Analysis of the magnetic field and force of LSM with permanent magnet Halbach array and ironless coil

Abstract

The LSM, or linear synchronous motor, with permanent magnet Halbach array and ironless coil possesses the dominant advantages of direct linear movement and being energy-saving. To analytically investigate the characteristics of this innovative LSM, its magnetic field and magnetic force are analyzed in this work. Based on the magnetic field of a single surface current, the field of a single permanent magnet with arbitrary magnetization angle is deduced. And the air-gap field of the motor is obtained by calculating the vector summation of the field generated by all the magnets in the array utilizing Denavit-Hartenberg transform technique. Given the form of three-phase current in the coil, the propulsion and normal force can be obtained. Finally, finite element method is introduced to validate the effedtiveness of the proposed analytical method, the result of which verifies the efficiency of the analytical method and the calculation error is within 5%. Also, it is concluded that the LSM composed of permanent magnet Halbach array and ironless coil is applicable for transportation. Compared to the widely utilized finite element method, the analytical method proposed in this work provides a faster and more convinent solution to analysis and design of the LSM with permanent magnet Halbach array and ironless coil.