI67 011 ver 2 7 July 2013 TELEMETRY VIEWING SOFTWARE The screenshot below shows the BMS Viewing software BMS Viewer E File BMU Log Setup About BMU Telemetry Min mV Max mV Min C Max
21. e vehicle After a short time to allow the inrush current from the contactor switching to subside on the 12V supply the BMS transitions to the Measure state 17 4 MEASURE Contactor 3 is also switched on to connect the Pack connection to the vehicle via the precharge resistor The vehicle will begin precharging The pack isolation test is run during this interval After a short time to allow the total pack voltage measurement to stabilise and the 12V current inrush from the contactor switching to subside the BMS transitions to the Precharge state 17 5 PRECHARGE The load will now be precharging The BMS begins a timeout error counter 2000ms by default to avoid a fault situation overheating the precharge resistor and also begins comparing the total pack voltage and DC bus voltage measurements When they match within a the precharge voltage threshold 20V by default precharge is regarded as complete and the BMS transitions to the Run state 17 6 RUN Contactor 2 is also switched on to directly connect the Pack connection to the load The relay and fan outputs are switched on If the ignition key is switched away from the run position back to accessories or the fuel door is closed then the BMS transitions to the Idle state 18 STATE OF CHARGE SOC REPORTING The BMS reports State of Charge SOC based on integrating the pack current coulomb counting The SOC is calculated in Amp Hours Ah based on the user set scale
22. ed pairs and a braided shield Using this cable will result in a robust installation with high immunity to noise low voltage drop in the power cable and reliable CAN communications Using alternative cabling will usually result in problems during operation VEHICLE CAN BUS CONNECTORS The connector used on the BMU and other Tritium devices for the CAN connection is a 6 way 3mm pitch Molex MicroFit connector The pinout is shown below as viewed from the wire side as you would look at it while inserting crimps The colours shown match those in the standard DeviceNet CAN cabling pairs 25 of 29 22 4 22 5 22 6 22 7 USER S MANUAL TRITIUM Battery Management System TRI67 011 ver 2 7 July 2013 BARE BLUE WHITE SHIELD GROUND CANH SHIELD GROUND BARE BLACK RED CAN SHIELDING If the recommended braided shield is used in the cable then terminate it to the SHIELD pin lower left corner on the connector on both CAN IN and CAN OUT connectors on each device On one device only in the network instead of using the SHIELD pin terminate the shield to the SHIELD GROUND pin upper left corner on the connector on both CAN IN and CAN OUT connectors to ground the shield for the entire network at this single point The usual place to do this is where power is fed into the network typically at Tritium s EV Driver Controls product CAN TERMINATION To implement th
23. ement System TRI67 011 ver 2 7 July 2013 HV SENSE FUSING All HV Sense connections should be fused with an appropriately rated fuse for the type of wire used for the sense connection This fuse should be low current since the sense wiring uses small wires and rated for the full DC pack voltage The fuse should be located towards the supply end of the sense wiring PACK CURRENT SENSE The BMU provides a mechanism for measuring pack current using a resistive shunt This is preferred over hall effect based sensors as it provides much lower drift allowing more accurate State of Charge SOC integration calculation The shunt must be located in the Battery HV connection of the pack as shown in the BMS wiring diagram in the Appendix SHUNT SELECTION The BMU Shunt Sense input has a full scale range of 25mV relative to the Battery HV Sense input This allows the use of a standard 50mV shunt running at half its rated current to minimise heat buildup and thermal drift effects since it will be installed inside the battery pack Choose a full scale range slightly over the expected maximum battery current As an example a Tritium WaveSculptor200 motor controller driving an induction motor may have an expected maximum power consumption of 90kW At a 400V battery voltage this is 225A Choose a full scale of 250A to allow some headroom on the measurement Since we wish to use a standard 50mV shunt at half rating you would therefore select a 500
24. ervicing 20 FAN PUMP CONTROL The BMU provides two 12V switched outputs to drive pack fans and pumps These are provided on a standard 3 pin KK connector as used in PCs and other IT equipment Both outputs are switched together ie both on or both off The 12V to power these outputs is sourced from the contactor supply input connection Refer to the datasheet for current and voltage ratings for these outputs Both connections provide a speed sensor input pin and this is measured by the BMU and reported as an rpm number for each connection on the CAN bus telemetry It assumes a 2 pulse per revolution sensor output as is commonly used for most PC cooling fans The BMS firmware switches both outputs on when the BMS is in Run mode once precharge has completed and the system is fully operational 20 1 FAN PUMP CONNECTORS The connector used for the pump fan outputs is a 3 way 2 54mm pitch Molex KK connector The pinout is shown below as viewed from the wire side as you would look at it while inserting crimps VARIES RED BLACK The pinout follows the standard used for PC cooling fans and pumps as found on 23 of 29 21 USER S MANUAL 5 TRI TI UM Battery Management System TRI67 011 ver 2 7 July 2013 any computer motherboard or peripheral Please note that the wire colours used on fans and pumps varies with each manufacturer RELAY OUTPUT 21 1 The BMU provides a voltage free relay o
25. firmware in the newer CMUs turns off the shunt resistors while taking voltage measurements to eliminate errors caused by the resistance of the sense wiring If using older CMUs it should be set to around 50mV for a typical pack to allow for the voltage drop in the sense wiring connections and cell impedance when 250mA of balance current is flowing This will be installation dependent Setting it too low will cause oscillations in the balance resistor switching and possibly erroneous voltage measurement reporting Setting it too high will give a wide band of voltage that various cells are balanced to giving a less than optimally balanced pack and slightly reduced pack capacity ZERO SOC THRESHOLD This voltage should be set to the point where the cells are considered fully discharged during normal operation It will be along the lower knee in the charge curve When a cell goes below this threshold the BMU reports SOC as 0 It is also the target minimum voltage used by motor controllers and other devices to not exceed during operation UNDER VOLTAGE THRESHOLD This voltage should be set to the minimum acceptable voltage for the cell If any cell voltage falls below this point then the BMS will move to the Error state and open the contactors immediately to protect the pack OVER TEMPERATURE THRESHOLD This temperature should be set to the maximum acceptable operating temperature for the cell If it is ever exceeded then the BMS will mo
26. from that CMU e Trust errors for a cell voltage have a yellow background e Cells outside the min and max voltage limits have a red background e Cells currently balancing have a blue background The minimum and maximum cells have bold text e Cells not present where the CMU has been programmed to monitor less than 8 cells have no text and a mid gray background COMMAND LINE OPTIONS In addition to double clicking on the executable the BMS Viewing software can also run from the command line where certain options can be set The supported command line options are described below s lt serial number gt This is used to specify the serial number of the BMU to connect to on the CAN bus when launched f lt filename gt Specifying a filename will enable logging in the BMS Viewer and all data will logged to the filename 28 of 29 24 5 TRITIUM USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 Using on the command line will enable logging in the BMS Viewer and will automatically choose a filename combining the serial number of the connected BMU device and the timestamp when the program was launched Note that when using this option that the log file will be rolled over at midnight each day u lt rate gt This option is used to determine the logging rate Currently one can choose between 0 2 1 10 and 60 second update rates example BMS Viewer exe s9566 u10 ADDITIONAL DOCUMENTATION
27. gainst each other to verify that the CMU is functioning correctly and that the cell voltage measurement can be trusted Measurements reported on the CAN bus telemetry come from the high resolution channel Measurements where the two channels do not agree are flagged as untrusted If any cells report an untrusted measurement the BMU will report a TRUST error on the CAN bus This is not treated as a fatal error and will not result in a pack shutdown The threshold where a trust error is generated is set in the BMU config and is currently factory set to 100mV Please note that due to the different response rates of the two A D converters it is possible to get a trust error briefly during sharp voltage transients on the cells for instance during rapid acceleration or regen braking events Whatever higher level vehicle system is handling BMS telemetry and user interface should be programmed to ignore trust errors that are present for less than some period eg 500ms of time FUSING The battery pack must be fused in each physical pack section with a fuse rated for at least the full DC pack voltage Note that it must be a DC rated fuse Selection of fuse type and current rating is beyond the scope of this document as it depends on expected load profile and duration cable sizing and temperature rating cable installation methods and short circuit rating of the pack among other factors CONTACTOR SELECTION The three contactors used
28. lue so as it knows what the expected precharge time is If this is not done then the precharge controller will either expect precharge to have finished when it has not resulting in an error state or it will expect precharge to take much longer than it really does resulting in a potential overload and a fire in the external resistor if there is a system fault CAVEATS Be aware that loads that draw current during precharge will cause the precharge sequence to fail and or the precharge resistor to overheat This is because the current drawn by the load will slow or possibly prevent the output voltage from rising meaning precharge never completes in the expected time The typical load that causes this problem is the DC DC converter used to charge the 12V auxilliary battery This problem can be avoided by using the relay output on the BMU to control an enable input on the problematic loads once precharge has completed and the BMU is in Run mode By default this relay activates in this manner 17 of 29 12 13 14 5 TRITIUM USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 TRUSTED MEASUREMENTS The CMUs measure their cell voltages using two separate front end circuits A D converters and voltage references One channel records with a high resolution 24 bit converter at a slow 2 Hz rate The other channel uses a mid resolution 12 bit converter running at several kHz These are cross checked a
29. mum at 3293mV Maximum voltage cell in the pack and its voltage The example shows Node CMU 12 Cell 4 is maximum at 3316mV Minimum temperature cell in the pack and it s temperature Maximum temperature cell in the pack and it s temperature e Total pack voltage e Total pack current Balance threshold voltage e Balance threshold minimum voltage balance voltage hysteresis e CMU count in system The next row shows Precharge status information on the left Current state Idle Precharge Run etc e Contactor 12V supply voltage presence mV on v4 or older BMUs 27 of 29 23 2 23 3 5 TRITIUM USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 The bottom row in the BMU section shows the various status flags e CMU Power supply OK e Any cell OverVoltage e Any cell UnderVoltage Any cell OverTemperature e Any cell untrusted e CMU and vehicle timeout errors The right hand side shows e Fan speed for both fans SOC and Balance SOC in Ah SOC and Balance SOC in CMU DATA The lower section of the program shows telemetry data from the CMUs one row per CMU The information shown is e CMU Serial number e CMU circuit board PCB temperature CMU external cell temperature e 1 8 cell voltage measurements The data is highlighted in various ways to quickly understand the system status e CMU serial number alternates between a white and light blue background each time a packet is received
30. o this Use a single length of cable to join all CMUs the BMU and both termination resistors together This can easily be achieved by crimping on a standard 10 way IDC crimp as the cable passes each device Pin 1 on each device is indicated by an arrow and the numeral 1 on the PCB and or an arrow moulded in the connector Make sure that the ribbon is oriented correctly on all devices Pin 1 should join to Pin 1 on every other device and should also be the polarity indication on the ribbon cable usually a red stripe The CMU CAN bus cable is electrically connected to vehicle ground at the BMU and therefore must be kept physically separated from any battery or other HV connections to at least the maximum voltage rating of the pack 9 of 29 7 2 5 TRITIUM USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 BMS MASTER UNIT FORM FACTOR The BMS Master Unit BMU is supplied as a 1 6mm thickness Printed Circuit Board PCB conformally coated without an enclosure It is designed to be installed inside the battery box in a weather sealed area along with the cells themselves This means that all connections to the pack remain inside the battery pack enclosure simplifying fusing and wiring installation requirements The BMU should be mounted to a flat surface using 7x M3 standoffs of sufficient length to allow the appropriate clearance distance between the components on the PCB and the mounting surface
31. or is therefore 450V2 470R 430W The expected precharge time is given by the time constant TAU R Ohms C Farads where the voltage on the capacitor should change by 63 of the difference each TAU time interval Precharge should be within 95 of the initial value within 4 TAU and to 99 within 5 TAU intervals as an exponential decay For the example system TAU 376ms so the expected precharge time of 4 TAU 1 5 seconds Choosing a gt 500W resistor is unnecessary as this rating is only needed for a short amount of time during normal operation However the resistor cannot be too small as if a fault situation occurs such as a short circuit in the motor controller then this power will be dissipated continuously for the entire expected 16 of 29 11 5 5 TRITIUM USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 precharge time until the precharge controller realises that precharging has not occurred properly and goes into an error state For safety the resistor in the example system should be chosen to tolerate a one off event starting at the expected maximum ambient temperature of 430W for 1 5 seconds Searching through available off the shelf options from Digikey the RH series from Vishay is chosen as a likely candidate According to the datasheet located at http www vishay com docs 50013 rh pdf for short time overloads a power rating of 12x the nominal power is acceptable for a 2 second du
32. ors draw a large current inrush during turn on and a poor connection will result in contactor chattering and or precharge fault trips This connection draws no current when the BMS is in the off state and does not have to be routed via the ignition key Connecting it to a permanent source of power rather than via the ignition key allows the BMS to operate the contactors without the ignition key switched on for example during charging 14 of 29 10 2 11 11 1 11 2 5 TRITIUM USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 CONTACTOR OUTPUT CONNECTORS The connectors used for the Contactor drive outputs are a 4 way 4 2mm pitch Molex MiniFit Jr connector The pinout is shown below as viewed from the wire side as you would look at it while inserting crimps The colours shown match those used by the Gigavac GX11 and GX12 family of contactors WHITE BLACK AUX GROUND BLUE RED PRECHARGE CONCEPT Loads such as motor controllers inverters DC DC converters and other high voltage high power electronics contain capacitors across the DC bus If these are suddenly connected to the battery pack by closing a contactor or switch then there will be a very large inrush current thousands of Amps followed by a voltage surge due to the battery and cabling inductance This inrush current will damage the devices and weld contacts together and the voltage surge can also
33. ration Using a 50W resistor this equates to an overload rating of 600W starting at an ambient of 25 C Therefore this 50W resistor is acceptable for the external resistor in this application based on maximum fault power During normal operation the capacitors contain a charge of 0 36C giving an energy storage of 81 Joules Note that this is a lethal amount of energy During an RC precharge type event the same amount of energy that is eventually stored in the capacitor is also dissipated in the resistor If not mounted on any additional thermal mass and assuming that 20g of the resistor s total mass is aluminium specific heat 0 897 J g C 81 Joules will give a temperature rise of AT Q mc 4 5 C also well within limits During a fault situation where 430W is being dissipated in the resistor the same thermal calculation shows a temperature rise of 48 C above the starting temperature This also is within limits The maximum acceptable operating voltage for the 50W resistor is 1285V so our maximum of 450V is also within limits Therefore a 470 ohm 50W RH series wirewound aluminium resistor would be a suitable choice of external resistor for this application of precharging 800uF to 450V in 1 5 seconds Other devices on the HV bus such as DC DC converters and battery chargers will add significant extra capacitance and must be factored into these calculations Note that the BMS must be programmed with the correct timeout va
34. rom the Tritium EV Driver Controls via the CAN bus as detailed in the following sections ERROR The BMS is in the Error state if any of the following conditions are true e The 12V contactor supply is not present or is undervoltage Any cell Over Voltage Any cell Under Voltage Any cell Over Temperature Any CMU communications packet is overdue CMU timeout e Packets from the EV driver controls are overdue vehicle timeout e Missing CMU or cell Extra CMU or cell e Contactor feedback mismatch to the commanded state of the contactor In the Error state all contactors are switched off to isolate the pack The relay 21 of 29 USER S MANUAL Battery Management System TRI67 011 ver 2 7 July 2013 5 TRITIUM and fan outputs are also switched off If all errors are removed then the BMS will transition to the Idle state if the ignition key is switched to the accessories position and the fuel door is closed It requires this active user intervention to move to Idle and will otherwise remain in the Error state 17 2 IDLE In the Idle state the BMS waits for a command from the EV driver controls All contactors are switched off The relay output and fans are also off If the ignition key is switched from the run position to the start position or the fuel door is opened then the BMS transitions to the Enable state and begins a precharge sequence 17 3 ENABLE Contactor 1 is switched on to connect the Pack connection to th
35. sitive rail Wire the Battery HV and Shunt sense wires to their respective sides of the current shunt in the negative rail Refer to the BMS wiring diagram in the Appendix for more details Please note that this sense wiring must be rated for the full pack voltage although it is low current so a small gauge wire can be used Check the relevant wiring standards regarding wire rating and colours for example NCOP14 in Australia specifies Orange wire for all battery pack and other HV system wiring The Battery HV and Shunt sense wires should be twisted together to minimise noise pickup between the BMU and the shunt It is suggested to have these wires no longer than 300 400mm HV SENSE CONNECTOR The connector used for the HV Sense is a 10 way 4 2mm pitch Molex MiniFit Jr connector The pinout is shown below as viewed from the wire side as you would look at it while inserting crimps The colours shown match those recommended in most EV wiring standards for HV DC wiring ORANGE ORANGE ORANGE N C N C N C N C N C ORANGE ORANGE The sense points are as follows e Vehicle HV Sense Vehicle side of Contactor 2 Battery HV Sense Battery side of Contactor 2 e Battery HV Sense Battery side of 25mV Shunt ShuntA Vehicle side of 25mV Shunt Shunt B Battery side of 25mV Shunt 12 of 29 8 2 9 1 9 2 9 3 5 TRITIUM USER S MANUAL Battery Manag
36. to break the HV DC connections must be appropriately rated for the currents and voltages seen during both normal use and during fault situations Typical parts used in automotive sized packs are the Tyco EV200 or the Gigavac GX11 or GX12 series Selection of these parts is beyond the scope of this document 18 of 29 15 15 1 15 2 USER S MANUAL 5 TRI TIUM Battery Management System TRI67 011 ver 2 7 July 2013 OPERATING THRESHOLDS There are six user settable thresholds that control the operation of the BMS These should be set based on the maximum acceptable limits for the cells used in the battery pack along with reference to the charge discharge curves for selecting the balancing points These operating points can be programmed into the BMU over the CAN bus using the BMS Setup software and a Tritium CAN Ethernet bridge Settings that are required at the CMUs are passed to them from the BMU when the system starts The SOC vs Voltage curve for a typical Lithium chemistry cell is shown below along with the location of the various thresholds Over Voltage Threshold Balance Threshold Cell Voltage Zero SOC Threshold Under Voltage Threshold State of Charge SOC OVER VOLTAGE THRESHOLD This voltage should be set to the maximum acceptable voltage for the cell If it is ever exceeded then the BMS will move to the Error state and open the contactors immediately to protect the pack BALANCE THRESHOL
37. utput to use for signalling devices in the vehicle that are not capable of receiving CAN bus data This can be used for example to control the enable input of a DC DC converter or drive a relay or HV contactor A coil suppression diode must be used if driving this type of load Refer to the datasheet for current and voltage ratings of the relay The relay is active when the BMS is in Run mode The connector also provides 12V and GND pins which are sourced from the 12V contactor supply power These can be conveniently used in conjunction with the relay to switch 12V out to a load that requires power for instance to drive another relay fan or contactor RELAY OUTPUT CONNECTOR The connector used for the Relay output is a 6 way 4 2mm pitch Molex MiniFit Jr connector The pinout is shown below as viewed from the wire side as you would look at it while inserting crimps RELAY RELAY RELAY NC NO COMMON 12V CINOLUNID EOI The 12V and Ground pins in this connector are wired on the BMU PCB to the Contactor 12V supply connector and can be jumpered across to the relay pins to provide 12V output on relay active or inactive switch loads to ground etc depending on the jumper arrangement The Relay pins in this connector are wired directly to a small relay on the BMU PCB Refer to the datasheet for the ratings on this relay 24 of 29 22 22 1 22 2 22 3 5 TRITIUM USER S MANUAL
38. ve to the Error state and open the contactors immediately to protect the pack CHARGER CONTROL To charge and balance the pack correctly the BMS must be able to control the charging current in a continuous manner Therefore a charger that is able to be controlled remotely is required Battery management systems and chargers that use on off control will result in slow and or poor balancing of cells Suitable chargers that the BMS currently supports are the Brusa NLG series and the TC Charger range with CAN bus option Please contact Tritium regarding support for other types of chargers The BMU runs a PID control loop based on maximum individual cell voltage with the aim of raising it up to the Balance Threshold voltage It will issue current setpoint commands to the charger to achieve this goal This control strategy results in the minimum possible charge time as the charger will be ramped up to maximum current rapidly and stay there until the maximum cell reaches the target voltage at the end of the constant current portion of the charge cycle At this point charge current will be gradually ramped down at whatever rate is necessary to keep the maximum cell at the target and adsorbing as quickly as possible the constant voltage portion of the charge cycle Therefore it does not matter at what rate the cell is adsorbing charge the 20 of 29 17 17 1 5 TRITIUM USER S MANUAL Battery Management System TRI67 011
39. ver 2 7 July 2013 control loop will keep it at the optimal amount at all times As the maximum cell reaches 100 SOC the charging current will have been gradually reduced down until it matches the balance current of 250mA At this point the maximum cell will be at the target voltage held at that point by the balance resistor and lower cells in the pack will be rising at the rate governed by the 250mA charge When the minimum cell reaches the target voltage then all cells are in balance and the pack is at 100 SOC This time difference between maximum and minimum cells reaching the target voltage is usually only a few minutes for a well balanced battery pack Therefore the power wasted in the balance resistors during this time is a trivial percentage of the total charge energy Note that the very first balance may take considerable time if the cells are grossly out of balance Worst case time is the Ah capacity of the cells divided by the 250mA balance rate divided by the out of balance percentage eg 90Ah 0 25A 20 72 hours OPERATING STATE The BMS can be in any one of six states depending on operating conditions commands and errors The states are reported on the CAN bus and shown in the BMS Viewer software The states are in the most commonly seen sequence Error e Idle Enable e Measure e Precharge e Run States transition from one to another based on various thresholds and timers and on user commands f
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