Diagnosis of Open-Phase Faults and High Resistance Connections in Six-Phase PMSM Drives

Although multiphase machines can operate with one or more disabled phases, the diagnosis of an open-phase fault (OPF) is important in order to reconfigure the control strategy. High resistance connection faults (HRCFs) are created by unsecured and damaged connections and if not detected early on can evolve to OPFs. In the case of six-phase machines, currently available diagnostic methods consider that secondary current components are zero in healthy operation. However, control over these current components is necessary to take advantage of the additional degrees of freedom in six-phase machines. Hence, this paper proposes a fault diagnosis method for both OPF and HRCFs for six-phase PMSM drives, which considers the operation of the machine with non-zero references for the secondary current components. The proposed method monitors the mean value of the reference current errors and the second order harmonic of the secondary currents in a synchronous reference frame. The included simulation results, obtained with Matlab/Simulink software, and experimental results demonstrate the effectiveness of the proposed diagnostic method.