Compared with EMS, the PEMS reduced the suspension power loss on a large scale, released little quantity of heat, and cought realize larger air gap. It was more difficult to control the PEMS, especially the probability of suspension contact prevented it from practical application. In this paper, a new structure of magnet in PEMS was put forward, which made the system redundancy. The theory analysis and simulation showed its rationality and availability, and the new structure cought complete the assignment of suspension and protection against suspension contact well. At last this paper analyzed the workability of the controller.