A novel adaptive SMO-based simultaneous diagnosis method for IGBT open-circuit faults and current sensor incipient faults of inverters in PMSM drives for electric vehicles

Fault diagnosis and identification play a crucial role in ensuring the high reliability of permanent magnet synchronous motor (PMSM) drive systems used in electric vehicles. However, detecting and differentiating insulated gate bipolar transistor (IGBT) open-circuit (OC) faults and current sensor (CS) incipient faults in PMSM drive inverters pose challenges due to their similar effects on phase current distortion. To address this issue, this article proposes a novel diagnosis strategy that enables simultaneous detection of IGBT OC faults and CS incipient faults in inverters of PMSM drives. First, a comprehensive inverter system model is built that incorporates IGBT OC faults and CS incipient faults. Next, to distinguish between these two fault types, the comprehensive inverter system undergoes augmentation and nonsingular coordinate transformation, effectively decoupling it into two subsystems: one exclusively containing IGBT OC faults and the other solely dedicated to CS incipient faults. Subsequently, adaptive sliding mode observers (SMOs) are constructed to accurately estimate the reconfiguration state of each subsystem. Finally, by using observer residuals, fault diagnosis algorithms with adaptive thresholds are proposed to locate defective IGBTs and detail the process of CS from incipient fault to fault or even failure. Experimental results and comparisons validate the rapidity, robustness, and effectiveness of the proposed diagnostic algorithm for simultaneously diagnosing IGBT OC and CS incipient faults.