Fuel Efficiency of Toyota Prius Could Increase 10 Percent With New Semiconductor | Edmunds

Fuel Efficiency of Toyota Prius Could Increase 10 Percent With New Semiconductor


Just the Facts:
  • Toyota says it has developed a silicon carbide (SiC) semiconductor that could increase the fuel efficiency of the Toyota Prius and other hybrid vehicles by 10 percent.
  • The new semiconductors will be installed in power control units on hybrid and electric vehicles.
  • SiC semiconductors withstand heat and conduct electrical current much more efficiently than traditional silicon semiconductors.

TOYOTA CITY, Japan — Toyota says it has developed a silicon carbide (SiC) semiconductor for use in automotive power control units that could increase the fuel efficiency of the Toyota Prius and other hybrid vehicles by 10 percent.

The 2014 Toyota Prius returns 51 mpg in city driving and 48 mpg on the highway, according to the EPA.

In a hybrid or electric vehicle, the power control unit (PCU) is responsible for modulating the amount of current going to the motor. Without it, the throttle would simply be an on-and-off switch. The PCU also helps charge the battery by sending it electricity that is generated during braking.

But pushing current through any electrical component results in heat, and heat results in the loss of power. In the case of traditional PCUs, that loss can amount to about 25 percent of the system's total electrical power loss, with an estimated 20 percent of that total attributed directly to conventional semiconductors made of silicon.

Enter the SiC semiconductor.

Although SiC occurs in nature, it is rare, and so it has been synthetically produced for more than a century, primarily for use as an abrasive. Automotive applications include ceramic brakes and clutches, as well as LED lighting and other electrical components.

In electrical devices, SiC's big advantages are that it can withstand higher voltage and suffer considerably less power loss at high temperatures than silicon. Toyota says it believes the switch to SiC semiconductors will result in a PCU that flows current 10 percent more efficiently and is 80 percent smaller than existing versions.

The latest Toyota SiC semiconductors have been developed in conjunction with Denso Corporation. Both companies began experimenting with SiC in the 1980s and have been working together on projects since 2007.

At this point, Toyota has installed the jointly developed SiC PCUs in prototype hybrids and has been driving them on test courses to measure their gains in efficiency. Toyota says it will begin test-driving vehicles outfitted with the new PCUs on public roads in Japan within a year.

Toyota also says it has established a clean room at one of its plants to continue the development of SiC semiconductors and ramp up production of the latest generation of PCUs.

Edmunds says: Toyota is working hard to improve the fuel economy of vehicles like the Prius, something that will benefit consumers who are grappling with high prices at the pump.

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