2-D Analytical Model for Outer-Rotor Consequent-Pole Brushless PM Machines

Abstract

Consequent-pole permanent-magnet machines are of particular interest owing to their special features. They have alternate hard and soft magnet poles. In this paper, a two-dimensional (2-D) analytical model is proposed for outer-rotor slotted-stator consequent-pole brushless PM (CPBLPM) machines. The model is developed from the quasi-magneto-static Maxwell's equations, which are analytically solved. The magnetic flux density expressions are initially derived and then other quantities such as the no-load induced voltage, electromagnetic torque, reluctance torque, cogging torque, self and mutual inductances as well as unbalanced magnetic forces (UMF) are computed. The suggested model is generic and applicable to CPBLPM machines with any number of poles and phases, type of magnetization patterns and current waveforms. A case study is presented to evaluate the performance of the proposed model. The accuracy of the 2-D analytical solutions is verified against those obtained from the finite element method (FEM). The proposed method can replace the FEM in designing and optimization of outer-rotor consequent-pole permanent-magnet motors.