Research On The Modeling And Application Technology Of The Full-bridge Converter With Isolated Transformer

Power and its corresponding converting are the foundation of modern electrical and electronic computer control. In all types of power converters, PWM switching power converter is the leading type, for its various structure types, rapid development, technology leadership and the ease of realization. With the advancement of technology and power industry, the switching power supply has been widely used in industry, transport, electric power, telecommunications, household electrical appliances, and other fields, And its design and manufacture have become an extremely active and popular technology.DC-DC switching converter is a special nonlinear system due to the periodic switching of the circuit topology in operating. The research on its topology, parameters optimization and simulating model, not only can greatly reduce the developing cycle and cost, but also can promote to improve the power transforming performance and enhance its working stability. Combining practical project, this thesis studied both the steady-state and dynamic performance of DC-DC switching converter, adopting neutral network technology, genetic algorithm technology and transmission-line modeling and numerical simulating method. An industrialization prototype was designed to validate the theory and technology presented in this thesis. The work on specific included the following areas:First, this thesis systematically studied the basic characteristic and status quo of DC-DC switching converter modeling technique, analyzed the classical modeling ideas, methods and their own characteristics, introduced the transmission-line modeling method based on transmission-line theory, summarized and compared the problems needed to resolve of current modeling techniques.Secondly, the thesis researched the engineering design of switching converter, detailedly analyzed various working states of full-bridge converter with isolating transformer, theoretically deduced converter's dangerous working intervals, and presented a new method to optimize the main circuit layout by the professional software- Cadence. To shorten the developing cycle and decrease the researching costs, the BP neutral network technology was adopted to establish the nonlinear relation between converter's design parameters and their corresponding circuit performances in the process of engineering design. The genetic algorithm was also used to optimize the circuit parameters, and the final simulating results indicate that the dynamic performance of converter is remarkably improved by the optimization of layout and parameters.The transmission-line model based on uniform transmission-line theory has a clear physical conception and good transient analyzing performance, but both the modeling theory and the modeling technique of circuit components is still immature. So the thesis mainly researched the equivalent transmission-line model and equivalent distribute parameters of converter's main circuit components based on uniform transmission-line modeling theory, and got their linear and nonlinear transmission-line models , simple linear transmission-line models, and their equivalent circuit models, including capacitor, inductance, coupled component, and power switching component and so on, which set up the integrated dynamic modeling technique system of power electronic circuit. In addition, the improved transmission-line model of switching devices was put forward for the first time, and its rationality was proved by its admittance.Full-bridge converter with isolated transformer is a complex power electronic system, so the numerical stability and convergence of digital simulation has a direct impact on the application of dynamic transmission-line modeling technique. This thesis detailedly and comprehensively analyzed both the local and global truncation error of transmission-line model for circuit components, studied its numerical stability and convergence, and perfected the theoretical basis of computer simulating model for power electronic circuit. Moreover, considering the stiff phenomenon, variable time step technique was also studied, which laid the foundation for converter's numerical simulation.Finally, by the M-file of MATLAB, this thesis set up the numerical transmission-line simulating model for full-bridge direct circuit converter with isolating transformer. An industrialization prototype was developed on the basis of the optimizing design and simulating results, on which EMC and type tests was researched. The testing results, compared with the simulating one, validated the efficiency of the optimizing engineering design and simulating model for DC-DC switching converter.This thesis summed up the latest research at home and abroad, tried to look for the new way of analyzing and modeling for DC-DC switching converter, and proposed a simple, effective, accurate and practical method to analyze DC-DC switching converter. The research mainly focused on theoretical analysis ,computer simulation and practical experiment, provided theory basis for its design, and promoted to raise the design efficiency and optimize the performance.