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GE previews new high-efficiency traction motor for hybrid and electric vehicle applications

by Jack Rosebro

GE prototype motor-1
The new prototype motor. Click to enlarge.

General Electric engineers have successfully tested a prototype hybrid and electric vehicle motor with a peak power level of 55 kW and the ability to operate continuously at up to 105 °C (221 °F), using conventional transmission fluid as the motor’s sole cooling agent.

The motor—which GE says is 3 to 5% more efficient than existing motors—could potentially extend the range of a plug-in vehicle. It was developed as part of a $5.6-million US Department of Energy (DOE) project, and performs well over a range of bus voltages, from 200V to 650V.

The permanent-magnet motor uses a concentrated (solenoidal) winding, and is extremely compact, with a stator diameter of approximately 23.4 cm (9.2 inches), and a length, including end turns, of approximately 13 cm (5 inches). Power density is about twice that of today’s motors, according to GE.

The motor can use a transaxle’s fluid to cool both the rotor and the stator, producing a continuous 30kW of output over a range of 2,800 to 14,000 rpm at 105 °C.

Alternately, the motor can use a hybrid vehicle’s engine coolant to limit operating temperature, rather than a separate, dedicated coolant loop, GE Senior Engineer of Electric Machines Ayman El-Refaie noted that many current production motors are limited to a continuous temperature of 65 °C (149 °F).

GE also developed new high-resistivity magnets for the motor, which reduce magnetic losses and reduce or eliminate the need to use more costly segmented magnets.

General Electric has discussed licensing the motor technology with electric motor manufacturers as well as automakers, and hopes to see commercial application in the automotive sector by 2015.

This technology is scalable and flexible enough that it can be leveraged in a number of capacities,” commented El-Refaie, noting that GE plans to explore additional potential product applications, including higher efficiency industrial motors, high-speed oil and gas compressor motors, and generators for aerospace applications.

Next steps include a four-year project, during which time GE engineers will seek to produce a motor with similar performance characteristics, yet with no rare-earth magnets.



Excellent news for future lighter EVs. This would do for an AWD vehicle and could be fitted in or near wheel to reduce/eliminate some of the mechanical parts. Could also be used as a light weight genset for HEVs/PHEVs.

The added 5% in efficiency would bring it close to 99% and the 2X gain in power density would bring it close to 6hp/lb.

Rare Earth is not so rare. There are many potential mines waiting to be opened whenever the price is right.


This is what we really need: one of the big boys to jump in and start mass producing these things. When the price on a good motor is down around $1,500 then we'll be able to use the extra to buy more batteries.

Throw in something like those $160/kWh Zinc-air batteries...and this gets really interesting



Would be a great motor to drop in to drive a rear axle even just a mild hybrid on the front axle would give you ~200hp 4WD vehicle which would make up for the hybrid premium. It would also help that its not that fussy about cooling if its going to be rear mounted and only used when required


The high coolant temperature allows a smaller radiator and less airflow.  This compounds the advantages in weight, cost and efficiency.

If we want rare earths, all we really need to do is start using thorium in nuclear fuel.  Thorium is a byproduct of rare-earth refining, and is expensive to separate.  There is currently no significant market for thorium, so it is effectively a waste product.  Turning it into a revenue stream would immediately make a lot of thorium-rich RE deposits profitable to refine.


"Power density is about twice that of today’s motors, according to GE."
is very misleading, tells little. If they were sure of superiority of their design, they'd for sure have said how many kW/kg, as some axial flux motor makers did.

BTW Bosch already makes similar motors, a whole range. PSA Peugeot Citroen uses Bosch motor to drive rear wheels in their through-the-road hybrid.


MG...average good motors have a power density of about 3 hp/lb and the best are up to 5 hp/lb. If this motor is 50% better than today's good units, its power density may be around 4.5 hp/lb.


@ Harvey,
There are some e-motors used in recently launched EVs with low power density.
For example e-motors in Renault EV Fluence, and Kangoo electric. On their specs page (French) I found they use motor of 130 kg developing about 50 kW. Big difference in power densities between those motors (I think made by Continental, synchronous AC with slip rings), and the one from Tesla roadster.



How much is that in metric?


About 7.3 kW/kg.


Some twenty months ago, GE declared, to highly positive media coverage, they would purchase 25,000 EV's(~6,000/year: an average 500+/month) by 2015.

Have over 10,000 EVs been bought or has this followed their trend in tax payments?


Sorry for being lazy Anne.

Here are the conversions:

Assumimg that 1.0 hp = 0.746 Kw and 1 Kg = 2.2 lbs

1. 3 hp/lb = about 4.9236 Kw/Kg

2. 5 hp/lb = about 8.2062 Kw/Kg

3. 4.5 hp/lb = about 7.38738 Kw/Kg



I fully agree with the Metric system with one exception.

Could you convince EU to do like Japan and state fuel consumption in Km/l instead of the odd l/100Km


in Europe another HP is used for vehicle power:
... Mazda3 ... den 2.0 l MZR 110 kW (150 PS) oder den 1.6 l MZR-CD 85 kW (115 PS)!

1598cc in-line 4-cylinder, 16-valve, DOHC, 105ps (77kW) at 6000rpm and 145Nm at 4000rpm

There 1 HP = 0.733 kW (1 kw ~ 1.36 HP or PS)

and Wiki - Horsepower

Another thing - l/100Km or Km/l (or mpg).

Usually all consumer goods prices are expressed as say $/lb, $/kg, $/oz, $/bbl, and not kg/$.
European "l/100Km" mostly follows that pattern, ie how many litres to buy for 100 km.
American mpg reminds of vehicle range, like miles per tank. Probably comes from the time when fuel was ridiculously cheap in US, cheaper than drinking water. It used to be "Fill'er up". When fuel is expensive, you may fill just half, if driving infrequently.

Perhaps now that fuel is not that cheap in US, it makes more sense to use quarts per 100 miles, than mpg. It could make it easier to calculate how much fuel you have to buy.


MG...I fully agree that Kw should be used instead of various values of HP but I still prefer the Japanese metric way to state fuel consumption.


I wonder how bad their previous motors were that they could boost their efficiency by 5%?

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