Industry perspective on power electronics for electric vehicles

Abstract

Driven by the global effort towards reduction of carbon dioxide emissions from cars, the gradual phase out of fuel cars accompanied by the rise of electric vehicles (EVs) has become a megatrend. Despite the rapid growth of electric vehicle markets worldwide, the leading manufacturers recently announced notable price reductions to compete for market shares. From the technology perspective, for fast charging and extended driving range, more electric vehicles now shift to 800-V batteries with the traction inverters based on wide-bandgap SiC, which can lead to higher efficiency and higher power densities compared with the Si counterparts. However, to further reduce the SiC substrate and epitaxy cost remains a challenge. By contrast, for the DC–DC converters and onboard chargers of electric vehicles, the power switches based on GaN enable fast switching, which can significantly reduce the module form factors. However, the high-voltage reliability concerns associated with the heteroepitaxial defects affect the widespread adoption of GaN in electric vehicles. In this Review, we present a comprehensive discussion of the state-of-the-art power electronics for electric vehicles based on Si, SiC and GaN technologies from the device to circuit and module levels. Various competing technologies are evaluated in consideration of not only efficiency but also cost and reliability, which constitute the three main pillars supporting the continuous growth of electric vehicle power electronics. This Review discusses the state-of-the-art power electronics in electric vehicles based on Si, SiC and GaN from an industry perspective, with a particular focus on the module power densities, efficiencies, costs and reliabilities with the 800-V battery.