Z-matched Active Common-mode Canceller for the Suppression of Common-mode Current in an Inverter System

Abstract

In a vehicle, radiational noise generated by the common-mode current in an inverter system is the cause of electromagnetic issues affecting in-vehicle radio antennas. This paper proposes a new method “Z-matched ACC” for suppressing the common-mode current at the AM band. Using this method, the exciting current of the common-mode transformer, which reduces the common-mode current suppression effect higher than 100kHz in conventional voltage-cancellation ACC, flows into a Z-matched circuit rather than into a motor parasitic capacitor. Therefore, the Z-matched ACC can suppress the common-mode current at the AM band. The suppression effect of the Z-matched ACC is superior to the conventional ACC from 100kHz to 10MHz. In addition, the Z-matched ACC can reduce the size of the common-mode transformer compared to the conventional ACC by reducing the ET product applied to the common-mode transformer.