Low Stress Ultra-high Boost DC-DC Converter And Its Stability Control Based On Coupling Inductor Technology

The vigorous development of industry makes fossil energy getting scarce,and brings a lot of pollution problems.Therefore,many scholars over the world begin to devote themselves to the study of green renewable energy application field.Electric energy is the power for the normal operation of the whole industrial production system.How to get the electric energy in an environmentally friendly way and reduce the huge pollution caused by electric energy generation is the premise of our research on new energy power generation.And our country is vast in territory which provides very important condition for the sustainable development of new energy power technology.High boost DC-DC converter plays an important role in new DC power generation systems such as photovoltaic power generation,bio-power generation and fuel cells.With the continuous improvement of the new energy power generation system,people find that the voltage boost capacity of the traditional DC-DC boost framework is limited,which makes it unable to carry out higher voltage conversion,and even produces many defects and problems in the process of voltage boost conversion.In order to overcome the problem that the boost capacity of traditional DC-DC boost framework is too low in DC new energy power generation system,this thesis takes the design of stable high boost DC-DC converter as the main purpose,and proposes A Low-stress and Ultra-high boost Coupling-inductor DC-DC converter(LUBCL)by summarizing the characteristics of various boost structures,and integrating the advantages of various boost topologies.The topology studied in this thesis can achieve a higher DC-DC voltage boost under the condition of reasonable duty cycle and turns ratio of coupling inductors,which makes the voltage boost capability of the topology not only decided by the duty cycle of switching tube,but also by the turns ratio of coupling inductors,so as to select the voltage boost interval of DC-DC converter reasonably.At the same time,the clamp capacitance inside the converter can absorb and utilize the leakage energy between the primary and secondary coils of the coupling inductor,thus reducing the voltage stress of the switching device and reducing the device loss of the converter.Finally,the performance of the proposed converter is compared with that of the advanced boost converters.The advantages of the proposed converter are analyzed in terms of the boost capacity,the number of devices used in the whole frame and the stress between the devices.In the theoretical stage,a series of DC-DC topological families that can perform boost conversion are designed based on the characteristics of the traditional boost structure.Firstly,the structure of all topology family members is analyzed in detail,and then a converter with the most obvious advantages is selected in terms of gain and device stress.Finally,the performance of the selected converter is studied,and various working modes of the converter under CCM state are analyzed.The gain of the converter and the voltage and current stress of each device are calculated.At the same time,analyzing the loss of each component and the overall working efficiency of the converter with the parasitic resistance of components,which provides a reference for the production of the subsequent experimental prototype.Then the small signal model of the converter is obtained according to the working state of the converter switch tube on and off,and then the transfer function between the input and output of the model is derived.Through the initial bode diagram of the model,PID correction is done,and then the stability of the converter system under correction is verified.Subsequently,PID parameters are adapted to further improve the stability and robustness of the system.In the experimental stage,combined with the data and results of the theoretical stage,the device model of LUBCL is determined.Because of the maximum output power of the photovoltaic panel selected in the experiment is 100 W,the maximum transmission power of the main circuit of LUBCL is determined to be 100 W,so as to ensure that the LUBCL circuit can work normally.Firstly,the open-loop experiment is carried out to observe the voltage and current waveforms of each semiconductor,and determine the voltage and current stress of each component to ensure the stability of the LUBCL circuit when it is working.Secondly,a closed-loop experiment is carried out with the auxiliary circuit to detect the robustness of the LUBCL circuit when the input and output are disturbed.Finally,the LUBCL circuit is applied to the photovoltaic booster system,so that the electricity generated by the photovoltaic panel is transferred to the high voltage DC bus.