Coupling Capacitance Characteristics and Design Optimization Method of CT-Type Isolated Power Supply for High-voltage SiC Devices

Gate driver’s isolated power supplies with low coupling capacitance are critically important to reduce the dv/dt noise for high-voltage SiC devices’ applications. This paper investigates coupling capacitance characteristics and proposes an optimal design method for the isolated power supply with the novel current-transformer (CT) structure. Firstly, this paper analyzes the structure of CT-type isolated power supply and establishes a 3D simulation model by ANSYS Q3D. Then influence characteristics of CT-type’s critical parameters, including the magnetic core’s diameter, height, and winding structure, are studied and clarified. The optimization design rule is proposed to minimize the coupling capacitance. Finally, a testbed of a CT-type power supply is established to validate the effectiveness of the theory. Results show that the coupling capacitance of the CT-type power supply can be suppressed to a small value of 0.74 pF, which achieves a 70% reduction compared to commercial isolated power supply RHV3 series.