Structural Optimization And Fractional Order Control Of Heavy-duty Maglev Platform

Magnetically suspended bearings(AMBs)are a new type of supporting be arings,which realize rotor suspension without mechanical contact between stato r and rotor by magnetic force.They have very broad application prospects in aerospace,machinery industry and life sciences.Maglev platform relies on the balance of controllable electromagnetic force generated by electromagnet or hyb rid electromagnetic structure and external force such as platform gravity to ach ieve its own suspension.It integrates the typical mechatronics technology of tr aditional control engineering,electrical engineering,mechanical engineering and computer science.Heavy-duty Maglev Platform has become a research hotspot because of its high accuracy and heavy load.At present,the integer order PID control method is mostly used in the do mestic research on the control of magnetic levitation device,and substantial re suits have been achieved in theoretical research and experimental verification.Maglev system is a highly non-linear and open-loop unstable system.It is diffi cult to deduce the mathematical model of its second-order unstable process.H owever,for the heavy-duty maglev platform,the control accuracy,stability and other control performance requirements are higher,so the control algorithm is put forward higher requirements.As a generalized form of traditional integer-order PID controller,fractional-order controller has more adjustable parameters and wider tuning range,so its mathematical model is more accurate and contr of effect is better.In this paper,the structure of the electromagnet is designed for the heavy-duty magnetic levitation platform,and the structure of the electromagnet is optimized.The magnetic levitation structure with simulated magnetic force up to 6803N is obtained.The simulation results of different shapes of permanent magnets are also compared and analyzed.In addition,a fractional order controller is designed on the basis of the h eavy-duty magnetic levitation platform which has been processed in the laborat ory.The platform has undergone a load test with an air gap of 5 mm and a 1 oad of 600 kg.Taking a single electromagnet of the platform as the research object,a second-order dynamic model is established and a fractional-order cont roller for the platform is proposed.The stability region of the fractional-order controller is obtained by variable substitution and mapping of Riemann surface.The parameters of the controller are tuned and the fractional-order controller with excellent control performance is obtained.The influence of the key param eters of the fractional-order controller and its integrator components on the per formance index of the controller is analyzed by MATLAB simulation.The ord er controller is optimized.Finally,a fractional order controller with overshoot of 10%,no steady-state error and adjusting time of 0.05s is obtained.The rob ustness of the optimized fractional order controller is verified by simulation.T his paper also discusses how to establish dynamic models of unstable second-o rder processes for different magnetic levitation structures.In this paper,the heavy-duty Maglev Platform is taken as the research obj ect,and the structure of the electromagnet is designed and optimized.The mag netic force meets the requirement of load and weight.In this paper,the dyna mic model of the unstable second-order process is deduced,and the fractional-order controller with excellent control performance is obtained,which satisfies the requirements of stability,robustness,control accuracy and response speed o f the heavy-duty maglev platform.The differences and application conditions o f different magnetic levitation structures in deriving dynamic models of unstabl e second-order processes are also discussed.In this paper,the method of discrete fractional calculus operator is not us ed in the implementation of fractional order controller for heavy-duty maglev p latform,but the method of plane root locus is chosen to realize the fractional order controller in general frequency domain.This method is easy to understan d and realize the fractional order controller.At the same time,it lays a found ation for further research on fractional order controller applied to heavy-duty Maglev Platform in extended frequency domain and paves the way for the con trol research of heavy-duty maglev platform,which has engineering application value.