Single and Multiple Open-Switch Fault Diagnosis in Electric Drives via Zero-Current Interval Analysis

Abstract

In this work, a new and simple method for open-switch fault diagnosis in electric drives based on zero-current detection is proposed. The approach requires only two phase current sensors, with the measured currents being normalized and separated into positive and negative half-cycles. A variable-sample-time moving average is introduced for post-processing the signals. Zero-current interval detection is employed to diagnose both single and multiple open-switch faults. The proposed method was experimentally validated under various fault conditions, including single-switch, crossed-switch, full-leg, and two upper- or lower-switch open-circuit faults. Experimental results demonstrate that, despite its simplicity and ease of implementation, the method reliably detects all single and double open-switch fault scenarios in less than one electrical cycle, across different motor operating conditions.