Controllable passive electromagnetic resistance there is no displacement sensor. Its structure is similar to squeeze film damper: rotor of rotating machinery by rolling bearings or sliding bearing on the core. The spring supports on the base of the iron core. Using spring stiffness design, for supporting the rigidity of the system. On the frame around four concentric iron core electromagnet. Are of the same size on each coil DC excitation voltage.
Controllable passive electromagnetic damper stiffness throughout the frequency range of the value is negative, and with the increasing frequency of negative stiffness value reduced. Stiffness values close to zero in the high frequency area. This damping characteristics consistent with rotating machinery required high frequency small damping of low-frequency damping characteristics. In controllable passive electromagnetic damper size determined, stiffness and damping value depends only on the static excitation current or excitation voltage. Change excitation voltage change of stiffness and damping, and the damper is controlled.