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Hitachi develops 11 kW permanent magnet motor without rare earth materials

Conventional industrial 11 kW induction motor (left) and Hitachi’s new 11kW motor (right). Source: Hitachi. Click to enlarge.

Hitachi has developed a high-efficiency 11 kW permanent magnet synchronous motor without using rare earth (neodymium, dysprosium) materials; the work follows on its 2008 announcement of a prototype 150 W motor that used cores made of amorphous metal coupled with ferrite magnet rotors. (Earlier post.)

Hitachi says the new 11 kW motor has an efficiency of about 93%, and delivers IE4 performance (the highest of the International Efficiency classes—Super Premium Efficiency—defined by IEC 60034-30) from a size smaller than that of a comparable conventional motor. The company is targeting commercialization for industrial applications in 2014.

The earlier 150 W prototype motor showed an efficiency of 86%.

Arrow points to the amorphous iron core. Source: Hitachi. Click to enlarge.   Laminated structure of the amorphous core. Source: Hitachi. Click to enlarge.

The new 11 kW double-rotor, axial-gap motor uses a laminated stator core based on a low-loss amorphous iron material. Hitachi says that the losses from its laminated material are about 10% of those of conventional electromagnetic steel laminations.

Amorphous metal has a disordered atomic structure in contrast to the crystalline structure of conventional metals, and features a high tensile strength and extremely low magnetic losses. As such, it has been a target of interest for motor development for decades. Its adoption, however, has been hampered by the cost of manufacturing—an issue which Hitachi says it is addressing.

To optimize the efficiency of the laminated design, Hitachi used 3D magnetic field analysis software to analyze the various characteristics of the core laminations.

Hitachi developed the technology with support from Japan’s New Energy and Industrial Technology Development Organization (NEDO).



axial-gap motor

Honda and Nissan have some patents on great axial gap motor designs, that have been recently issued. This magnet technique has yet to be proven on larger motors. EVs can have 100 kW to 150 kW motor designs and that is where the advantages can be realized.


eAssist uses a 15kW motor


That is inductive, like the Tesla. These are synchronous motors.


Right I am skeptical if this can be called "permanent magnets" motor, I also wonder how easy is to make the amorphous metal core, production of amorphous metal is quite tedious (deposition of very thin layer of metal on fast rotating cylinder for ultra-fast cooling) the rate of production is pretty slow.

But coming from Hitachi it is certainly something to take seriously


No rare earths?????!!!!

How dare they! Stealing one of the anti-ev/anti-renewable crowd's favourite talking points.


The large Tesla Motors inductive unit seems to do just fine with a single speed reducer, I think it is something like 6 to 1 or more.

1200 rpm at the wheels should get you more than 90 mph and the Tesla motor can run up to 13,000 rpm. It just depends on what you want to do.

Toyota and Honda went for permanent magnets. There are permanent magnet materials that do not use rare earth minerals, they are just not as strong a magnet.


Switched reluctance motors can be an alternative to permanent magnet when you want a high torque, you have to deal with the complex control of these engines and their not so smooth output, but we should see solutions coming in a no so distant future


"SJC says:
That is inductive, like the Tesla. These are synchronous motors."

so what difference does that make?.. its still driven by an AC 3 phase inverter that is ultimately powered by a DC battery. This could possibly replace the motors used in the Leaf and iMiev if needed.

The question is what is the curie temperature of these magnets?


It makes a lot of difference, but I won't go into that if you don't already know.


Im interrested to buy a hydrogen fuelcell car with this electric motor.


Well good AD, we are glad you are interested.


I don't see any reason why the curie temperature would be different in a metallic glass magnet than in a crystalline magnet.


its an induction motor with the squirrel cage replaced by PM, results?.. less heating in the rotor.. YAWNN

another PM motor driven by 3 phase AC



If that is what you want to believe the difference is, then that is your business. If you want to really learn, go find information on motors and learn.



You are simultaneously snotty and uninformative.

It seems thought that you are just interested in telling people that you are cleverer and better informed than them.

If you want to share informtion, do so.
If you have nothing else to share than your high opinion of yourself, no-one else cares.


so will this result in cheaper motors?.. or is this amorphous iron really expensive?



It is not my job to inform you nor anyone. I am not a motor expert, but I know there is a difference. This is all that I am saying, learn.

The brief statement was made by Herm about the eAssist. It was not clear what the point was, so I pointed out that they were not the same kind of motor, that is all.



Early protoypes had the dual 7.4/14.3 ratios which obliged the driver, seeking to accelerate to top speed, to change gear at 60mph(11,900rpm) with the motor then spun down to 6200rpm to accept the 7.4 ratio. This required the instantaneous dissipation of almost 75% of the rotational kinectic energy of a copper caged rotor the size of a 1lb coffee tin. Easier said than done.

This design error proved insurmountable in the short term. The production TESLA roadster is a single ratio geared 8.27 : 1.

Magnetic iron losses are only a problem for synchronous AC machines which have permanent magnets. With these the stator iron loss is proportional to road speed irrespective of the stator current.

With an induction motor, on the other hand, stator iron loss disappears with removal of the applied stator voltage and its current. The effect therefore is that a vehicle equipped with an induction motor drive will coast much further.

With 300% overcurrent using an AC synchronous motor you are likely to demagnetize the rotor and permanently and seriously degrade its performance.

With 300% overcurrent an induction motor can deliver 300% nominal torque. This is normally done below base speed so that the current drawn by the inverter does not exceed the nominal battery rating.

I would emphasise that induction motors for EVs should be equipped with copper rotors not aluminum. Such motors have the capability to deliver efficiencies in the low nineties.


Here is a good cut away shot of the eAssist motor/alternator. It is a 15 hp (11.2 kW) motor.


Sure would like to see the automotive people do some work on external rotor motors.

Some experimental ones have exceeded 97%. They eliminate the need for any gearing.

The only negative aspect is it's very hard to keep them from tearing up if you build them too large and run them too fast. (Centrifugal force)

Seems like an interesting experiment would put multiple small motors driving each wheel.

You heard it here first.


Did you see:
Clutchless electronic gear shifting:

They supposedly use the same version of AC motor used in original Tesla Roadster, with 2-spd transmission, which weighted 70 lbs (the later one in Tesla is 110 lbs). This guy was part of Tesla Motors team, later they parted ways.

On the site it shows a 250 hp (180 kW) motor, Motor Sync Time: 80 milliseconds.

So it looks like they found a way to slow down the motor quickly enough for smooth gear shift without additional friction clutch.

BTW do you have any idea why AC Propulsion didn't make a smaller version of the motor, say in the range of 50 - 100 kW, which could be used in regular passenger cars.
Perhaps they lost all their R&D department, and now are just selling existing IP.
Probably smaller motors would have somewhat lower power density, and lower efficiency, but would still be good enough.


my cryptic remark about eAssist was just to remind everyone that even a small 15kW motor is very useful.


This is somewhat off topic but not too bad.

A lot has been said about rare earths lately. China had most of the worlds production capacity and that was fine when they didn't have an internal use for them, but now they do. Rare earths are not rare. What is rare is an ore source with economically recoverable amounts of the metals. They also tend to be in mixed ores and the rare earths are hard to separate because of their chemical similarity. Anyway, there are many places with rare earths but few people who actually want to invest large amounts of capital in something that will take years to develop and may or may not pay off if the demand declines. But, the Chinese government did. however no one in this country did (actually, Molycorp is now developing a source, but only recently). We don't need to though, we have our oil friends. The ones who take our money and give to people who blow up our buildings. It's all good for business.

As with everything we do it is about how much can be made in the next quarter. The future is unimportant to a CEO.


Good news for locally produced rare earths. A new local Alumina mine (ORT.A-X) will start soon and produce alumina on a very large scale + 7 rare earths @ 500 g/T, including dysprosium, neodymium, gallium, scandium, praseodymium, lanthanum and yttrium. This new very large mine may never produce enough alumina for the 10 large local aluminium plants but may satisfy the local market for rare earth for many years to come.


It looks like the eAssist is smaller than the Hitachi for the same output (about 11 kW). The Tesla motor puts out a lot for its size and the Remy motors used in the GM dual mode are powerful also.

I don't think rare earth minerals will be the pacing item for EV acceptance. If I were Toyota selling 200,000 Prius and depending on them, I might be concerned.

That is part of a business plan, you have to look at input supply disruptions and Toyota probably did not consider it a problem.

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