A zero-voltage-switching current source inverter with three-stage space vector modulation for low-input voltage stand-alone applications

In this paper, a three-stage space vector pulse width modulation (SVPWM) along with soft switching is proposed for a high-voltage transfer ratio single-stage threephase current-source inverter (HVTR-CSI) to reduce switching losses and improve inverter efficiency. The proposed SVPWM strategy utilizes the conduction state of the energy storage switch as the zero vector and assigning effective vectors action modes. The zero-voltageswitching (ZVS) of the energy storage switch is achieved by resonant parameters and controlling the turn-on time of the active clamp circuit. The circuit topology, operation principle, high-frequency switching process of the studied CSI are thoroughly analyzed, and detailed calculations of the circuit parameters and soft-switching design are performed. Experimental results on a 1 kW 24 VDC/84 VAC 3-phase AC prototype show that the modulation improves the CSI peak efficiency by 1.15% compared to sinusoidal pulse width modulation (SPWM). This study provides an effective design approach for the HVTR-CSI in terms of reducing switching losses.