Open-switch fault detection and faulty switch identification of PWM inverter in PMSM drives using DOB based voltage information

In this paper, a disturbance observer (DOB) based open-switch fault detection and faulty switch identification schemes in a permanent magnet synchronous motor (PMSM) drive system are proposed. The proposed scheme is achieved by monitoring the disturbance voltage information based on the DOB. For this purpose, the DOB is implemented at the synchronous reference frame to estimate the voltage disturbances using the system input and output signals where the system inputs are the reference voltages and the system outputs are the inverter output currents. Then, the estimated disturbance voltages are transformed into the phase variables which have important information on the open-switch fault condition. By observing three-phase disturbance voltage information, the open-switch fault detection as well as faulty switch identification algorithms can be effectively realized even if the inverter has multiple (more than one) open-switch faults. Because the proposed fault detecting scheme does not require additional hardware or complex calculations, the proposed scheme can be easily applied to common electric drive systems. The reliability and feasibility of the proposed fault detection and faulty switch identification schemes have been verified through the simulation results under various open-switch fault conditions.