Ricardo Develops Rare-Earth Free Electric Motor

APR 21 2015 BY MARK KANE 53

Ricardo RapidSR electric motor prototype

Ricardo RapidSR electric motor prototype

Ricardo presented its next-generation electric vehicle motor prototype called RapidSR for use in electric vehicles.

It’s an 85 kW Switched Reluctance Motor, which doesn’t have magnets, rare earth elements or rotor windings.

According to the press release, it’s a compact package that’s light weight and low cost. Though first it needs to be tested in real-world automotive applications.

We are impatiently waiting on first EVs with this type of motor to see what the real benefits are.

“The new electric vehicle (EV) motor has been designed and built in prototype form by Ricardo as part of a collaborative research and development project, RapidSR (Rapid Design and Development of a Switched Reluctance Traction Motor). Using a conventional distributed stator winding, the Ricardo synchronous reluctance electric machine is a highly innovative design that makes use of low-cost materials, simple manufacturing processes and uncomplicated construction. It has a rotor made from cut steel laminations, which are used to direct and focus the flux across the air gap. By maximising this flux linkage between the stator and rotor, performance can be optimized within a tightly packaged, low weight and rare earth element free design.”

“Since its launch in 2012, the RapidSR project has been researching the design of next-generation economic electric motors that avoid expensive and potentially difficult to source rare earth elements typically used in permanent magnets. By developing effective CAE led design processes as well as prototype designs, the team has created a framework for the future design and manufacture of electric vehicle motors that offer the performance, compact packaging and light weight required for EV applications, but at a significantly reduced cost compared to permanent magnet machines. Ricardo’s partners in this research include project leader Cobham Technical Services – which is developing its multi-physics CAE design software, Opera, as a part of the project – and Jaguar Land Rover. The research is being co-funded by the UK’s innovation agency, Innovate UK.”

Paul Rivera, MD of the Ricardo hybrid and electric vehicle systems business stated:

“As the market for electric vehicles grows globally, there is an imperative to explore alternatives to permanent magnet traction motors which require the use of expensive and increasingly difficult to source rare earth elements. The Ricardo prototype that we have announced today demonstrates what can be achieved by using the latest electric machine design processes in the creation of a high performing, compact, lightweight, and rare earth element free concept.”

Dr Will Drury, Ricardo team leader for electric machines and power electronics commented:

“By bringing together state-of-the-art simulation technology with advanced electric machine design we have created a highly credible next generation EV motor concept that shows considerable promise. The Ricardo prototype is now built and will be rigorously tested over the coming weeks in order to validate the extremely positive results that it has shown in simulation, as a concept that provides an exceptional balance of performance, compact package, light weight and low cost.”

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53 Comments on "Ricardo Develops Rare-Earth Free Electric Motor"

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would be interesting to know the efficiency.

I don’t think there is much efficiency benefit, its all about low cost of manufacture. But the controller is more complicated, which offsets some of the cost benefit.

FYI, Tesla does not use magnets or Rare earth elements in their electric motors.

The Tesla does however have a lot of copper in its rotor, while this motor’s rotor is made of laminated steel. So this motor would be considerably cheaper to manufacture.
However I doubt it could handle the power the Tesla AC does in such a compact package.

Wikipedia gives a nice explanation of Switched Reluctance Motors. It’s a type of a DC “stepper motor, an electric motor that runs by reluctance torque. Unlike common DC motor types, power is delivered to windings in the stator (case) rather than the rotor.”



Always trikes me how compact as compared to a IC engine. Also so few parts involved. Yet I understood that the scheduled maintenance cost of a Model S for example is 600 USD/500 EUR per year, which is comparable to a ICE of similar size. Anyone out there owning a leaf or a I3 to inform me was is their scheduled yearly maintenance costs ? (tires changing not included, just the basic annual check up at the garage).

I just finished a 2 year lease of a LEAF. I believe the annual checkup is free for the first 3 years. They run battery diags and check your brake pads. I had heard the reprograming they were doing hurt acceleration and regen levels, so I never took mine in. The only maintenance cost I had was a new pair of front tires over the 2 years / and nearly 24k miles.

Thanks, then at least for a Leaf the maintenace costs are lower than for a ICE car.

I’ve got 24k miles after 18 months on my leaf, and haven’t had to do anything yet, except for the battery check.

Also, Tesla’s $600 annual maintenance is optional (warranty isn’t affected if you don’t do it). It’s just for peace of mind.

No friction wear, means no maintenance required.

Better get your brake fluids checked/flushed/changed… It is in your owner’s manual.

It is in the owner’s manual for the LEAF, but it’s a very, very conservative view of the life of brake fluid. Changing your brake fluid every 2 years, in most cases, is way overkill. Have your TRUSTED mechanic test the brake fluid, not just change it because the manual says to.

If people are willing to sign up for the non mandatory maintenance program then Tesla would be foolish not to take their money.

My first service of my Volt was at 19000 miles at 1 3/4 years to get the oil changed.

Your only significant maintenance cost for an EV like the Leaf will probably be new tires every 2-3 years. The LRR tires used in EVs don’t seem to last very long.

Not much maintenance on a Volt even with an ICE on board. I changed the oil early (which was the free first one) @ 15kmi. With some filters and a few other things, I came away with $106 spent.

Normal oil change interval is determined by the computer and mandatory at 2-years.

The ELR came with 4yr-40k-mi maintenance included.

I’m 2.5 years into a 3-year lease on my Leaf. The annual inspections cost nothing.

@Sublime: They reflashed my car at Year 1, but I didn’t notice any performance changes.

Nissan supposedly wants the brake fluid to be flushed every 2 years in the Leaf (at customer expense), but my dealer never mentioned it. Brake fluid flushing is a good practice, but 2 year intervals seems excessive.

After 23k miles in hilly western PA, the brake pads are still in great shape, but the OEM tires burned off in 10k miles.

Have you thought about getting your next set at one of those tire chains like America’s Tires? I got my last set for a large, heavy van there, and they offer all sorts of add-ons, like nail penetration/flat warranty and free replacement, etc which you probably don’t need. But one thing they did offer was something ridiculous like 60,000 mile/5 year warranty on the tires. I was like: “Really? For an 8,000lb van?” and they said “Yep.” For our HEAVY EVs, those types of tire warranties might be a good deal.

Oh, and free rotations for life.

I don’t know about yours, but mine seem to rotate on their own while I’m driving.


The annual check up on my Leaf cost $240 USD, for that service they replace the brake fluid and cabin filter (recommended annually), rotate the tires, and do a battery check with battery health report provided. Also the standard multipoint car inspection (top off wiper fluid etc). I drive enough that I need my tires rotated every 6 months and they charge $25 for that service which also includes the multipoint inspection.

All in it costs me $265 USD a year in required Leaf maintenance.

You’re getting screwed. Your brake fluid doesn’t need to be changed nearly that often, even if you’re using your car as a taxi. Have a trusted mechanic TEST the brake fluid. Don’t just change it because they say to.

Tesla is ALUMINUM car.

Do not compare it to “same size”, but to “same size” + “same price tag” + “same aluminum”.

I had my yearly Zoe-inspection with a changed airconditioning-filter and some minor things (like brake and wiper fluids). All in all 97 Euro.

zero costs so far. About 13k, 15 months.

The savings in maintenance costs by EVs over ICEs during the service life of the vehicle is regularly portrayed by small EV makers like GEM/Polaris and Good Earth/Firefly as being in the ~80% range.

As someone who has serviced these vehicles at the dealer level I can tell you this is far from a realistic number. They have maintenance issues, just different ones from ICEs.

Major automakers do a much better job and their EVs will require less and less maintenance as the production technology matures.

I’ve seen some wildly different numbers thrown out for how much an EV owner should expect to save on maintenance and repair costs over a gas guzzler owner. An EV1 advocacy site claimed 90%, which frankly seems excessive to me. A Ford-related site claimed about 40% savings, which sounds more likely. Obviously not every model of plug-in EV is going to have the same level of reliability, but common sense says that a vehicle which has far fewer parts to wear out should have significantly less maintenance and repair costs.

A couple of Consumer Reports articles make it clear that no, you won’t save on maintenance costs for a Model S as compared to the average gas guzzler. However, many online comments claim that you -will- save money as compared to other luxury cars. But that’s anecdotal evidence, so I won’t claim it’s definitive.

What I think very nearly every Tesla Model S owner -will- agree on is that you get a lot more value for the money you pay Tesla for maintenance. Their customer service record and satisfaction level are exemplary.

Or, to put it another way: Tesla Model S maintenance ain’t cheap, but you get great value for your money.

I wonder why it has 6 wires coming out from it? Most AC motors have 3 wires.

SRM have a problem with cogging, so the more poles you have the less of an issue that becomes. However more poles means faster switching requirements, so you need to find a happy medium. Most commercial SRMs therefore have a 6 pole stator (and 4 pole rotor).

More poles and control wires…

It’s basically a stepping motor that is stepping fast. So all that “cogging” as Sublime eloquently describes it means more vibration and noise.

Plus the power consumption is not constant, unlike a sinusoidal machine where the summation of 3 phases is a constant.

A stepper motor’s only redeeming feature is low cost, and even then it is offset by a more complicated controller.

Power switching electronics are getting cheaper and faster, while copper is only going to get more expensive. Down the road, trading controller complexity for cheaper motor materials will be a welcome exchange.
I also think SRMs are potentially more efficient, but there honestly isn’t much to gain there.

“Power switching electronics are getting cheaper and faster”

Well, there is a limit. As power requirement goes up, it will be harder and harder to switch faster. Not to mention the magnetic hysterisis issue which ultimately limit how fast you can switch.

Would someone here know from which company does Tesla get their motors from ?

Tesla gets their motors from a new company, called “TMC”. 😉

I ask that question because when Tesla first made the roadster it is likely the industry had no electric engine that was ready made for cars. So it is likely the roadster had an engine that was originally produced for a different use. It would be interesting to know for which use. There are a zillion lines about Tesla on the net but so far I could find nothing regarding the origin of those AC motors.

Ugh! This thing keeps deleteing me.

Anyway the first Tesla ROadster motor had aluminum bars which kept overheating. They changed them to copper.

This is technially a cheaper version of the induction motor that has cheaper “rotor” core…

You still need magnetic field to generate torque. You still get that from stator field. The only difference is that you don’t need to generate a strong magnetic field in the rotor so it will be cheaper to produce. But your torque will vary more as it switches from each pole and start/stop will be harder to control.

I also believe the 0 rpm torque will be lower as well.

I think several EV makers now use electric motors which have no rare earth magnets in them, not just Tesla. I’m not even sure Tesla was the first to eliminate that. What I find more interesting is the idea that you can build an electric motor without needing to have wire windings on the rotor. That could be a great money-saver, and not just by not having to use copper; aluminum works almost as well, altho it’s somewhat bulkier. But the physical act of having to wind all that wire around a rotor makes electric motor manufacturing a rather tedious and exacting process. In Tesla’s manufacturing process, many of the steps of putting wire windings on the rotor are done by human hands, because robots can’t do it reliably. However, just because you -can- build an electric motor without wire windings, doesn’t mean that motor can be used in a well-designed EV. As I understand it, all modern production EVs use AC induction motors. This motor is a different type; a switched reluctance motor. Would this type of motor have the same power curve, the same advantageous torque output over a high range of running speeds? It seems doubtful. Since… Read more »
The short answer is “no”, but you’ve brought up too many other issues to be addressed first. There is nothing unique abut the Tesla motor, it is the same basic 100+ year old design used in pumps, AC locomotives and even the ceiling fan over your head. Tesla chose AC induction because they wanted high horsepower motors. Permanent magnet motors are a bit more efficient, but rely on high quality magnets. Rare earths make the best magnets, but other materials can successfully be used with some compromises, as GM demonstrated with Volt 2. The problem with making high horsepower PM motors is the difficulty and physical danger of handling huge magnets (big ones can crush your hand). Both PM and induction motors are sinusoidal AC machines which require overlapping 3 phase stator windings. So far its proven to be easier to wind them by hand than use a machine because of the overlapping. Reluctance (stepping) motors are crude non-sinusoidal switching devices which have undesirable side effects like vibration, noise and non-constant power consumption, but fixed non-overlapping poles and non-magnetic core make them cheap to build. It is important to note there is nothing really new in electric motor design, it’s… Read more »

Right, the innovation that lead to our generation’s production EVs isn’t in the motor itself. It’s in the modern AC induction motor inverter, invented by Alan Cocconi when he worked at GM. Cocconi later helped found AC Propulsion, which made the tZero, which inspired the Tesla Roadster. Of course, that inverter only works -with- an AC induction motor, which is why all the EV makers are using that type of motor.

It’s interesting how this one guy’s invention lead to both GM’s EV1 and Tesla’s Roadster… and subsequent EVs at both companies. But I think -all- current production EVs use AC induction motors. I guess whatever patents GM/Cocconi had related to the inverter have expired.

Industrial variable speed AC drive controls existed long before GM adapted it for cars.

“Right, the innovation that lead to our generation’s production EVs isn’t in the motor itself. It’s in the modern AC induction motor inverter, invented by Alan Cocconi when he worked at GM.”

EVs have always been a technology waiting for right battery. Improvement and cost reduction of lithium ion batteries was the key enabling factor behind the start of the EV revolution.

EV revolution could have happened during 70s energy crisis, if there had been decent battery for EVs. Brushed DC motors of that era would have worked just fine with adequate efficiency. Just a little more maintenance would have been required due to brushes.

Work done by Cocconi and others to improve motors and power electronics sure has helped ,and will continue to help, in improving efficiency and reducing size and cost.

The only car that InsideEv’s readers have seen recently with “windings on the rotor” was that 1200 hp 1968 mustang. Almost all others do not have them. Tesla has bars.

Well, I saw an episode of “How It’s Made” that showed in detail the construction of the Model S, including showing the rather elaborate setup a Tesla worker went thru to prepare for the copper wires to be wound on a Tesla Model S motor.

But from the cutaway view seen in the link below, I guess the copper wire windings are on the stator, not the rotor. So if that is your point, then thank you for the correction.


“All modern electric EV motors are induction”.


So far as I know, every single modern production EV uses one or more AC induction motors to drive the powertrain. (Production cars, not necessarily prototypes.) Can you cite even one exception?


I think the Lightning GT was going to use in-wheel stepper motors, but that still hasn’t gone into production.

Volt, Leaf, Focus Electric, Fiat 500e, Spark, ELR, eGolf, Kia Soul, i3 all use permanent magnet motors, not induction motors.

The companies QCO mentions use synchronous motors simply to improve efficiency.

Tesla uses Induction motors since their namesake is given credit for the invention over a century ago. The synchronous motors used do not have any rotor current losses simply because they do not have any rotor currents.

Just to clarify for Lensman’s edification, a permanent magnet motor is by definition a synchronous motor, so you may see one or both terms together used to describe the same motor.

Admittedly, I got a grin from the term “switched reluctance”.

I couldn’t help but wonder if the phase-detractors were used to dampen side-fumbling via the concept of magneto-reluctance 🙂

Put one of these babies in the Turbo-Encabulator version of Volt 2.0 and you’ve got a Tesla beater!


No real info in the manufacturer’s copy, just advertising hype. Not even the number of poles. So what can I say? Its a pretty motor with some nice orangey wires.

Renault ZOE uses no magnets as well. In Europe around 25.000 ZOE are shipped. The next Generation engine will be used in ZOE, SMART Fourfour and Kangoo.

Renault ist the only mass production manufacturer who developed an own engine with integrated AC charger. They can charge up to 22kw AC 3-phase on TYP2/Mennekes, which is the European standard for AC.

Just today an upgrade kit to the Nissan Leaf fpr 22kw AC TYP2 was introduced by an Austrian company for 7500€. Reason: The TYP2 density is 60x higher than CHAdeMo. And a 22kw Wallbox is 10x cheaper than a 20kw CHAdeMO charger.

So other manufacturers care about rare earths as well.