A study of common mode noise current of bridgeless PFC circuit considering voltage change in Y-capacitors

Since the loss of input rectifying diode bridge in the conventional PFC circuit reduces the efficiency, the bridgeless PFC circuit has been proposed. However, the performances of EMC in some bridgeless PFC circuits are unsatisfactory. In order to improve noise performance, the noise mechanism should be investigated as the first step. In this study, common mode noise current of conventional bridge PFC circuit and totem-pole bridgeless PFC circuit have been analyzed considering the voltage change in Y-capacitors. Additionally a method has been proposed to suppress common mode noise current by about 40dB on the totem-pole bridgeless PFC circuit.