Coupled electromagnetic and thermal optimisation strategies for direct-drive linear permanent magnet synchronous motors

We present the design and fabrication of an actively cooled direct-drive linear permanent magnet synchronous motor for a wearable assistive device. We derive a detailed thermal model of the actuator for designing an air-cooling system. We combine this thermal model with a semi-analytical electromagnetic model of the motor to optimise the efficiency of the motor. Our fabricated motor has a nominal mass of 624g, and consumes 80W under a 100N load. The motor's static force production and its thermal performance were experimentally tested, suggesting that the motor can safely achieve ~132N/kg continuous force production at its nominal load.