#1 cleantech news, reviews, & analysis site in the world. Subscribe today. The future is now.


Published on April 17th, 2013 | by Zachary Shahan


Protean’s In-Wheel Electric Motors Coming To Market In 2014

April 17th, 2013 by  

At least, that’s what the company is saying. I covered Protean back in October 2012, so I’m happy to see that the company is moving forward. It looked like an exciting technology to me at the time, and Gas2’s Chris DeMorro (a normally pretty skeptical guy who reserves his enthusiasm for clear wins) also seems quite excited in this Gas2 repost below. I just hope the plans are legit and the technology is as awesome as it sounds. Here’s the Gas2 repost:


The holy grail of electric vehicle technology is in-wheel electric motors, which put power directly to the street and eliminate a host of other parts. In-wheel electric motor maker Protean claims that by next year, production of their revolutionary product will begin.

Weighing just 68 pounds, but capable of delivering 100 horsepower and 735 ft-lbs of torque per wheel, the Protean in-wheel electric motor would eliminate things like driveshafts, differentials, and transmissions. That reduces the cost and complexity of electric drivetrain setups, and drops a whole lot of weight as well. Mercedes tuner Brabus used two Protean motors in their beastly diesel-electric hybrid to great effect.

That’s only a few of the advantages of in-wheel motors though. Each motor can be controlled independently, allowing for more control in dicey situations. Protean also claims their electric motors can reclaim up to 85% of the kinetic energy via regenerative braking. The Protean system can also be retrofitted to existing vehicles fairly easily.

Sounds amazing, right? With production scheduled for next year though, I am left wondering… what automakers are signed up for this awesome tech? Or will Protean sell these as stand-alone units directly to customers? So many possibilities… what will come of it all?

Tags: , ,

About the Author

Zach is tryin' to help society help itself (and other species) with the power of the word. He spends most of his time here on CleanTechnica as its director and chief editor, but he's also the president of Important Media and the director/founder of EV Obsession and Solar Love. Zach is recognized globally as a solar energy, electric car, and energy storage expert. He has presented about cleantech at conferences in India, the UAE, Ukraine, Poland, Germany, the Netherlands, the USA, and Canada. Zach has long-term investments in TSLA, FSLR, SPWR, SEDG, & ABB — after years of covering solar and EVs, he simply has a lot of faith in these particular companies and feels like they are good cleantech companies to invest in. But he offers no professional investment advice and would rather not be responsible for you losing money, so don't jump to conclusions.

  • Cynthia Avishegnath

    A university in Japan developed the in-wheel motor concept. Where directional steering is further effected by differential speed between the left and right wheels.

  • Maksani

    Update? 2014 has come and gone. Still waiting for my kit.

  • danwat1234

    I’m interested in converting my 1999 Civic into a mild hybrid. I wonder if we can buy kits for conversion from Protean in the future?

  • Arlan Moreno

    So if I were to build a electric car conversion using these motors then I would have a car with 400hp and 2940tq. Imagine the company who bought the Fisker Karma bodies removing the electric motors installing a 1 liter 3 cylinder and having the motors in all four wheels.

  • running roach

    How is water and dirt getting into the hub going to affect the electric motor.

  • arne-nl

    Here’s a complete bolt-on plug-in hybrid conversion unit: http://www.greencarcongress.com/2013/04/linamar-20130418.html

    • Bob_Wallace

      Moving the motors inboard and connecting to the wheels does make it easier to protect the motors from the elements.

  • arne-nl

    In wheel motors make such a lot of sense, the question is not whether but when EV’s will get these. Frees up a lot of space inside the vehicle and that gives a lot of freedom to the designers. Car manufacturers just LOVE design freedom.

    The 4 main issues so far (as I see them) are:
    1 Cost. Two motors instead of one is simply more expensive. The differentials/driveshafts/reduction gears that are being used now are commodity items in the car business and therefore relatively cheap.
    2 Torque. A high rpm low torque motor is smaller and cheaper than a low rpm high torque motor that is required for a wheel motor.
    3 Unsprung weight. I am not that much of a car buff, but they say high unsprung weight negatively affects handling and ride comfort.
    4 Exposure. An electric motor is still a quite delicate piece of equipment. You’ll want to have it in a safe, protected spot. In the wheel the motors are exposed to more vibrations and dirt.

    Nothing in this list poses a fundamental problem. All can be overcome by better design, advanced materials and mass production. I am certain the in wheel motor will be standard in the future, but we’ll have to wait.

    • Bob_Wallace

      On the unsprung weight issue…

      “A stock 2007 Ford Focus was compared with an identical vehicle modified with 66 lb (30 kg) of ballast fitted to each wheel. The weight was distributed between rotating and nonrotating unsprung masses as to broadly replicate Protean Electric’s PD18 (18-in diameter) wheel-hub-motor unit. The project plan included three phases of analysis and testing.

      Phase 1 focused on modeling of different modifications, including suspension spring, bushing, and damper rates, and different tires and pressures, and their effects on the IWM-equipped vehicle. It was determined that simply fitting a standard Focus ST suspension (an upgrade on the stock base car) would be a good practical solution.

      In phase 2, the stock vehicle was modified with the Focus ST suspension. This setup included revisions to the front and rear spring rates, dampers, and the rear antiroll bar. In phase 3, the Focus with the modified ST suspension was retested. The process included a subjective vehicle assessment, objective ride and handling tests, on-road shake measurements, and two-post shaker rig measurements.

      The studies concluded, and the presenters argue, that while the vehicle carrying the greater unsprung mass at each wheel did display perceptible differences compared with the stock vehicle, those differences were minor and can be mitigated using “normal engineering processes within a product development cycle.”

      By fitting the upgraded ST-level suspension to the car replicating one equipped with Protean PD18 in-wheel motors, the vehicle’s handling and on-center tracking were improved back to reference. Overall, the effort conducted by Protean Electric, Lotus Engineering, and Dunamos may help convince skeptics that the addition of 30 kg of unsprung mass per corner will not adversely impact overall vehicle dynamics and can be addressed fairly easily with cost-effective countermeasures.


      Furthermore, it seems to me if you’re using electric motor to control the vehicle height rather than liquid/air shocks then the unsprung weight wouldn’t matter. Feed a bit more power to the motor as the wheel travels downward in order to maintain the same amount of force between vehicle and wheel, capture that power back as the wheel comes back up.

      Michelin, I believe, used motors rather than springs and shocks in their suspension.

      • arne-nl

        Thanks for the info. I already suspected that suspension changes can counter most of the drawbacks of higher unsprung weight. Active, programmable suspension is even better of course. But still a while off.

        That brings me to another favorite of mine: complete active suspension/wheel motor/brake/steering units with power electronics and a standardised vehicle interface (both electrically and mechanically).

        Building a car then becomes simply designing a strong box for the passengers to sit in and making sure it has sockets for those standardised wheel units on all corners. Then connect the cables and you have a car!

        • Bob_Wallace

          I’m with you. Mainly because I see that as the best route toward a good variety of 4wd models. If in-hub motors/suspensions can be bolted on front ends and plugged into the wiring harness then any car model can be released in a 4wd version.

          And with with electric/active suspensions 4wd vehicles could ride lower to the ground on smooth roads and raise themselves up when more ground clearance is needed.

          Apparently Michelin had programmable suspensions in a working prototype in 2004. And here’s a great 2008 video of their prototype showing what the suspension can do.


      • VirtualGathis

        This sounds alarmingly like they utterly failed to understand the details of these motors prior to testing. The line about adding 66 pounds of unsprung weight implies they added 66 pounds on top of the existing systems they install inside the wheel already. This would have resulted in an erroneous result. By adding 66 pounds they effectively compared stones and oranges.

        “Unsprung weight!!!!!” is an argument I see often about the Protean motors. Usually by people who utterly failed to research the motor. I blame the authors of these articles for that as they have not addressed it in years. Since the second year these motors were out the bloggers and news authors report the weight but never mention the hardware that they replace inside the wheel. They also do not run comparisons of before and after weight.

        If you read the data on the company’s website or the historical data starting with the mini QED you will see that there is a large amount of unsprung mass being replaced by the Protean Motors.

        Reaching back to the mini QED quoting the article I first read: http://www.gizmag.com/go/6104/
        “The in-wheel motors and magnesium alloy wheels, and tires, have a total mass of 24kg. The original assembly mass on the MINI One was 22.5kg.” I have to interject here that is a difference of 3.3 pounds not 66, and on a mini whose braking hardware weighs less than most. To finish the quote: “With so little difference in unsprung mass (the brake hubs and discs have been removed), and full regenerative braking, the ride is claimed to be no different.”

        I have had some argue that using an electric motor to replace the friction brakes is a risky proposition. The thing to keep in mind is that these motors can generate 200hp each of stopping force. It can be done in a passive way so even if the battery is flat it can still stop. Try this experiment sometime: take an electric motor, hang a weight on it, get it spinning then short the leads (not by hand preferably). The motor will stop the load due to conflicting magnetic fields inside, and if it is large compared to the load it will happen very quickly.

        • Bob_Wallace

          Interesting. Very little change in weight if mechanical brakes are eliminated. Not sure if the world would accept that, at least at first.

          “It can be done in a passive way so even if the battery is flat it can still stop.”

          Don’t you mean even if the battery is fully charged?

          • VirtualGathis

            No. I’ve never thought of the battery being full causing trouble. That statement is because folks tend to think the braking comes from running the motor backwards and not understanding that an electric motor can stop without input power, well, beyond that of spinning wheels. there are other options if the battery is full. Like trains and dynamic breaking the kinetic energy could be dumped as heat with a resistive heater.

          • Bob_Wallace

            Got it. I had thought of using a resistor as a full battery dump. My thinking of a full battery would be a lack of somewhere to ‘push’ the power, an open circuit offering no resistance.

            I’m on my second orbital sander. The first was a Porter Cable which was great but wore out. When I turned it off it quit spinning right away. I’m now using (have about used up) a cheaper brand model which continues to spin long after its turned off. You have me thinking that the reason is that the cheaper brand saved a few pennies by not including a resistor/brake.

            All that said, it seems like some sort of mechanical “emergency brake” would be required. That puts things back into heavier hub land.

          • VirtualGathis

            If you are talking about an emergency stop the motors can do that without friction brakes. They just need a manual bypass of the electronics. The 66 pounds already includes a manual “parking” brake.

  • bussdriver78

    Read about this or somebody similar many years ago – it sure took a long time for somebody to do it. The problems with these is the wheels will impede performance so they will not be sporty features. Also, there is a serious wear issue as the bearings go so one has to watch the bearings and they will not last as long as conventional bearings either. These were issues before. Not to say they don’t solve other problems but there is a reason why it didn’t happen before. I’m surprised they went with such a conventional design when a “pancake” motor avoids many of the issues and there are smart patents on those designs which result in 40% size reductions… When is somebody going to combine these designs?? oh, that’s right– the patent holders are too greedy to just take cut.

    • Bob_Wallace

      Michelin developed an in-hub wheel and built a prototype car a few years back. There’s a video of it on Toob.

      Why would there be a serious wear issue with the bearings? Like any wheel bearings they are supporting the weight of the vehicle and going around in circles. It’s just a matter of sizing them correctly.

    • Scotland

      Popular Science wrote about a company, Unique Mobility, in an article in 1986. Do a Google search on “Popular Science Unique Mobility”.

      Their description in the same article about the hypothetical hybrid car that would use the motor was remarkably similar to serial hybrid cars like the Chevy Volt, except they imagined a flywheel would capture energy from regenerative braking.

      • Scotland

        Oops – Meant to say that this idea (a motor at each wheel) is not new and has been around for a while. Unique Mobility was working on the same exact item in 1986.

  • Mohan Raj

    Please bring this on, this will enable EVs to have a higher range and increase its sales.

    • Ray

      I have told my friends about this type of motor. They are all waiting for a golf cart version to make an easy 4×4 out of an simple golf cart. Pls send me some info if anyone can help on this subject.

Back to Top ↑