Evaluation of TCM and CrCM modulation for Totem Pole PFC

Recently totem pole FPC becomes popular due to the minimum component number and less common mode EMI noise. With the availability of GaN switches, high frequency switching is applied in totem pole PFC to achieve high power density. Triangular Current Mode (TCM) and Critical Current Mode (CrCM) modulation minimize switching loss and are good for high frequency. In this paper, two modulations are evaluated. Simulation results show CrCM is simple for implementation but does not achieve Zero Voltage Switching (ZVS) in full range with wide frequency variation at different load conditions; while TCM requires complex calculation for on/off timings to ensure ZVS at full range with narrow frequency variation. CrCM has higher THD than TCM due to discontinuous input current. Power switches loss is measured in simulation by Simetrix. Device with lower Qoss is preferred.