Toyota Motor Corporation, in collaboration with Denso Corporation
(Denso) and Toyota Central R&D Labs., Inc. (Toyota CRDL), has developed a
silicon carbide (SiC) power semiconductor for use in automotive power control
units (PCUs). Toyota will begin test driving vehicles fitted with the new PCUs
on public roads in Japan within a year.
According to a company statement, through use of SiC power
semiconductors, Toyota aims to improve hybrid vehicle (HV) fuel efficiency by
10pc under the Japanese Ministry of Land, Infrastructure, Transport and
Tourism's (MLIT) JC08 test cycle and reduce PCU size by 80 percent compared to
current PCUs with silicon-only power semiconductors.
SiC power semiconductors have low power loss when switching on and
off, allowing for efficient current flow even at higher frequencies. This
enables the coil and capacitor, which account for approximately 40pc of the
size of the PCU, to be reduced in size is what the company claims.
PCUs play an important role in hybrids and other vehicles with an
electrified powertrain: they supply electrical power from the battery to the
motor to control vehicle speed, and also send electricity generated during
deceleration to the battery for storage. However, PCUs account for
approximately 25 percent of the total electrical power loss in HVs, with an
estimated 20 percent of the total loss associated with the power semiconductors
alone. Therefore, a key way to improve fuel efficiency is to improve power semiconductor
efficiency, specifically by reducing resistance experienced by the passing
current. Since launching the “Prius” gasoline-electric HV in 1997, Toyota has
been working on in-house development of power semiconductors and on improving
HV fuel efficiency.
Source: Toyota Motor
Coproration