Design Of High Efficiency Step-up/Step-down DC-DC Converter Based On H-bridge Topology

In recent years, portable devices such as handheld computer, personalcommunication equipment and other consumer electronics products obtained therapid development, the electronic products are powered by a lithium battery. Lithiumion battery voltage as the state of charge and discharge change will change greatly, sothat the battery voltage may be higher, may also lower than the supply voltage,battery voltage step-up/step-down DC-DC converter will change into a stable DCvoltage. A smooth transition between the step-up and step-down modes and improvethe efficiency of transition models is a hot and difficult research step-up/step-downDC-DC converter.This paper firstly introduces the working principle of H bridge boost/buckconverter and proposed problems. System in the process of step-up and step-downconversion,with skipping cycle, produces larger output ripple, this article put forwardunder the mode of the transformation, increase the inverting H bridge work patternsas transition mode, to minimize the output ripple of the system. In transition mode inorder to get high conversion efficiency, thus improving the inverting H bridge model,to improve the conversion high efficiency of the system.Secondly, this paper derives asmall signal model of H bridge boost/buck converter three working modes includingboost mode, transition mode, Buck mode,and builds the system domain model bySISOTOOL tool, to determine the compensation scheme of the system, and then useSimulink to build the H bridge boost/step-down converter system, the purpose is toverify the compensation scheme in three work mode. Finally, this paper adopts theCMOS process design of H bridge0.35um TSMC step-up/step-down DC-DCconverter, extract the netlist，Hspice simulation and analysis, the results show thatunder the condition of overloading. Finally, this paper adopts the CMOS processdesign H bridge0.35um TSMC step-up/step-down DC-DC converter, the inputvoltage range is2.7-5.2V, VFB for1.2V, switch frequency range is300KHZ-2MHZ, output the maximum current of600mA. Extract the electrical network, under the condition of the switching frequency of1MHZ, Hspice simulation and analysis,seen from the simulation results, When the output resistance R=5.5and R=33overloading situation respectively,system in the booster mode conversionefficiency of91%and94%, in the boost/buck mode conversion efficiency of75%and83%, conversion efficiency of73%and79%in step-down mode, transition modeof ripple is30mv; When the output resistance R=50light load conditions, theinput voltage of2.7V,3.3V,4.2V, system conversion efficiency of79%,65%and73%respectively. Above results show that the implementation of the DC circuit tosuit the requirements of high efficiency, low ripple.