LibreSolar
Short-circuit protection behavior and results
Description
The short-circuit test was performed to evaluate the behavior of the BMS under fault conditions and ensure proper protection mechanisms are in place. The test helps determine if the system correctly detects and reacts to a short-circuit event by shutting down the power section.
Configuration and determination of actual short-circuit current
The short-circuit delay was set to 1, as outlined in datasheet section 13.6.7.2 Protections: SCD: Delay, which should trigger an immediate shutdown of the power section. The configuration for the short-circuit delay is:
thingset =Conf {"sShortCircuitDelay_us":1}
The short-circuit current limit was configured to 0, theoretically resulting in a 33.3 A limit. However, the measured short-circuit current was 38.5 A, determined by gradually increasing the current until the BMS initiated a power shutdown. The configuration for the short-circuit current limit is:
thingset =Conf {"sShortCircuitLimit_A":0}
Figure 1 shows the current (yellow) and pack voltage (red) traces during the short-circuit event. The orange point marks the moment when the current reaches the shutdown point of the BMS, determined by gradually increasing the current.
Short circuit test
The short-circuit test was performed with a continuous current of 35 A, using a Deutronic electronic load to apply the short circuit. Figure 2 illustrates the test results, with the blue line representing the gate voltage, the yellow line showing the current, and the red line indicating the pack voltage. When the current exceeds 38.5 A, it takes ~40 µs to initiate the gate shutdown of the MOSFETs. In total, ~80 µs is required from detection to safely power down the output.
