Three level LLC series resonant DC/DC converter

Paper presents a three level soft switching LLC series resonant DC/DC converter. ZVS is achieved for each main switch without any auxiliary circuit. Voltage stress of each main switch is half of input voltage. ZCS is achieved for rectifier diodes. Wide input/output range can be achieved under low frequency range because of two-stage resonance. Only one magnetic component is needed in this converter. Efficiency is higher in high line input, so this converter is fit for power products with hold up time requirement. The principle of operation and the characteristics of the new converter are analyzed and verified on a 500 V/spl sim/700 V input 54 V/10 A output experimental prototype, whose efficiency is 94.1% at rating condition.