Papers by Author: Feng Yu Yang

Abstract: There are some problems in moving coil linear motor for Electro-hydraulic servo valve, such as big weight, small electromagnetic force, long response time and small bandwidth. After simulation analysis on permanent magnet placement and permanent magnet magnetization direction, it is found that distribution of magnetic field lines is uneven, magnetic flux density is low, and magnetic field lines are not vertical with the coil current direction. To solve these problems, a new type of linear force motor with 5 rings stack Halbach permanent magnet array structure is put forward. Through using the new structure, the weight and volume of motor can be reduced, and the electromagnetic force can be increased. Simulation results show that for the new structure, under the coil displacement change, the output electromagnetic force changes little and can maintain good linearity. Using permanent magnet with same volume, the electromagnetic force produced by new force motor is 2.5 times as it is produced by current motor. If the electromagnetic forces produced by two structures are same, the step response time of new type can be decreased of 14.3%, and the bandwidth can be improved to 2 times.

Abstract: There are some problems in the permanent magnetic circuit of the current permanent magnet biased magnetic bearings, such as small magnetic force, low magnetic flux density and lack of self-stabilization. To solve this problem, a new hybrid radial magnetic bearing structure has been proposed. The nonlinear model and linearization equation of the new hybrid radial magnetic bearing capacity has been established by current molecular method and virtual displacement theorem. It is found that the permanent magnetic bearing can achieve self-stabilization in the radial degrees of freedom and can reduce the total displacement of negative stiffness. The results show that the air gap flux density is greatly improved by the new hybrid magnetic bearing with Halbach array structure. Current stiffness and displacement rigidity is closely related to initial current and initial gap of the equilibrium position. Near the equilibrium position, current stiffness and displacement rigidity are linear relationship. With the increase of air gap, it remains a good linearity. While with the decrease of air gap, it presents nonlinear characteristics..

Abstract: Based on mechanical phenomena between two fixed magnetic, when the distance is short, the electromagnetic force are linear,therefore,we can make full use of the characters and make it to be permanent magnetic spring replacing the mechanical spring in hydraulic relief valves. Through the use of the Rare-earth magnetic springs in relief valves, we find it is more sensitive to load. Besides these, the rare-earth magnetic springs have a long life and high temperature resistance without failure by fatigue. So the study and design of permanent magnetic spring type relief valve have large application and research value.