Magnetic field and thrust of moving magnet synchronous surface motor

To solve the difficulty of lower speed and precision of the conventional stage, a moving magnet type synchronous surface motor (MMSSM) with slotless iron yoke and Halbach array is designed, where the stator and mover are composed of four electromangetic coils and four Halbach arrays respectively. The magnetic field distributions are derived analytically in terms of magnetic scalar potential with the method of separation of variables. On the basis of the analytical field, the expressions of the flux linkage, back-electromotive force (EMF) and thrust force are acquired and examined, and the chief design parameters, such as air gap length, pole number, magnet thickness and coil thickness, are optimized to maximize the thrust force of the MMSSM. A comparison between the results of the proposed method and finite element analysis verifies the feasibility and credibility. The proposed method facilitates the characterization of MMSSM and provides a basis for system dynamic modeling and simulation and servo control development.