Given the direction the car industry is heading, there is a huge need for automotive electric motors that offer exceptional performance but are cost-effective too.
We’re moving towards a world where we can’t be as reliant on fossil fuels as we have been for the past few decades. Our lives are surrounded by the products made from oil, most notably in the cars we drive every day.
But every time we turn the ignition key and use a little more petrol of diesel, we deplete the limited natural resources at our disposal. Not only that but we fire more CO2, NOx and particulate matter into the atmosphere.
Which is why there has been a recent push to develop and bring to market electric and plug-in hybrid vehicles, reducing our impact on the environment.
We’ve all seen the battery electric Tesla Model S and plug-in hybrid Mitsubishi Outlander PHEV as we drive around, and the number of these types of vehicles is only going to increase. But while discussions about the batteries these type of cars use are constantly appearing there is another component that is also undergoing a revolution – the motor.
Batteries may be an integral part of an electric or plug-in hybrid vehicle, but without an electric motor there’s nothing for the stored electricity to power. It would be like car manufacturers spending all their time developing the fuel tank and ignoring the engine, which is why a number of firms are spearheading motor innovation.
At the moment cars such as the Tesla Model S use a traditional synchronous electric induction motor to provide power to the wheels, and while they are effective, improvements can be made to make the technology more efficient and increase performance.
One company, Equipmake, (though it isn’t the only one), has developed the spoke motor – a type of electric motor where the magnets are arranged like the spokes of a wheel – to help improve efficiency and performance.
Equipmake says the technology is more powerful, compact and lighter than its competitors and, most importantly for the automotive industry, it can be mass produced. Given the direction the car industry is heading, there is a huge need for automotive electric motors that offer exceptional performance, are cost-effective but can also be made in large numbers.
The technology isn’t new, but developing it so it can be easily produced has been one of the main challenges in bringing the technology this far.
Equipmake and the spoke motor are the brainchild of Ian Foley, managing director at the firm. His career has been eclectic, starting out with Lotus F1 working on active suspension, moving through endurance racing where he designed and built paddle shift transmissions in the 1990s), and was then asked by Max Moseley to develop a hybrid system for F1, which became the Williams F1 KERS project in 2009.
And it is from that innovation – which was essentially a flywheel – that he developed the spoke motor.
With its roots in the Williams KERS flywheel and the fact it is light, powerful and compact shouldn’t be a surprise, but the crucial design aspect of the spoke motor and what Equipmake is doing, is that it’s also a very well-cooled interior permanent magnet motor. Cooling is key to motor performance, the cooler you can keep the magnets, the closer you can run the motor to maximum power output for longer periods.
The motor in the base model of the Tesla Model S produces 270kW of power and 441Nm of torque, but producing maximum, or close to maximum output, is a challenge because of thermal issues. It’s easy to get peak power for a short period of time, it’s hard to have sustained peak power, because you run the risk of overheating.
Equipmake’s APM200 motor weighs around 40kg, can run at 10,000rpm and has peak power and torque figures of 220kW/450Nm. Those figures, Equipmake believe, make it the most power and torque dense motor of its type.
The APM200 is still in the early stages of its development but applications are already presenting themselves.
Key projects so far include the supply of motors for an upcoming plug-in hybrid supercar, called the Ariel Hipercar, and the entire powertrain for an electric bus project (the latter has huge potential and could be the global answer for many cities who are faced with air pollution problems).
The Ariel Hipercar will grab the most attention as it’s a vehicle that will produce 880kW of power and 1,800Nm of torque helping propel it to 60mph in only 2.4 seconds.
The HIPERCAR, which stands for High Performance Carbon Reduction, is destined for full release in 2019 and Ariel production in 2020.
HIPERCAR’s focus is on extreme performance, agility and usability, coupled with zero and ultra-low emissions. The car will be available in four-wheel drive and two-wheel drive variants, and with the spoke motor at its core, Equipmake hopes it will show the potential of the technology at the extreme edges of the performance map.
But it is perhaps the second application which will show how this new motor technology can benefit a wider audience.
Equipmake is developing a low cost electric bus drivetrain to provide a turnkey solution for coachbuilders to enable more widespread adoption of electric buses – something that so many dense urban areas could benefit from as they strive to reduce vehicle emissions and improve air quality.
The Equipmake EBus drivetrain utilises two APM200 motors, mated with Semikron SKAI inverters. The battery technology is provided by the latest generation batteries from AESC, which provides the batteries for the most successful electric vehicle, the Nissan LEAF.
The first prototype vehicles will begin testing in the second quarter of 2019, with in service testing starting the following year.
As vehicle manufacturers move closer to fully electrifying models, whether they are battery electric or plug-in hybrids, spoke motor technology could be the answer to bringing these vehicles to the masses, whether that’s in privately owned cars or used to power public transportation.
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