Research On Single-point Electromagnetic Levitation Control System Based On Improved LADRC

Electromagnetic levitation is a technology that levitates objects by using electromagnetic force to overcome gravity,with the advantages of frictionless,low-maintenance and noiseless,and is now widely used in industrial manufacturing,medical devices and transportation.However,the existing electromagnetic levitation system controller suffers from poor antiinterference performance and low levitation stability;at the same time,the chopper suffers from low switching frequency,high output current ripple and high levitation energy consumption.In order to solve these two problems,this paper focuses on the single-point levitation system,the design of the levitation controller based on improved linear active disturbance rejection control algorithm and the development of a levitation chopper based on silicon-carbon switching devices.First,a mathematical model of the system is created based on the principle and structure of single-point electromagnetic levitation,and the model is linearized and stabilized.A position outer-loop controller based on the linear active disturbance rejection control(LADRC)algorithm and a current inner-loop controller based on the PI regulator are designed based on the system’s inherent characteristics.Second,in order to solve the problem that the linear extended state observer in the traditional LADRC degrades the system anti-interference performance due to insufficient disturbance estimation.The structure of the linearly expanding state observer is improved in this paper by designing a two-stage cascaded linearly expanding state observer to improve perturbation estimation accuracy and speed,thereby improving the system’s anti-interference performance.The superiority of the improved LADRC in improving disturbance estimation and suppression performance is analyzed from a frequency domain perspective in this paper,as is the system’s stability,and the effectiveness of the improved LADRC algorithm is analyzed and verified using simulation.Again,the traditional levitation chopper based on the silicon switch device is optimized by the use of silicon-carbon MOSFET for the problem of low frequency switches,high switch loss,and large output flow waves.The corresponding drive circuit is designed by analyzing the switching process of the silicon-carbon MOSFET.The experimental wave-shaped test results show that the interruptor’s output wave shape is consistent with the theoretical analysis,and the voltage and current fluctuations in the switch process are smaller.The silicon-carbon MOSFET based levitation chopper can support higher switch frequencies,effectively reducing the size of output current,which benefits system stability.Finally,this paper designs an integrated control and drive single board with levitation controller and levitation chopper,and conducts experimental research on single-point levitation control based on it.The experimental results show that the improved LADRC not only has good position tracking performance,but also has stronger anti-interference performance compared to the traditional LADRC and PID control.Compared with conventional LADRC,the improved LADRC control algorithm can help the system reduce the amount of position fluctuation by37.5% on average and shorten the regulation time by 36.9% on average.