Abstract: To reduce suspension power loss, a structural optimal design strategy of hybrid magnet with permanent magnet (PM) and electromagnet for middle-low speed maglev train is proposed, without changing the F-type guideway and vehicle structure. A structure scheme of hybrid magnet is presented, that permanent material is placed on one side and the pole area can be adjustable. According to the nonlinear magnetic force expression of hybrid magnet, the restricted relationship about the electromagnet force, thickness and pole area of PM, ampere-turn of electromagnet, and the maximum magnetic energy product of PM is investigated. Then a structural optimal design method of hybrid magnet based on constrained nonlinear programming theory is given. The experiments on a single bogie show that the carrying capability of hybrid magnet is equivalent to that of traditional electromagnet, but the suspension power loss of hybrid magnet is much less.

Key words: Multi-restricted conditions, Permanent-electro magnet, Energy saving, Middle-low speed maglev train, Structural optimal design