Automotive technology going more electric. Good news.

This is very interesting. Smaller, more efficient e-control units will be beneficial to HEVs, PHEVs and BEVs development and cost.

ICE machines would have taken almost a full century to match the equivalent level of efficiency increase.

ICE machines news will progressively disappear from most posts to make room for advanced battery packs updates and advanced HEVs, PHEV, BEV, e-garden tools, e-pleasure boats, e-bikes news.

Automotive manufactures will need to design solutions to meet their specific needs in electronic and electrical power management with the move to electrification.
Battery research, motor, systems and electronics.
Good to hear of these successful outcomes

Note this technology being installed in million dollar Fuel Cell Vehicles where cost is not a high consideration.

SiC is often touted for VHF HDTV transmitters where they can substitute for thermionic tubes in the output stages at the 4Kv voltage level. EVs on the other hand can get by using much lower voltages.

For the more down to earth mainstream EVs of any stripe, I would say, for existing liquid cooled inverters at 650 Vdc and 80kw power levels, using silicon IGBTs remains an economical and reliable solution.

Future developments should include the use of upconverters preceding the inverter, similar to Gen II Prius. This technique can be useful to Tesla like vehicles also when they encounter gearbox design issues.

The more interesting feature here is Nissan becoming a semiconductor manufacturer in its own right. In future I think we may see increasing inhouse developments and less partnerships with electrochemical startups and established semiconductor companies.

Under direction of their excellent CEO and driven by a commitment to build electric drive lines for Project Better Place, Nissan will be the winner in leading the development of mass market BEVs. A BEV's main drive system is the motor, battery and power control. Efficiency in all three is extremely important to the overall efficiency of the whole car.

"The company aims to further reduce the inverter size by employing SiC diodes on the transistor."...what does this mean? Is the writer saying: "...by employing SiC transistors"?

I saw a car assembly line and it reminded me of how many components go into an I.C.E. automobile. Not just the engine and transmission, with all their individual components, but the cooling, exhaust and fuel systems too. BEV would be really very simple by comparison.

- Lad, I may have jumped the gun on the silicon carbide transistors, in retrospect I think they are staying with silicon transistors. The following stuff you may already know but I'll add it for interested readers.

So what's the deal with silicon carbide diodes ? Well briefly, SiC diodes are as fast as silicon Schottky diodes but whereas Schottkys are restrained to a max of 45vdc these SiC go up into the hundreds of volts ratings.

When I say FAST I am referring to reverse recovery times. Basically if you change the polarity quickly enough across any diode it temporarily 'forgets' what it is supposed to be doing. In other words a forward biased diode exhibits high impedance (forward recovery) and a reverse biased diode remains highly conductive - like a short circuit (reverse recovery). This latter state is the most dangerous for inverter duty. It is not the diode connected in antiparallel to each transistor that is the problem rather the diode belonging to the transistor above or below it, as the case may be.

Generally speaking transistor turn-on must be slowed to about three times the diode recovery to avoid a catastrophic event ! This creates heating in the transistor which has to spend more time in a partially conducting state carrying 1/3 full load current while the full line voltage is impressed across it. A faster diode means you can risk switching the transistor on faster, reducing the time spent in the partial conducting state. Meaning a cooler transistor.

SiC diodes will survive temperatures of 400 deg C whereas pure Silicon is limited to 175 deg C so expensive liquid cooling can be displaced by much cheaper forced air cooling. Nissan stated this somewhat indirectly as a design goal in the text.

The close diode/transistor proximity tells me they won't be letting those heatsinks go above 125 deg C anyway since there can easily be 50 deg c differential between the die and the heatsink. However advantage of Schottky speed is what you're after and SiC chemistry certainly provides that.
T2

SiC diodes will survive temperatures of 400 deg C whereas pure Silicon is limited to 175 deg C so expensive liquid cooling can be displaced by much cheaper forced air cooling.

Hybrids already have liquid cooling systems.  SiC devices allow the power components to be cooled by engine coolant (too hot for silicon), which is not only very cheap and compact but also allows the waste heat to be used for cabin heat.

The three most difficult tasks in deploying electric autos is putting the same energy in a battery that is the same size and weight as a 15 gal. fuel tank, recharging it safely in the same time as it takes to refuel a 15 gal. tank , and lastly and very important is having a clean source of electricity to recharge the batteries in 60+ million autos in the same 24 hour day.
We have a long way to go to acomplish this.
I have been wishing for the electric auto for 40 years and it looks as I will never get to own one. Life is just to short!

@T2:
Thanks for the info and additional dissertation. I can envision the general circuit quite nicely with your explanation. And as we all know heat is wasted energy and in the case of electronic circuits, it is caused by a resistance to electron flow of some form or other, i.e., the offset voltage of the junctions in semiconductors.

@Engineer Poet:
Carrying away the heat via liquid cooling or air and using the heat for comfort and/or keeping Li Ion batteries at operating temps seems a good use of the generated heat.

@Unknown:
If you can last a couple of more years, I think you will see Nissan BEVs moving on the roads with about 100mile ranges, which should account for most people's mileage needs. As battery technology progresses, you should see this range increase over time to about 300 miles with quick charge stations available to charge the batteries in five to ten minutes or robots that will exchange the batteries in five minutes. Ideally you would want to keep the BEV as light as possible so you would want to size the batteries to be only as large as necessary to do the job so you don't carry extra weight to decrease efficiency. perhaps a modular approach to adding batteries would be good solution.

Quoth Just watching:

The three most difficult tasks in deploying electric autos is putting the same energy in a battery that is the same size and weight as a 15 gal. fuel tank

Why just the fuel tank?  The battery converts energy to work, so it replaces the engine too.  Electric motors are about the size of a transmission.

recharging it safely in the same time as it takes to refuel a 15 gal. tank

Again, why?  We probably can accomplish this, but why must the electric meet or exceed every specification of the ICE vehicle?  What's wrong with 20 minutes to charge, or 30?

lastly and very important is having a clean source of electricity to recharge the batteries in 60+ million autos in the same 24 hour day.

We don't have a clean source of fuel for the ICE vehicle, so this is just escalating the demands.

We have a long way to go to acomplish this.

Especially if you arbitrarily increase the difficulty of the job for no good reason.

Please explain to this former Navy ET why diodes are needed for an inverter? Inverters convert DC to AC while diodes do the opposite. Since batteries are already DC devices they make the use of diodes in an inverter redundant. OTOH for use as rectifiers for the purpose of regenerative braking high power diodes are a must. I believe this post is an example of using a PR people who are totally ignorant about the technology they are reporting about.

Lad:

I fully agree with you that PHEVs and BEVs will be around in large numbers shortly after 2010.

Standardized Modular battery packs (various standard sizes as we have with the AAA, AA, C and D cells etc) and connectors would be an ideal solution. The average vehicle could be equipped-designed to accept 4 to 6 (5-10 KWH) plug-in battery modules. Users could install as many modules as required for their daily trips. Extra modules could be installed (rented?) for longer trips and/or whenever the price goes down.

Tom:  inverters are required to drive both induction and brushless DC motors.  You need diodes because the conversion systems use inductors as energy storage, and switching off the drive voltage to an inductor requires a "freewheeling" diode to eliminate voltage spikes.

@Ing-Poet:

If large Calera Cement factories (by Constantz) were co-located with existing and/or new coal fired power plants, most CO2 emissions could be captured and used by the adjacent Calera cement plant while eliminating the normal one on one CO2 created by existing Portland cement factories.

In other words, you could get both clean coal electrical energy + clean cement.

This type of win-win solution could help to reduce overall CO2 emissions while supplying clean electrical energy for our PHEVs and BEVs.

Of course, converting existing Portland Cement factories to Calera Cement factories would require large initial capital investments but since on-going production cost would be about 10% lower it may be economically viable.

There are solutions to the current clean power problem.

Well harvey D - shame Calera cement appears to be vaporware in terms of its environmental value.

SiC diodes are oten touted for use in semiconductor pulse width modulation driver circuits to reduce the power losses through reverse conduction spikes. They are supposed to reduce the radio interference from these circuits, reduce the component count and increase efficiency.

They are not that widely accepted as a great step forward - I think Nissan is just generating as much publicity as possible.

Voltage spikes can be controlled by zener diodes and large capacitors but this article didn't specifically make that point. Zeners work by becoming a high current carrier at a designed voltage threshold and essentially convert electricity to heat leaving less energy for work. It still looks like this device is best used for regenerative braking and not for inverters.

Tom, I strongly suggest that you look at the way these devices are used in the context of complete systems.  You will find it very enlightening, for instance, the inverter systems are bi-directional.

A US company already sells SiC diodes it also sells light emitting diodes. There have been experiments with SiC transistors. The inverters and motors are a high cost of electric cars. Perhaps there should be a start made with low efficiency low power motors with brushes. They have been used on street cars for more than a hundred years and are still used for many locomotives. The higher efficiency of inverter drives may not pay for themselves as compared to motors with brushes in cars. But in high quantity, inverter drives may be less costly. Every PC computer power supply has had inverters in it since 1980.

The high efficiency of new hydraulic motors may make electric hybrids less interesting. High pressure gas pushing on fluids can give very high torque. See INNAS HYDRID.

Everyone can have a partial plug-in-hybrid simply by installing the largest deep-cycle batteries that will replace the ordinary battery. The alternator can be disabled with a switch until the battery loses too much charge. This can be all automatic. This way, the ignition, lights, fans, radio et cetera are all powered by a battery charged at home.

There is no chemical battery and motor combination that will ever weigh less and take up less room than an engine and diesel tank. This is why Plug-In-Hybrids are useful and attractive. There should be no battery electric vehicle allowed on any US road. It may need only a small engine and fuel tank, but this feature must be required to stop forever and talk of limited range. If you wish to be pure and un-sullied by the petroleum industry, you can buy only organic certified ethanol to run on. ..HG..