1. Technical specifications
Technical specifications
BMS IMD is designed to measure the insulation resistance between the positive and negative poles of the tractive system battery and the chassis (ground) of the vehicle.
Specifications
| Parameter | Value |
| Supply voltage, V | 9 to 30 |
| Current consumption @ 12V, mA (maximum) | 100 |
| Battery voltage range, V | 20 to 900 |
| Battery current consumption during resistance measurement, mA (maximum) | 0.1 |
| Measurement range, kOhm | 10 to 10000 |
| Accuracy, % (maximum) | ±10 |
| Response time for generating an alarm signal, s (maximum) | 20 |
| CAN bus speed, kbps | 125, 250 (default), 500, 1000 |
| Dimensions (length × width × height), mm | 140 × 60 × 14 |
| Weight, g | 30 ± 5 |
| Operating temperature range, °С | -40 to +85 |
Rated insulation voltage, AC 50Hz, 1 minute, VRMS (minimum): 1) Between chassis and battery lines, 2) Between chassis and power lines, 3) Between power lines and battery lines | 3500 |
| Header types | Molex series Micro-Fit |
Overall and mounting dimensions
Operation description
The BMS IMD measures the insulation resistance between the battery positive pole and chassis and between the battery negative pole and chassis of the vehicle by connecting the bias resistors. Battery poles and chassis commutation occurs only while measuring the insulation resistance.
The device is constantly connected to positive and negatives poles of the battery and constantly measuring its voltage. If battery voltage is below the configured value (16V by default), an undervoltage error occurs.
After connecting or disconnecting the bias resistor, the device waits for the end of the transient process. The criterion for the end of the transient process is stabilization of the measured voltage values within the established limits (tenths of a percent of the battery voltage, default 0.5%). If the transient time exceeds the value set in the settings (10 seconds by default), the device generates an alarm signal.
The BMS IMD provides self-diagnosis. The test period can be set in the settings (default 60 seconds). During self-diagnosis, one of the test resistors gets connected and a check of insulation resistance occurs. Based on the test results, the measurement error of the connected resistance nominal value is determined, which should not exceed the value set in the settings (default 10%). If the device is in an error state or the self-test fails, the self-test is repeated until it passes.
The average resistance measurement time is 3 seconds.
A typical connection diagram is shown below.
