Design and analysis of Enclosed Rotor Halbach array Brushless DC Motor for spacecraft applications

This paper presents the design and analysis of a novel machine family-Enclosed Rotor Radial flux Halbach array Permanent Magnet Brushless DC motor (PMBLDC) for spacecraft applications. Initial design, selection of major parameters and air gap magnetic flux density are estimated using the analytical model of the machine. The proportion of the halbach array in the machine was optimized using FE to obtain near trapezoidal flux pattern. Enclosed Rotor Halbach array motor configuration is found to deliver high torque density, high efficiency, zero cogging torque, better positional stability, high torque to inertia ratio and zero magnetic stiction suiting space requirements. The machine provides uniform air gap flux density along the radius thus avoiding circulating currents in stator conductors and hence reducing torque ripple.