High-Frequency Model for Analyzing Leakage Currents in Electronic Pole-Changing Induction Motor Drive

This article presents a high-frequency model to analyze leakage current (LC) in electronic-pole-changing (EP-C) induction motor drives (IMDs). LC flows through parasitic capacitances in inverter-fed drive systems, resulting from the equivalent common-mode voltage (E-CMV) generated by the inverter's high-frequency pulsewidth modulation (PWM) strategy. Furthermore, for EP-C operation, different PWM strategies are required to operate IMD in different pole-phase combinations. Additionally, high-frequency LCs contribute to electromagnetic interference in the system. Thus, it becomes essential to analyze in all different IMD's pole-phase combinations. This is because nature of these patterns is critical for both steady-state and pole transition operations in EP-C IMD, as they may lead to drive failure due to the breakdown of parasitic capacitances. Consequently, this article proposes an analysis to examine E-CMV and LC patterns using the switching function concept and a high-frequency IMD model for EP-C IMD operation. Furthermore, this analysis assists in deducing PWM strategies with optimal switching frequency ranges for smoother EP-C operation. To demonstrate the proposed analysis, two pole-phase combinations (3-ϕ, 12-pole, 9-ϕ, 4-pole) in EP-C IMD are considered with different PWM techniques. The analysis is conducted in the ANSYS simulation environment and verified experimentally.