3-Bridge LLC Resonant Converter Capable of Responding to Various Battery Charging Voltages

A novel three-bridge LLC resonant converter with wide output voltage gain characteristics and a control method is proposed in this paper. By adding one more operation mode to the conventional three-bridge LLC resonant converter, the proposed converter can operate in a narrower frequency control range. Moreover, the converter is changed to five operation modes according to the switching pattern of the main switch for wide output voltage control. In each operation mode, frequency modulation is performed to control the output voltage, and morphing control is used to control the stable output voltage in mode transition. This paper presents a three-bridge LLC resonant converter with five operation modes and verifies the validity and applicability of the proposed converter through an experiment using a 6 kW prototype