High current power modules for electric vehicles

This paper discusses developments in power module technology suited for electric vehicle traction motor drive applications. These modules must have high current capability, low on-voltage, low switching losses, and be able to withstand a large number of thermal cycles. Advances in silicon IGBT technology has significantly improved their on-voltage and switching characteristics. The typical on-voltage for a state of the art 100 Amp IGBT die is under 2.0 volts. This reduction in on-voltage allows less silicon to be used for a given current and improves efficiency. A low inductance power module has been developed, using a specially designed circuit layout and lead structure, to reduce voltage overshoot during high speed switching. In terms of packaging, metal matrix composite (MMC) technology has been used to greatly improve reliability and design flexibility, without sacrificing thermal performance. In particular, silicon carbide/aluminum (SiC/Al), a moldable MMC whose thermal expansion coefficient can be tailored has been used to design integrated packages that have excellent reliability as compared to copper based power modules.