Magnetic field analysis and performance assessment of Halbach array permanent magnet brushless dc motor for satellite payload drive mechanism

Magnetic field analysis of the Halbach array permanent magnet brushless dc machine was carried out. Initial designs, selection of major parameters, prediction of airgap field density are carried out by using the analytical model. Performance of three types of machine configurations, Slotless PMBDC, Coreless enclosed rotor type with and without Halbach array magnet of same envelope are analyzed using FE. Coreless PMBDC machine delivers maximum torque with minimum ripple among the three configurations. The proportion of flux focusing magnet is optimized to deliver are obtain near trapezoidal flux pattern in the airgap. The machine was realized and tested. Power consumption for 2Nm at 50 RPM is 43% lesser than that of conventional slotless PMBDC machine of same size. As the machine is coreless, cogging torque and magnetic stiction are eliminated and hence provide better pointing stability.