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. The proposed converter can get tightly regulated dual-output voltages by adding only one auxiliary switch and PWM IC to conventional LLC resonant converter. 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 switching (ZVS) or zero-current switching (ZCS), it has several favorable advantages such as high-efficiency, low switching loss, improved electromagnetic interference (EMI), and reduced burden on the cooling system. This paper presents a dual-output LLC resonant converter applicable to the PDP TV power supply. The proposed converter achieves maximum power conversion efficiency of 96.5% at full load condition. The operational principle, theoretical analysis, and design considerations are presented. Also, to confirm the operation, validity and features of the proposed converter, experimental results from a 420W, 200V_dc/50V_dc prototype are presented.