Common-mode Noise Suppression by Recovery Charge Difference Compensation in a Balanced Bridgeless PFC

Abstract

Electric vehicles are expected to become popular, and the charger for charging the battery is mounted on the vehicle. The on-board charger consists of a power factor correction (PFC) circuit and a DC/DC converter, and low noise is required to reduce the mass and weight of the noise filter. This paper proposes improvements to the balanced bridgeless PFC circuit for suppressing the common-mode noise. The ground voltage at the load side fluctuates due to the difference in recovery electric charge between the pair of diodes in the rectifying section of the PFC, and the common-mode noise performance deteriorates. By providing a bypass path for recovering the difference in recovery current, it is possible to suppress the common-mode current flowing out to the system power supply side even when the device performance varies. Since the proposed method reduces the common-mode noise by 20dB at 175kHz compared to the conventional balanced bridgeless PFC, it is able to satisfy the CISPR standard with a single common-mode filter.