Research On Circuit Equivalent Model Simulation Technology Of Traveling Wave Tube

As a high-power amplifier,the traveling wave tube amplifier(TWTA)is widely used in the field of satellite communications.The traveling wave tube amplifier is mainly composed of a traveling wave tube(TWT)and electric power conductor(EPC).When designing a TWTA,circuit simulation software is usually used to simulate and analyze the EPC,but the TWT lacks the corresponding circuit-level simulation model,so the system simulation of TWTA cannot be realized,especially for the simulation of various faults of TWTA.Directly using real TWT devices to test or verify TWT amplifiers can easily damage the TWT performance and cause great waste.Therefore,it is urgent to carry out the research on the circuit-level simulation model of TWT,and carry out the comprehensive simulation of TWTA based on the circuit,which not only helps to realize the system design of TWTA,but also provides important support for EPC design and fault analysis of TWTA.In this thesis,a circuit-level simulation model of the TWT is established based on the principle of the traveling wave tube.The circuit-level simulation model of the TWT includes the equivalent circuit model of the TWT and the equivalent circuit model of the TWT fault.The equivalent circuit model of the TWT is established by the mathematical model of the TWT,which can simulate the DC characteristics of the collector during normal operation.The TWT fault equivalent circuit model is established on the basis of the TWT equivalent circuit model,which can simulate the transient response of the voltage and current of each pole of the TWT when different faults occur.The main work content and innovation points are as follows:1.Based on the principle of the electron gun,the influence of the voltage of the electron gun on the output current of the electron gun is analyzed,and the mathematical model of the electron gun is established by mathematical fitting.The model establishes the relationship between the output current of the electron gun and the voltage of each electrode of the electron gun,which lays the foundation for the subsequent establishment of the energy distribution expression of the collector inlet.2.The energy conversion process in high frequency structure is analyzed,and the energy distribution expression of collector inlet is established by combining the mathematical model of electron gun and the above analysis.This expression determines the relationship between the energy distribution at the collector inlet and the input power and the voltage at each electrode of the electron gun,which is an important part of the mathematical model of the traveling wave tube.3.Based on the energy recovery principle of multistage step-down collector,the relationship between collector current and collector voltage is analyzed.Combined with the energy distribution expression of the collector inlet and the above analysis,the mathematical model of TWT is established,which can solve the collector current under different electron gun voltage,input power and collector voltage.4.Based on the mathematical model of TWT,the equivalent circuit model of TWT is established by using PSpice language.The model can simulate the transient response of the collector current of the traveling wave tube during normal operation,which lays the foundation for the establishment of the equivalent circuit model of the TWT fault.5.Analyze traveling wave tube faults and build circuit-based fault models.Combining the fault model and the equivalent circuit model of the traveling wave tube,the equivalent circuit model of the traveling wave tube fault is established,and the model realizes the simulation of the voltage and current of each pole of the traveling wave tube when the traveling wave tube fails.According to the structure of the traveling wave tube amplifier,a fault simulation system of the traveling wave tube amplifier is built,and the fault circuit model of the traveling wave tube is simulated and verified in the system.