High-Efficiency and Low-Cost Tightly Regulated Dual-Output $LLC$ Resonant Converter

A new high-efficiency and cost-effective dual-output LLC resonant converter is proposed in this paper. It can achieve tightly regulated dual-output voltages by using the only one auxiliary switch and pulsewidth modulation IC. Therefore, it features a simpler structure, less mass, and lower cost of production. Furthermore, since all power switches are turned on or off under zero-voltage or zero-current switching, it has several favorable advantages such as high efficiency, low switching loss, and reduced burden on the cooling system. To confirm the operation, validity, and features of the proposed converter, the operational principle, theoretical analysis, design considerations, and experimental results from a 420-W 200-V_dc/50-V_dc prototype applicable to the plasma display panel TV power supply are presented. The prototype shows as high power conversion efficiency as 96.5% at full load condition.