World’s First Wireless In-Wheel Electric Motor


Wait… whatWireless hub motors? Must be some kind of little wirelessness, like control circuits or some smartphone app, right?  No.

This is a hub motor system designed by the University of Tokyo, as a test bed for an idea that you can power a motor directly, with induction, ultimately through power supplied in the roadway.  Think electric trolly cars without the overhead wires.

Here’s how it works, kind of:

High-power induction-supplied hub motor for EVs

High-power induction-supplied hub motor for EVs

The system is jumping a 10cm gap, at the moment, and induction, according to the laws of Physics, is an extremely lossy proposition.

This technology will pave the way for the development of advanced electric vehicles, including those that receive electricity wirelessly from transmitting coils that are embedded under road surfaces,” Hiroshi Fujimoto, an associate professor at the University of Tokyo specializing in electric vehicle control said.

Read more here: First wireless in-wheel motor system developed for electric vehicles

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26 Comments on "World’s First Wireless In-Wheel Electric Motor"

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I assume the brakes do not rely on the wireless power transfer.

If the idea is for power to eventually come from the road, wouldn’t it make more sense to put the receiver in a parallel position, under the floorboards, not in a perpendicular one, on the wheels?

And that unsprung weight as to give a terrible ride!
Bad idea in search of a solution.
Do we really want our powertrain to roll into all the potholes and be exposed to every elements we have on the road? No thanks

See my comment below about unsprung weight. One advantage of 4 motors is individual control of each wheel and each motor can also be smaller.

Wow, talk about unsprung weight!

There are other in-wheel motors (not wireless) that have addressed the unsprung weight issue.

You need to find the Protean video where it is chirping, and hopping over a speed bump at 15 mph. lol

Kdawg, I’m a fan of in-wheel motors and believe they could be the future of EVs. I especially like the Protean Drive, which integrates the brake system. I believe a lot of the unsprung weight could be offset by ditching the rim and mounting a Tweel directly to the motor housing.

Talk about one of “THE WORST” Ideas of Modern Day Technology…It’s Just Plain “BAD” Anyway You Look at it!

They should put it on the Mirai that would make a perfect bad ideas cartel.

+ 1
Perfect idea! Lol; Don’t be surprised if Toyoa runs with it.

…and drive it on a Solar Roadway! They could call it “Worst Technologies of the Century Cubed”!


It’s a prototype, as in proof of concept. Google glasses started as goggles tied to a computer hanging from a waist belt.
The technology will advance and become smaller long before it is commercialized.

I can see the use of hub motors for large trailer trucks, especially with multiple duallies or dump trucks, basically any vehicle with very large wheels and already heavy weight. But on conventional vehicles it adds unnecessary unsprung mass, as well as locating such mass outwards instead towards the center, in addition to subjecting harsher vibration to the motors.

The only unsprung mass should really be the wheels and tires. It’s why performance wheels all tend to be as light weight as possible.

Yeah, now if you can just get this with inductive charging too, you might be able to get the efficiency down close to ICE. What are they thinking?

Ever wonder why there are no hub motors already? No, it’s not the unsprung weight problem, it’s even simpler…motor bearing wear.

When you use the motor and its bearings as the wheel bearings, you load them heavily and abuse them badly which affect and changes the critical gap between the rotor and the stator of the motor…a gap that must be maintained within thousandths of an inch. Solve that problem and I’ll buy stock in your company.

as they Say Back in England., “Poppy Cock”….There must be a Hidden Agenda Here, Because it’s SOOOooooo SENSELESS!

No agenda and not poppycock. Wheel bearing failure is a very common problem in automobiles; a bearing failure in a hub motor could cause the rotor to collide with the stator and lock up the wheel…a dangerous conclusion.

In electric motors the smaller the air gap, the more torque that is developed by the motor. The air gap is usually designed to be as small as possible. A worn bearing can causes this gap to change and the motor to lose torque.

Having said this, I point out currently there is a lot of success in using hub motors in bicycle conversions; but, they are a lot different than using them in an automobile suspension. I like the idea of the hub motor; but, I don’t know of any that have been built that have lasted in long term road usage.

Hub motors or in-wheel motors never do seem to make the transition from prototype to mass produced car, in passenger vehicles. As I recall, the i-MiEV used four in-wheel motors in the prototypes, but not in the production model. As you say, Lad, I think it’s a matter of them wearing out too quickly, and that’s at least partly due to being subjected to the constant pounding of bouncing around with the wheels.

But there was an article recently about one of those giant trucks using in mining, and that used four independent hub motors. A diesel-electric hybrid drive train, like a diesel-electric locomotive, as I recall.

They approach it in the wrong way. It is interesting on a purely tech experiment point of view but if they want to apply something like that in real they should rather look at using the wheel itself as the mobile piece of a linear motor. The magnet would be above the wheel and the upper part of the wheel would act as the moving part of a linear motor. Since that upper part of the wheel would be permanently replaced as the wheel goes round, it would propel permanently. The only strange thing is that the linear motor would need to push the top of the wheel frontwards in order to have the bottom of the wheel going backwards and thus result in a forward movement of the car. The linear motor would obviously have a varying gap between the fixed magnets above the wheel and the wheel itself according to suspension movements but overall it would remain about constant. This would result in no unsprung weight at all, would not require bearings (since it is a linear motor) and would keep the sensitive magnetic parts of the motor safe in the car casing right above the wheel behind… Read more »

Second though, the gap can actually be much smaller if the magnet is not above the wheel but on the side of it. This is especially interesting for the back wheels that don’t need to turn and have a very finely predictable Y position.

That is two bad ideas packed together, unnecessary induction transmission losses and motors in the wheels instead of safe inside the car chassis.

contempt prior to investigation
thank god the wright bros thought outside the box not closed minded like a bunch of you !

“They laughed at Columbus, they laughed at Fulton, they laughed at the Wright brothers. But they also laughed at Bozo the Clown.” — Carl Sagan

I think you picked the wrong Bozos to idolize.

“This technology will pave the way for the development of advanced electric vehicles, including those that receive electricity wirelessly from transmitting coils that are embedded under road surfaces”

That will likely happen right after pigs learn to fly.

I’m reminded of the stunt where somebody built an airplane powered by an oil-fired steam engine, just to prove it could be done. Of course, it had only a few minutes’ flight time.

Just because you can do something doesn’t mean you should.

Given sufficient thrust, pigs fly quite well.

“Just because you can do something, doesn’t mean that you should”.

– This is my commentary on these guys who drive LEAFs and i3s over mountains and on long excursions for the sake of, “it’s possible”. When will we see the end of those?