The fast switching speed of silicon carbide (SiC) MOSFETs has enabled converters to operate at higher switching frequencies with enhanced efficiencies, achieving performance improvement in motor drive systems. However, the high voltage slew rate (dv/dt) due to faster switching speeds results in excessive transient overvoltage at motor terminals, known as the reflected wave phenomenon (RWP). This paper systematically examines the motor terminal overvoltage in cable-fed SiC motor drive systems considering the effects of parasitic elements of SiC MOSFETs and load current during switching transitions. Starting with a half-bridge inverter, the switching transitions are analysed in detail and then extended to three-phase inverters. The theoretical and experimental results show that besides the rising edge of the inverter output waveform, the falling edge also affects the RWP depending on the load current polarity. Also, the motor terminal overvoltage has a non-uniform envelop which depends on the rise/fall switching times of the generated voltages of the SiC inverter, where these times vary with the load current due to the device parasitic capacitance.
|Number of pages||232|
|Publication status||Accepted/In press - 1 May 2020|
|Event||2020 IEEE Energy Conversion Congress and Exposition - Detroit, Michigan, United States|
Duration: 11 Oct 2020 → 15 Oct 2020
Conference number: 12
|Conference||2020 IEEE Energy Conversion Congress and Exposition|
|Period||11/10/20 → 15/10/20|
Zhou, W., Diab, M., & Yuan, X. (Accepted/In press). Impact of Parasitics and Load Current on the Switching Transient Time and Motor Terminal Overvoltage in SiC-Based Drives. 225. Paper presented at 2020 IEEE Energy Conversion Congress and Exposition, Detroit, Michigan, United States.