It is said that the new testing
technology in Toyota could make hybrids and other vehicles with electric powertrains more
efficient. Using a "Camry" hybrid
prototype and a fuel cell bus, Toyota Motor Corporation will bring a brand new
technology to the streets of Japan for testing this
year. The yearlong experiment in Japan will judge the performance of the
new power semiconductors that use a silicon carbide (SiC) material, fitted to a
Camry hybrid saloon prototype and a hydrogen fuel cell-powered bus.
Power semiconductors are found in
the power control units that control the motor drive power in hybrids and other
vehicles that use an electric powertrain. These units regulate the use of
electricity, send power from the battery to the motors when the car is being
driven, and recharge the battery with energy that’s accumulated when the car is
stopping or decelerating.
The type of semiconductors used at
present account for about 20% of a vehicle’s electrical losses, therefore
making them more efficient is potentially a good way to increase the efficiency
of the complete powertrain.
If we compare to the current silicon
power semiconductors, the new, high-quality SiC type create less resistance
when electricity flows through them. This technology has been developed
jointly by Toyota, Denso Corporation and Toyota Central R&D Labs, as a
result of an extensive research and development project.
In the hybrid prototype, the
automaker is installing SiC power semiconductors (transistors and diodes) in
the PCU’s internal voltage step up converter and the inverter that controls the
motor. It will collect data, including PCU voltage and current, driving speeds,
patterns and conditions, such as outside temperature.
Comparing this information with data
from the silicon semiconductors now in use, Toyota will evaluate the level of
effectiveness improvement achieved.
The road test will take place mostly
in Toyota City over a period of about a year from
early February.
The information gained from the
tests will be reflected in Toyota ’s development program, with the
goal of putting the technology to practical use as soon as possible.