Electric rotors have become a crucial component in the move to electrification within the transport sector, intensified by fast-approaching Net Zero deadlines. The challenges faced in the application of the rotors include the amount of centrifugal force generated at such high speeds, which makes it difficult to keep the magnets in place, and the subsequent current losses, which reduce the overall efficiency of the machine.

Polar Technology Management Group, an engineering and manufacturing business based in Oxfordshire, utilised their significant expertise in composite technology to develop high-speed optimised Carbon Fibre Reinforced Polymer (CFRP) sleeves for use in electric rotor applications. They have been chosen as the supplier for a number of different high-performance vehicle Original Equipment Manufacturers (OEM’s) and are currently producing thousands of sleeves for respective contracts.

The benefits of using CFRP as the sleeve material are its superior strength and tensile properties, allowing for a lightweight solution that still ensures retention of the magnets and that resists the centrifugal forces in high-speed applications. Specifically, the sleeves enable rotors to operate at speeds upwards of 30,000 RPM, whilst minimising current eddy losses and system air gaps.

Polar Technology assumes the design authority for the CFRP sleeve, taking the customer rotor specification, selecting materials, and then developing a design which meets the criteria and is proven through analysis and testing.

For the manufacturing process, Polar Technology employs its market-leading filament winding facilities to create the sleeves and worked with their customers to test and perfect a press-fitting technique to fit the sleeves to the rotors. The benefit of this process is a higher retention pressure compared to sleeves that are wound directly onto the rotor, which generates a higher power output for the final product.

Daniel Chilcott, Business Development Director at Polar Technology, said: “Continued increased performance and efficiency in electrical machines is an emerging trend and something our composite sleeve technology is directly supporting. We are delighted to see our customers scale and continue to push the envelope”

Polar Technology will be showcasing its innovative rotor sleeves during Advanced Engineering, taking place at the NEC, Birmingham on the 30th and 31st October 2024. 

For more information on our composite retention sleeves, please click here: Composite Retention Sleeves (lentuscomposites.co.uk)

Or to speak to our commercial team about a potential enquiry, click here: Contact Us (polartechnology.co.uk)