Switch Open Fault Detection Method of Asymmetric Six-phase Permanent Magnet Synchronous Motors Using DC-Link Current Ripple Analysis

This paper proposes a switch open fault detection method for a dual three-phase inverter system by using the DC-link current ripple analysis in an asymmetric six-phase permanent magnet synchronous motor (PMSM). When a switch open fault occurs, specific ripple components appear in the DC-link current at either the fundamental or double the fundamental frequency, depending on the type of open fault. To extract these ripple components, the proposed method applies a variable high-pass filter (VHPF), followed by a variable all-pass filter (VAPF) to introduce a 90-degree phase shift and enable peak value estimation. A low-pass filter (LPF) is then used to suppress high-frequency noise, and correlation analysis with phase current signals is conducted to detect the fault. The proposed algorithm requires no additional hardware and has been experimentally validated using a propeller benchmark system. The experimental results demonstrate its effectiveness in identifying not only the occurrence of faults but also the specific faulty phase.