A Phase Current Reconstruction Method for Open-End Winding Permanent Magnet Synchronous Machine to Reduce Immeasurable Regions of High Modulation

Aiming at improving the accuracy and reliability of the reconstructed current of open-end winding permanent magnet synchronous machine (OEW-PMSM) systems, a phase current reconstruction method of a common dc bus type OEW-PMSM system is proposed to reduce the immeasurable regions of the medium vector modulation method. In the immeasurable regions of high modulation, the reference voltage vector is synthesized by alternating the medium voltage vectors with the same effect and using the large voltage vector as an auxiliary. The alternation of medium voltage vectors can provide sufficient dc bus current sampling time and sampling data for the control system. In high modulation region, the reconstruction of three-phase currents is achieved and the zero sequence current is obtained by using the proposed method. The proposed method can be implemented based on triangular carriers and does not increase the additional times of switch. The unchanged PWM generator facilitates the practical application of this method in digital controllers. Finally, the effectiveness of the proposed method is verified through simulation and experiments, improving the accuracy of the reconstructed current and the reliability of the system.