New Semiconductor Could Improve Vehicle Fuel Economy By 10 Percent

cartechboy writes: "Automakers are scrambling to increase vehicle fuel economy every year as regulations increase, so when an automaker finds a way to possibly increase fuel economy by 10 percent with one new part, that gets some attention. Today that automaker is Toyota, and the part is a new semiconductor. Toyota's power control units (PCU) in its hybrids use semiconductors to govern the flow of electricity between the battery and the electric motor. Unfortunately, they're also an electrically restrictive component. Toyota says the PCU accounts for a quarter of the total electrical power losses in a hybrid drive system, and semiconductors alone make up a full fifth of the total. Reduce electrical losses through a semiconductor, and you can make your hybrid system (and therefore your car) more efficient. Toyota has done this, in theory at least, using a new silicon carbide material for its semiconductors, rather than a standard silicon unit. The future could be shaped by individual parts, and this new semiconductor tech is one piece of that puzzle."

Comments

Fuel economy?

[Anonymous Coward]

The summary makes it sound more like electricity economy.

Re:Fuel economy?

[ShanghaiBill]

The summary makes it sound more like electricity economy.

The article isn't any better. It is so badly written that I can't really tell what they are trying to say. I think they have reduced electrical losses by 10%, which is totally different from increasing efficiency by 10%. I believe that most electric vehicles are already over 90% efficient, so increasing that by 10% would be almost impossible.

Re:Fuel economy?

[bzipitidoo]

10%+ increase in efficiency gets automakers' attention? No it doesn't.

If they were really serious about fuel economy, they'd go to work on the aerdynamics for starters. Current vehicles have far too much air resistance. And actually they know this. They don't improve the aerodynamics for several reasons. They're afraid the public will think it ugly, and they think it will cost more to manufacture. One of the simplest improvements are skirts for the rear wheels. Every time it's been tried, the public rejects it. Another easy improvement is smoothing the underside. But that costs more, and not just during manufacturing. It also increases maintenance costs as it's one more item that has to be removed to service much of the car.

Re:Fuel economy?

[Iniamyen]

Electric vehicles are nowhere near 90% efficient. Keep in mind this includes more than the electric motor efficiency (some electric motors may be 90% efficient.)

Re:Fuel economy?

[SydShamino]

Well, the products do have to sell, and as you point out they have tried.

Given that rear-view cameras are soon mandatory, some automakers have asked to replace side mirrors with cameras, too. Maybe the public won't reject this and it will greatly help with aerodynamics.

Re:Fuel economy?

[dyslexicbunny]

Yep. Unlike aircraft, there just isn't a significant desire by the auto manufacturers to really get serious about drag reduction. It's really a shame too since things like wheel skirts are really simple.

I think part of the problem is that they intentionally put them on the most unconventional looking cars just to help ensure they don't sell because people are hesitant to significant change. I'd rather they step up and tell people how much fuel that would save with them on and what that would cost annually. And have it as a package you can put on at the dealership.

Re:Fuel economy?

[Bengie]

Most electric motors above 125hp have a "Minimum Nominal Efficiency" of 92% and higher. According to this quick Google result: http://www.engineeringtoolbox....

Re:Fuel economy?

[Anonymous Coward]

What good would rear skirts be if no one wants to buy them and/or remove them?

Re:Fuel economy?

[ArcadeMan]

I prefer mp4...

Re:Fuel economy?

[Iniamyen]

This is not the same as the vehicle's overall efficiency. Batteries and drivetrains are nowhere near 90% efficient.

Re:Fuel economy?

[Anonymous Coward]

So, if they increase it by another 10% with another advance, I should expect to see gas to be overflowing out the fuel filler door?

(I wish...)

Re:Fuel economy?

[ShanghaiBill]

Tesla claims an overall efficiency of 88% for their cars, from grid to wheels.

Re:Fuel economy?

[LordLimecat]

Any hard numbers on how much skirts would help? Because when I check how much "opening windows @ 55mph" vs "closed windows" affects my mileage, I cannot find any measurable difference (as measured my an OBD2 scanner). I get the impression that there just arent that many significant gains to be had in aerodynamics.

Re:Fuel economy?

[Iniamyen]

This is pretty interesting, but it's not clear exactly what that 88% represents. I'm not sure what "overall drive efficiency" is. They put a picture above the 88% figure that has elements that probably aren't in the "drive efficiency" number -- misleading at best. It probably doesn't count the grid->battery efficiency (why else would they include the word "drive"?)

Re:Fuel economy?

[kybred]

I'm waiting for someone to make the Mythbuster's Dimpled Car. They got nearly 10% better MPG in their test.

Re:Fuel economy?

[calidoscope]

The benefits in the modest increase in efficiency are not so much from reduced energy usage, but the higher efficiency reduces the amount of waste heat that has to be removed from the PCU. The higher junction temperatures allowable with SiC makes the cooling task even easier. What has Toyota excited is that the PCU with SiC is much smaller than the PCU with standard silicon power devices.

Re:Fuel economy?

[bzipitidoo]

Here are some hard numbers: the Aerocivic. With home made modifications to the shape, this guy doubled the fuel economy of an ordinary Honda Civic, from its pretty good factory rating of about 47 mpg to 95 mpg.

Re:Fuel economy?

[jrumney]

In a hybrid, improved electrical economy is improved fuel economy.

Re:Fuel economy?

[bzipitidoo]

Yes, dimples work. Dimples are one kind of vortex generator. But, a golf ball has to have dimples all over it because it tumbles. On a car, vortex generators are best on trailing edges only. Likely Mythbusters would have gotten even better fuel economy if they'd used dimples only in the right places. The Corbin Motors Sparrow had some. There are also vortex generators intended to be added to the sides and tops of truck trailers, at the rear edge.

Re:Fuel economy?

[davester666]

I don't know where they get the "10%" from.

TFS states:
1. "Toyota's power control units (PCU) in its hybrids use semiconductors to govern the flow of electricity between the battery and the electric motor."
2. "Toyota says the PCU accounts for a quarter of the total electrical power losses in a hybrid drive system, and semiconductors alone make up a full fifth of the total."

So, "a quarter" = 25%, and 1/5 of 25% is....5%

Re:Fuel economy?

[tomhath]

The numbers you quote aren't quite right (his highway mileage with 10% ethanol gas is mid-60s), and he also replaced the engine to get some of that improvement. But overall it seems he did reduce wind drag by a lot. Boxy SUVs are especially bad in that regard.

Re:Fuel economy?

[AmiMoJo]

They couldn't dimple the entire car body for safety reasons, unfortunately. The bonnet (er... hood) in particular has to be fairly flexible and smooth that if you hit a pedestrian their skull isn't smashed when their head hits it. Maybe the doors and roof would be okay though.

Re:Fuel economy?

[Cyberax]

88% efficiency means that out of every 1KWt*hr you pull from your outlet, 0.88KWt*Hr will be used to propel the car. And it's the TOTAL efficiency, including the battery charging overhead.

I have a Chevy Volt with 10.5KWt*hr of battery storage, it takes about 11.2KWt*Hr to charge it completely. So we're talking about ~5% loss during the charging. With other losses in the high-voltage system, the 88% figure seems believable.

Re:Fuel economy?

[Anonymous Coward]

We are talking about Toyota caring about the Prius, which already has a 0.25 Cd, damn low by car standards. Yes, for the typical car (Crown Victoria) you are correct (0.33 Cd), but it seems that your argument is a bit misdirected in this case.

Re:Fuel economy?

[Shalhav]

There may not be a significant desire by consumers to get serious about drag reduction. If the desire was serious, carmakers would hardly refuse the money for changing their aerodynamics.

I think part of the problem is that they intentionally put them on the most unconventional looking cars just to help ensure they don't sell

Hmmm .... I could MAYBE see that, if they are forced to sell them at a loss, or if they didn't want consumer's money. But really, I think you are ignoring half the equation: consumers want all of these at once: Cheap, aerodynamic, acceleration, space, speed, good looks, low maintenance costs, longevity. If they want a thing enough, they have to pay for it. Auto labor unions ARE a factor outside buying and selling, though. Japanese companies don't have the legacy of a mafia-like organization forcing workers to fork over dues and making the companies accept less productivity on top of it. Small wonder American employees who have any vision for the future prefer working for them.

Re:Fuel economy?

[stoatwblr]

Air resistance isn't a major issue until you hit about 45mph. The vast majority of the world's motoring fleet spends the vast majority of its time well below that speed (which isn't to say the gains aren't worthwhile above that speed, but there are better targets to aim for)

Modifications which improve efficiency at low speeds and in stop-start traffic have the greatest overall effect.

Re:Fuel economy?

[bzipitidoo]

Circumstances are changing. The way our road system and automobiles work now, yes, efficiency at low speeds is more important. But improvements to combustion engines won't amount to much if we all end up switching to electric cars as I think likely in the next few decades. However, aerodynamics will still be important. Going electric will address the issue of low speed efficiency so well that we'll have to look elsewhere for improvements. Being able to shut down while waiting at a red light is a huge gain, and electric motors can handle that easily.

Another definite possibility is switching to driverless cars, and the removal of all traffic lights as such cars would coordinate so well with each other that lights would no longer be needed. We'd be traveling around faster, and that would of course make aerodynamics more important.

Only way aerodynamics won't matter is if we travel in a vacuum, and that's not too likely any time soon. Can't see the gains of enclosing a highway in an airtight tube and pumping out all the air as ever more than the costs of building and maintaining it and equipping cars with pressurized cabins and fresh air. Might compromise and go with reduced air pressure, but then aerodynamics would still matter.

Re:Fuel economy?

[AutodidactLabrat]

Instead of a Union, the Japanese have a corporate Lord who directs everything for the benefit of said Lord, like workers living 7 to a bungalow, sleeping under desks (normal behavior), mandatory FREE overtime.
Small investors ripped off via Land-value swaps and Mafia style Keiritsu,
Capitalism without remorse.
Otherwise known as Mafia

hmm, sounds like a piece of Koch Brother's Wet Dream America

Unexpected bonus:

[Anonymous Coward]

And it's hard as hell, practically indestructible. Toyota is considering integrating automotive black boxes into this component as well.

Straight to the point:

[Anonymous Coward]

Are these SiCFETS with lower R(on), or improved SiC IGBTs, or what?
I wouldn't think so, because silicon carbide transistors isn't brand spanking new, unless you count a few years old as new.

Re:Straight to the point:

[jonsmirl]

Amazingly content free press release. No clue what these devices are. This is just fluff reporting with no details.

Re:Straight to the point:

[joe_frisch]

SiC FETS and IGBTs have been around for a while from Cree and other vendors.

I'm really surprised that they can get a 10% improvement in overall efficiency from this. I would have thought that the switching electronics was already in the 90% efficiency range, and SiC isn't going to reduce the losses to 0.

The article says that the switchers are 20% of the LOSSES, not 20% of the power. I hope they losses are not 50% (!!!!!)

Maybe they meant that the switching LOSSES would be reduced by 10% - that I believe. That's a nice improvement, but a BIG difference from a 10% mileage improvement.

Re:Straight to the point:

[BronsCon]

I think the article (and by transition, the summary) inverted the terminology, in which case, a 10% reduction in losses is a 10% of 10%, or a 1% improvement in efficiency.

Re:Straight to the point:

[avandesande]

Perfect for /. No point in RTFA....

Re:Straight to the point:

[Anonymous Coward]

Pretty straight forward in the summary: Silicon carbide power switching components seem to be more efficient than current silicon parts - somebody made up some impressive numbers to get their funding extended, we'll be hearing more in a year or two whether or not this is actually worth anything.

Any word on the source of the SiC?

[jeffb (2.718)]

My favorite local semiconductor manufacturer produces SiC wafers (and power components), and has seen a nice stock-price bump over the last day or two. Wonder if it's related to this news?

Re:Any word on the source of the SiC?

[Mordok-DestroyerOfWo]

[foxworthy]
If you have a favorite local semiconductor manufacturer, you might be a /.er
[/foxworthy]

Re:Any word on the source of the SiC?

[Anonymous Coward]

i can't imagine hearing fox news talk about semi conductors.

[em] how is this worthy of fox? [/em]

Re:Any word on the source of the SiC?

[fyngyrz]

you are.... unworthy

Re:Any word on the source of the SiC?

[Anonymous Coward]

Skip to 3:30

Individual parts

[DM9290]

"The future could be shaped by individual parts, and this new semiconductor tech is one piece of that puzzle.""

Apart for the fact that this new semiconductor tech isn't an individual part, then sure.

Why not use this in an all electric car?

[Anonymous Coward]

Wouldn't this be also an all electric car improvement as well?

Is that news ?

[Anonymous Coward]

I guess just everyone which is somewhat involved in high voltage DC electric engine control (for whatever purpose) has already heard about SiC.

Misleading Title

[Anonymous Coward]

This only seems to be for hybrids with an electric drive system, and probably (by proxy) fully electric cars that use Toyota's proprietary PCU. The summary makes it seem like you could take one of these semiconductors and apply it to any car and boost fuel economy.

Re:Misleading Title

[SydShamino]

You can put it in your hybrid and all-electric cars and boost your fleet fuel economy, which is what these automakers are graded on. The summary left out the important word "fleet".

You know what else increases fuel economy?

[CastrTroy]

You know what else increases fuel economy? Not driving everywhere. OK, I understand it doesn't really increase the fuel economy, but I find it odd that people drive absolutely everywhere. Just about everyone I know who owns a car refuses to walk or take the bus, even if that would actually be an easier/cheaper option.

Re:You know what else increases fuel economy?

[the_humeister]

Also driving slower, not driving full throttle and hard braking to a stop light/sign, etc.

I used to have an 2008 MkV Jetta with the 2.5L gasoline engine. The government said I should be getting 21/29mpg city/highway. My best was 46 mpg driving from Sacramento to San Diego. Now I have a Prius V, and I get better gas mileage than that without even trying.

Re:You know what else increases fuel economy?

[bill_mcgonigle]

You know what else increases fuel economy? Not driving everywhere.

As driving gets better and cheaper, people drive more. It's not surprising - driving has benefits and gives people pleasure, either directly or indirectly. If it costs $2 to drive to the beach, I go in a heartbeat. If it costs $200 I stay home.

Improving the human condition is great, but just don't expect improved MPG to do much for overall fuel consumption outside of commuting (where group options may be better anyway).

Re:You know what else increases fuel economy?

[CanHasDIY]

Also driving slower, not driving full throttle and hard braking to a stop light/sign, etc.

Or you could just buy a diesel.

I used to have an 2008 MkV Jetta with the 2.5L gasoline engine. The government said I should be getting 21/29mpg city/highway. My best was 46 mpg driving from Sacramento to San Diego. Now I have a Prius V, and I get better gas mileage than that without even trying.

I bought my wife a 2012 Jetta TDI, and she regularly gets 45-50 MPG, even with her lead foot. But even our old gas Jetta was getting somewhere in the range of 25-35.

Re:You know what else increases fuel economy?

[Kardos]

Buses take longer. There's only so much time per day, if you spend it waiting for buses, you get less done.

Re:You know what else increases fuel economy?

[neminem]

You have to factor in time, as well. I *do* walk and take public transportation, when the combination of effort, time and money one of those options costs seems nicer than driving - for instance, driving into downtown LA, is a lot faster than taking the light rail if there isn't traffic, but there's usually traffic, plus then when you get there you have the immense fun of finding parking. So it's often (not always) nicer taking the train, so I do. On the other hand, I tried taking the bus once across town. It's pretty cheap, but it takes bloody forever, so it's unlikely I'll ever try that particular experiment again, given that taking a car across town is far more convenient. If public transportation were more convenient, I imagine people would use it more. (That's not particularly insightful, though; seems pretty obvious, really.)

Re:You know what else increases fuel economy?

[hurfy]

lol, I am always amazed how many people pass me as we approach a red light. Is buying brake pads a fun experience I have been missing out on?

Re:You know what else increases fuel economy?

[the_humeister]

The problem with diesel cars in the USA is that they're more expensive than current hybrids (particularly the Prius) and diesel fuel is on average more expensive at the pump than 87 octane gasoline.

Re:You know what else increases fuel economy?

[Anonymous Coward]

And considering there's typically only one or two people per bus, they take-up a lot more room than cars would.

Re:You know what else increases fuel economy?

[CanHasDIY]

The problem with diesel cars in the USA is that they're more expensive than current hybrids (particularly the Prius)

The hell they are:

2014 Jetta TDI Value Edition: $21,295

2014 Beetle TDI: $24,595

2014 Chevy Cruze Diesel (no options): $24,310

2014 Prius Base Model: $24,200

Seems to be just about the same to me, save the Jetta; mine was a bit more (~$28,000), but that's because I sprung for every option except satnav. Seems the real problem is lack of options, unless you're a VW or Chevy fan.

diesel fuel is on average more expensive at the pump than 87 octane gasoline.

Yea, but you get almost-if-not-more-than twice the miles out of the same amount of fuel, so it ends up being a net win. I will concede that the sticker shock of diesel fuel does cause a lot of people's brains to shut off, and thus, not see the benefit.

Re:You know what else increases fuel economy?

[SydShamino]

On the other hand, you can get diesel for SUVs or trucks, so if you need one of those diesel is often your most fuel-efficient option.

Re:You know what else increases fuel economy?

[BronsCon]

You must live in an area with shitty public transportation, then, if so few people are using it. In the SF Bay area, buses and trains are commonly standing-room-only during the day.

Re:You know what else increases fuel economy?

[Hamsterdan]

Diesel cars have much better mileage, more torque and diesel engines normally last longer than regular cars.

but I agree hybrids are better for city use.

Re:You know what else increases fuel economy?

[Anonymous Coward]

If you bathed more often, I wouldn't be so unenthusiastic about sitting next to you on the bus. And please stop picking your nose in public. It's kinda gross.

Re:You know what else increases fuel economy?

[evilviper]

Just about everyone I know who owns a car refuses to walk or take the bus, even if that would actually be an easier/cheaper option.

I just recently checked bus prices, and I got to the destination several times faster driving, on $20 in gasoline, versus a $40 bus ticket.

Prices serve as a very good proxy for efficiency... Based on prices, I do not believe that buses are more efficient for short to medium trips in the US.

Re:You know what else increases fuel economy?

[evilviper]

I forgot a significant detail... That's $20 in fuel for the ROUND TRIP, while the $40 ticket price was one-way, and not just took longer, but required substantial travel by foot to reach the destination from the nearest station.

Re:You know what else increases fuel economy?

[Anonymous Coward]

shitty public transportation

You Republicans are an embarrassment to humanity. I live near Alamo Square in San Francisco, and we have shitty mass transit. Even at 9pm when I head home, the busses are too fucking full. That is why it is shitty. Only a Republican like you could claim otherwise. You and your kind disgusts me. Statements like your lie above are why I fled Texas. Fuck you and your Shrub ruler. A bus that wasn't overfilled would be wonderful. Calling that shitty is a fucking lie, and you should feel bad for spewing that lie.

Re:You know what else increases fuel economy?

[dbIII]

and diesel fuel is on average more expensive

Which appears to be an odd "only in America" thing. The stuff is cheaper to make at the refinery.

Re:You know what else increases fuel economy?

[dbIII]

On the other hand, you can get diesel for SUVs or trucks

Hence the reaction of most of the rest of the world when confronted by a petrol driven POS offroad vehicle from the USA.
"That's not a real offroad vehicle. Even little old apartment dwelling Japanese men wearing white gloves build far better offroad vehicles than that piece of shit built by a company run by drunken rednecks."

Re:You know what else increases fuel economy?

[dbIII]

Meanwhile in China alone there are millions of counter examples a day that laugh at your outlier. Still sucks to be hit for that much for a ticket though.

Re:You know what else increases fuel economy?

[evilviper]

My example isn't an outliers, it's typical pricing. And pricing in China has no relevance at all. In the US, bus travel is incredibly inefficient.

Re:You know what else increases fuel economy?

[geekoid]

With the benefit of more noise, carcinogens, soot and NOx.

Re:You know what else increases fuel economy?

[geekoid]

Interesting. My friends in former eastern block countries love american off road vehicles as then seem to be the only ones the last in ares where the roads aren't good.

Re:You know what else increases fuel economy?

[geekoid]

Buss are the least environmentally friendly thing you can take.
By a long shot.
If everyone on a bus instead drove a car that got greater then 19MPG, less gas would be used overall and a hell of a lot less emissions.
Buss where designed so the poor people can get to work.
That was their purpose. No being environmentally friendly, or quicker, or convenient.

Re:You know what else increases fuel economy?

[geekoid]

buss that aren't standing room only lose money. But if you cross the price point, no one uses them. Would you pay 15 bucks a trip? Just to sit on a buss that is far worse for the environment then any car sold today? If you are concerned about money and the environment, you should be driving a 3 cylinder car.

I have no idea why you are making this about political ideology. It's really just math.
Buss cost more and pollute more. far more, then cars.

Re:You know what else increases fuel economy?

[AmiMoJo]

Only because public transport sucks where you live. In Tokyo it is often faster than taking your own car. Buses and trains come every few minutes, and the time you spend waiting is more than made up for by avoid the traffic jams, parking and filling your car up every now and then.

You get more done because the time you spend travelling is not wasted controlling a car. You can browse the net on your phone, post to Slashdot and answer emails, play games or just relax.

Re:You know what else increases fuel economy?

[Anonymous Coward]

Current diesel engines are cleaner options than the gasoline ones ...

Re:You know what else increases fuel economy?

[CanHasDIY]

Yea, because the processes of mining rare-earth minerals and converting them into batteries is so clean and environmentally friendly.

try the solar magnet powered starcars

[Anonymous Coward]

0-60 in the wink of an eye (just above ground contact),,, 100,000+ miles per 'charge', neural navigation etc... http://www.youtube.com/results?search_query=solar+magnet+engines what's not to like? it can also run our homes & shops when parked nearby, plus we could breath easy again after our atmosphere restores itself... more momkind style new clear options every day,, not on tv,, no bomb us more mom us,, no drone us no bone us,, free the innocent stem cells,, feed the starving innocents (in our charter) etc... see you there

Another idiotic asinine summary

[oldhack]

All that verbiage to say nothing except "Toyota" and SiC.

completely ungrounded

[Anonymous Coward]

lots of options with no lifetime of oil addiction, never ending usery style payments etc... http://www.youtube.com/results?search_query=solar+magnet+aircraft

Math challenged?

[Anonymous Coward]

The PCU is 25% of the losses; the semiconductors a fifth of this or 5% of the losses. If the new semiconductors are perfect, then we reduce the losses by 5%. In order for this to increase efficiency by 10%, the current efficiency would have to be 33% or less.

I really hope that is not true...

Re:Math challenged?

[hurfy]

Took me a sec to decipher that too. I think the PCU statement is irrelevant and they cut the losses in half. Perhaps the connectors in the PCU cost 5% thus 25% instead of 20%

Overall rather light on actual info and a little heavy on the headline. We don't have a good substitute for 'fuel economy'. "Increases eMPG" I suppose is the most accurate but sounds kinda strained.

Re:Math challenged?

[SydShamino]

100% of the losses are "the total losses"
25% of the total losses are in the PCU
20% of the total losses are in the semiconductors. The summary repeats the word "total" to clarify this, but you misread the summary as 20% of PCU losses are semiconductor (or 5% of total) which is not correct.

If 20% of the total losses are in the semiconductors, and the new ones have half as much loss, then the net result is the elimination of 10% of the existing total losses.

Key word: COULD

[Anonymous Coward]

Then again this new semiconductor could make a Prius get worse fuel economy than a top fuel dragster.

Re:Key word: COULD

[Anonymous Coward]

Feel free to compete against a Prius:

the,
Dealership

Old News

[Anonymous Coward]

How is this news? SiC semiconductors including Schottky diodes, JFETs and MOSFETs have been commercially available since 2008. My first design to use SiC JFETs and diodes was in solar power inverter developed back in 2009 (and yes the RDSon and revers recovery times are indeed exceptional). Stay tuned for: "Toyota discovers wonder metal by adding carbon to iron"

Re:Old News

[DerekLyons]

How is this news? SiC semiconductors including Schottky diodes, JFETs and MOSFETs have been commercially available since 2008. My first design to use SiC JFETs and diodes was in solar power inverter developed back in 2009 (and yes the RDSon and revers recovery times are indeed exceptional).

"Commercially available with the specs you need for a solar power inverter" does not necessarily equate to "commercially available with the specs Toyota needs".

dark matters II the hogwash; aired on POT..

[Anonymous Coward]

(Personal Open Terminal). in this episode mutant crown royal dna is composted in the lhc. 'we're going to grow something here' was the official statement? viewers are feeling ill frequently... tbc,,, re; story; decommission 10% of humvees & other heavy equipment WMD style 'transportation', just in new jersey to start.....

A better power MOSFET switch: Big deal.

[kheldan]

It's not as big a deal as they're making it out to be, really. It's got a lower 'on' resistance. Similar reductions in power lost to waste heat could be accomplished by using more MOSFETs in parallel. Don't get me wrong, it's a useful development, but it's not earth-shaking news either.

Re:A better power MOSFET switch: Big deal.

[viperidaenz]

It has a faster recovery time too. More MOSFET's won't change that.
Faster recovery time means they can run at a higher frequency and use smaller inductors to convert the voltage. Lower inductance means less copper, less resistance. So not only is there less loss in the transistor, there is less loss in other components.
If you keep adding more MOSFET's, you need to keep increasing the drive current or they'll switch slower.
While a MOSFET is switching, the resistance can be quite high. Even if faster silicon carbide transistors had the same Rds, there would be lower losses during switching.

Re:A better power MOSFET switch: Big deal.

[NoKaOi]

Coming up with a new MOSFET with a lower on resistance is a big deal, particularly if it has broader uses outside of automobiles (the article doesn't really have much in the way of details). Allowing anything with MOSFET to be 10% more efficient and with less heat, yeah, that's a big deal.

Now, the article mentions silicon carbide. Cree already makes silicon carbide MOSFETs (although they're expensive), so as far as I can tell (please, somebody correct me if I'm missing something), either this isn't news and Toyota just ran some calculations on how much power they'd save by changing components, or Toyota has come up with something new that the article is too general to say.

Re:A better power MOSFET switch: Big deal.

[kheldan]

That's kind of my point, actually, it's not really news. These sorts of developments happen all the time and really nobody but engineers who need to use them notice. This smacks more of Toyota trying to generate some positive press for themselves than anything else.

Wouldn't it be wrapped up in patents?

[viperidaenz]

That's why CREE are the only ones who make white LED's on silicon carbide.

Re:Wouldn't it be wrapped up in patents?

[AutodidactLabrat]

Actually, Cree does it because they vend the 4H SiC used in these things.
Everyone else uses either AlN or BN or Diamond film

Well ... about that

[Anonymous Coward]

You just summarize the argument against rolling taxes into displayed prices. Diesel fuel isn't more expensive. Diesel fuel taxes are significantly higher than gasoline. This isn't a bad thing in all; diesel vehicles *as a fleet* do a lot more damage to roads (think semi's).. However, that leads to the flawed belief that a higher efficiency fuel is inherently worse. It would be much better for the US if almost all vehicles were diesel.

Fuel Economy =/= Less Fuel Consumption

[Mister Liberty]

Jevons’ paradox.

Electricity != fuel

[Hamsterdan]

Battery efficiency is not the same as fuel efficiency.

Accolades and Salutations!

[Anonymous Coward]

This is the first and possibly only time a Foxworthy joke is appropriate on /. I applaud you!

paging wagnerrp

[Anonymous Coward]

We need your precious self-hatched theories about semiconductors!!! Please explain to us with your heat theory how these transistors work!

Re:paging wagnerrp

[fyngyrz]

If you let the smoke out...

oh, never mind.

Let the big boys talk umkay?

[Anonymous Coward]

reductions in power lost to waste heat could be accomplished by using more MOSFETs in parallel

Wanna know how I know you aren't an electrical engineer?

Your statement would make more sense if the cause of their inefficiency was that they were running the MOSFETs at the upper edge of their rated current carrying capacity and they're burning up but they aren't. No matter how many MOSFETs you parallel, each junction inside has a voltage drop across it. That voltage drop is (mostly) constant regardless of the forward current. These little voltage drops here and there are wasting power as heat when ideally we want that power put into the motor windings. Anything you can do to eliminate these drops is a little more battery range. I know nothing I say will stop you from playing armchair engineer but this IS a big deal to those of us who care. You obviously don't. Go back to watching Sons of Guns while you jack off your M16 and let us get back to making your next car.

Re:Let the big boys talk umkay?

[Anonymous Coward]

It's not enough that you correct someone, you have to mock and insult the person while doing so. You're an asshole.

Re:Let the big boys talk umkay?

[Anonymous Coward]

It's MOSFETS, right? They've got this thing called RDS(on), right?. Look it up. It's in the data sheet. Notice that it's given as a resistance, not as a voltage drop. What happens when you parallel resistances? I mean being a big boy sparks type and all.....

Re:Let the big boys talk umkay?

[kheldan]

Go back to 4chan, kid.

Re:Let the big boys talk umkay?

[mirix]

It's even better when they're completely wrong.

MOSFETs have no fixed voltage drop, just a resistance. Paralleling them indeed reduces the resistance, and hence losses and drop.

The d-bag GP is thinking of BJTs ("normal" transistors), which do have a more or less fixed voltage drop (it varies somewhat with current and temperature).

Re:Let the big boys talk umkay?

[Anonymous Coward]

I've designed power electronics and you guys are both wrong.

The limit is never one variable, as if you're doing engineering right, changing any parameter puts you in a worse efficiency. Convex optimisation, perhaps you've heard of it?

The reason you can't simply gang up a bunch of MOSFETs for lower Rds, is because by doing that you increase gate capacitance, and have a higher gate drive current. You lose more efficiency driving the extra gate capacitance than you gain by lowering Rds and Lds. By switching to SiC MESFETs you gain better Cg/Rds ratios and that's where you get the extra efficiency. Of course you can lower your Fsw, but then you need larger, more lossy output filters.

Found a better site

[AutodidactLabrat]

Looks like Toyota has produced the pinch-channel Class I V transistor in SiC with no minimum offset / gain.
Seriously, holy grail for current steering.
Can't find the vendor of the raw SiC so no idea about Delta-V / Delta-I limits but looks very good
10% net reduction in loss.

Re:Found a better site

[Twelfth Harmonic]

Link?

Re:Found a better site

[Anonymous Coward]

How was this moderated informative without providing a link to back it up?
Furthermore, what the hell does this combination of words even mean? I'm not dumb, but I'm not an electrical engineer either. "Steering" is certainly a car-related word, but the rest of this might as well be gobbledegook.

Re:Found a better site

[AutodidactLabrat]

Yike! Thought I did. Hang on, I'll go look for it Damn. I seem to have lost it HA!! http://newsroom.toyota.co.jp/e... Looks like they are going for 10% NET fuel economy increase.

10% of what, exactly?

[Anonymous Coward]

A typical sedan might use about 20 mechanical kilowatts to maintain speed on the freeway. Cars aren't perfectly efficient, but even if they were (aside from the transistors in the drive inverter) this article would claim a 2 kilowatt improvement. That's about how much total loss I would expect to see at full load.

3-4 years ago I used to design traction inverters for a living, and when delivering 200 kilowatts to the motor, I was losing about 3.5 kilowatts to heat in the transistors.

I'm willing to believe that they've started making more efficient transistors that reduce the inverter losses. 10% reduction of losses in the electrical side of the house I could believe, but that's not 10% on the whole car.

Jevons Paradox does not apply

[spage]

A 150-year old observation about markets and business production does not apply to individuals spending money to reduce consumption. Sure, a few people who overspend to get a more fuel-efficient car will maintain their gasoline budget and take extra trips in it, but far more will take the money saved on fuel and spend it on other things. Sure, those things have their own energy costs, but a fancy Apple gizmo has far less embodied energy than the gasoline the owner saved. Besides, those wacky environmentalists spending $$$ to consume less energy are likely to spend some of the money saved on additional energy-saving measures.

Read the Wikipedia article more carefully, there are so many caveats and non-linearities that it really is a weak argument even before you consider individual consumers' motivations.

Do you know what an outlier is?

[dbIII]

Globally the consequence of extreme price gouging you are seeing locally is an exception instead of the rule. Using it to suggest that public transport is always a bad idea is either stupid or dishonest.

Re:Do you know what an outlier is?

[Anonymous Coward]

Globally the consequence of extreme price gouging you are seeing locally is an exception

What he's seeing is the consequence of paying workers pennies per hour. They don't have the option of owning a car, so efficiency isn't a factor.

Re:Do you know what an outlier is?

[evilviper]

Globally the consequence of extreme price gouging you are seeing locally is an exception instead of the rule.

On the contrary, public transit is subsidized. The opposite of gouging. To implicate gouging, you need evidence, and you've provided NONE.

Using it to suggest that public transport is always a bad idea is either stupid or dishonest.

You're the idiot that chose to expand this topic out to the other parts of the world. This was clearly about the US, until you went nuts and started talking about China, as if it had any relevance.

In the US, it's stupid and inefficient to take the bus.

Re:Do you know what an outlier is?

[dbIII]

You're the idiot that chose to expand this topic out to the other parts of the world

So why is that being an idiot? Please explain why it is not a relevant example if somebody other than your local bus company can get their shit together?

Re:Do you know what an outlier is?

[evilviper]

Please explain why it is not a relevant example if somebody other than your local bus company can get their shit together?

But you didn't point to just some other bus company... You went straight to THE OTHER SIDE OF THE PLANET, where the economics are completely, totally, and utterly different.

Why isn't this simple and obvious fact, painfully obvious to you?

Re:Do you know what an outlier is?

[dbIII]

Fair enough, I see the confusion comes from a simple disagreement:

Based on prices, I do not believe that buses are more efficient for short to medium trips in the US.

I strongly dispute that prices in this case are a measure of efficiency. In a monopoly situation there are stronger drivers of price. That's why I think considering the situation globally is the only fair comparison if you want efficiency to be a factor. Doing so means the utterly ridiculous $40 price gouge you describe above would be an outlier. If you want a US only situation then all you have to do is consider two or three decades ago or probably some regions of the US today.

I have to explain? OK then

[dbIII]

The ones that make it for export are things like Jeeps and not the wide variety of piece of shit fake offroad vehicles designed to make their buyers feel tough, so long as they never dare to get dirt on it.
Jeeps can come with diesel. They are built for a practical and not cosmetic purpose.

I thought the POS label would be enough for people to work it out that I am describing the utter lemons and not every thing on the road.

Your invented point has no meaning

[dbIII]

Why isn't this simple and obvious fact, painfully obvious to you?

Because this was never about the USA in the first place but about fuel economy and public transport costs. You shifted that goalpost yourself for some reason that is unclear and IMHO totally irrelevant to the discussion.
Besides, while it may be true NOW in the US where your bus company has a local government mandated monopoly it was not true in the past when there were multiple purely commercial bus companies.