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YASA Motors named UK’s Best Enterprise in the Lloyds TSB/Telegraph Enterprise Awards

YASA Motors, the Oxford University spinout developing high-torque, high power density Yokeless And Segmented Armature (YASA) motors (earlier post), has been named the UK’s Best Enterprise in the Lloyds TSB/Telegraph Enterprise Awards and won £50,000 (US$79,000).

The Yokeless And Segmented Armature (YASA) topology is a new type of axial flux motor that features a very high specific torque (torque-to-weight ratio), a high efficiency (typically up to 95%) and the possibility for low cost manufacturing. The topology is based around a series of magnetically separated segments that form the stator of the machine. The step change in the specific torque of the motor (30N·m/kg is typically at least 2-4 times better than the best alternatives, according to the company) comes from the combination of patented improvements in the magnetics, the cooling and the packaging of the motor.

“We’re looking at installing these high-performance electric motors in the new generation of electric and hybrid vehicles that will come on to the market in 2016/2017 as the design cycle for a new vehicle is four to five years,” says Tim Woolmer, 30, YASA’s founder and chief technology officer, who invented the motor for his DPhil project at Oxford University.

... “Electric cars will take some time to become popular as they are still relatively expensive to buy. But by reducing the magnetic materials in the motor, we are helping to make electric cars far cheaper to produce.”

(A hat-tip to David!)



Shockingly high specs.
Here is the Yasa-400:

Max torque 400Nm
Continuous Torque 220Nm
Peak output 165kw
Continuous output 85kw
Total weight less than 20kg
Size 280mm by 75mm

Ideally I'd like to see a less powerful version of these at each wheel, throwing away the mechanical steering and the differential.

Since typical engine blocks seeem to weigh over 150kgs, then using this as well as the weight losses from not having an exhaust system etc should result in the weight, particularly in the 2015 time frame we are talking about allowing increases in battery energy density, to come down into the ball-park of conventional cars.


Yes, with such high power density, four quarter size, very light, mass produced in-wheel e-motors is a potential reality. That would leave a lot more room for batteries and passengers.

Future much higher performance batteries + light in-wheel high power density e-motors + lighter control system + light weight composites frame and body could make an under one tonne affordable 5-passenger e-car.


It may only be a four seater not 5, but the Mitsubishi iMiEV is only 1080kgs right now.
I'd expect something on the lines of the Toyota FT-Bh with an electric motor to come in at maybe 900kgs.


It's annoying, to say the least, to hear someone favoring an in-wheel-motor solution again and again. No matter how light an in-wheel-motor motor may be, it inevitably increases the unsprung mass of the wheel. This subsequently leads to increased wear of tires and schock absorbers as well as handling instability and decrease of overall driving comfort.
Near-by-wheel mounting is acceptable because none of the a. m. disadvantages appear and the advantages are nearly the same as by in-wheel-mounting. Additionally, the motor itself, receives far less abuse than in a bouncing wheel.


On balance, I tend to prefer the housing of motors inboard, mainly because a valuable motor is rather exposed to damage if housed in the wheels, as well as because of the issue of unsprung weight you mention.
However, the issue is not so one-sided as you present, and a number of different metrics and well as unsprung weight have to be considerd, and the engineering compromises and work arounds explore.
Here is Protean, who do not agree with you:

And here is Nissan, which is considering in wheel motors for the next generation:

'Mr Nakamura said Nissan was “really seriously testing” in-wheel electric motors for the new-generation of electric-powered cars that will follow the Leaf, which he said was built on an existing internal combustion engine car platform.
He said the next generation of EVs would be designed specifically for battery-electric propulsion, presenting opportunities for major changes to packaging through space-saving technologies such as in-wheel electric motors.
In-wheel motors use the wheel hub as part of the motor, driving the wheel directly without any mechanical losses, although with the downside of increased unsprung weight.
“Not all cars can go in-wheel motor, but we are really seriously testing,” Mr Nakamura said.
“The in-wheel motor feels much more direct. And also a very good point is that you can control torque right and left, which is almost like four-wheel steering.
“If you turn, it is totally different – no understeer and very, very precise handling.”


This and the EVO are good designs. Two EVO motors are used in the Infiniti EnergE concept two seat sports car at 400 horsepower with the Lotus range extender.

Axial design motors may find their place in EVs, hybrids and EREVs, they are light, powerful and simple. There are lots of good designs in our future that is not all that far away now.


Evo seems to be at lower power densities:

'EVO’s latest design has a demonstrated peak power density of 5 kW/kg (2.5 kg/kW nominal). (Weight measurements included all motor/generator components including housing, shaft and resolver.)'

Its not totally clear whether the figures for Yasa incluude the same components though, and so they may be closer than the 2:1 differential which appears on the surface.


Ultra light in-wheel combined e-motor/generator/controller + air-less ultra light tires + composites ultra light wheels + much lighter mechanical brakes should not weight much more than current heavy steel wheels + heavy steel rotors/drums and brakes + heavy tires + heavy drive shaft etc.

All three components could be standardized and mass produced, by the millions, at much lower cost, in many low labor cost countries.

It could lower the weight and cost of future electrified vehicles while leaving more essential interior space for passengers etc.

The advantage of fully controlled AWD could be significant.

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