Wide output voltage range LLC resonant converter for 800 V electric vehicles battery chargers
摘要
In this paper, a wide voltage gain LLC resonant converter based on topology reconfiguration is proposed. The primary inverter bridge can be configured as a full bridge or a half bridge with topology morphing control. With an added auxiliary switch, the secondary rectifier can be configured as a full bridge rectifier or a voltage doubler rectifier by controlling the auxiliary switch to be always off or on. Moreover, a third rectifier mode is proposed with pulse width modulation (PWM) of the auxiliary switch. Thus, the operation modes are extended with different combinations of primary inverter structures and secondary rectifier structures. The proposed scheme can achieve four times voltage gain expansion with several feasible combinations of operation modes which are suitable for 800 V electric vehicle battery chargers. A detailed analysis on the principles of the third rectifier structure, the voltage gain, and quality factor Q of different operation modes has been presented. Finally, a 1 kW laboratory prototypes with 400 V input and 100 V ~ 900 V output is built to verify the feasibility of the proposed scheme. The efficiencies of two combinations of operations modes are compared. Experimental results show that combination II of operation modes can an achieve a efficiency of more than 96.3% over the whole output voltage range and a 97.6% peak efficiency under a full load.