Filter Design for $\mathrm{d}v/\mathrm{d}t$ and Leakage Current Reduction in SiC Motor Driving System

The most advanced motor drive inverters are utilizing wide bandgap (WBG) devices, such as silicon carbide (SiC) MOSFETs. These devices offer several advantages, including small size, good thermal conductivity, low on-state resistance, and excellent high-frequency performance. As a result, SiC devices are considered a viable alternative to traditional silicon devices. However, it is crucial to limit the
$\boldsymbol{d}\mathbf{v}/\boldsymbol{d}\mathbf{t}$
and overvoltage on the motor winding within a specific range. The use of SiC devices can lead to increased
$\boldsymbol{d}\mathbf{v}/\boldsymbol{d}\mathbf{t}$
on the motor winding, reaching up to
$\boldsymbol{10}\ \mathbf{kV}/\boldsymbol{\mu}\mathbf{s}$
in certain cases. Additionally, the overvoltage can reach 180% when short cables are employed. Ideally, the
$\boldsymbol{d}\mathbf{v}/\boldsymbol{d}\mathbf{t}$
should be restricted to
$\boldsymbol{2.5}\ \mathbf{kV}/\boldsymbol{\mu}\mathbf{s}$
, and the overvoltage limited to 30%. High
$\boldsymbol{d}\mathbf{v}/\boldsymbol{d}\mathbf{t}$
and overvoltage levels can cause partial discharge and accelerate the aging of the motor's insulation. To address these issues, various approaches can be employed. The simplest and most effective method involves adding a resistor to the gate of the SiC MOSFET to dampen the switching process of the switching tube. This effectively reduces the
$\boldsymbol{d}\mathbf{v}/\boldsymbol{d}\mathbf{t}$
and overvoltage problems. However, this approach comes at the cost of significantly higher losses, and its efficiency may be even lower than that of using traditional IGBTs as a switching tube inverter. Another effective solution is the implementation of a passive filter, which offers simplicity and low losses compared to other methods. The key is to effectively address the
$\boldsymbol{d}\mathbf{v}/\boldsymbol{d}\mathbf{t}$
and overvoltage issues at the motor side. In this paper, a passive LCR filter with a small size is proposed, and its performance is validated on a permanent magnet synchronous motor (PMSM).