Comparative study of electromagnetic performance of alternative Halbach and conventional radially magnetized permanent magnet brushless motors

In this paper, the static and dynamic electromagnetic performance, including the airgap field distribution, the back-emf waveform, the cogging torque, and the torque-speed characteristic and the efficiency, of three alternative Halbach permanent magnet brushless motors, employing anisotropic bonded NdFeB Halbach cylinder with and without rotor back-iron, as well as segmented Halbach cylinder with sintered NdFeB magnets, are compared by finite element analyses and measurements, together with a conventional radially magnetized permanent magnet brushless motor.