Research On A Hybrid Excitation Electromagnetic Damper And Its Performance Of Semi-Active Vibration Isolation

It is essential to provide an ultra-stable and ultra-quiet environment for spacecraft working in outer space.However,the micro-vibration which is sensitive and has small amplitude and wide frequency band will affect the normal work of sensitive loads and reduce the work accuracy,such as the imaging accuracy of reconnaissance cameras,testing accuracy of fluid dynamics.Due to their advantages of fast response,non-contact,easy adjustment of damping force and no liquid leakage,electromagnetic dampers are widely used in vibration control.A hybrid excitation electromagnetic damper which can adjust damping force is designed and its damping characteristics is analyzed in this thesis.In combination with the micro-vibration environment,a hybrid excitation electromagnetic vibration isolator is designed for micro-vibration control.Firstly,the structure scheme of a hybrid excitation magnetic damper is designed according to the working environment of spacecraft.The gap magnetic field of a hybrid excitation electromagnetic damper under no-load and working conditions is analyzed based on a layer approach and Kirchhoff's law of magnetic potential difference.According to the law of conservation of energy to analyze damping power.Simulation analyze of the influence of system parameters on the damping characteristics.It was found that the damping coefficient increases approximately linearly with velocity,then decreases,and finally tends to be gentle.In order to improve the vibration suppression effect of the vibration isolation system,it is necessary to increase the damping coefficient in the resonance frequency range.According to static gap magnetic field simulation results,gap magnetic field intensity is increased from 0.873 T to 0.921 T by the structural parameters' optimization.Transient simulation results represent that the trend of velocitydamping force curve is basically consistent with analytical results,the error is the effect of eddy current thermal effect,magnetic flux leakage,irregular clearance flux density waveform,etc.In order to achieve an ideal vibration isolation effect over the entire frequency range,it is necessary to use semi-active control to the resonance area.This thesis discusses the problem of using PID controller to improve the vibration suppression effect in the resonance area while decrease the effect in the vibration isolation area.A time-frequency PID controller is designed to apply the corresponding PID parameter values to different frequency bands to achieve the ideal skylight stiffness damping control effect.The result shows that the amplitude of the resonance area is reduced by about 50%,and it can effectively guarantee the passive vibration isolation effect.At the same time,an adaptive Smith predictor is proposed to solve the time-varying and delay characteristics of the system dynamically.The system can reach stability in a short time,and the error is small.A vibration isolation effect evaluation index was used to suit the entire operating frequency range,and using it analyze the vibration isolation effects of passive vibration isolation and PID semi-active control.A hybrid excitation electromagnetic passive vibration isolation platform is designed and manufactured.Then based on the passive control of the hybrid excitation electromagnetic damper to experiment the single-degree-of-freedom vibration isolation system.The results show that the damping coefficient differs from the analytical analysis by 9.59% because of the magnetic flux leakage,eddy current thermal effects,etc.We can verify the reliability of the model of the damping magnet force of the hybrid excitation electromagnetic damper.