Stator inter-turn fault detection in SPM machines using PWM ripple current measurement

In this presentation, a novel method of inter-turn fault detection based on the measurement of a high-frequency pulse-width modulation (PWM) ripple current is proposed. The method uses the ripple current generated by the inverter itself as a means to detect inter-turn faults. High-frequency impedance behaviours of healthy and faulted windings are analysed and modelled, and the ripple current signature due to inter-turn faults is quantified. A simple analogue circuit is designed to extract the PWM ripple current via an RMS band-pass filter, and the filtered RMS current is used for fault detection. In addition, the method also identifies the faulted phase. The method is tested in simulation on a five-phase alternate slot-wound surface-mounted permanent magnet (SPM) machine.