Optimal torque control with radial force compensation for multiphase PMSMs under an open-circuit fault

Abstract

Open-circuit (OC) faults of permanent magnet synchronous machines (PMSM) yield deviations from the desired torque and result in undesired radial forces, which cause vibrations and noise. Multiphase PMSMs give additional degrees of freedom for the control of the machine, which allow to (partially) mitigate the impacts of an OC fault. Therefore, a fault-tolerant control strategy with radial force compensation under single open-circuit (OC) faults is developed in this paper for multiphase PMSMs. It is based on a magnetic equivalent circuit (MEC) model, which ensures a high model accuracy even for motors with non-fundamental wave behavior and magnetic saturation, and which is applicable to arbitrary multiphase PMSM designs both for the healthy-circuit (HC) and the OC fault case. The proposed method allows to minimize the torque tracking error, the power losses and the radial forces. The results of the proposed fault-tolerant control strategy, which are presented for an experimentally validated model, prove that almost complete mitigation of an OC fault is possible.