One-Chip Active EMI Filter With Integrated Buck Converter and Self-Malfunction Detection for CE Noise Reduction

This article presents an active electromagnetic interference (EMI) filter (AEF) implemented by one chip, including an EMI management-integrated circuit (EMIC) and power-management-integrated circuit (PMIC). The designed IC was fabricated by a 0.18 mu m Biplor-CMOS-DMOS (BCD) process. By virtue of a designed buck converter implemented PMIC within the IC area, the integrated EMIC with PMIC can operate with a 15 to 45 V dc supply as well as a 12 V dc supply to operate EMI noise compensation. Through experimental validation using a real three-phase inverter motor system, the noise attenuation performance of the AEF was found to excel beyond that of a two-stage L-C passive EMI filter, achieving approximately 6 dB improvement at 150 kHz, while exhibiting no resonance peaks above 1 MHz. Further, the AEF effectively maintains the conducted emissions (CE) noise levels below the established CE regulations throughout the entire frequency range. The single-chip design integrates a malfunction detection mechanism that automatically shuts down the dc power supply in the event of an EMIC failure, thus ensuring enhanced safety and practicality.