Conduction Mode EMI Issues in SiC Inverter-fed Industrial Motor Drives

Conduction mode Electromagnetic Interference (EMI) noise is categorized into common mode (CM) and differential mode (DM) noise based on their current paths, with a frequency range spanning from 150 kHz to 30 MHz. These noises affect the overall performance, reliability and safety of industrial drives and surrounding equipment. Stringent standards exist to limit the emissions across various sectors, including industrial, automotive, aerospace and military applications. It is well-established that SiC converters offer superior performance and play a significant role in designing compact systems. When SiC inverters are used in applications involving induction motors and BLDC motors, such as electric vehicles and pumping systems, addressing adverse effects like CM/DM EMI issues is crucial. This must be achieved while minimizing weight and volume to fully leverage the benefits of SiC inverter-fed drive systems. 

This talk will begin by introducing the fundamental concepts of conduction mode EMI, its impact on motor drive systems and the methods used for its measurement. We will then delve into three EMI filters with modified designs, aimed at enhancing the performance and reducing the volume for the induction motor drives case. One of the primary challenges we'll address is related to CM inductors, which can occupy a significant portion of the motor drive's space, especially when designed for higher frequencies like 200 kHz. Our modified EMI filters effectively minimize volume, weight and cost while simultaneously improving overall performance.

Furthermore, we will briefly discuss the distinctions in CM EMI issues for BLdc motor drives compared to induction motor cases. This is particularly relevant as BLDC drives are increasingly employed in high-voltage applications exceeding 200 V. This necessitates effective modeling and practical solutions for CM EMI issues specific to BLDC motor drives.