Description

This paper presents a pulse width modulation (PWM) controlled series resonant converter for a universal EV charger. This work focuses on boost mode of a series resonant converter. By adapting two PWM boost switches with full bridge rectifier, it is possible for a series resonant converter to cover a very wide range of gain with a high and flat efficiency curve. As the output voltage increases, the secondary side rectifier of the proposed converter gradually converts from a full bridge rectifier to a voltage doubler rectifier. Since the switching frequency is fixed to the resonant frequency in boost mode, the proposed converter naturally achieves “two peak efficiency points” with full bridge and voltage doubler rectifiers. Two peak efficiency points limit the efficiency drop over a wide range of gain, and that is the reason the proposed converter achieves a high and flat efficiency curve. The effectiveness of the proposed converter and control has been verified on an 800 V input and 200–950 V/3.3 kW output prototype.