External Characteristics Analysis Of Push–pull Transformer And The Variable Cross–section Manufacturing Method Of Core

With the large-scale development and ultilization of fossil fuels leads to strained resource, environmental pollution, climate change and other global challenges which seriously threatens human survival. The pattern of energy development based on the traditional fossil fuels is unsustainable. Fossil fuels are limited but clean and green energy such as solar energy, wind energy is iexhuastiable. The clean and green power generation technology will shine with extraordinary splendor in current energy revolution based on the inverter.As the core of push-pull voltage source inverter, the push-pull transformer has many advantages such as AC/DC insulation, simple circuit topology, less switching devices, smaller power volume, low cost, no dead zone and its compensation circuit, moreover, it is easy to control input and output voltage/current. However, affected by the complicated energy flows and DC bias of the push-pull transformer and the multi-valued nonlinear characteristic of magnetic materials, which make the relevant parameters of push-pull voltage source inverter for theoretical study and engineering practice more difficult to obtain. What is worse, the mathematical model and simulation scheme which has great value to engineering application is still difficult to achieve. Therefore, the development and application of the push-pull voltage source inverter leads to be restricted.Based on the push-pull transformer of push-pull voltage source inverter, this thesis firstly presented the current situation and development trends of the inverter, classified the inverters according to different methods and summarized the common voltage source inverter and its characteristics. In the next place, this paper focused on the control theory of push-pull voltage source inverter and the simulation of SPWM control signal, established the mathematical model of power frequency transformer with single phase multi-windings under the different load situations, simulated it with MATLAB/simulink and compared with theoretical calculation. Moreover, this paper also analyzed the operating principle of the push-pull voltage source inverter in detail, completed the mathematical model which objectively reflects the real operation characteristic and provided the control system simulation model according to the modulation principle of SPWM.Furthermore, based on simulation results of the push-pull voltage source inverter control system, mathematical model show a close agreement with the simulation results, and the simulation results are verified by comparison with mathematical analysis. This thesis could also provide a valuable important reference for a new inverter control system analysis and modeling, and explore the new inverter control system such as AC push–pull inverter control system, push–pull high frequency voltage/current source inverter control system and single/three phase voltage/current source or any other kinds of inverter control systems.Finally, this paper also had a preliminary study on the variable cross-section manufacturing method of core which could provide a practical basis for subsequent manufacture of magnetic element and the hardware implement of push-pull voltage source inverter control system.