A Hybrid Control Strategy for Half-bridge Three-level LLC Resonant Converter

Abstract The half-bridge three-level LLC resonant converter uses the resonant process of the inductance and the capacitance to transfer energy. It has the advantages of low voltage stress on the switch and high efficiency, but there are problems such as narrow voltage gain range. To widen the voltage gain range of the converter, a hybrid control strategy for a half-bridge three-level LLC resonant converter is proposed in this paper. The voltage gain of the converter is divided into three gain intervals: low, medium and high. Burst control is used in the low gain interval, phase shift control is adopted in the middle gain interval, and frequency modulation control is adopted in the high gain interval. The experiment results show that the proposed control strategy can realize a wide range of output voltage gain of the converter.