Investigating the EMI Mitigation in Power Inverters Using Delay Compensation

Electromagnetic emissions (EME) of electric and electronic units should comply with national and international standards. Software approaches to reduce the conducted EME are preferable, since they do not require additional on-board hardware. Many techniques have been developed, with different levels of efficiency. This work aims to analyze a new software approach to mitigate the conducted emissions of three phase power inverters, focusing on those used to drive brushless DC motors (BLDC). This has been done reducing the conducted Electromagnetic Interferences (EMI) common mode (CM) component through software compensation of parasitic delays. The technique is verified both analytically and experimentally, and its performances have been compared to the Spread Spectrum Modulation (SSM) ones. The proposed approach shows better performances with respect to SSM below 24 MHz. The results confirm the effectiveness of the delay compensation technique in terms of CM conducted emissions reduction. Moreover, the proposed approach has no drawbacks on safety and it does not present reductions in the inverter efficiency.