A simple open-switch fault detection and diagnosis method for permanent magnet synchronous machines drive system based on DC-link current

In the industry, there is still a substantial amount of old in-service equipment without a fault warning function. To provide an effective fault monitoring scheme for the in-service motor drive system inside the equipment, this paper proposes a fault diagnosis method based on the DC-link current at the power side, which can complete the fault monitoring task only outside the equipment without disassembly and assembly of the equipment and the inside installation of sensors. The effect of open-circuit faults on DC-link current is thoroughly examined and classified into four classes. To locate the faulty switching component of voltage-source-inverter (VSI), one electric period of DC-link current is split into six regions according to the current vector position. And the relationship between current vector regions, fault signatures, and fault locations is summarized. Additionally, a low-pass filter is used to smooth the DC-link current and reduce the bandwidth limit of current sensors. Open circuit faults can be detected and located by identifying the fault signature in the DC-link current and rotor position. Finally, the effectiveness and robustness of the proposed method are verified by experiment results.