Evaluation of Three Improved Space-Vector-Modulation Strategies for the High-Speed Permanent Magnet Motor Fed by a SiC/Si Hybrid Inverter

The large current ripple caused by the limited switching frequency significantly degrades the control performance of the high-speed permanent magnet motor drive system. To mitigate the current ripple, the switching frequency of the inverter should be high enough. The purpose of this article is to reduce the current ripple of the HSPMSM drive system. First, a Silicon-Carbide/Silicon(SiC/Si) hybrid inverter is designed. The designed hybrid inverter consists of two SiC-MOSFETs and six Si-IGBTs, and the circuit modals of the SiC/Si hybrid inverter are analyzed. Second, based on the SiC/Si hybrid inverter, three improved space-vector-modulation (SVM) strategies are proposed. The core principle of the proposed SVM strategies is that most of the switching actions are transferred from the Si-IGBTs to the SiC-MOSFETs. The benefit from the low switching loss of the SiC device is that the total power loss can be significantly reduced. Besides, the SiC-MOSFETs can create the zero-voltage-switch condition for the Si-IGBTs, and then the switching loss of the Si-IGBTs can be almost eliminated. Finally, to verify the effectiveness of the proposed methods, sufficient simulations and experiments are implemented. The stator current ripple, total-harmonic-distortion, and the conversion efficiency of the inverter in the full power range are compared under the same condition based on the full-Si-IGBT inverter, the full-SiC-MOSFET inverter, and the SiC/Si hybrid inverter. The evaluated results sufficiently verify the superiority of the proposed SiC/Si hybrid inverter and the improved SVM strategies.