Curtis / HPEVS

Using a Curtis Instruments motor inverter with an Lithiumate BMS.

The Lithiumate Pro (rev 2.23 and above) is compatible out-of-the-box with the Curtis Instruments AC motor inverter (VCL Version 5.0 or higher) using the High Performance Electric Vehicle Systems (HPEVS) implementation.

Connect the BMS and the inverter through the CAN bus.

Terminate the CAN bus with two terminators, one at each end. (The Lithiumate Pro BMS has an internal termination can can be disabled.)

The Lithiumate Pro transmits messages to the Curtis / HPEVS AC motor inverter by default.

To disable these CAN messages, in the GUI, go to the "Configure" tab, the "Communicate" sub-tab, the "Message to devices" box, the "Motor driver" box, and select "None".

The Curtis / HPEVS inverter does not need any configuration to work with the Lithiumate Pro BMS.

The speed for both devices must be set to be the same.
The default CAN bus speed for the Curtis / HPEVS inverter is 250 kbps.
It's far easier to change the rate for the Pro, because of its friendly GUI.

Unless disabled (see above), the Lithiumate generates the following message for the Curtis / HPEVS series motor inverters.

Notes:

• Multi-byte values are big-endian (Motorola standard): the MSB (Most Significant Byte) is in the lower numbered data byte (the left most byte in the following tables)
  (The specs from HPEVS show big-endian in the top section, and little-endian in the bottom section, but it's really big-endian)
• The default bus speed is 500 kbps
• Period from BMS controller: 100 ms (HPEVS specifies 104 ms, minimum and maximum period are not specified)

ID	Bytes	Byte 0	Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7
300h	8	Low cell voltage (1)		High cell voltage (2)		Pack current (3)		Pack amphours (4)
		MSB	LSB	MSB	LSB	MSB	LSB	MSB	LSB

Notes:

1. [0.1 mV] Normally, minimum cell voltage; if LLIM, then a very low value is reported, to disable discharging, regardless of settings in the Curtis / HPEVS inverter
2. [0.1 mV] Normally, maximum cell voltage; if HLIM, then a very high value is reported to disable charging, regardless of settings in the Curtis / HPEVS inverter
3. [0.1 A] Signed, positive = discharging
4. [Ah] Pack capacity

ID	Bytes	Byte 0	Byte 1	Byte 2	Byte 3	Byte 4	Byte 5	Byte 6	Byte 7
301h	8	SOC (1)	High temperature (2)	Low temperature (2)	12 V supply voltage (3)		Flags (4)	Highest cell ID (4)	Lowest cell ID (4)
					MSB	LSB

Notes:

1. [0.5 Ah]
2. [°C] signed
3. Fixed value [V] Since 12 V fits in the low byte, the high byte is always 0
4. Flags (the specs from HPEVS number the flag bits 1 through 8 instead of 0 through 7):
   • Bit 0: Error (Mil) Output - set if there is any fault
   • Bit 1: DTC: Internal Comm Fault - set if there is a bank communication fault
   • Bit 2: DTC: Low Cell Voltage Fault - set in case of undervoltage
   • Bit 3: DTC: Current Sensor Fault - not applicable
   • Bit 4: DTC: Internal Memory Fault - not applicable
   • Bit 5: DTC: Internal Logic Fault - not applicable
   • Bit 6: DTC: High Voltage Isolation Fault - set if an isolation loss is detected
   • Bit 7: Charge Interlock - set if powered by both VS and VL