Common-Mode EMI Modeling and Analysis for GaN-Based Full-Bridge CRM PFC under Unipolar PWM Scheme

Abstract

Bridgeless power factor correction (PFC) circuits achieve higher efficiency with less components but generate higher electro-magnetic interference (EMI) noises than conventional boost PFC. This paper firstly introduces a novel control scheme that adopts unipolar double-frequency PWM scheme and critical mode (CRM) operation for single-phase full-bridge PFC rectifier, aiming at increasing power density and efficiency. To evaluate the EMI level of full-bridge PFC with the proposed control scheme, a universal common mode (CM) model is presented and the CM voltage noise equation is derived, which are also applicable to other full-bridge applications under different PWM schemes. Finally, the CM model is employed to compare three configurations of inductor from the EMI point of view for a GaN-based full-bridge PFC.