Research On High Gain DC-DC Converter

In recent years,due to the increasingly serious environmental pollution caused by the burning of primary energy sources such as fossils,the development of new energy sources has become increasingly urgent.At present,the new energy technology has been relatively mature and a large number of developments are photovoltaic power generation technology.The direct output voltage of the solar panel of the photovoltaic system is relatively low,and it needs to be boosted by a DC-DC converter during the grid connection process.Therefore,high-gain DC-DC converters have become a focus of current research.The output voltage of a classic Boost converter is only determined by the duty cycle,which results in a limit duty cycle when high gain output is required,which not only causes the boost effect to be unsatisfactory,but also causes large current spikes to cause safety to the equipment.Threat.New circuit structures such as coupled inductors and switched capacitors have emerged at the historic moment,providing ideas for improving circuit performance.Based on the traditional quasi-Z source DC-DC converter and based on a novel CLC voltage doubler unit and coupled inductor technology,this paper proposes a quasiZ source coupled inductor high gain DC-DC converter based on a new voltage doubler The working principle and DC steady-state characteristics of the new circuit are analyzed in detail,the converter gain expression is derived,the circuit parameter design expression is given,and the converter loss and efficiency are also analyzed.The research results show that:(1)The converter has the characteristics of input and output common ground,which is suitable for new energy applications.(2)The circuit gain is not only related to the duty cycle,but also the circuit gain can be adjusted by the turns ratio of the coupled inductor.The circuit can obtain a very high voltage gain by adopting a small duty cycle and an appropriate coupled inductor turns ratio.(3)The switching tube in the circuit is no longer directly connected to the output side,and the device stress is significantly reduced.(4)The use of switching elements with low voltage levels improves the efficiency of the converter.Finally,the correctness of the theoretical analysis was verified using PSIM software.A closed-loop control analysis based on sliding mode control for a quasi-Z source coupled inductor high gain DC-DC converter based on a novel voltage doubler unit proposed in this paper is performed.The small-signal model of the converter is established by the state space averaging method;the open-loop Bode diagram of the system is drawn by plotting the relationship between the duty cycle and the output voltage using Matlab software,and the system open-loop frequency domain indicators are obtained,and the system is corrected Analysis,but the effect is very limited.Therefore,the controller of the converter was designed as a whole using fixedfrequency sliding mode control,and expressions such as equivalent equivalent control were obtained.Simulation models were built by Matlab for simulation analysis.The system obtained good control results and very good The feasibility and effectiveness of the control method are verified.