Research On High Voltage Gain DC-DC Converter

With the continuous increase of human demand for energy,environmental pollution and gradual reduction of energy have become the focus of discussion in various countries,and the development of sustainable green energy has become the goal of research in various countries.Solar energy is clean,environmentally friendly,inexhaustible and inexhaustible is the most ideal energy source.In the photovoltaic power generation system,the output voltage of the photovoltaic power generation board is much lower than the input voltage of the grid-connected inverter,so it is necessary to use a high-boost DC-DC converter to boost the low voltage to a high voltage.The voltage boost ratio of the classic boost DC-DC converter is relatively low and cannot meet the purpose of voltage boost.In order to improve the voltage gain of the converter,this paper studies a single-input staggered parallel high-voltage gain DC-DC converter.The main research contents are as follows:First of all,this article introduces the research background and significance of DC-DC converters,and introduces the research status at home and abroad.Secondly,through the analysis of several DC-DC converter topologies,the advantages and disadvantages of non-isolated converters and isolated converters are analyzed and compared,and interleaved parallel converters are selected as the basic research topology.Build a mathematical model of traditional interleaved parallel converter,and perform simulation analysis.Switching inductance units are used to replace the independent inductance in the interleaved parallel converter.The latter stage is composed of capacitors and diodes to form a boost unit,and the front and rear stages form a new topology.Then the working principle of the converter is introduced,and the four modes are analyzed.Derivation of the correlation relationship expression of the components in the converter through Kirchhoff's law(KVL),the expression of the voltage gain combined with each mode,and the corresponding current relationship and voltage stress of the switching device,and the proposed converter Parameter design and device selection.A simulation model is built in MATLAB/Simulink.The simulation results show that the proposed converter can achieve high voltage gain at a certain duty cycle,reduce the voltage stress of the switching device,and verify the effectiveness of the proposed topology.In terms of hardware,the TMS320F28335 control board is used to analyze the operation needs of the converter,and the driving circuit and sampling circuit of the switching device are designed.Finally,in the actual environment,the output voltage of the photovoltaic power generation panel is unstable,and a closed-loop control strategy is needed to satisfy the converter output voltage stability.By analyzing the difference and connection between the voltage loop control method and the current loop control method,the voltage outer loop current inner loop double closed loop control method is selected.The time-averaged equivalent circuit method is used to derive the dynamic model of the converter,the small-signal model of the converter is obtained,and the PI controller is designed to adjust the deviation signal,and some glitch fluctuations are filtered out by designing the filter selection filtering method.The software design of the system is introduced,mainly including the main program flow,the interruption flow of the analog-to-digital conversion module,and the PWM wave generation flow.