Recent Development of Halbach Permanent Magnet Machines and Applications

Halbach magnetised PM brushless machines are novel in that their magnetisation is self-shielding. They offer many attractive features, such as sinusoidal airgap field distribution and back-emf waveform, negligible cogging torque, potentially high airgap flux density and no need of rotor back-iron. Hence, they have recently attracted many research and development interests and extensive exploitation for their applications. This paper starts with a brief introduction of Halbach machines and compares the relative merits of ideal and segmented Halbach machines, as well as shaped magnet machines. It then describes various recent applications which exploit their novel features, ranging from automotive, aerospace, industrial servo, to domestic appliances. Finally, it reports an integrated design of sensorless high-speed Halbach motors.