Fault Diagnosis of Current Sensors for Dual Three-Phase PM Machines Based on Harmonic Current

High reliability is crucial for dual three-phase permanent magnet machines (DTP-PMSM) employed in electric aircraft. However, with the increased phases, more sensors are required, leading to a higher possibility of failures. In this paper, a diagnostic methodology utilizing harmonic currents is proposed to identify the type of current sensor faults. First, the mathematical model and current characteristics of the DTP-PMSM are derived. Then, the diagnosis mechanisms of current sensor faults based on the internal relationship between the harmonic space (x-y) currents and the zero sequence (o1-o2) currents under faulty conditions are thoroughly analyzed, which perform very effectively in discerning subtle fluctuations in current patterns by using the second-order differencing method. Moreover, a flexible threshold-setting method is adopted to enhance the speed of the algorithm without compromising robustness. The effectiveness and speed of the proposed fault diagnosis algorithm are verified through experiments.