Single-Phase Inverter Scheme for Permanent Magnet Synchronous Motor Drive with Resonant Capacitor

This paper proposes a method of driving a permanent magnet synchronous motor (PMSM) with a single-phase inverter and a capacitor. The proposed system combines variable speed and load control capability of the inverter and phase shift capability of the capacitor to provide high power density. In the system, stator voltages can be boosted above the dc voltage by resonance of stator windings and capacitor. Due to wider available voltage range, the proposed system provides greater maximum power than the conventional three-phase drive. Also, it has wider operating range and reduced torque ripple than existing single-phase drives as power imbalance due to single-phase excitation is mitigated by capacitor. In this paper, operating characteristics and operable area of the proposed drive are analyzed, and a torque control method is proposed to minimize copper losses. The feasibility of the proposed PMSM drive and control method is verified by experiments with a 3.5kW PMSM.