Introducing a silicon carbide inverter for hybrid electric vehicles

This paper presents a power converter that can be used in hybrid electric vehicle applications. The unique characteristic of this converter is that it is based on silicon carbide (SiC) semiconductors. It is intended for a belt driven alternator and starter (BAS), a design suggested by general motors, in a mild hybrid car. SiC is an innovative technology that seems to have many advantages compared to the silicon that is commonly used today. It is believed that it is going to replace silicon in many applications. The idea to use SiC for a hybrid electric vehicle (HEV) application was born when trying to reduce the size, weight and cost and therefore increase the power density of vehicle´s electronics. The proposed design focuses on the different functions of a BAS and the converter´s behavior in each case. A hybrid vehicle is simulated, functioning accordingly to the BAS design and the power flow over the power semiconductor devices is calculated. The aim of this work is to estimate the converter´s losses over a standard driving cycle and decide if it is possible then to use the combustion engine´s cooling system to cool the semiconductors as well, something obviously impossible when working with silicon semiconductors, as an internal combustion engine (ICE) operates in higher temperatures than silicon can stand.