Linear Modulation Region Expansion Strategy Based on Voltage Vector Angle Regulation for PMSM Drives With Small DC-Link Capacitor

Modulation fluctuations will decrease the linear operation range and cause the reduction of dc-link utilization for reduced dc-link capacitance motor drives. In this article, a novel strategy for expanding the linear modulation region based on voltage vector angle regulation is proposed. The phase relationship between the voltage reference and the dc-link voltage fluctuation is carried out creatively to clarify the reduction of linear modulation margin. Based on the impedance matching method, the linear modulation region can be expanded by reducing the phase differences with the regulation of voltage vector angle. According to parameter and performance analysis of the proposed method, the dc-link utilization can be improved by 13.2%. Experimental results validate that the effectiveness of the proposed method.