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Toyota Describes Better Power Chips

May 27, 2014 in Electric Drive, Hybrids, Technology by Rich Piellisch  |  No Comments

Silicon Carbide Units May Boost Vehicle Efficiency by 10%

Silicon carbide power semiconductors for automotive power control units could substantially boost the efficiency of hybrid electric vehicles, says Toyota, citing work by its own Toyota Central R&D Labs and Denso Corp.

Silicon carbide PCUs in lieu of today’s silicon-only units could improve the overall efficiency of hybrid electric vehicles by slashing electrical power loss, Toyota says.

Silicon carbide PCUs in lieu of today’s silicon-only units (left) could improve the overall efficiency of hybrid electric vehicles by slashing electrical power loss, Toyota says.

The automaker is hoping of a gain of 10% as measured under the Japanese Ministry of Land, Infrastructure, Transport and Tourism’s (MLIT) JC08 test cycle. And, PCU size could be reduced by 80% as compared to current units with silicon-only power semiconductors.

“PCUs play an important role in hybrids and other vehicles with an electrified powertrain,” Toyota explains: “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.”

Toyota says it’s been looking into better power control units for hybrid electric vehicles since launching the Prius in 1997.

Toyota says it’s been looking into better power control units for hybrid electric vehicles since launching the Prius in 1997.

‘Reducing Resistance’

But PCUs account for some 25% of the total electrical power loss in HVs, Toyota says, with an estimated 20% of the loss associated with the power semiconductors. “Therefore, a key way to improve fuel efficiency is to improve power semiconductor efficiency, specifically by reducing resistance experienced by the passing current.”

Enter silicon carbide. “SiC power semiconductors have low power loss when switching on and off, allowing for efficient current flow even at higher frequencies,” Toyota says. “This enables the coil and capacitor, which account for approximately 40% of the size of the PCU, to be reduced in size.”

The automaker said it has already achieved a 5% improvement in fuel efficiency in test vehicles and aims to commercialize the technology by 2020.

Toyota says it’s been working on the issue since launching the Prius hybrid in 1997, and that it will begin test driving vehicles fitted with the new PCUs on public roads in Japan within a year.


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Source: Toyota media with Fleets & Fuels follow-up

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