LC Type dv/dt Filter Design with Clamping Diodes for SiC MOSFET-based Motor Drives

Ultrafast semiconductors such as Silicon Carbide (SiC) and Gallium Nitride (GaN) have enabled the development of highly efficient and compact power electronic systems. These devices have very short rise and fall times, leading to very high rates of change of voltage (dv / dt), which can cause overvoltages in motor drive applications with long cables. This can result in winding insulation failure, bearing failure, increased common mode currents, and Electromagnetic Interference (EMI). Hence, mitigating the harmful effects of switching dv / dt is crucial. This paper presents an improved analysis and design procedure for an LC-type dv / dt filter with a diode clamp at the inverter output to attenuate overvoltages at the motor terminals. The proposed design approach aims to simultaneously minimize the size of the filter inductors as well as the filter losses. The filter's effectiveness is confirmed through switching circuit simulations. A hardware prototype of a 2-level Voltage Source Inverter (VSI) along with an LC-type dv / dt filter with clamping diodes is constructed in the laboratory. Experimental results are presented to showcase the effectiveness of the proposed method.