Research On Control Strategy Of Beam Supply Based On Dual Mode Control

At present,ion electric propulsion technology is one of the most advanced and promising aerospace propulsion technology.With the rapid development of China's high-power ion electric propulsion technology,the power level of the ion thruster power processing unit(PPU)is also getting higher and higher,with high efficiency and high functional density becoming the future development direction of PPU.Because of its high specific impulse characteristics,ion electric propulsion can effectively reduce the volume and mass of the propellant working fluid,which has become an important index parameter for the advanced performance of the satellite.The beam supply is the core part of the electrical processing unit.Optimizing the control of the beam supply is the key to designing an efficient high-power ion PPU.However,the current research on the DC/DC conversion technology of the beam supply has the problems of poor dynamic performance and poor system robustness.Research on the beam supply control strategy is great significance to the development of high-power ion electric propulsion technology in China.The main research of the paper are as follows:(1)Based on the analysis of the structure and working characteristics of the ion thruster beam system,the paper introduces the application status of the beam supply at home and abroad,and controls the DC/DC conversion of the beam supply according to the latest beam supply actual application status.The technical development needs are elaborated.According to the multi-operating conditions of the beam supply DC/DC converter and the technical requirements to meet the wide range of output voltage,beam supply based on the dual-mode control method is proposed.The multiple operating conditions required in the field of detection and attitude adjustment have certain practical significance.(2)According to the application requirements,the new hybrid dual H-bridge beam supply DC/DC topology design is designed to analyze the working principles of the DC/DC converter in the phase-shift mode and parallel(PWM)dual mode control,According to the functional requirements and performance indicators of the application,the two working modes are switched to combine the efficiency advantages of the parallel mode under light load and the series mode under heavy load to achieve the best in the system,mainly from the input filter inductor and capacitor design,The power tube and the selection of fast recovery rectifier diodes and other parameters for the design of the DC/DC main circuit of the beam supply.On this basis,a small-signal model of a new double H-bridge beam supply is established.(3)Aiming at the problem of the effect of load change on the output voltage in the new hybrid double H-bridge topology beam DC/DC full-bridge converter,firstly,through the classic voltage and current double closed-loop PID control strategy research,and the system simulation experiments verify the correctness of the control method;secondly,an improved sliding mode variable structure control method is proposed,which combines the classic linear voltage and current double closed-loop system control strategy with the sliding mode control strategy(SMC),based on the equivalent control law and the sliding mode control strategy with improved switching control rate to form a complete sliding mode control law,and the improved sliding mode control method is compared with the traditional double closed-loop PID control,and the output voltage curve and abnormal work are carried out through the Matlab/Simulink simulation platform.The interference experiment under the condition and the simulation experiment of switching between the two working modes show that the improved sliding mode control has good dynamic performance and strong robust performance.Finally,a physical prototype was built in the laboratory.On the basis of the main circuit parameter design meeting the beam supply design index,the prototype experimental platform and Matlab/Simulink were used for collaborative experimental analysis.The experimental results were basically consistent with the theoretical values.The correctness of the control strategy further verifies that the voltage of the beam supply DC/DC converter under the dualmode control in this paper can be output in a wide range,and the system has good robustness and good dynamic quality.