Analysis and compensation of the output voltage imbalance in a four-switch half-bridge PFC

This paper provides the compensation strategies of the output voltage imbalance on the four-switch half-bridge (HB) power factor corrector (PFC). Conventionally, the imbalance compensation is achieved by PWM switching control in four-switch HB PFC. But, the output voltage imbalance compensation will be failure while the imbalance phenomenon excesses a threshold to limit the load range in the four-switch HB PFC. To enlarge the desired range of load variation, a dc component is injected in the input current to eliminate the output voltage imbalance further as the load varies to be not modulated with conventional PWM. By the integrated control strategy, the results of output voltage imbalance and power factor will be discussed and verified with experiments.