Relative $\beta$ -Axis Residual Voltage Signal Based Fault Detection for Inverter Switch Open-Circuit Failure

With the ever-increasing application of permanent magnet synchronous machine (PMSM) drives, the requirements for safety and reliability are raised. This article presents a detailed analysis of the open-circuit fault behavior of the inverter power device by comparing the reference voltage and the actual output voltage under both healthy and faulty conditions. The reference voltage is predicted by real-time switching state of inverter power device while the actual output voltage is estimated by a healthy machine model. It is found that the relative β-axis residual voltage of the fault phase remains unchanged during open-circuit fault, however, it is not the case for the healthy phases. This unique fault behavior is exploited for open-circuit fault detection in the PMSM drives. The voltage residuals are used to construct fault indicator and their polarities are employed for fault location identification. Average detection time is 5% electric cycle which is much faster than the existing method. Finally, the effectiveness and robustness of the proposed technique are verified under various load and speed conditions via a triple three-phase PMSM drive.