TM4 Improving Electric Motor Design & Launching 3 New SUMO MD Motors

JUN 17 2016 BY MARK KANE 18

TM4 electric motors

TM4 electric motors

We have often heard that electric motors are already so sophisticated that their future performance improvements will be marginal.

Now, TM4 encourages us that there is still room for innovation.

The Canadian company announced three new models of its SUMO MD series motors, which use 25% less rare-earth magnets – and also offers up to 45% more torque and speed inside the same package of their predecessor (power output stands at 250 kW peak).

TM4’s motors are best suited for heavy duty applications like electric buses and trucks.

“TM4 will introduce three new SUMOTM MD powertrain options at the 29th Electric Vehicle Symposium & Exhibition (EVS29), offering an increase of up to 45% in torque and speed, thanks to a new technological advancement.

Until now, the main rotor technology found in TM4’s electric motors was based on surface mounted permanent magnets. The desire to limit the use of rare-earth magnets has resulted in a technology choice that leverages the reluctance torque of TM4’s external rotor design and decreases by 25% the use of these elements. By substituting some of the magnets with soft magnetic composites (SMCs), variable reluctance adds up to 45% extra torque and operating speed compared with previous technology in same package dimensions.

The new technology was developed in house with the support of Rio Tinto Metal Powders and the National Research Council of Canada (NRC). This partnership has made possible the conception and production of an innovative motor design combining new materials, a new forming process and an optimized fabrication method.

The LSM200-2200,2600 and 3000 will be officially launched at the EVS29 expo as part as a cocktail reception at booth 1101 on June 20th at 16h30 EST.”

Stéphane Poulin, Vice-President Engineering at TM4 Inc. said:

“We improved the torque density and operating speed range while maintaining a competitive price. One of the decisive criterias when selecting a powertrain is how much performance you get for the price, weight and packaging. This new motor design allows us to optimize our direct drive powertrain systems on all of these aspects.   TM4 is constantly seeking ways to improve, through innovation, its products and services to serve its customers better.”

More about new SUMOTM MD here.

TM4 announces technology advancement and the launch of 3 new SUMO MD electric motors

TM4 announces technology advancement and the launch of 3 new SUMO MD electric motors

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18 Comments on "TM4 Improving Electric Motor Design & Launching 3 New SUMO MD Motors"

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Whoever said there was no room for improvement?!? What is true is that electric motors are already so efficient as to leave little room for improvement. But in other respects there’s plenty of scope.

25% less rare earths? I prefer motors that doesn’t use any, such as the induction motor that Tesla uses.

But with less efficiency and torque, it matter specially on those heavy hauler vehicle.

Yes. Induction motors can have a high efficiency at a certain point, but not on the whole operation map of the motor. SPM motors have a >90% efficiency across most t the operating range. It makes them a good choice for direct-drive.

250kw motor is only 228kg or 505lbs. Such a lightweight motor.

Especially considering the brutal torque figures it puts out. An IC engine with similar performance would likely need to be a couple of times heavier.

250kW is only 335HP.

That is less than the motor used in the Ford Focus RS.

How much do you think the 2.3L turbo charged 4 cylinder weigh in the Focus RS?

Certainly not “couple of times heavier” of 505lbs…

So why don’t manufacturers just use 2,3l turbo charged four cylinders in semi trailers that weigh 40 tons and more?


Compare these motors to a 330 HP, 9 L diesel, like the Cummins ISL.


“So why don’t manufacturers just use 2,3l turbo charged four cylinders in semi trailers that weigh 40 tons and more?”

Because few hundreds of pounds isn’t a big deal in a 40 tons trailer…

The original topic is about weight/power ratio for ICE.

Aviation ICE engines are always good in terms of weight/power ratio…

Nissan has IC engine with 400hp which is 40kg with gearbox will be less than 100kg.
YASA motors has 200kw motors with 790Nm weight 37kg
Emrax motor 268 is 200kw and 20kg.
Tesla roadster electric motor is 220kw 33kg and could use reduction gear 20kg or less.
For so high torque this motor will need insane current(a lot amps)

Yet none of these motors are good to direct-drive a bus or a truck. They would all need a gearbox, which are a rare/expensive thing for electric motors at that power level, Especially multi-speed ones. Right now TM4 and Siemens are main companies supplying direct-drive motors for this market.

One kW per kg is nothing special. Pretty standard for industrial motors. Tesla Model S AC induction motor is 300+ kW at around 70 kg.

Seimens has a 250 kW motor that’s 50 kg. They designed it for Airbus’s electric airplanes.

TM4 also have motors that have high power density. Its not complicated, you just need to increase the RPM. But these direct-drive motors are made to replace not only the diesel engine, but the whole transmission. That need to be factored in for the power to weight calculations. High RPM motors use gearboxes, these don’t.

The intelligent and efficient combination of permanent magnets and reluctance in a permanent magnet synchronous motor were a big focues for BMW i while developing the motors for i3 and i8. Just like TM4 state this leads to decreasing use of rare earth materials, but more importantly to higher power density and a larger useful RPM band.
However, BMW i has filed a number of patents on this technology that TM4 will have had to circumvent without risking IP-realted litigation with BMW i, possibly be virtue of thier external rotor design vs. BMW i’s internal rotor…


little bug… performance curves red HV2600 and yellow HV2200 ?? well I guess no one really cares and neither should I 😉

You guys sħouldn’t focus on motor power, but on torque. These SUMO motors aren’t meant for regular cars, but for hauler trucks, buses and such. That’s why they have 1100 Nm of torque for 250 kW instead of 430 Nm of torque for 320 kW like the Tesla.

Torque is what moves a payload, which is what’s needed for heavy vehicles. But from the article itself, it isn’t clear, I admit.

That’s right. This motor is not for passenger vehicles. no need to worry about the 228kg weight. For passenger car you can design a 50kg motor which has 250kW power. And it will use only 10% of rare earth magnets compared to the 228kg motor.

Permanent magnet motors are superior in every way against induction motors. Tesla uses induction motors because the chinese are still having monopol on rare earth magnets. Between 2008-2009 they became very expensive and every motor manufacturer was very worried about the future of rare earth magnets.

Meanwhile the price is down again. So nobody is worried about it nowadays. Only Tesla is stuck with the induction motors. All other ev makers use Permanent manget motors.

That’s because they are superior to all other kinds of electric motors in every way you look at them. Weigth, power, torque, thermal performance.
Price/kW is much the same.