Magnetic Field Analysis of A Halbach Array PM Spherical Motor

Halbach magnetized rotors are being developed for various application, since they offer a number of attractive features. For example, the Halbach array air gap field distribution is inherently sinusoidal; the magnets have a higher working point which can increase the power density; due to the self-shielding magnetization, rotor back-iron is not essential so that the mass and inertia can be reduced. Resulting from the above merits, Halbach array motor has the features of high efficiency, little volume, and light weight. This paper demonstrates the fundamental principle of Halbach array PM spherical motor. By using the Laplace´s equation and the boundary conditions, the magnetic field is formulated, which is compared with FEM. The results by two methods are basically in agreement. In our study, we find out that by selecting appropriated parameters of the PM poles, Halbach array PM spherical motor can be optimized.