Dual LC parallel multi-resonant DC-DC converter with wide output-voltage range

Although LLC converters have widespread applications due to their advantages of high efficiency, high power density, and soft switching, in wide voltage gain range applications, a large switching frequency range is inevitably required, which may bring difficulties in converter design and efficiency improvement. In this paper, a dual LC parallel multi-resonant converter (MRC) is introduced. The converter contains two parallel LC resonant branches in the resonant tank, which exhibit the notch filter characteristic on the gain curve. It enables the converter to provide wide voltage gain regulation, soft startup, and overcurrent protection over a limited frequency range. Compared to other five-element MRCs, since the converter provides different current loops for the fundamental wave and the third harmonic to transmit active power, the circulating reactive energy and stress on the resonant components are reduced. Finally, a detailed design procedure for a 3.3 kW converter prototype with an output voltage range of 250-450 V is provided. In this paper, a dual LC parallel multi-resonant converter (MRC) is introduced. The converter contains two parallel LC resonant branches in the resonant tank. It enables the converter to provide wide voltage gain regulation, soft startup, and overcurrent protection over a limited frequency range. image