Optimal design of permanent magnet brushless AC machines for electric vehicle applications

Permanent magnet brushless ac machines are ideally suited for traction applications, since they are energy efficient and have a high specific torque and a high peak to continuous torque capability. Further, they can be field-weakened to facilitate constant power operation over an extended speed range without compromising the VA rating of the drive. However, they must be design optimised with due regard to their duty cycle, their thermal management, the volt-ampere constraint of the drive and any space envelope constraints. A design methodology which accommodates these aspects into the electromagnetic design synthesis process has been developed and employed to design a traction machine for a small urban vehicle.