Synchronous Demodulation of Control Voltages for Stator Interturn Fault Detection in PMSM

In this paper, a new technique for stator winding interturn fault detection in current-controlled permanent magnet synchronous machines is proposed. The method is based on online extraction of the second harmonic component of the voltage reference vector in the dq frame. It will be shown that the amplitude of this harmonic depends on the interturn fault severity and the fault detection is realized by comparing the magnitude of the control voltage second harmonic, derived using a proper time-domain transformation, to a predefined threshold. This is a low-cost method in CPU burden time. The experimental results show the validity of the proposed method.