Toyota sees 10 percent better mileage with a new transistor

Bigger ain't better: New PCU left, old PCU right

Bigger ain’t better: New PCU left, old PCU right

Whenever you think that conventional car technology can’t possibly be more improved, there is always a surprising twist that shows that it can. Today, Toyota showed how it will save gas with a better transistor. Using a fancy silicon carbide power semiconductor in the controller of its electrified cars, Toyota aims to improve the fuel efficiency of its hybrids by 10 percent. That’s what Kimimori Hamada, project general manager of Toyota’s electronics development division, told reporters today in Tokyo.  

The wafer

The wafer

Fuel efficiency is all about converting energy into motion instead of heat. In an ICE, a lot of energy is wasted through the radiator and out the exhaust pipe. In an electrified car, be it a hybrid, a BEV, or one of the coming fuel cell vehicles, a lot of power is likewise lost as heat, this time between the cooling fins of the power control unit (PCU.) Toyota figures that 20 percent of the total loss goes on account of power transistors, big chunks of silicone that switch loads of up to 200 amperes, comparable to what runs through the electric panel of a good-sized American house. The Toyota way hates muda, or waste, be it gasoline-powered, or transistorized.

Using silicon carbide transistors, there will be less resistance to the passing current, and more of the energy will be delivered straight to the wheel. At the same time, the packaging size of the PCU will be drastically slimmed down to about one fifth of the current bulky volume. Hamada thinks the technology will be ready for prime-time at around 2020. Until then, the engineer has to battle a nasty enemy: Cost. “The new technology is much more expensive than the old, by an order of magnitude,” Hamada said today. The faster and wider the new technology will be implemented, the cheaper it should get.

Toyota developed the new technology in-house, together with the group’s main parts maker Denso. If other automakers plan to harness the power of the efficient transistor, then they better develop their own. Toyota does not plan to share the semiconductor with other companies, Hamada said.