In this paper, a surface-inserted double-layer Halbach permanent magnet (PM) machine model is presented and analyzed. Based on a linear superposition, the magnetic field is analytically calculated and optimized. It is concluded that the air-gap field and the electromotive force of the double-layer Halbach machine are derived and better than those of single-layer Halbach machine. The prediction results of the analytical and the finite element models have a good agreement.

Surface-inserted permanent magnet (PM) machines; double-layer Halbach magnets; magnetic field; analytical optimization