An Active EMI Filter Using Predictive Pulsed Compensation for Common Mode Noise Suppression of Boost Converters

To suppress the conducted electromagnetic interference (EMI) of power supplies, the passive EMI filter (PEF) composed of inductors and capacitors is usually adopted. However, the large volume of PEF limits the further improvement of power density. This study presents an active EMI filter (AEF) based on predictive pulsed compensation (PPC) to suppress the common mode (CM) noise of boost converters. The proposed AEF is easy to implement and low cost. Its core circuit contains an online adjustable voltage source, a half-bridge driver, and a pair of Y-capacitors. The circuit generates a rectangular pulse with adjustable amplitude to cancel CM noises. Besides, this research contributes by identifying and resolving the challenges that hinder the application of PPC-based AEF to boost converters, including the amplitude, time delay, and edge slope of the pulse. The position order of AEF and PEF is also discussed. A prototype with 48 V input and 100 kHz switching frequency is tested experimentally to verify the proposed AEF. Experimental results show that the proposed AEF achieves a 21 dB reduction in CM noise at 200 kHz and consumes only 45 mW of power. Furthermore, the proposed AEF achieves a 47% reduction in volume compared with the conventional PEF.