Direct-Driven Interior Magnet Permanent-Magnet Synchronous Motors for a Full Electric Sports Car

The design process of direct-driven permanent-magnet (PM) synchronous machines (PMSMs) for a full electric 4 × 4 sports car is presented. The rotor structure of the machine consists of two PM layers embedded inside the rotor laminations, thus resulting in some inverse saliency, where the q-axis inductance is larger than the d-axis one. An integer slot stator winding was selected to fully take advantage of the additional reluctance torque. The performance characteristics of the designed PMSMs were calculated by applying a 2-D finite-element method. Cross saturation between the d- and q-axes was taken into account in the calculation of the synchronous inductances. The calculation results are validated by measurements.