Damping force switching type electromagnetic damper using relay and capacitor

Abstract

In general, semiactive dampers have high performance of vibration control compared to passive dampers, but in order to adjust an optimized damping force for the damper, several condition of vibration systems, such kind of force, acceleration and displacement etc., is always monitored using sensors, and the resisting force of the damper is switched by the information from the sensors. One of the authors has researched before about an electromagnetic damper which converts kinetic energy into electrical energy and generates damping force by dissipating the energy electrically through terminal circuit of the generator. Since a voltage which is generated by the generator is proportional to a rotational speed, a velocity of the damper can be determined by measuring the voltage. In this study, a unique sensor less semiactive damper that generates the electromagnetic damping force by using the generator instead of the speed sensor in order to obtain switchable damping and improve the vibration control effect without any sensors. By connecting the terminal circuit of the generator with a resistor, rectifiers, a solid state relay and a capacitor, the voltage from the generator rises when the acceleration or speed exceeds a border, causing the relay to close and the damping force to passively switch. It is possible to adjust the switching timing by the capacitor. In order to confirm the effects, the damper was fabricated, and its resisting force characteristics of the damper were verified by experiments. Next, seismic vibration tests were conducted using a shaking table to investigate the vibration control effect of the damper by comparing the experimental and calculated results.