Engineers at the University of New South Wales (UNSW) have developed a new high-speed magnetically driven motor for electric vehicles (EVs), which can potentially be used for HVAC systems.
UNSW engineers have built a new high-speed motor which has the potential to increase the range of electric vehicles.
The design of the prototype IPMSM type motor was inspired by the shape of the longest railroad bridge in South Korea and has achieved speeds of 100,000 revolutions per minute.
The maximum power and speed achieved by this novel motor have successfully exceeded and doubled the existing high-speed record of laminated IPMSMs (Interior Permanent Magnet Synchronous Motor), making it the world’s fastest IPMSM ever built with commercialised lamination materials.
Most importantly, the motor is able to produce a very high power density, which is beneficial for EVs in reducing overall weight and therefore increased range for any given charge.
The new technology, developed by a team headed by Associate Professor Rukmi Dutta and Dr Guoyu Chu from the UNSW School of Electrical Engineering and Telecommunications, is an improvement on existing IPMSMs, which are predominantly used in traction drive of electric vehicles.
An IPMSM type motor has magnets embedded within its rotors to create strong torque for an extended speed range.
However, existing IPMSMs suffer from low mechanical strength due to thin iron bridges in their rotors, which limits their maximum speed.
But the UNSW team has patented a new rotor topology which significantly improves robustness, while also reducing the amount of rare earth materials per unit power production.
The new design is based on the engineering properties of the Gyopo rail bridge, a double-tied arch structure in South Korea, as well as a compound-curve-based mechanical stress distribution technique.
Motor advantageous for other applications
The new IPMSM prototype motor was developed using the UNSW team’s very own AI-assisted optimisation program which evaluated a series of designs for a range of different physical aspects – namely electrical, magnetic, mechanical and thermal.
The program evaluates 90 potential designs, then selects the best 50 per cent of options to generate a new range of designs and so on, until the optimum is achieved.
The final motor is the 120th generation analysed by the program.
Apart from electric vehicles, the motor has many other potential applications. One of them is large heating, ventilation, and air conditioning (HVAC) systems which require high-speed compressors to use a new form of refrigerant which significantly reduces the impact on global warming.
It can also be utilised in high-precision CNC machines that are highly demanded by the aviation and robot industries. The UNSW high-speed motor technology can allow such high-precision CNC machines to mill or drill with minimal diameters.
Another application is as an IDG (Integrated Drive Generator) inside an aircraft engine to provide electrical power for aircraft systems.
The UNSW team’s new motor also offers a significant cost advantage over existing technology and uses less rare earth materials such as neodymium.
“Most high-speed motors use a sleeve to strengthen the rotors and that sleeve is usually made of high-cost material such as titanium or carbon fibre,” Dr Chu said.
“The sleeve itself is very expensive and also needs to be precisely fitted and that increases the manufacturing cost of the motor.
“Our rotors have very good mechanical robustness, so we don’t need that sleeve, which reduces the manufacturing cost.
“And we only use around 30 per cent of rare earth materials, which includes a big reduction in the material cost – thus making our high-performance motors more environmentally friendly and affordable.”
