High current and thermal transient design of a SiC SSPC for aircraft application

Solid-State Power Controllers (SSPCs) are critical components in the development of electric aircraft and must be small in size, fast in response, and have high reliability. The development of Silicon Carbide (SiC) semiconductor switches provides a series of improvements for the SSPCs in both electrical and thermal performances. In the proposed SSPC design, SiC MOSFETs die are mounted on cast-aluminum traces, under which are an aluminum nitride (AlN) layer and an aluminum composite baseplate. The concept of i²t and its application in solid state protection is discussed. Transient thermal characterizations of SiC MOSFETs are provided on this nearly-all-aluminum package by Finite Element Analysis (FEA). Electrical experiments are combined to demonstrate critical transient thermal performance of a 120A-nominal/1200A-fault, 320Vdc SSPC designed for 350°C SiC transient junction temperature.