Virtual Field-Orientated Control for Doubly Salient Electromagnetic Machine with Torque Ripple Reduction

This article proposes a virtual field-oriented control to reduce the torque ripple and improve the torque–ampere ratio of doubly salient electromagnetic machine (DSEM). Since the DSEM adopts stator excitation and the rotor only provides a magnetic circuit, the traditional rotor field-oriented control cannot be directly applied to the DSEM. At the same time, it is challenging to establish the rotor field vector due to the nonsinusoidal excitation back electromotive force (EMF) of DSEM and the influence of reluctance back EMF. In order to address these issues, the virtual rotor field vector (VRFV) is established through the equivalent model of DSEM based on the coordinate transformation theory. The phase of the current vector of DSEM is then oriented based on the phase of VRFV to improve the torque–ampere ratio. At the same time, the amplitude of the current vector is adjusted based on the amplitude of VRFV to reduce the torque ripple caused by the excitation back EMF. Furthermore, the amplitude of VRFV is modified to optimize the amplitude of the current vector, thus reducing the torque ripple caused by the reluctance back EMF. Finally, an experimental 18/12 DSEM system is employed to demonstrate the effectiveness of the proposed method.