Electromagnetic Interference (EMI) in Variable-Speed AC Electric Drives: Mechanisms and Solutions

Abstract

This study investigates the electromagnetic compatibility (EMC) performance of a variable-speed drive (VSD) system in industrial applications, where managing electromagnetic disturbances is crucial for reliable operation. The analysis is structured in two main parts to provide a comprehensive evaluation of the system’s behavior. The first part focuses on characterizing electromagnetic interactions within the complete system by examining electromagnetic disturbance (EMD) spectra and identifying common-mode (CM) propagation paths. A spectral assessment of conducted disturbances enables a detailed understanding of coupling mechanisms, the identification of propagation pathways, and an evaluation of the associated conducted emission risks. This step is essential for determining potential sources of interference and implementing suitable mitigation techniques. The second part quantifies conducted emissions injected into the electrical network, which can affect the performance of surrounding electronic equipment. The proposed model is applied in a structured approach to analyze and mitigate electromagnetic disturbances, with an emphasis on evaluating common-mode current propagation and assessing the influence of individual VSD system modules on EMD generation. To ensure accurate results, various testing conditions and configurations are considered. High-frequency (HF) spectral analysis is conducted over the 50 kHz – 30 MHz frequency range, in compliance with EN 55022 (Class A) normative requirements, ensuring adherence to industry standards and improving system robustness.