Design of a permanent magnet synchronous motor integrated in the wheel rim on wheelchairs

This paper describes the design of an axial flux permanent magnet synchronous machine (AFPM), with concentrated windings for wheelchair application. The AFPM is integrated in the wheel rims, ensuring a space saving solution. The design takes advantage of new material types like high grade permanent magnets, iron powder core material and epoxy for encapsulation and structural support. Wheelchair producers have tough demands on motor performance, which requires a rugged motor construction. High sidewalk edges and other everyday obstacles for wheelchair users require the motor to deliver short durations of high torque. The wheelchair is able to take turns from independently controlled motors, all operated from an onboard joystick remote control. Long operation time of the traction system is important to ensure the users comfort. Using a direct driven AFPM would remove gear solutions, and gives an overall higher efficiency. Hence, a longer operation time for the user is achieved