A new high-speed electric motor could help solve range woes of EVs

Researchers at the University of New South Wales Sydney have developed a new electric motor that can clock 100,000 revolutions per minute. The high power density achieved as a result of this new design could help reduce the weight of electric vehicles (EVs) and thereby increase their range, a university press release said.

EV makers around the world have been looking for ways to address the range anxiety of their battery-powered vehicles. One of the options is to increase the size of the battery pack, which also increases the weight of the vehicle, creating more problems to solve.

The other option is to reduce the weight of the electric motors, and the way to do so is by increasing their speed. A motor spinning at high speed can be shrunken in size, which can reduce not only its weight but also its energy consumption. When applied to an EV, it can help increase the range with the same battery pack.

AI-assisted optimization program

Conventional Interior Permanent Magnet Synchronous Motor (IPMSM), used by EVs in their traction drives, embed magnets in their rotors to create strong torque. However, the low mechanical strength of their iron bridges limits their maximum speed. The researchers used a new rotor topology that not only increased the robustness of the motor but also decreased the rare earth materials needed to produce it by as much as 70 percent.

Researchers at the UNSW used an artificial intelligence (AI) assisted optimization program that evaluated a wide range of aspects such as electrical, magnetic, mechanical, and thermal to optimize the electric motor design.

Developed in-house, the program evaluated 90 such designs and then selected the top 50 percent of them to generate new designs, and the iterative process was repeated till the desired optimum was reached. The final motor used by the researchers is the 120th generation that was analyzed by the program.

What they achieved was the absolute maximum speed of 100,000 revolutions per minute and a peak power density of 7kW per kilogram, the press release said. This is also twice the existing high-speed record of laminated (IPMSMs), which are used in traction drives of EVs, making it the fastest IPMSM ever built.

How can the motor be used?

"For an electric vehicle motor, we would actually reduce the speed somewhat, but that also increases its power," said Guoyu Chu, a post-doctoral researcher who worked on the project. "We can scale and optimize to provide power and speed in a given range – for example, a 200kW motor with a maximum speed of around 18,000 rpm that perfectly suits EV applications."

Apart from EVs, the motor could be used in large heating, ventilation, and air-conditioning (HVAC) systems that use high-speed compressors as well as high-precision CNC machines. The motor can also be deployed inside aircraft engines as an Integrated Drive Generator (IDG) to provide power to electrical systems.

The researchers are confident that their motor can be quickly commercialized, bringing its advantages to the market sooner than we can anticipate. "If an electric vehicle manufacturer, like Tesla, wanted to use this motor, then I believe it would only take around six to 12 months to modify it based on their specifications," Chu added in the press release.