Research On Non-isolated High-gain Combined Cuk Converter

In recent years,with the increasing status of solar energy in the field of new energy,photovoltaic power generation technology has been become the focus of research.The method proposed in this paper was under the background of photovoltaic power generation technology.It is difficult for traditional DC/DC converter to achieve the voltage that required in grid-connected due to the low voltage gain in the photovoltaic power generation.Therefore,the purpose of this paper is to find a DC/DC converter that can achieve high voltage gain,low voltage stress,small current ripple,small volume and high transmission efficiency.Firstly,the equivalent Cuk converter was derived based on the Cuk converter in this paper.These two converters were combined to obtain a non-isolated and high-gain combined Cuk converter.On the basis of the combined Cuk converter,two extended structures were added to get a higher gain DC/DC converter.Secondly,the coupled inductor was added to the combined Cuk converter to obtain a non-isolated and high-gain combined Cuk converter with coupled inductors.The capacitor-diode is not only a part of the structure of the Cuk converter,but also serves as a clamping circuit for the switching element,which can not only reduce the voltage stress of the switching element but also absorb the energy of the leakage magnetic inductance,and also reduce the voltage spike generated by the leakage magnetic inductance.It also retains the continuity of the output current of the Cuk converter and greatly improves the voltage gain of the combined Cuk converter.The working mode and performance of the converter in continuous and discontinuous were further analyzed and the parameters of the converter were designed.Then,on the basis of the non-isolated and high-gain combined Cuk converter with coupled inductors,the double voltage unit was added to obtain a non-isolated and high-gain combined Cuk converter with a coupled inductor double voltage unit,which further improves the voltage gain and reduces voltage stress for the converter.The working mode and performance of the converter were further analyzed in continuous and discontinuous.The performance of all the converters mentioned in this paper were compared and the parameters of the converter were designed.Finally,the simulations were carried out to verify the theoretical analysis on the basis of the above-mentioned two converters and the results were completely correct.Then,the experimental prototype was built and the experimental results were completely consistent with the previous simulation results.It was verified that the theoretical analysis of the two converters mentioned above were completely correct.The paper has 86 pictures,6 tables,and 82 references.