Keeping up its from-all-angles approach to efficiency, Toyota has found yet another way to eke out up to ten percent more precious MPGs in its hybrid vehicles, this time electronically. The automaker has announced the development of new silicon carbide (SiC) power semiconductors for use in power control units, which it will begin testing on Japanese roads within the next year.
Toyota PCU with silicon power semiconductors
The PCU using the silicon carbide compound offers less electrical resistance, which improves efficiency when passing current between the battery and electric motor. It also loses less power after shutting off, and can operate at a higher frequency. The net power loss of the new PCU is just one-tenth of the current silicone-only version (the latter accounting for 20 percent of total electrical power loss in today's hybrids). The result, so far, is a claimed five-percent improvement in fuel economy in test vehicles, with the potential of ten percent by the time the new SiC power semiconductor comes to market.

Additionally, the carbide wafers allow for smaller a power module, coil and capacitor, thus allowing the entire PCU to be 80 percent smaller (see the side-by-side comparison in the accompanying photo, which you can click to enlarge).

We've got a while to wait before we start to see the carbide technology to start making a real-world impact. Toyota aims to begin using the SiC units in 2020. By then, with improvements in the company's other key efficiency factors - engine technology and aerodynamics - cars like the Prius will likely see significant gains in fuel economy. Read more in the press release below.
Show full PR text
Toyota Develops 'Diamond-like' Computer Chips to Boost Hybrid Mileage

May 20, 2014

Toyota City, Japan – Toyota is using one of the hardest materials in nature after diamonds to develop a semiconductor chip it hopes will improve the fuel efficiency of its hybrids, such as the Prius, by as much at 10 percent. The company and its partners announced today that they have developed a silicon carbide (SiC) power semiconductor for use in automotive power control units. Toyota plans to begin test-driving vehicles with the technology on public roads in Japan within a year. The chips, made from carbide - one of the hardest materials in nature, theoretically have superior characteristics such as one-tenth the electrical power loss and 10 times the drive frequency. Toyota said the chips would also allow it to reduce the size of current automotive power control units by 80 percent. The automaker said it has already achieved a 5 percent improvement in fuel efficiency in test vehicles and aims to commercialize the technology by 2020. The new chips, along with improved engines and aerodynamics, are key steps the company is taking to continue advancing hybrid powertrains, a technology it pioneered nearly 17 years ago.


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    • 1 Second Ago
  • 18 Comments
      danfred311
      • 2 Hours Ago
      This is straight up lies. SiC can reduce switching losses, not conduction losses and there is no effing way it will result in 10% improvement. One a good day, maybe 1%. Maybe. If the old IGBTs were old tech.
      sebringc5
      • 2 Hours Ago
      How about an accurate sidenote. My friend is a longshoreman in Long Beach and he says tons of Hyundais go through there. WHY would they go up to Port Hueneme? All the best, Aaron Lephart smartcar451.com
      Spec
      • 2 Hours Ago
      Improving the power semiconductors will improve ALL electrified vehicles (pure EVs, plug-in hybrids, fuel cell cars, hybrids, etc.). But leave it to Toyota to only talk about it in the context of conventional hybrids.
        Chris M
        • 2 Hours Ago
        @Spec
        Good point. When these new SiC power transistors come on the market, they will find uses in all electrified vehicles, which will be almost all of them. I wouldn't be at all surprised if another EV manufacturer beats Toyota to the market with these. I'm sure Tesla engineers keep up with all the latest improvements to power electronics.
          Rotation
          • 2 Hours Ago
          @Chris M
          They've been on the market for years. Toyota didn't invent them. American company Cree is the largest maker of SiC power components. Have been for years.
      BipDBo
      • 2 Hours Ago
      Toyota's hybrid technology is remarkable. I would have thought any improvements were at very diminishing returns, so I'm surprised that there is such a large potential gain in just one component. They've made such a good technology that it should be offered in all types of vehicles. They first offered it in a simple 2 row commuter (Prius), and the new Prius line are really all the same type of car, simple 2 row commuter. Even the Camry and Avalon are such. Every other hybrid they have that isn't a 2 row commuter is very high priced. The Lexus hybrids aren't exactly cheap and again, they are all 2 row commuters, faster and nicer, but still the same basic type of car. The Highlander is the only exception, being a three row CUV, but it is very pricey with the base model starting at around $42K. I would like to see them branch out and put their hybrid systems in the Sienna minivan and a pickup, likely the Tacoma. With the volume they have on this technology, they should be able to offer it at a fairly low price.
      • 2 Hours Ago
      I have a 2014 Camry hybrid. Love the car, only have 500 miles on it and I am getting 32 mpg already and this is all stop and go driving. Now if I could only get the Bridgestone tires replaced so I don't have vibrations due to them being out of round I will have an almost perfect car.
        mark
        • 2 Hours Ago
        32 mpg is kinda crappy since I speed every where and chirp the tires pulling away from lights and my 09' Camry hybrid is averaging 41 on this tank. Once you learn how to use it to it's max. it's a nice car to drive and actually does decent when it comes to the pump.
        paulwesterberg
        • 2 Hours Ago
        Wow, so people are still impressed by 32mpg? That's so 1999.
        lad
        • 2 Hours Ago
        I guess 32 mpg isn't bad for a "large" car; if you replace the tires go for low-rolling resistance tires and pick up an increase in mpg. Just think what Toyota can do when there's a better battery and it finally comes around to dropping all that Federal funding for the fuel cell nonsense and settles on building a true BEV Prius. Ain't hard, just remove the ICE and install batteries.
          Chris M
          • 2 Hours Ago
          @lad
          Make sure the tires are fully inflated, too. Under-inflation causes a noticeable drop in fuel economy.
      treehugger.inc
      • 2 Hours Ago
      This is a great improvement in efficiency and it will be interesting to see how many patents Toyota has for this. I hope there is a lot of prior art since NASA has been working with this stuff since at least 2007.
      Rotation
      • 2 Hours Ago
      It's silicon, not silicone. And the reason the module can have a smaller inductor (coil) and capacitor is because it can (as mentioned above) operate at a higher frequency. The whole system is acting like a switching power supply (like in your PC power supply) and as such the power conversion is broken down into "bites". It "breaks off a hunk" of input energy, converts it to the desired voltage and moves that hunk out. If it can do this faster, then each hunk becomes smaller. And since you have to store the hunk in the inductor and the capacitor while converting it, those can be smaller with smaller hunks. Oh, and by the way, Toyota didn't come up with this idea, they're just adopting an existing technology. http://www.cree.com/Power
        CeeJayABG
        • 2 Hours Ago
        @Rotation
        "Just adopting existing technology" Rather an understatement, just as Tesla was "just adopting existing" Li-ion 18650 technology. First of all, name a >50kW SiC-based motor drive built in any but experimental/prototype applications. There aren't any that I can find. Even MHI, who MANUFACTURES AND MARKETS SiC devices, has only recently built a prototype integrated Inverter/motor drive for over the road testing, and from their publicity shots it isn't nearly as well-packaged as the Toyota/Denso machine. Secondly, Toyota/Denso aren't just mounting existing devices into a circuit. The result would be unaffordable by production standards. They are cutting chips from the wafer and mounting naked devices into power modules, and doing so in circuit architectures that will exploit all the advantages of the SiC device while addressing the challenges of reducing size of conductors and board layer limitations. This is real production engineering of a much smaller, less expensive, more rugged, and more efficient power electronics hardware. Third, although we can't know it to be certain, the photos released of the Toyota TS040 LeMans series hybrid car systems display some remarkably packaged electric power systems. I suspect the 1st/2nd finish at Silverstone and 1st in Belgium are a preview of just how well the whole SiC thing is going to turn out.. And if you think Cree can do anything like this and make it affordable and sufficiently rugged for the most competitive business on earth -- automotive production -- you may certainly bet on them, as have many disappointed investors who didn't understand CREE is largely a story stock on which one makes money from volatility-driven promises and press releases. Toyota and Denso, OTOH, are the global leaders in vehicle electrification with millions of power electronics-based products on the road.
          CeeJayABG
          • 2 Hours Ago
          @CeeJayABG
          Rotation, I invite you to naked die placement of multi-hundred amp devices, shrink the size of conduction paths carrying these currents while maintaining board integrity in order to achieve a board density higher than extant today, and build these not only with five nines of yield, be my guest. Nobody in the world is doing that, and if you think this is "gobbledygook", you've proven you don't understand the challenge. Good job referencing MHI's link: you proved my point by apparently not reading my challenge: it's a prototype. In fact, MHI has built a prototype MUCH larger than the Toyota /Denso version, and is only now road testing it. Yes, you can buy Cree devices and build a motor drive. And it will cost you much more than extant technology. That's why THEY'RE NOT IN CARS. SiC is not even being used in aerospace yet where the cost basis is 5-10x automotive. None of the muli-tens of kW drives nor the solid-state power distribution assemblies on the F35 or the B787, the two most electric aircraft in production, apply SiC, even though sufficiently large devices were available during detailed design/development. What Toyota/Denso is doing is exploiting the advantages of the technology for volume and performance at a cost affordable to production. To Forum technology hobbyists, that's ho-hum. In the real world of production, it's what makes things actually available.
          Rotation
          • 2 Hours Ago
          @CeeJayABG
          What a bunch of gobbledygook. Who cares if Toyota/Denso are just mounting existing devices in to a circuit? I never said there were. They still didn't invent this. Why you think it's hard to make a motor controller from SiC when Cree offers 1200A/300V half-bridge SiC modules I don't know. Just go get two or more and you can set up your own up to 600HP motor drive (minus a lot of tolerances of course, but I still think you'll eek out more than 50kW). If that's not good enough, you can buy a 60kW one from Mitsubishi. http://www.mitsubishielectric.com/news/2014/0213-d.html Automotive production is not the most competitive business on earth. Give me a break. I do agree CREE is a terrible stock. Not sure where you got the idea I said otherwise. No Toyota is not the global leaders in vehicle electrification anymore. They're a player, sure, but they ceded their leadership role a while back by not significantly advancing beyond the 2nd gen hybrid synergy drive for 8 years now (debuted in 2006).
      Dave
      • 2 Hours Ago
      "The result, so far, is a claimed five-percent improvement in fuel economy in test vehicles, with the potential of ten percent by the time the new SiC power semiconductor comes to market." This is great stuff that appears to have application not only to hybrids but to future BEVs and FCEVs as well. Its great to see how Toyota sweats the details before releasing products.
        Letstakeawalk
        • 2 Hours Ago
        @Dave
        Side note: Hyundai's FCVs have arrived at the Port Hueneme in CA. Customer deliveries should happen within the next few weeks.
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