Adaptive Passivity-based Control Of Differential Magnetic Suspension

Magnetic levitation technology has been widely used because of its advantages of no friction,no wear,no noise,no lubrication and so on.However,maglev system is a multi-input multi-output system with strong coupling and highly nonlinear characteristics.Its bearing capability and kinematic accuracy depend on the performance of the controller.Therefore,it has great significance to intensive study the controller.In order to ensure the high precision and strong robustness of the suspension system,this thesis takes the electromagnetic support part of the vertical direction of the platform as the research object to design the controller.The main research contents are as follows:Firstly,through domestic and foreign literature review,the structure and working principle of the magnetic levitation system have been deeply understood.On this basis,the dynamic model of maglev platform is established by using Lagrange equation.Secondly,the high nonlinearity of the magnetic levitation system will reduce the accuracy and robustness of the system,aiming at this problem,a passive controller based on the Euler-Lagrange?EL?model is designed.The simulation results show that the robustness,precision and dynamic performance of the maglev system under the control of passive controller are improved.But passive controller based on EL model can only improve system performance by damping injection.Therefore,a passive control strategy based on the Port Controlled Hamiltonian with Dissipation?PCHD?model is designed.Compared with the passive control based on EL model,the passive control based on PCHD model can determine the control law through the new energy storage function and damping injection,which makes the maglev system obtain good performance.The magnetic levitation system is often influenced by disturbance factors,aiming at this problem,the passive controller based on PCHD model is improved.Adaptive passive controller is designed based on passive control and adaptive L₂ disturbance suppression theory.The simulation results show that adaptive passive control can obviously enhance the ability of the maglev system to suppress interference and make the system more accurate.Finally,when each single electromagnetic system is controlled independently,it is difficult to eliminate the air gap unsynchronism caused by the inaccurate measurement of the sensor and the inconsistency of the structure parameters of the electromagnet.And the magnetic levitation exists coupling.There is no necessary synchronization mechanism among the single magnetic levitation devices under independent control.In order to solve these problems,an adjacent cross-coupling control method is proposed,and a position compensation controller is introduced.The simulation results show that the adjacent cross-coupling controller can reduce the air gap synchronization error and improve the dynamic synchronization performance of the air gap.