Reflected Wave Challenges and Mitigation in 2L SiC Motor Drives: Cable Modeling and Split-Phase Topology

Abstract: The fast-switching (high dv/dt) capability of wide band gap (WBG) power devices, such as silicon carbide (SiC), has enabled the development of high-efficiency and compact motor drives. However, high dv/dt brings concern of exacerbated reflected wave phenomenon (RWP) in cable-connected motor drives. RWP causes motor-side overvoltage and drive-side overcurrent, stressing motor winding insulation and power devices, ultimately lowering system reliability.

From the perspective of RWP modeling, high dv/dt implies high-spectral content at high frequency (HF) and necessitates length-extendable HF cable modeling for accurate prediction of RWP transients. Furthermore, for RWP suppression, particularly in two-level (2L) drives, it is desirable to utilize a SiC-based topology with a simple structure and lower control complexity, which provides enhanced RWP mitigation while maintaining high efficiency.

In line with these objectives, this webinar introduces a cable modeling approach that encompasses the characterization of HF phenomena, including skin and proximity effects, mutual coupling, and common mode (CM) parasitic elements. The proposed modeling approach also addresses the impact of infrastructural parasitics and unavoidable additional impedance networks, such as lead wires, on RWP. A software package has been developed to facilitate fast cable model generation from measured impedance data. Following the cable modeling, the webinar delves into a brief overview of RWP mitigation techniques and evaluation of 2L Split-Phase topology as a feasible alternative to the standard 2L topology with an output reactor for enhanced RWP mitigation in 2L SiC-based motor drives.