Silicon Carbide Tested By Toyota To Save Energy In Its Future Hybrids

Toyota announced it is using one of the hardest materials in nature, silicon carbide, to develop a semiconductor chip it hopes will improve the fuel efficiency of its hybrids, such as the Prius, by as much at 10 percent.

The company and its partners announced May 20 that they have developed a silicon carbide (SiC) power semiconductor for use in automotive power control units (PCUs). Toyota said it plans to begin test-driving vehicles with the technology on public roads in Japan within a year.

Toyota Motor Corporation developed this new power semiconductor in collaboration with Denso Corporation (Denso) and Toyota Central R&D Labs., Inc.

PCUs play an important role in hybrids and other vehicles with an electrified powertrain such as plug-in hybrids and hydrogen fuel cell vehicles: they supply electrical power from the battery to the motor to propel the vehicle, and also send electricity generated during deceleration back to the battery for storage. However, PCUs account for approximately 25 per cent of the total electrical power loss in hybrids, explained Toyota, with an estimated 20 per cent of the total loss associated with the power semiconductors alone.

Left: PCU with silicon power semiconductors (production model) Right: PCU with SiC power semiconductors (future target)

Left: PCU with silicon power semiconductors (production model)
Right: PCU with SiC power semiconductors (future target)

Toyota added the new semiconductor chips would allow it to reduce the size of current automotive PCUs by 80 percent and that it has already achieved a 5 percent improvement in fuel efficiency in test vehicles.  Toyota aims to commercialize the technology by 2020.

As SiC enables higher efficiency than silicon alone, Toyota CRDL and Denso began basic research in the 1980s, with Toyota starting to participate in 2007 to jointly develop SiC semiconductors for practical use.

The company added that in December last year, Toyota established a clean room for dedicated development of SiC semiconductors at its Hirose Plant, which is a facility for research, development and production of devices such as electronic controllers and semiconductors.

In addition to improved engine and aerodynamic performance, Toyota stated it is positioning high efficiency power semiconductors as a key technology for improving fuel efficiency for hybrids and other vehicles with electrified powertrains. Going forward, Toyota said it will continue to boost development activities aimed at early implementation of SiC power semiconductors.

Toyota is exhibiting the technology at the 2014 Automotive Engineering Exposition, held between May 21 and May 23 at the Pacifico Yokohama convention center in Yokohama, Japan.