Performance characteristics of permanent-magnet and reluctance machines to meet EV requirements

With electric vehicles (EVs) in focus, increasing international attention is being given to the question of choice of motor type for this application. The contending inverter-fed drives include induction, reluctance and permanent-magnet motor types. Recent reviews have indicated that variable-frequency permanent-magnet synchronous motor drives have strong prospects for adoption in 5-10 years. The authors describe how the performance requirements for drive motors for electric vehicles are broadly: high torque capability from zero speed up to a base speed, with voltage rising up to its maximum value at base speed and limited to that value at higher speeds; constant power capability over a speed range of typically 3.1 above base speed, with limited values of voltage and current; high efficiency over a wide range of operating conditions; low weight; small volume; low cost; good controllability; and low torque ripple