A Flux−Linkage Torque Ripple Suppression Method of Dual−Series FPMSMs Decoupling Control Based on Dual−Frequency Vector Modulation

Abstract

A novel cross−series connection of two five−phase permanent magnet synchronous motors (FPMSM) supplied by single inverter can halve the number of required power units and current sensors. This, along with a decoupling control strategy for FPMSMs in series based on an improved dual−frequency vector modulation (DFV−SVPWM) and a flux−linkage torque ripple suppression method with current compensation are proposed in this paper, each of which have great significance for multi−unit industrial equipment. The third harmonic flux−linkage will produce torque ripple in the FPMSM in series, which has an adverse effect on accuracy. In this paper, a synchronous decoupling mathematical model of dual−series FPMSM with harmonic flux−linkage is established to analyze the decoupling relationship between torque and current. In addition, an enhanced DFV−SVPWM with higher modulation ratio is proposed for the decoupling control of double motors in series. Furthermore, based on the torque influence of two series−connected motors by harmonic flux−linkage and the decoupling control with improved DFV−SVPWM, a torque ripple compensation method with current compensation is proposed, which can effectively suppress the torque ripple of FPMSM with harmonic flux−linkage and not affect the other. The correctness and superiority of the scheme are verified by simulation and experiment in this paper.