Precise Correction of Current Zero-Crossing Distortion of Totem Pole PFC Converter

The Totem-pole rectifier working in Continuous Conduction Mode (CCM) suffers the obvious current distortion at the zero-crossing area. The traditional closed-loop current controller design tries to reduce the zero-crossing distortion by making a tradeoff between the low-frequency reference tracking effect and high-frequency disturbance suppression, resulting in the harmonics increase. To solve this problem, this research analyzes the distortion from a different view and proposes the Precise Correction method. The distorted condition of current is extracted in the zero-crossing vicinity. And then an additional nonlinear compensation is added outside the original current control loop, which can eliminate the current distortion without introducing extra harmonics. The proposed control strategy is verified by simulation and experiment. With the Precise Correction method, the current distortion is eliminated and the unity power factor is achieved.