A novel inductively coupled RLC damping scheme for eliminating switching oscillations of SiC MOSFET

Abstract

Abstract Severe switching oscillations of SiC MOSFET seriously affect its efficient and reliable application. Herein, a novel inductively coupled RLC damping scheme is proposed to eliminate switching oscillations. Distinctive from existing RLC resonators, the setting that the resonant frequency of the secondary RLC damping is equal to that of the power loop is abandoned. Additionally, prior‐art analytical techniques of RLC resonators are based on seeking the peak impedance, which considerably undermines its suppression effect. First, a two‐port network is linearized from switching oscillations, where the characteristic equations are deduced. Then, parametric regions where the switching oscillations can be eliminated are determined by actively assigning poles via the root locus method. Consequently, the damping effect of the proposed scheme, as well as the resulted switching losses, shows its superiority over the state‐of‐the‐art snubbers. The proposed scheme is favourable in practical applications since it is less insensitive to parasitics enabling selection of snubber resistors with higher power ratings. It also avoids unusual temperature rise resulted by snubber losses due to oscillation suppression in the power loop as snubber losses are transferred to the secondary circuit. Theoretical analysis and experimental comparisons are conducted to verify the effectiveness of the proposed scheme.

Keywords

• electromagnetic compatibility
• electromagnetic interference
• insulated gate bipolar transistors
• MOSFET
• power convertors
• power electronics