Design of High Power Converter with Single Low Ron Discrete SiC Device

Abstract

With the development of SiC technology, the on-resistance of discrete devices drops rapidly and can potentially replace the expensive power modules in high power converters. Unlike parallel discrete devices or a power module with built-in parallel dies, using a single device does not need to slow down the gate driver speed hence can achieve lower switching loss. However, there are still many challenges that need meticulous design considerations. This paper uses the 1200V TO-247-4 package device as an example to provide detailed guidance on device selection, loop optimization, insulation, thermal management, and mounting. A DC-DC converter design example is given with a very low loop inductance and excellent thermal performance. The air-cooled hardware demonstrates the hardware limitation is around 40kW in an 800V to 470V buck operation. Normalized to the Ron of the two devices used, this demonstrates an extremely high power density figure of merit of PDFOM=87kW/cm2.