Magnetic field modeling of linear machines with double-layered Halbach arrays

The magnetization patterns of permanent magnets affect the magnetic field distribution of electromagnetic machines significantly. A tubular linear machine with double-layered Halbach arrays is proposed in this paper to enhance the magnetic flux density, and thus the force output. The magnetic field of the machine is formulated analytically with vector potential and Bessel's functions. The analytical model is validated with numerical results. Furthermore, the effect of back iron on the design is also analyzed. The study shows that the employment of double-layered Halbach arrays and back iron does help to improve the performance of the linear machines. The result helps the design optimization of electromagnetic linear machines.