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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).



There are a few much superior motors around like the Yasa-400 permanent magnet with higher efficiency (up to 98% at ideal speed), higher torque density (30 Nm/Kg) and higher power density (9 Kw/Kg). However, the Prius e-motor with a power density of only 1.37 Kw/Kg could be improved shortly.

Generally speaking, permanent magnet motors (with rare earths) have the highest all around performance and are ideal for future electrified light weight vehicles/cars. The Yasa e-motors are very good examples of what can be accomplished with PM.


From a buyers perspective, I don't think they care. As long as it performs, has range and is reliable, there is no concern.

If they start producing 1 million EVs per year and there are not enough magnets, there would be a problem. I mentioned all the batteries for all the packs for 1 million EVs per year and was told "no problem". Well any component in shortage is a problem, it only takes ONE and the car does not ship.


SJC...many people have started to worry or at least pay more attention to the efficiency of the vehicle they drive around. The (total vehicle life time cost) difference between a 90% efficient heavy e-motor and a 96% to 98% much lighter permanent magnet e-motor could be as much as 10% to 15% due to reduced battery back size required, less weight and cost for the same extended range BEV.

The days of 15% efficient ICEVs and $2/barrel crude may be over sooner than we think.


The quoted figures of 95% efficiency are misleading, the motor does not have that across the whole operating range all the time. Under heavy loads of acceleration the motor drops well below that.

What people care about is performance, range and reliability, cost and maintenance come into play as well. Give them cost effective and reliable transportation and they really don't care if it is one kind of motor or another, as long as it works well and is affordable.


ICEVs performance and efficiency depend a lot on the ICE used.

BEVs performance will also depend a lot on the e-motors used.

Future knowledgeable (BEVs) buyers will learn to make the difference.


@ SJC The quoted figures of 95% efficiency are misleading, the motor does not have that across the whole operating range all the time. Under heavy loads of acceleration the motor drops well below that.

Agreed but a 0 to 60 ramp at linear accel takes only 352 feet or 117 yds. Now suppose you continue to drive 3 miles,say, which is equivalent of 5000 yds and takes 3 minutes , I doubt the initial 8 secs of inefficiency will impact this picture by even one per cent.

And another thing, while on the subject of electric motor efficiency. There is a big difference between the culture of motors used for industrial as opposed to those used in automotive applications.

Let's say we have an industrial motor running at 1500rpm 50Hz 480Vac and drawing 10 amps @ 92% effcy.

And let's say that we rewind that same motor for an automotive application by filling the stator slots with as much wire as before but this time with wire that has eight times the cross section of that used previously.

For one thing we won't have room for many wires in the slot (about 1/8 as many) but each wire will be able to carry eight times the current or 80 Amps. Wouldn't you agree ?

OK, then would you also agree that with eight times less turns of wire that the applied voltage has to be about one eigth lower that is 480/8 or 60 volts ?

So we have this automotive motor running at 1500 rpm and providing the exact same torque as before except that it is running with 60Vac and 80 amps and with the original effcy of 92%. Let us further assume that the 8% loss in efficiency is wholly due to the electrical resistance of the wire, we know it's not but let us assume for the sake of argument.

OK, now let us increase the applied voltage and frequency in step by eight times with the current maintained at 80 amps. When we finally reach 480Vac the frequency will be 400Hz and the motor will be turning at 12,000 rpm. A quite reasonable value for 75mph in an EV.

If the situation is examined it is somewhat obvious that with the same torque at 1500 rpm but now at 12,000 rpm that the motor is producing eight times the power.
Not only that but since the current remained constant the copper resistive loss has not changed. The same resistive loss as at 1500rpm is now accompanied by eight times more output power.
That means the 8% loss divided by eight times more power output and is really just 1% of this new power.

In other words the 92% motor actually becomes 99% efficient merely by speeding it up. And that's not snake oil.

Except that not all of that original loss was due to the resistance of the wire. About 50% of that original motor loss is in fact attributable to the magnetic flux side of the machine - the so called iron loss.

But this post is long enough.


I believe Toyota is making (or is about to) 1 million hybrids every year.

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