A simple switched capacitor compensator to minimize zero-crossing distortion in single-phase PFC converters

This paper explorers techniques for minimizing zero-crossing distortion in single-phase PFC converters from the angle of topologies. Zero-crossing distortions of typical single-phase PFC topologies are compared in theory to reveal that cusp distortion is predominant responsible for zero-crossing distortion. PWM rectifier with the capability of bi-directional current can minimum and eliminate zero crossing distortion even though there is phase displacement in current loop at the cost of increasing switching loss and larger boost inductor. Then, a simple switched capacitor compensation scheme with low voltage rating switching devices and low switching frequency is presented to minimum zero-crossing distortion. Furthermore, the proposed switched capacitor circuit can be added to existing single-phase PFC converters without modification of original topologies and controllers, hence it is economically feasible. Numerical simulations are given to validate the theoretical analysis and effectiveness of the proposed scheme. With switched capacitor compensator, single-phase PFC converters demonstrate good input performance.