Relay fault diagnosis circuit and method

Abstract

The invention discloses a relay fault diagnosis circuit and a relay fault diagnosis method. The method comprises the following steps: S01: after a circuit is electrified with low voltage, controlling a detection branch selecting unit (100) by a BMS control unit (200) to perform corresponding voltage detection branch gating operation; S02: detecting the voltage at the two ends by the currently gated voltage detection branch; S03: comparing voltage detected by the voltage detection branch and judging the adhesion state of each relay according to the comparison result; and S04: if each relay in the step S03 does not adhere to each other, performing operating control on the corresponding relay, gating the corresponding voltage detection circuit to perform voltage detection, and judging the failure state of the corresponding relay according to the detected voltage. The detection branch detection unit can perform random switching among multiple to-be-detected voltage circuits, so one voltage detection unit can detect multiple paths of voltage values, the component cost of voltage detection is greatly reduced, a BMS hardware circuit is simplified, the BMS occupied space is beneficial for being reduced and the BMS performance is more stable.

Description

technical field [0001] The invention relates to the field of relay diagnosis, in particular to a relay fault diagnosis circuit and method. Background technique [0002] With the rapid development of electric vehicles, the performance requirements for the power battery of electric vehicles are becoming more and more stringent, so the fault diagnosis of high voltage relays is becoming more and more important. refer to figure 1 At present, the commonly used method for diagnosing high-voltage relays in the BMS of electric vehicles needs to detect multiple voltage values, and the detection of each voltage value corresponds to an independent voltage detection circuit, such as the internal total voltage detection circuit, external total voltage detection circuit, power battery The voltage detection circuit between the total positive terminal and the negative terminal, the voltage detection circuit between the negative positive terminal and the total negative terminal of the power ...

AI Technical Summary

Problems solved by technology

However, the existing high-voltage relay diagnostic methods can only diagnose that the high-voltage relay is in a sticking state, and cannot accurately diagnose whether the high-voltage relay is in a failure state, and the diagnostic results are not comprehensive, which in turn affects the performance of the BMS

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