Mganetizing Inductor ON/OFF Control for LLC Resonant Converter with Wide Input Voltage Range

Abstract

When applying LLC converter in wide range application, it becomes less attractive due to the sacrifice of magnetizing inductance value, which leads to the increase of circuit current and conduction losses. Meanwhile, wide switching frequency operating range is also required, which makes the magnetic components and gate driver circuitry design complicate. Therefore, in this paper, a magnetizing inductor on/off control strategy is proposed for the LLC resonant converter. By turning on/off the auxiliary magnetizing inductance, the voltage gain range can be extended while maintaining a narrow switching frequency range. In addition, the overall system efficiency can be improved due to the large magnetizing inductance and reduced circulating current. Experiment validation is provided for the proposed topology.