A Novel dv/dt Filter for SiC-Based 2-Level DC-Fed Motor Drive with Long Cables

Wide band gap (WBG) devices represented by silicon carbide (SiC) MOSFET and gallium nitride (GaN) HEMT bring advantages to motor drives, such as high efficiency, small volume and high switching frequency. But the fast switching characteristic will lead to high dv/dt, which may cause insulation breakdown and electromagnetic interference (EMI). In the case of long-term transmission, the motor terminal voltage can reach twice the bus voltage due to voltage reflection, which brings serious threats to the reliability and lifespans of motor drives. In this paper, an LCRL filter is proposed to mitigate the adverse effects caused by the fast switching transience of SiC MOSFET. Compared to conventional LCR filter, adding an inductor in parallel with the resistor can reduce the damping loss of the filter by shunting current. This paper analyzes its various performance and introduces a parameter design method. The proposed filter is compared with conventional dv/dt filter in some respects, such as power loss, the suppression effect of dv/dt, etc. The effectiveness of the proposed filter is verified by a series of experimental results.