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Master Slave Manual - REC Flipbook PDF
MASTER – SLAVE CONFIGURATION 4 www.rec-bms.com Slave Unit Connection Table Table 2: Slave Unit connection table.
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Rozna ulica 20, 6230 Postojna, Slovenia e-mail: [email protected]; www.rec-bms.com
BATTERY MANAGEMENT SYSTEM Master – Slave configuration
Features: -
robust and small design Master + max 15 Slave combination (max 225 cells) single cell voltage measurement (0.1 – 5.0 V, resolution 1 mV) single cell - under/over voltage protection single cell internal resistance measurement SOC and SOH calculation over temperature protection (up to 8 temperature sensors per Slave) under temperature charging protection passive cell balancing up to 1.3 A per cell with LED indication shunt current measurement (resolution 10 mA @ ± 300 A) 3 galvanically isolated user defined multi-purpose digital inputs/outputs 4 programmable relays (normally open and normally closed option) 12 V galvanically isolated supply (10.5 – 15 V) galvanically isolated RS-485 and CAN communication protocol error LED + buzzer indicator internal battery powered real time-clock (RTC) PC user interface for changing the settings and data-logging (optional accessory) LCD touch display for monitoring (optional accessory) hibernate switch one-year warranty
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MASTER – SLAVE CONFIGURATION General description of the BMS Battery management system (BMS) is a device that monitors and controls each cell in the battery pack by measuring its parameters. The capacity of the battery pack differs from one battery cell to another and this increases with number of charging/discharging cycles. The Li-ion polymer batteries are fully charged at typical cell voltage 4.16 - 4.20 V. Due to the different capacity this voltage is not reached at the same time for all cells in the stack. The lower the capacity the sooner this voltage is reached. When charging series connected batteries with single charger, the voltage on some cells might be higher than maximum allowed charging voltage at the end of charging. Overcharging the cell additionally lowers its capacity and number of charging cycles. The BMS equalizes cells’ voltage by diverting some of the charging current from higher voltage cells – passive balancing. The device temperature is measured to protect the circuit from over-heating due to the passive balancing. Battery pack temperature is monitored by Dallas DS18B20 digital temperature sensor/s. Maximum 8 sensors may be used. The BMS parameters are listed in table below.
Default Parameters: Table 1: Default parameter table. Parameter balance start voltage balance end voltage maximum diverted current per cell cell over voltage switch-off cell over voltage switch-off hysteresis per cell charger end of charge switch-off pack charger end of charge switch-off hysteresis per cell charger over voltage disconnection per cell cell under voltage protection error under voltage protection error hysteresis per cell cell under voltage protection switch-off cell under voltage protection switch-off hysteresis BMS slave under voltage sleep mode BMS over temperature switch-off BMS over temperature switch-off hysteresis cell over temperature switch-off under temperature charging disable Slave Unit absolute maximum package voltage Master Unit power supply voltage voltage to current coefficient max DC current Relay 1-4 at 100 V DC max DC current Relay 1-4 at 12 V DC max AC current Relay 1-4 at 230 V AC optocoupler output max voltage optocoupler output max current Slave Unit stand-by power supply Slave Unit disable power supply Slave Unit cell balance fuse rating (SMD) Master Unit stand-by power supply @ 12 V Master Unit disable power supply internal relay fuse (Master Unit)
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Value 4.05 4.15 up to 1.3 (3.9 Ohm) 4.18 0.007 4.15 0.1 4.165 3.28 0.03 2.95 0.1 41.5 and 37.9 60 5 55 -2 63 10-15 0.0078125 0.4 2 2 62 15 < 90 66 V multiple units can be chained in series if the current control inputs are galvanically isolated. Signal from Master unit should be chained through the devices (IO1 pin 4 – anode charger1 – cathode charger1 – anode charger2- cathode charger2 - IO1 pin 1).
Battery Pack SOC determination SOC is determined by integrating the charge in-to or out of the battery pack. Different Li-ion chemistries may be selected: Table 10: Programmed Chemistry types. Number 1 2 3 4
Type Li-Po High power Li-Po High capacity Winston/Thunder-Sky/GWL A123
Temperature and power correction coefficient are taken into consideration at the SOC calculation. Li-Po chemistry algorithms have an additional voltage to SOC regulation loop inside the algorithm. Actual cell capacity is recalculated by the number of the charging cycles as pointed out in the manufacturer’s datasheet. SOC is reset to 100% at the end of charging and Power LED turns ON until charger hysteresis is present.
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MASTER – SLAVE CONFIGURATION Master Unit Main Contactor and Pre-charge Resistor Connection Pre-charge resistor is used to charge the system capacitors before turning main contactor relay on. This prevents high currents through the relay and prolongs its life span. An external pre-charge resistor of 150 Ohm 50 W should be used. If there is no error in the system, the ignition signal starts pre-charge relay 4 and after 2 s the main contactor turns on.
Figure11: Pre-charge resistor connection.
System Error Indication System errors are indicated with red error LED by the number of ON blinks, followed by a longer OFF state. Red LED switch-off indicator turns on in case of: Table 11: System error description. Number of ON blinks
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ERROR
Single or multiple cell voltage is too high (cell over voltage switch-off).
BMS
TO-DO
BMS will try to balance down the problematic cell/cells to safe voltage level (2 s error hysteresis cell over voltage switch-off hysteresis).
• Wait until the BMS does its job.
Main contactor is connected, charger is disabled.*
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MASTER – SLAVE CONFIGURATION
2
3
4
5
6
7
Single or multiple cell voltage is too low (cell under voltage protection switch-off). Cell voltages differs more than allowed (cells differ more than set). Cell temperature is too high (over temperature switch-off).
BMS temperature is too high (BMS over temperature switch-off).
Number of cells, address is not set properly.
The temperature is too low for charging (under temperature charging disable).
BMS will try to charge the battery (2 s error hysteresis + cell under voltage hysteresis is applied). Main contactor is charger is enabled.*
• Plug in the charger.
disconnected,
Main contactor is connected, charger is enabled.* Cells temperature or cell interconnecting cable temperature in the battery pack is/are too high. Main contactor is charger is disabled.*
• Examine the battery pack if this occurs frequently.
disconnected,
Due to extensive cell balancing the BMS temperature rose over upper limit (2 s error hysteresis + 5 °C temperature hysteresis).
• Wait until the BMS cools down.
Main contactor is connected charger is disabled.* Number of cells at the back of the Slave Unit was changed from the default manufacturer settings. • Main contactor is charger is disabled.*
Set the proper number of cells, address.
disconnected
If cells are charged at temperatures lower than operating temperature range, cells are aging much faster than they normally would, so charging is disabled. (2 °C temperature hysteresis).
• Wait until the battery’s temperature rises to usable range.
Main contactor is connected, charger is disabled.*
8
Temperature sensor error.
Temperature sensor is un-plugged or not working properly. Main contactor is charger is disabled.*
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disconnected,
• Turn-off the Master and Slaves Units by enable switch and try to re-plug the temperature sensor connector. Turn Slave Unit back ON and restart the Master Unit. If the BMS still signals error 8, contact the service. The temperature sensors should be replaced. www.rec-bms.com
MASTER – SLAVE CONFIGURATION • Turn OFF Master and all Slave Units. Turn ON Slave Units and Master Unit.
9
Communication error.
Main contactor is charger is disabled.*
disconnected,
• Check the Master –Slave connection cable + remote ON/OFF cable • Check the Slave Unit voltage (is it below set threshold voltage ) • If the error repeats, contact the service.
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11
Cell in short circuit or BMS measurement error.
Tyco main relay is in short circuit.
Single or multiple cell voltage is close to zero or out of range, indicating short circuit, blown balance fuse or measuring failure. Main contactor is charger is disabled.*
If the main relay should be opened and current is not zero or positive the BMS signals error 11. When the error is detected, the BMS tries to unshorten the main relay by turning it ON and OFF for three times. Main contactor is charger is disabled.*
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Error measuring current.
Wrong cell chemistry selected.
• Check the cells connection to the BMS Slave Units. • If the same error starts to signal again contact the service.
• Restart the Master Unit
disconnected
Current sensor is disconnected or not working properly. Main contactor is charger is disabled.*
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disconnected,
• Restart the Slave and Master Unit.
disconnected,
• Turn-off the BMS by enable switch and try to re-plug the current sensor connector. Turn BMS back ON. If the BMS still signals error 12, contact the service. • Use PC interface to set proper cell chemistry
*If ignition pin is ON.
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MASTER – SLAVE CONFIGURATION RS-485 Communication Protocol
Figure 12: RS-485 DB9 male connector front view.
Table 12: RS-485 DB-9 connections. Pin 1 2 3 4 5 6 7 8 9
Designator A B AGND +5 V
BMS Unit is programmed as a Slave Unit and responds only when asked. Galvanically isolated RS-485 (EN 61558-1, EN 61558-2) serves for logging and changing BMS parameters. Dedicated PC software BMS Master control or another RS-485 device may be used for the communication. Messages are comprised as follows:
STX, DA, SA, N, INSTRUCTION- 4 bytes,16-bit CRC, ETX • STX start transmition (always) • DA - destination address to (set as 6) • SA - sender address (always 0) • N – number of sent bytes • INSTRUCTION 4 bytes for example.: 'L','C','D','1','?', - (combined from 4 ASCII characters, followed by ‘?’, if we would like to receive the current parameter value or ‘ ’,’xx.xx’ value if we want to set a new value • 16-bit CRC, for the whole message except STX in ETX • ETX- end transmition (always) Dataflow: • Bit rate: 56k • Data bits: 8 • Stop bits: 1 • Parity: None • Mode: Asynchronous
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MASTER – SLAVE CONFIGURATION Table 13: RS-485 instructions description. INSTRUCTION
DESCRIPTION
'*','I','D','N','?'
Identification
'L','C','D','1','?'
Main data
'C','E','L','L','?'
Cell voltages
'P','T','E','M','?'
Cell temperatures
'R','I','N','T','?'
Cells internal DC resistance
'B','T','E','M','?'
BMS temperature
'E','R','R','O','?'
Error
'B','V','O','L', '?'/ 'B','V','O','L', ' ','xxx' 'C','M','A','X','?'/ 'C','M','A','X',' ','xxx' 'M','A','X','H', '?'/ 'M','A','X','H', ' ','xxx' 'C','M','I','N', '?'/ 'C','M','I','N', ' ','xxx' 'M','I','N','H', '?'/ 'M','I','N','H', ' ','xxx' 'T','M','A','X', '?'/ 'T','M','A','X', ' ','xxx' 'T','M','I','N', '?'/ 'T','M','I','N', ' ','xxx' 'B','M','I','N', '?'/ 'B','M','I','N', ' ','xxx'
BMS ANSWER Answer “REC - BATERY MANAGEMENT SYSTEM” Returns 7 float values LCD1 [0] = min cell voltage, LCD1 [1] = max cell voltage, LCD1 [2] = current, LCD1 [3] = max temperature, LCD1 [4] = pack voltage, LCD1 [5] = SOC (state of charge) interval 0-1 -> 1=100% and LCD1 [6] = SOH (state of health) interval 0-1 -> 1=100% BMS first responds with how many BMS units are connected, then it sends the values of the cells in float format BMS first responds with how many BMS units are connected then it sends the values of the temperature sensors in float format BMS first responds with how many BMS units are connected then it sends the values in float format BMS first responds with value 1, then it sends the values of the BMS temperature sensor in float format Responds with 4 bytes as follows ERRO [0] = 0 – no error, 1 – error ERRO [1] = BMS unit ERRO [2] = error number (1-13) in ERRO [3] = number of the cell, temp. sensor where the error occurred
Cell END balancing
Returns float voltage [V]
Max allowed cell voltage Max allowed cell voltage hysteresis
Returns float voltage [V] Returns float voltage [V]
Min allowed cell voltage Min allowed cell voltage hysteresis Maximum allowed cell temperature Minimum allowed temperature for charging Balancing START voltage
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Returns float voltage [V] Returns float voltage [V] Returns float temperature [°C] Returns float temperature [°C] Returns float voltage [V]
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MASTER – SLAVE CONFIGURATION 'C','H','A','R', '?'/ 'C','H','A','R', ' ','xxx' 'C','H','I','S', '?'/ 'C','H','I','S', ' ','xxx' 'I','O','F','F','?'/ 'I','O','F','F',' ','xxx' 'T','B','A','L','?'/ 'T','B','A','L',' ','xxx' 'B','M','T','H','?'/ 'B','M','T','H',' ','xxx' 'V','M','A','X','?'/ 'V','M','A','X',' ','xxx' 'V','M','I','N','?'/ 'V','M','I','N',' ','xxx' 'T','H','I','S','?'/ 'T','H','I','S',' ','xxx' 'C','Y','C','L','?'/ 'C','Y','C','L',' ','xxx' 'C','A','P','A','?'/ 'C','A','P','A',' ','xxx' 'I','O','J','A','?'/ 'I','O','J','A',' ','xxx' 'R','A','Z','L','?'/ 'R','A','Z','L',' ','xxx' 'C','H','E','M', '?'/ 'C','H','E','M', ' ','xxx' 'P','A','R','V', '?'/ 'P','A','R','V',' ','xxx' 'R','E','3','L','?'/ 'R','E','3','L',' ','xxx' 'R','E','3','H','?'/ 'R','E','3','H',' ','xxx' 'R','E','3','T','?'/ 'R','E','3','T',' ','xxx'
End of charging voltage per cell End of charging voltage hysteresis per cell Current measurement zero offset Max allowed BMS temperature Max allowed BMS temperature hysteresis Number of exceeded values of CMAX Number of exceeded values of CMIN Number of exceeded values of TMAX Number of battery pack cycles
Returns float voltage [V] Returns float voltage [V] Returns float current [A] Returns float temperature [°C] Returns float temperature [°C] Returns integer value Returns integer value Returns integer value Returns integer value
Battery pack capacity
Returns float capacity [Ah]
Voltage to current coefficient
Returns float value
Package cell difference
Returns float voltage [V]
Li-ion chemistry
Returns unsigned char value
Number of parallel branches under-voltage relay 3 level under-voltage relay 3 level hysteresis Timer for min cell < min before under-voltage relay 3 turns off Relay 1 under voltage switch off Relay 1 under voltage switch off hysteresis
Returns unsigned char value Returns unsigned char value Returns unsigned char value Returns unsigned char value
'R','E','1','L','?'/ Returns float voltage [V] 'R','E','1','L',' ','xxx' 'R','E','1','H','?'/ Returns float voltage [V] 'R','E','1','H',' ','xxx' 'R','E','2','V','?'/ Relay 2 voltage Returns float voltage [V] 'R','E','2','V',' ','xxx' 'R','E','2','H','?'/ Relay 2 voltage Returns float voltage [V] hysteresis 'R','E','2','H',' ','xxx' 'O','P','2','L','?'/ Optocoupler 4 voltage Returns float voltage [V] 'O','P','2','L',' ','xxx' 'O','P','2','H','?'/ Optocoupler 4 Returns float voltage [V] hysteresis 'O','P','2','H',' ','xxx' Parameter accepted and changed value is responded with 'SET' answer.
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MASTER – SLAVE CONFIGURATION Example: proper byte message for 'LCD1?' instruction for BMS address 1 is:
RS-485 message are executed when the microprocessor is not in interrupt routine so a timeout of 350 ms should be set for the answer to arrive. If the timeout occurs, the message should be sent again. CAN Communication protocol:
Figure 13: CAN DB9 connector front view. Bitrate: 500 kbs 11-bit identifier: 0x032 Default settings TX only 8 byte message structure Terminate the CAN line by shorting PIN 1 and 2. Table 14: CAN DB9 connector pin designator. Pin 1 2 3 4 5 6 7 8 9
Designator TERMINAL CANL + TERMINAL GND GND CANH -
Table 15: CAN message structure description-package 1. Byte 1 2 3 4 5 6 7 8
Description State of charge [%] Battery pack voltage high byte Battery pack voltage high byte Battery pack current high byte Battery pack current high byte Battery pack temperature Error number Number of the cell or temp. sensor where the error occurred
Type Unsigned char
0-200 LSB = 0.5 % SOC
Unsigned integer
0-65535, LSB = 10 mV
Signed integer
−32768 to 32767 LSB = 10 mA
Signed char Unsigned char
-127 to 127 LSB = 1° C 0-13
Unsigned char
0-15
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MASTER – SLAVE CONFIGURATION Table 7: CAN message structure description-package 2. Byte 1 2 3 4 5 6 7 8
Description State of health [%] State of charge [%] Minimum cell voltage high byte Minimum cell voltage low byte Minimum cell voltage high byte Minimum cell voltage low byte Error number Number of the cell or temp. sensor where the error occurred
Type Unsigned char Unsigned char
0-200 LSB = 0.5 % SOC 0-200 LSB = 0.5 % SOC
Unsigned integer
0-65535, LSB = 1 mV
Unsigned integer
0-65535, LSB = 1 mV
Unsigned char
0-13
Unsigned char
0-15
CAN message is sent every 2 seconds with refreshed values.
Master Unit Charger Communication ElCon charger (TC Charger) uses three signal pins to control the charging current. Charging is enabled by connecting > 2 V @ enable pin. Charging current can be controlled by applying 2 – 5 V to enable input of the charger. 12 V signal from the charger is used to produce 2 – 5 V analog signal with internal optocoupler and RC low-pass filter. Charging current is decreased when the first cell reaches end of charge voltage. When all the cells reach end of charge voltage, SOC is set to 100% and charging hysteresis is set.
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MASTER – SLAVE CONFIGURATION Slave Unit Dimensions: BMS Slave Unit can be supplied without the enclosure if an application is weight or space limited. The dimensions of the BMS without the enclosure are 160 mm x 110 mm x 27 mm. A sufficient contact surface for balancing resistors should be provided. The PCB has four 3.2 mm mounting holes. The enclosure is made of black anodized aluminum.
Figure 14: BMS Slave Unit dimensions.
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MASTER – SLAVE CONFIGURATION
BMS Master Unit Dimensions:
Figure 15: BMS Master Unit dimensions.
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