Design of interior PM machines for field-weakening applications

There has been considerable recent interest in the use of interior PM machines for field-weakening applications such as traction which require a wide constant power speed range. This paper discusses the requirements of example constant power applications; explains how equivalent circuit analysis can provide useful insights into the machine parameter selection; demonstrates the importance of the choice of the rotor barrier locations and number of stator slots on the iron loss; and summarizes other machine design aspects such as modeling, calculation of losses and optimization.