| Traveling wave tube(TWT)is an important electric vacuum device,which is widely used in communication,radar,countermeasure and other fields because of its wide frequency band,high power and high efficiency.TWTs need to be equipped with multi-channel complex high-voltage power supply when working,and different traveling wave tubes are equipped with different power supply parameters.The traditional analog power supply is difficult to directly detect the state and control the parameters of the power supply,and often needs to be tailored according to the TWT,which has low flexibility.Digital power supply can effectively solve this problem by programming to realize voltage stabilization control and parameter adjustment.Control algorithm is the core of digital regulated power supply,which determines the key technical indexes such as voltage stabilization accuracy,stability and dynamic characteristics.In this paper,the Model-Free Adaptive Control(MFAC)algorithm is applied to TWT power supply,and a prototype of TWT power supply is designed and completed based on half-bridge LLC resonant voltage doubler.After testing,the prototype fully meets the technical requirements and achieves better performance than the traditional control algorithm.The main innovative work of this dissertation is as follows:(1)Based on fundamental wave analysis,the linearization circuit model of half-bridge LLC resonant voltage doubler is established.Symmetric voltage doubler rectifier circuit is difficult to calculate quantitatively because of its nonlinearity.Considering the voltage doubler rectifier circuit as a whole,the relationship between input and output is analyzed in the form of two-port network according to the conservation of energy,thus the mathematical expression of AC equivalent resistance of the voltage doubler rectifier circuit is derived,and the linearization circuit model of the half-bridge LLC resonant voltage doubler converter is established.According to this,the resonant parameters of the circuit are designed,and the correctness of the parameter design is verified by circuit simulation.(2)Design and implement a digital power controller based on model-free adaptive control algorithm.The nonlinear system with single input and single output is analyzed,the linearization method of the system and the design scheme of MFAC algorithm are given,and the convergence of the algorithm is proved rigorously in theory.According to the control scheme,the control of different types of nonlinear systems is simulated in MATLAB,and the simulation results show the effectiveness of MFAC.At the same time,a closed-loop circuit controlled by PID and MFAC is built in Simulink.Comparing the control effects of the two algorithms,the model-free adaptive control circuit shows better performance,which verifies the feasibility and superiority of the algorithm in the application of TWT power supply.The algorithm is implemented in C language,and other programs needed to realize digital power supply are designed and embedded in the main control chip of STM32F103,and the digital power supply controller based on model-free adaptive control algorithm is designed and realized completely.(3)A miniaturized and efficient prototype of TWT power supply is designed and completed.According to the index requirements of traveling wave tube power supply,a prototype of power supply is designed and manufactured.Build a test environment,burn control program,test the prototype power supply and record important parameters.Compared with the indicators,the prototype power supply can fully meet the requirements of TWT power supply.The correctness and rationality of the circuit design are verified at the physical level,and the feasibility and superiority of the MFAC control algorithm for the actual control of TWT power supply are also verified. |
