Modified Voltage Vector Modulation Strategy for Open-Winding FMDRM Drives With Switching Action Reduction Capable of ZSV Regulation

Thanks to the dc-biased sinusoidal current excitation, the flux modulated doubly-salient reluctance motor (FMDRM) drive is endowed with the zero-sequence voltage (ZSV) regulation ability to achieve dc-biased current control. The open-winding converter with a common dc bus is widely utilized and the ZSV regulation is achieved by redistributing the duration time of zero vectors, which significantly increases the number of switching actions, leading to additional switching losses. To achieve switching action reduction, this article proposes a novel voltage vector modulation strategy for ZSV regulation. According to the contribution to the common-mode voltage, the active vectors are divided into two groups. In addition, the desired ZSV is generated by modifying the duration time of the active vectors instead of zero vectors. Furthermore, two duty ratio calculation methods are put forward with different zero vector arrangements considering voltage stress balance. With the proposed scheme, the switching actions in each cycle can be reduced by at least one-third, which significantly increases the converter efficiency. Moreover, the harmonic regulation ability of the FMDRM drive is not sacrificed, which means that the motor performance will not be affected. Experiments are carried out to verify the effectiveness of the proposed scheme.