A team of researchers at the University of New South Wales (UNSW) has developed a new record-breaking high-speed motor that can extend the range of electric vehicles (EVs).
This new motor is the fastest Internal Permanent Magnet Synchronous Motor (IPMSM) ever built with commercially available laminated materials, achieving speeds of 100,000 revolutions per minute, breaking all previous high-speed records for laminated IPMSMs. doubles the speed of
IPMSM Functionality Using Rated Torque — The maximum continuous force available to push the rotor (the moving component within the motor) around its axis to produce power. This force is generated by permanent magnets embedded in the steel rotor.
The maximum speed of current IPMSMs is limited by iron bridges in the rotor, which reduces the mechanical strength of the motor.
However, the UNSW team improved the IPMSM’s mechanical robustness by developing a new rotor topology. The new rotor design also reduces the amount of rare earth materials required per unit of power generation.
A team led by Assoc. Professor Rukmi Dutta of the UNSW School of Electrical Engineering and Telecommunications and researcher Guoyu Chu took inspiration for the motor design from his Gyopo railway bridge in South Korea. The bridge features a double-knotted arch structure and compound curve-based mechanical stress distribution technology. .
Increased mechanical robustness
In an email to The Epoch Times, co-director Chu said there are three reasons why the rotor has good mechanical robustness.
First, the rotor structure is mechanically robust and has been successfully implemented and validated in civil engineering. The team then established a highly accurate analytical model for the mechanical strength of his IPMSM rotor.
“A detailed analysis allowed us to modify the double-tied arch structure and integrate it into the rotor design,” said Chu.
Finally, the rotor design was optimized using a multi-physics and multi-objective optimization package based on genetic algorithms.
“This UNSW-developed advanced optimization package helped us find the best balance between electromagnetic and mechanical design issues for the rotor,” he said.
The optimization package evaluated 90 designs and nominated the best 50% of them. From this selection, the program generated a new range of designs. The optimizer repeated this process until it reached an optimal design. For this motor, it was his 190th generation that the program parsed.
“One of the trends for electric vehicles is to have motors that spin faster,” Chu said. UNSW news release.
“All EV manufacturers are working to develop high-speed motors because the nature of the laws of physics allows them to shrink the size of their machines.”
Mr. Chu generally states that the higher the IPMSM, the higher the rated torque, and that the IPMSM’s output is equal to the rated torque multiplied by the speed (rotational speed of the rotor).
“So higher speeds mean lower torque requirements for IPMSMs with a given power rating, which means smaller motor sizes,” said Chu.
“And the smaller machines weigh less and consume less energy, so the vehicle has a longer range.”
Importantly, the new high-speed motors can produce very high power densities, thus reducing the weight of the motors. This is useful for electric vehicles as it extends the range on any charge.
“The higher speed allows us to make the inverter smaller and lighter, as well as the motor. The lighter weight helps reduce energy consumption. Chu explains.
“Furthermore, if the entire drivetrain can be optimized for high-speed motors, system efficiency can also be improved.”
Modification of motors for electric vehicles
Chu notes that the researchers sought to achieve the absolute maximum speed possible for the project, recording “more than 100,000 revolutions per minute” and a peak power density of “about 7 kW per kilogram.”
He said that for electric vehicles, the team will increase the motor’s power by slowing it down somewhat.
“It can be scaled and optimized to provide a specific range of power and speed, for example a 200 kW motor with a maximum speed of about 18,000 rpm, which is perfectly suited for EV applications,” he said.
He said he believes that if EV makers want to use this motor in their vehicles, it will take only six to 12 months to modify it to meet specifications.
“We have our own mechanical design software package that allows us to input our speed and power density requirements and run the system for weeks, giving us the optimal design to meet those needs.”
Other uses for motors
This new motor has many potential uses beyond its use in electric vehicles. For example, this high-speed motor allows you to drill or mill the smallest diameters on high-precision Computer Numerical Control (CNC) machines that are very popular in the aeronautics and robotics industries.
The motor could also benefit large heating, ventilation, and air conditioning (HVAC) systems that require high speed compressors to use newer types of refrigerants that are more environmentally friendly. Another possible application is an IDG (Integrated Drive Generator) that powers aircraft systems from inside a machine’s engine.
Additionally, the motor is cheaper than current technology and does not require rare earth materials such as neodymium.
“Most high-speed motors use a sleeve to strengthen the rotor, and the sleeve is usually made of expensive materials such as titanium or carbon fiber,” Chu said.
He pointed out that the sleeve was very expensive and had to be fitted precisely, which made the motor more costly to manufacture.
“Our rotors have such good mechanical robustness that we don’t need that sleeve, which reduces manufacturing costs,” he said.
“Also, with only about 30% rare earth materials, material costs are significantly reduced, making high-performance motors greener and more affordable.”