Design and analysis of zero cogging Brushless DC motor for spacecraft applications

This paper presents the design and analysis of a zero cogging halbach array permanent magnet Brushless DC motor (PMBLDC) meant for spacecraft applications. The design of the zero cogging BLDC motor requires the choice of slotless configuration. Three types of machine configurations, Slotless PMBLDC with radial, parallel and halbach magnetization were compared and analyzed using analytical models. It is found that unlike that of radial and parallel magnetized machines there exists an optimum combination between number of pole pairs and magnetic thickness for a halbach machine. For the requirements of high torque density, zero cogging torque, better positional stability, high torque to inertia ratio and zero magnetic stiction Coreless Halbach array PMBLDC motor is found to be the best configuration. Initial design, selection of major parameters and air gap magnetic flux density are estimated using the analytical model of the machine. Finite Element Analysis of the machine was done and the results are found to be in close agreement with the analytical results.