Indirect drive in-wheel system for HEV/EV traction

In-wheel traction allows simplicity and freedom for the design of hybrid-electric/electric vehicle (HEV/EV). However, the in-wheel motor increases the unsprung mass and hence deteriorates ride comfort and reduces the road holding capability of the car. To solve these problems, this paper proposes an indirect drive in-wheel traction system including a light-weight in-wheel drive and a specially designed rear suspension. A prototype of the in-wheel drive is designed based on the vehicle model of Volkswagen (VW) Lupo 3L. The prototype analysis shows that the proposed in-wheel system gives a balanced distribution of the vehicle weight and thus improves ride comfort. Design principles of the electrical motor used for this in-wheel system is further investigated. By reducing the permanent magnet height, the field weakening capability of a 24-slot 8-pole surface permanent magnet synchronous motor is visibly improved.