Design, implementation and analysis of an advanced digital controller for active virtual ground-bridgeless PFC

The paper presents a new digital control scheme for Active Virtual Ground-Bridgeless PFC (AVG-BPFC) in electric vehicle wireless charging application which is able to suppress the common-mode (CM) voltage induced from the conventional BPFC, where the best optimized solution between the system efficiency and Electromagnetic Interference (EMI) performance in the PFC state can be obtained. However, a resonant characteristic will be presented in the current waveform due to the converter form a LCL filter structure. It leads the controller design in the AVG-BPFC to become challenge. Thus, a triple loop control's architecture is proposed where inner loop is designed with boundary controller to eliminate the filter resonance and to control the AC voltage. In the mid-loop, deadbeat controller is applied to maximize the power quality by offering a precise current tracking function. A PI controller is adopted in the outer loop to regulate the output voltage. Such control scheme is implemented digitally on a 1.5 kW prototype. In the paper, theoretical models of the whole system are analyzed and the system performance is successfully verified in both of the steady state and transient state conditions. The experimental results show a good agreement with the theoretical knowledge.