Rapid Online Fault Diagnosis of High-Resistance Connection in PMSM Drive System through Self-Developed Dynamic Simulation Test System

Abstract

High-resistance connections (HRC) in permanent magnet synchronous motor (PMSM) drive system is a precursor of uncontrollable overheating or fire. However, the current HRC test environment is typically founded on fixed resistors and lacks the capability to simulate the dynamic characteristics of real-world HRC faults in a manner of stepless regulation. To fill the gap, a flexible HRC injection strategy is proposed in this paper. This signal is stimulated by a high-frequency equivalent circuit regulated by closed-loop hardware feedback mechanism, which is then integrated into a self-developed HRC dynamic test system. Meanwhile, to reduce dependence on online resources, a rapid online diagnosis method for detecting HRC in PMSM is proposed. Based on the two-phase current, the negative-sequence currents are calculated and subjected to Fast Fourier Transform analysis, fulfilling the requirements of low computational burden and real-time performance. Furthermore, the fault indicators derived from the mathematical model of PMSM in abc framework are established to detect the HRC fault, obviating the need for additional voltage sensors. Finally, various experiments are conducted under different loads and rotational speeds. The experimental results show that the proposed simulation system can solve the problems of HRC simulation with quick responses, continuous control, and high robustness in high-power circuits. The results also prove that the proposed diagnosis method can not only effectively detect the location of HRC, but also can precisely calculate the resistance.