| With the continuous consumption of fossil energy,energy issues have attracted more and more attention,and various new energy sources such as solar energy,wind energy,ocean energy,and fuel cells have also been used more as alternatives to fossil energy.In a new energy power generation system,a two-stage converter is usually required to process the electric energy generated by the new energy.In addition,some new energy power generation has the characteristics of wider output voltage range and lower output voltage,so the front-end converter as the interface device of new energy power generation needs to adapt to a wide range of input voltage or a lower input voltage.In this paper,the topology,modulation and control of wide-range input DC converters and the topology of high-gain DC converters are studied respectively.A three-switch Buck-Boost is studied for a wide range input converter.The three-switch Buck-Boost converter can be regarded as a cascade connection of a three-level Buck converter and a traditional Boost converter,which is very suitable for a wide range of input voltage occasions.For the three-switch Buck-Boost converter,a modulation method is improved so that it no longer has natural input uneven voltage characteristics.Then,the small signal modeling was carried out under this modulation method.Besides,the control system design was difficult to be caused by the non-uniform model.So a control method of using linear active disturbance rejection control to uniform the inner loop of the inductor current was proposed to make its design process of control system is greatly simplified,and the transition problem of control switching is solved.Finally,simulations and experiments prove the effectiveness of its analysis and control effects.Additionally,the three-switch Buck-Boost converter suitable for wide input range has different power electronic models under different modulation methods.Especially in some modulation methods,it may not be possible to unify its small signal model,which will cause difficulties in the design of the control system.It is also difficult to solve the problem of controller switching transition when work states changing.This article improves a modulation method that is realized by using different switching frequencies for the Buck switches and the Boost switch of the three-switch Buck-Boost converter,interleaving phase between the Buck switches and the Boost switch,and adding duty cycle offset.Compared with the traditional synchronous modulation and interleaved modulation originally used in the two-tube Buck-Boost,the modulation can also reduce the average inductor current of the three-switch Buck-Boost converter and obtain a compromise of the inductor current ripple performance.In addition,the small signal model of the three-switch Buck-Boost converter is unified under this modulation method,which makes the control design very convenient.Finally,the effectiveness of its analysis and control effect is verified by simulation and experiment.For high-gain DC converter,in order to obtain high gain of output voltage,this paper adopts a specific connection method to cascade boost converters,and obtains two high gain DC converters.Among them,the combined quadratic Boost converter has a very high output voltage gain.This connection method can reduce the voltage stress of power devices such as switching switches and diodes,and the interleaving control can also reduce the input current ripple of the converter.In addition,the combined zero input current ripple Boost converter can obtain almost zero input current ripple,which is especially suitable for occasions such as fuel cells that require harsh input current ripple.Finally,the effectiveness of its high gain and zero input current ripple effect is verified by simulation and experiment. |
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