Comparison of Halbach magnetized brushless machines based on discrete magnet segments or a single ring magnet

This paper compares the air-gap field distribution, cogging torque, back-electromotive-force waveform, and efficiency of brushless machines having a Halbach magnetization produced by either discrete magnet segments or a single ring magnet. Results deduced from finite-element analyses are compared with measurements, and the performance of Halbach magnetized machines is compared with that of machines equipped with radially magnetized magnets.