Fault-tolerant torque control of a three-phase permanent magnet synchronous motor with inter-turn winding short circuit

Abstract

System reliability and fault tolerance are very important features in safety-critical applications with electric motors. An inter-turn winding short circuit is one of the most common fault cases, which makes the fault-tolerant torque control a crucial task. In this paper, a novel fault-tolerant model-based torque control strategy for a three-phase permanent magnet synchronous motor (PMSM) with an inter-turn winding short circuit is proposed. The control scheme has a cascaded structure with a one-step model-predictive control (MPC) in the outer loop and subordinate PI current controllers. The control strategy is based on a magnetic equivalent circuit (MEC) model. Thus, magnetic saturation and non-fundamental wave behavior of the PMSM are systematically taken into account in contrast to existing works on this topic in the literature. The parameters of the inter-turn winding short circuit are identified by a model-based fault-identification method. The high torque control accuracy of the proposed control scheme is proven by a number of different experiments performed on a test stand.