A Phase Control Method for Electrolytic Capacitor-less IPMSM Drive System Based on Phase-locked Loop

In an electrolytic capacitor-less motor drive system, a film capacitor replaces the electrolytic capacitor in the dc-link. As the capacitance decreases, the inverter output power can directly affect the grid input power. However, the capacitor causes the grid current to lead to the grid voltage. To handle this problem, the power relationships among the capacitor, the inverter output, and the grid input are analyzed. A novel q-axis current reference method is proposed. Moreover, a phase feedback controller has been implemented to eliminate the phase error between the fundamental component of the grid voltage and current. From the simulation results, the effectiveness of the proposed method has been verified. The proposed method improves the displacement power factor, and the total power factor is up to 98% under each work condition.