Experimental Investigation of Common Mode Voltage in 3-Phase 3-Level Induction Motor Controllers

Abstract

Variable AC drives have evolved from manual to automated systems, driven by advancements in power electronics. This technology enables smooth control of induction motors (IM) via power electronics converters. However, these converters can experience periodic faults, often undetected due to their minimal impact on operations. Early detection of these faults is crucial to prevent escalation into severe issues, necessitating real-time monitoring of the entire drive system. This paper presents an experimental investigation on a three-phase, three-level inverter-fed induction motor driving a pump load. Various Impedance Networks (INs) have been designed to mitigate leakage currents and are connected to the inverter circuit. A detailed investigation into system parameters, such as Total Harmonic Distortion (THD) and Common Mode Voltage (CMV), was conducted under different loading conditions to evaluate the inverter's performance. Simulation results and experimental validation confirmed that the proposed Impedance Networks reduced the CMV and current THD to Vdc/4 (up to 75%) and 5.84% respectively in the simulation. In the Hardware set up Current THD has been brought down to 12.7%. They guarantee to effectively enhance the system's power quality, making them suitable for high-power quality applications.