Research On Improved Quadratic DC/DC Converter

With the rapid development of the global economy, fossil energy(coal,oil,natural gas,etc.) has not been satisfied with the growing demand of energy consumption in the world. The pollutant produced by the fossil fuels causes a large area of the country haze pollution and a large number of emissions will make the problem of global warming become more serious. In order to alleviate the problem of environmental pollution and the world energy crisis, the development and utilization of green renewable energy is very important. New energy power generation system such as Wind power generation, solar power generation, fuel cell, super capacitor hybrid system, geothermal power generation and tidal power generation system are becoming more and more adverted. The wind power generator, fuel cell and solar cell have the characteristics of low output voltage and wide variation range. If a plurality of fuel cells or solar cell in series, any of these problems with a battery plate will make the whole system to a standstill. Thus, in the new energy power generation system requires a DC/DC converter. This converter not only has high ratio boost capability, and can stabilize the output voltage when the input voltage is changed in wide range.At present, high gain and wide input DC/DC converters for new energy power generation system mainly include two types of isolated and non isolated. After analyzing the advantages and disadvantages of two types of converters, according to the principle of cascade converter, an improved quadratic DC/DC converter is constituted. The converter not only has the advantages of the traditional quadratic boost converter, and the storage capacitor voltage stress is smaller than that of the traditional quadratic Boost converter.This article is mainly including five items:(1)The high gain and wide input DC/DC converters are classified and summarized, and the cascade principle of the traditional quadratic Boost converters is introduced.(2)According to the cascade principle, an improved quadratic DC/DC converter is formed, and the different operation modes of the converter are analyzed in detail. The formula of the voltage gain is derived, and the main waveform of the circuit is given. Then the inductive current ripple,capacitor voltage ripple and main circuit device voltage stress of the improved quadratic DC/DC converter are derived.(3)A mathematical model is established for the continuous conduction mode of the improved quadratic DC/DC converter. The main transfer function of the circuit is given. According to the characteristic of the transfer function, choose to use current program control strategy.(4)A DC/DC converter which is suitable for the new energy generation system is designed by using the improved quadratic DC/DC converter. First, the main converter circuit parameters were chosen. Then the inner control circuits designed in detail, including the artificial slope compensation circuit, sampling network, current inner and outer voltage design. Finally, the static and dynamic performance of the improved quadratic DC/DC converter are simulated by Psim simulation software. The main work waveform are given, which proves the correctness of the theoretical research and design.(5)According to the theory and simulation analysis, a small power prototype is designed. The results of the experiment are consistent with the theoretical research and simulation results.