Analysis and Design of Modified Half-Bridge Series-Resonant Inverter With DC-Link Neutral-Point-Clamped Cell

In this paper, a modified half-bridge (HB) resonant inverter topology with a dc-link neutral-point-clamped cell is proposed. A pseudo asymmetrical voltage-cancellation PWM method and a control strategy are introduced. The proposed topology can maximize the inverter output power factor, and minimize variations in the switching frequency. In addition, most switches are clamped to half of the dc input voltage at turn-off, increasing the overall efficiency of the system for a wide load range. The efficiency of the proposed inverter is improved up to 7% at light-load conditions compared with that of the conventional HB inverter. Informative expressions for performance comparison between the proposed inverter and its counterpart are provided. In addition, the losses in the inverter primary components are analytically analyzed in detail. For validation, a 120-W prototype is implemented, and experimental results are presented.