Evaluation of Topologies and Active Control Methods for Overvoltage Mitigation in SiC-Based Motor Drives

Silicon-carbide (SiC) based power converters are gaining momentum as a genuine alternative to silicon based counterparts for motor drive applications that require high efficiency, power density, and operating temperatures. However, the motor terminal overvoltage due to the reflected voltage phenomenon across power cables is more pronounced in SiC-based drives due to the fast-switching speeds of SiC power devices. Since the resultant overvoltage has severe effects on motor winding insulation, several approaches have been developed to mitigate the motor terminal overvoltage including passive filtering techniques and active control methods. With passive filters being widely assessed and reviewed, this paper evaluates the effectiveness of the active control methods, including multilevel converters, soft-switching techniques, and modified PWM schemes, in a qualitative and quantitative comparative study. The active control methods, along with the adopted power converter topologies, are assessed considering their effectiveness in motor terminal overvoltage mitigation, component count and rating, power loss, reliability, and pros and cons. Experimental results based on a three-phase 7.5kW induction motor are provided to support the comparative study.