Investigation on Torque Evaluation and Optimum Structure of Permanent Magnet Motors

Abstract

A new calculation method has been developed in order to evaluate torque ability of permanent magnet motors, such as dc brush and brushless motor, stepping motor and synchronous motor. In this method, motor constant k_M which is proportional to rated torque is calculated from number of pole pair p, phase linkage flux Φ, total area of winding slots S_T and coil one turn length l₁ Results of evaluation show that magnetic structures with non-lapconcentric windings and the ones with inductor-teeth on PM or HB-type stepping motors are excellent. And finally a design method has been also developed for a optimum structure in permanent magnet motor with non-lapwindings.