Design of PM synchronous and brushless DC motors

The first part of this paper surveys the design tools required to maintain a competitive design capability in brushless PM motors, including the appropriate software for design, drafting, analysis, and simulation; the use of magnetic materials test facilities; the use of a precision dynamometer; and the use of flexible controllers. The second part discusses the design of PM brushless AC machines for flux-weakening capability, to give a wide speed range at constant power. The IPM parameter plane concept is used to classify the various classes of PM motor and to define an optimum combination of reluctance torque and permanent-magnet torque to maximize the constant-power speed range. Results are presented for an axially-laminated interior-magnet motor with a constant-power speed range of 7.5:1. This is 2-3 times the capability of induction motors, and is achieved at the same time as a slightly improved rated-lead efficiency and power factor