Particularities of torque production in small synchronous motors with permanent magnet excitation

Quantitative considerations are made regarding the influence of the stator winding resistance value on the electromagnetic torque production in permanent magnet synchronous motors (PMSM). Taking into account the variety of permanent magnetic material grades, shapes and constructive arrangements, there are considered three types of magnetic circuits frequently utilized in PMSM: isotropic, with direct (classical) anisotropy, or with reversed anisotropy. There are analyzed by numerical simulation the influence of a nonzero stator winding resistance value and the influence of the anisotropy degree, comparatively on the excitation and reluctance torque developed in small synchronous motors with permanent magnet excitation.