A model-based buck-type active filter using proportional-resonant controller and GaN HEMTs

To filter the 120Hz output current ripple in our previously designed 7.2kW single-phase EV charger, this paper proposes to equip the charger with a buck-type active filter. 650V/60A enhancement mode GaN HEMTs provided by GaN Systems Inc are adopted to work at hard-switching mode. Experimental results indicated that four such switches could be paralleled to hard switch on/off ~240A, which is the key for the buck-type active filter. A model-based proportional-resonant controller is adopted to smooth the output current. Such control will enhance the dynamic response of the active filter, compared to the conventional PI controller. The experimental output current ripple and power loss analysis are given.