Research On Suspension Current Characteristics And Current Follow-up Control Strategy Of Suspension Chopper

Suspension control technology is one of the core technologies of magnetic levitation trains.The single electromagnet suspension control system can be decomposed into a first-order current loop subsystem and a second-order suspension control subsystem.They can be independently commissioned and greatly reduce the levitation control system for debugging difficulty.The current loop design requires the load current to follow the reference current as soon as possible within a certain frequency range.The stable current output of the suspension chopper ensures the safety and stability of the levitation system.Therefore,improving the performance of the chopper and optimizing the current control strategy of the chopper make it very important for the chopper to achieve a continuous and stable current output.For this reason,this paper takes the floating chopper as the research object and takes the chopper coil current follow-up effect as the research object.It mainly focuses on the Simplorer-based suspension chopper device-level simulation circuit parameter design and model construction,different circuit control structures and different current follower effect under the condition of changing interference factors and the influence of the current control method of the suspension chopper on the control effect are analyzed.The main research contents and results are as follows.Based on the analysis of the control principle of the single electromagnet model and suspension chopper,a component-level circuit simulation model of suspension chopper based on Simplorer and Simulink was built,aiming at chopper power supply,transmission line inductance,filter and input capacitance,absorption capacitance,coil distributed capacitance and suppression inductance were used to design the main circuit parameters.Specific selection calculations were made for the main units such as the IGBT and the drive circuit.The Simplorer and Simulink joint simulation model diagrams and specific simulation parameters were also presented.Based on the suspension chopper circuit model constructed in Chapter 2,the twolevel and three-level of two-quadrant and four-quadrant current follower simulations are performed in the control structure of the circuit.The load inductance changes in the influencing current control and the power supply.The voltage variation,sudden change of external force and time-varying disturbance factor of the reference current are used to simulate and compare the load current of the floating chopper following the actual control effect.In the aspect of load inductance change,the current follow-up effect is verified under different load inductance values,air-gap interference conditions and the current follow-up effect is verified under different voltage levels,different amplitudes and frequency time-variant interference conditions in the power supply voltage variation.The reference current of the load is compared and analyzed for reference current follower effects under different amplitudes and different frequency interference conditions.Finally,three control methods based on PID control,segmented PID control,and PID Control Strategy Based on BP Neural Network are studied for the load current follow-up control effect of the suspension chopper.Based on the above three control strategies,the simulation model is built to solve the problem.The follow-up of wave current,follow of 10 Hz sinusoidal current,load inductance and current follow-up under power supply voltage disturbance conditions are compared and analyzed.The simulation results show that the PID Control Strategy Based on BP Neural Network has the best control effect in current follow-up control accuracy,dynamic performance response and anti-jamming performance.