Fault diagnosis scheme for single and simultaneous open-circuit faults of voltage-source inverters on the basis of fault online simulation

This paper presents a fault online simulation (FOS)-based diagnosis scheme for single and simultaneous open-circuit faults of voltage-source inverters in closed-loop-controlled permanent magnet synchronous motor (PMSM) drive systems. First, the hybrid model (HM) of the motor drive system is established, and the current observer is designed according to the normal HM to detect the fault. This approach can eliminate the effects of speed and load transients and significantly improve the immunity to false alarms. The fault class is then judged according to the current vector phase to reduce the computation load and improve diagnostic reliability. Finally, the fault is isolated on the basis of the FOS technique, the possible fault types are simulated online using the HM, and the simulated residuals between the simulated and measured currents are used for fault isolation. The suggested method avoids extra sensors, is robust to false alarms, and has a relatively fast diagnosis speed. Simulations and experiments validate the proposed diagnosis scheme.