Open-Phase Fault Control in Open-Winding PMSM System with Common DC Bus

Open-winding permanent magnet synchronous machine (OW-PMSM) with common dc bus has been widely researched for its good performance and strong ability of fault tolerance. This paper presents an open-phase fault control scheme of the OW-PMSM with common dc bus. The voltage vector distribution of the OW-PMSM system under the open-phase state is analyzed and compared with the normal one. Analysis result shows that the number of the voltage vector in the OW-PMSM system under open-phase fault is reduced from 64 to 16. Based on the voltage vector distribution of the fault state, a unified modulation scheme is proposed in this paper, in which two orthogonal voltage vectors are selected to synthesis the reference voltage. Consequently, the sector identification can be avoided and trigonometric function is no longer involved in the modulation process on the fault tolerant control. The arrangement of switching states can be configured universally. Besides, considering the characteristic of the voltage vectors under fault condition, the proposed scheme can also be applied in different fault states, including inverter fault, while no structural modification is required. Simulation results validate that the OW-PMSM can still be well controlled with the proposed method when the open-phase occurs.