Method and device used for detecting inverter fault

The invention discloses a method and a device used for detecting an inverter fault. The method comprises steps that after an inverter in an uncontrollable rectification state arrives a preset time-delay value, an actual current value passing through a supporting capacitor is acquired; the actual current value is compared with a preset current value, and a state value of the actual current passing through the supporting capacitor can be determined; saturation limit integration of the state value is carried out; zero-crossing detection of a result acquired through integration is carried out, and whether the supporting capacitor is in fault is determined on the basis of a detection result. According to the method, only utilizing internal voltage and current sensing devices of an inverter in the prior art, online detection on breakdown meltdown of the supporting capacitor can be realized, early warning can be further realized, and the method is simple and easy to realize.