Research And Design Of Superconducting Magnet Power Supply For Gyro-TWT

Gyro-TWT is widely used in millimeter wave radar,communication,electron cyclotron resonance heating and other fields because it can produce high-power and broadband microwave in millimeter wave band.The superconducting magnet power supply provides the excitation current for the superconducting magnet coil to produce the steady-state strong magnetic field required by the Gyro-TWT.It is an important part of the Gyro-TWT superconducting magnet system.Its output current stability,ripple and other indicators directly affect the stability of the magnetic field,and then related to the output power and gain of the Gyro-TWT.In addition,the efficiency and volume index are of great significance to expand the application scenario of Gyro-TWT.Therefore,the research of superconducting magnet power supply is very necessary.Combined with the actual needs of thermal measurement experiment of Gyro-TWT,this thesis studies and designs the 2T superconducting magnet power supply.The main research contents are as follows:Firstly,according to the technical requirements,a switching converter main circuit topology scheme based on phase shifted full bridge ZVS converter is proposed.Using its soft switching characteristics and phase-shifting control mode,the efficiency and output regulation range of superconducting magnet power supply are improved,and the noise interference to measuring devices is reduced.Based on the analysis of the working principle and design considerations of the converter,the calculation process of the key components of the main circuit is elaborated,and the selection suggestions are given based on the calculation results;the Matlab/Simulink simulation software is used for the open-loop simulation of the main circuit.The results show that the output range,output voltage ripple and soft switch of the main circuit meet the requirements,and verify the rationality and effectiveness of the main circuit design.Secondly,according to the control requirements of high stability and low ripple of output current,a dual closed-loop digital control system design scheme based on PID voltage inner loop and RST current outer loop is proposed.The inner voltage loop can quickly suppress the disturbance of input voltage fluctuation and load changes;the current outer loop adopts the RST control algorithm to solve the problem that the single-degreeof-freedom control algorithm cannot combine tracking and regulation performance,effectively suppressing disturbances such as load changes and measurement noise,while eliminating the overshoot of the output current during the transition between excitation and constant current states.Through the analysis of the influence of duty cycle loss,the small signal model of the main circuit and the control to output transfer function are given.Further,the parameters of PID controller and RST controller are adjusted by Bode diagram method and independent target tracking and regulation method respectively.Finally,the closed-loop simulation of voltage inner loop and current outer loop is carried out by using Matlab/Simulink simulation software.The results show that both loops have good tracking of the reference input and suppression of disturbances and can fully meet the requirements of high current stability and low current ripple on the performance of the control system,which verifies the structural rationality and parameter effectiveness of the control system design.