Efficient Design Method for an FF-CSCC Active EMI Filter for High-Noise Inverter-Fed Motor Drives

Abstract

This paper presents an efficient design guideline for feedforward current-sensing current-compensation (FF-CSCC) active electromagnetic interference (EMI) filters targeting high-noise inverter-fed motor drives. Shielded cables between an inverter and motor can significantly increase conducted emission (CE). Under high-noise conditions, the current amplifiers used in an active EMI filter (AEF) lead to performance degradation due to reduced current gain. To prevent this, an effective mitigation strategy is to employ multiple parallel AEF modules. However, inverter-fed motor drives operate at a fundamental switching frequency lower than the CE regulation band, resulting in inefficient compensation of signals that do not require attenuation. To address this, this paper introduces a high-pass filter (HPF) at the sensing stage to block irrelevant low-frequency components. Although the HPF effectively attenuates low-frequency noise, it also causes phase leading, which degrades AEF performance. To compensate for this and improve performance, it also proposes a phase compensation circuit (PCC). Experimental results confirm that the proposed HPF and PCC significantly reduce the number of AEF modules required for CE compliance.