Making the Impossible, Possible – Overcoming the Design Challenges of In Wheel Motors

For many, in wheel motors offer a panacea for vehicle design. However history shows the delivery of an acceptable in wheel motor is a deeply challenging task which is dedicated to understanding aggressive torque and speed requirements behind demands on vehicle performance such as high speeds or sustained hill climb, and even aggressive driving, all of which are allowed by delivery of high continuous torque; limited in wheel packaging space, harsh environment, and safety requirements. Protean Electric is entirely focussed on overcoming these challenges and believes that, with its novel technology, it has delivered a product that will allow vehicle manufactures to exploit the benefits of in wheel motors. Protean’s in wheel solution is based on a direct drive, permanent magnet brushless machine with an outer rotor. High torque is delivered from a space envelope based on high ratio between the motor radius and axial length and the key to maintaining this high continuous torque is effective thermal management of the motor. Power electronics together with control circuitry is integrated into the motor architecture, while the wheel bearing provides the mounting point for the motor. This paper offers a holistic view of an in wheel motor design with special attention to overcoming the design challenges presented by harsh operating environments, high performance demands and safety aspects.