The Research Of Single-Phase High-Frequency Link AC/AC Converter

With the development of the times,large numbers of high-precision instruments are invented.As a result,clean power are received more widespread attention Currently,in the AC conversion areas,there are two main types of transformation techniques: AC/DC/AC conversion technology and AC/AC conversion technology.This thesis will take Buck AC/AC converter with high frequency link as the main goal to achieve the most direct AC power conversion.In this thesis,a brief introduction of the concept of AC/AC converter,classification and topology is made firstly.Then,the development and application prospects is described.And the object of study in this thesis is determined..Secondly,a in-depth study of works of the AC/AC converter's main circuit is made,using a method similar to phase-shifted full bridge in the DC power control.And the magnetization state of the high-frequency transformer is analyzed briefly.In response to the input harmonic issues,a suppression method is discussed in detail.After this,a small signal modeling is made for AC/AC converter,and a dual closed-loop control is made based on single-phase dq transform which is used in the field of single-phase photovoltaic grid in recent years.Then,a overall hardware design is made to determine the type of power devices,high-frequency transformer parameters,and filter parameters.After that,a detailed presentation about the control circuit part is conducted,including the sampling circuit,driver circuit,signal modulation circuit and protection circuit,and related software design process is introduced.After completing the basic design of the circuit,simulation experiments can be conducted on the MATLAB/SIMULINK platform.And its output voltage and current waveforms of different loads is shown respectively.When there is a harmonic input,the waveforms of output voltage and current is also shown in this thesis.And its anti-interference performance test is conducted here.On this basis,simulation studies for the other two control strategies that has been proposed before are carried out.By contrast,the pros and cons of three different feedback control strategies are listed.Finally,through the analysis,it is shown that the strategy used here has a good dynamic regulation performance,strong harmonic elimination capacity,and it can realize no static error control and so on.Finally,taking the ARM chip as the control core,a prototype is built to do principle experiment.Through experimental waveforms,it can be seen: The topology and control strategy can achieve ZVS on part of the cycloconverter switch.And it has advantages on load capacity,immunity performance,and its output voltage has low harmonic content.