Protean Launches Production In-Wheel Electric Motor

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The benefits for dedicating an electric motor to each wheel of a vehicle were clear to see in Drive's recent video of the Mercedes-Benz SLS AMG Electric Drive.

Make those motors in-wheel units, and in theory you get even more benefits.

It's a design that in-wheel motor company Protean has been perfecting over the last few years, and has debuted a production version at the 2013 Society of Automotive Engineers World Congress.

We last saw one of Protean's designs back in May 2012, helping to power an already-potent BRABUS Mercedes-Benz.

The company has also demonstrated its motors in a Ford F-150 pickup truck, a Vauxhall Vivaro cargo van, and a Chinese Trumpchi family sedan.

Protean markets its in-wheel motor for both hybrid and all-electric applications. Each unit sits in the space behind a wheel, supplying power exactly where, and when, the driver requires.

It's certainly powerful, with each motor alone producing 75 kW (100 horsepower) and 735 pounds-feet of torque.

Each also weighs "only" 68 pounds which probably isn't so good for unsprung mass--all the weight not supported by the car's suspension, affecting handling, steering, responses and ride quality. Protean does say that the extra unspring mass can be compensated for in other ways though, reducing the effects of significantly heavier rolling stock.

And with claimed economy improvements of up to 30 percent (depending on battery size), the benefits may offset the negatives for many. Protean also says up to 85 percent of the vehicle's kinetic energy can be recovered when braking.

Perhaps the motor's biggest benefit is that it can be retrofitted to almost anything, as demonstrated by the electic mix of demonstration vehicles.

There's no word on when the first vehicles equipped with Protean in-wheel motors will hit the road, but the benefits for larger vehicles in particular could be significant.


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Comments (18)
  1. The obvious way to reduce the unsprung mass would be to integrate the rim bead onto the hub motor. Then, they could elimintate the separate rim. If they integrated the new non-neumatic tires, they could further reduce the weight and eliminate the spare.

  2. I'm not a fan of in-wheel motors, every time you'd encounter standing water, your motors would be at least partially under water it may even be salt water. Then there is dirt and stones and the motors would be bouncing with the wheels through every pothole. Plus because of the weight added to the wheels I'm sure some modification to the suspension will be needed. BMW tuned there suspension systems to adapt for run-flat tires, so you know they have to do more then just add the motors. I'm not sure we'll see these in-wheel motors spark a revolution.

  3. I agree with you on every point you mentioned.

    But the upsides are simple design and a true AWD system that is easy to control and change. Also, the four wheel steering with vector control will become way easier. Changes are also easier to implement. Few lines of sw can modify the driving experience signficantly with this.

    Of course, all the issues that you raised are still the downsides.

  4. I'd rather see the motors in the car like the Mercedes SLS E-drive, that way the weight is in the car and the motors are safer. And think about carbon ceramic brakes, they were invented to reduce unsprung mass, there wouldn't be much of a point to ceramic brakes if you put motors in the wheel.

  5. Those are definitely real down-sides to hub motors. But, if they can really increase the efficiency by 30%, that is a huge benefit that outwieghs some of the negatives. Plus, they can increase interior/luggage space, facilitate cooling and eliminate drive shafts and U-joints by moving the motors out to the wheels.

  6. How much more spacious do you need a Model S to be?

  7. Model S will not be very popular for many Europeans. They want small, easy-to-park cars. They will very much like the space inside the vehicle that is freed up by wheel motors.

  8. I love the Model S, but I am looking for something smaller and less expensive. Maybe, Tesla will come out with their new economy model sooner than planned.

  9. The most water sensitive part of the motor are the ball bearings, and all cars have these. No difference there.

    The other parts of the motor can be coated to withstand the water. Or made of materials that are not ruined by (salt) water.

    We need to remember that all technlogy becomes cheap once mass produced. This motor will be no exception, and the risk associated with the more exposed location of the motor will prove a minor thing.

    The upside is that you free up space inside the vehicle and get a lot of freedom in designing the car. No drive shafts and motors will have to be accommodated. Design freedom works like a magnet. That reason alone will make the wheel motor a guaranteed hit.

  10. Also, turning a FWD into an AWD or RWD will be really easy. Maybe make it so buyers can configure it themselves. AWD for the winter, RWD/FWD for the summer season...

  11. I see in-wheel drive systems as the most logical progression of the electric car. It will allow a flexibility in car design like nothing before.

  12. +1 Read your reaction only after posting my response.

    The design flexibility is my main point too. It will prove irresistible.

  13. These are about twice the weight of an average 15in wheel and tire and this gap closes compared to the old steel wheels.
    As for any water problem they would have to be pretty stupid to overlook this so I shouldn't worry. Other advantages would be the elimination of torque reaction between power unit and driven wheel in a conventional drive that requires chassis stiffening and tuned motor mounts capable of handling that torque. Elimination of drive shafts and CV joints is another plus.

  14. Oh for Heavens sake! The word is 'Eclectic'! Don't you lot have spelling and grammar checkers? (I really wouldn't expect journos to be able to get right all on their own these days!)

  15. I'm guessing you mean "get *it* right", Martin?

  16. And "Heaven's", for that matter. Unless you're referring to several Heavens, in which case the apostrophe should be at the end.

  17. Well, I know retrofits aren't their target market, but... say I have an old Chevy S-10 pickup (which I do) or similar. This is clearly the easiest way to turn that into an EV. Sure, it may drive like crap, but it's an around town car anyway. Of course, a target market strategy like that will see them bankrupt in a year! Still... it's tempting. Sooooo easy to retro, at least in theory.

  18. Wheel motors don't have enough starting torque at that low RPM so have to be many times larger than a geared motor.

    Nor are motors running at 500rpm's eff.

    Even with the rim as part of the motor just the magnets and copper weigh too much.

    The only place hub motors work is in MC's and bikes where to can help start up a hill, the controlling spec, so it doesn't have to be so overbuilt.

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