Overvoltage Stress on AC Motor Winding Insulations Driven by Fast-Switching Inverters: A Study

This paper reviews the high-frequency overvoltage challenges in SiC-based motor drives, focusing on two major issues: the overvoltage caused by reflected waves when a motor is fed through a long cable by an inverter, and the uneven voltage distribution across the stator windings, which both stresses the turn-to-turn insulation. This paper categorizes various passive and active mitigation techniques reported in the literature to address these challenges. Key approaches, including passive and active dv/dt filters, are analyzed for their effectiveness in reducing dv/dt, mitigating overvoltage, and enhancing the reliability of electric motors. The paper also presents experimental results, highlighting the challenges, complexities, limitations, and tradeoffs associated with each technique.

I. Introduction

As the trend toward electrification accelerates, power converters used in applications such as electric shipboards, electric vehicles (EVs), and aircraft must deliver high performance while becoming more compact [1]-[3]. Power transistors are crucial in determining both the size and efficiency of a power converter. Over the past decade, wide bandgap (WBG) power transistors, e.g., gallium nitride (GaN) and silicon carbide (SiC) metal–oxide–semiconductor field-effect transistor (MOSFET), have seen widespread adoption due to their advantages, including faster switching speeds, higher voltage-blocking capabilities, and the ability to operate at higher temperatures compared to their silicon (Si) counterparts. These benefits result in enhanced efficiency and performance, as well as a reduction in the size and weight of passive components and cooling systems within the power converters [4], [5].