dv/dt filter design incorporating machine impedance and voltage slew rate for WBG-based electric drives

The trend towards high power density and high reliability of electric drive systems in mobility applications pushes the use of high-speed machine in combination with Wide Band Gap (WBG) power semiconductor technology. Replacement of Si power technology with WBG without mitigating high voltage slew rates dv/dt degrades machine winding insulation. Of the different mitigation techniques employed, especially the passive LCR filter at the output of the inverter cannot be optimally designed without consideration of the inherent low impedance of the high speed machines. This paper presents the analytical techniques used for LCR filter design for motor drives and introduces the technique to incorporate machine impedance Zdm for optimal design of the parameters to achieve high efficiency. An analytical technique based optimization algorithm is introduced for the reduction of filter inductor volume to achieve high power density in these applications. The proposed design methodology is evaluated in simulations and experiments with Gallium Nitride (GaN) based inverter technology.