Investigation of Radiative Interference in Variable-Frequency Drives (VFD)

Alternating current (AC) motor applications are commonly controlled using variable-frequency drives (VFDs), which provide benefits such as enhanced system controllability and improved energy efficiency. Despite these advantages, VFDs are associated with challenges, particularly the generation of electromagnetic interference (EMI). This study examines the radiative EMI characteristics of VFDs and evaluates straightforward technical solutions, with a primary emphasis on shielding techniques, to mitigate their impact. For a low-power VFD, a test system was specifically designed for this investigation. The analysis revealed that the most significant broadband EMI emissions originated from the motor cable and the VFD unit itself. By implementing appropriate shielding strategies, we substantially reduced the EMI signal strength, with some cases demonstrating complete suppression. Furthermore, this experimental setup will serve as a practical component in laboratory exercises for undergraduate students, offering hands-on experience with EMI analysis and mitigation methodologies.