A single stage three level resonant LLC AC/DC converter

This paper presents a new single stage three level resonant power factor correction AC/DC converter suitable for high power applications (in the order of kilowatts) with a universal input voltage range (90-265Vrms). The proposed topology integrates a boost input current shaper with a half-bridge three-level LLC resonant DC/DC converter. The converter operation is controlled by means of a combination of phase-shift and frequency control. The phase-shift between the switch gate pulses is used to regulate the dc-bus voltage to a specified level for all loading conditions, whereas, frequency control is used to tightly regulate the output voltage. An auxiliary circuit is used in order to balance the voltage across the two debus capacitors. The input inductor operates in discontinuous conduction mode. The effectiveness of the proposed converter is verified for a 2.3kW, 300 kHz converter with an input voltage range of (90-265Vrms) and a DC output voltage of 48V