Research And Design Of The System Of Wide Input Four Switch Buck-Boost Converter

DC-DC converter becomes an important part that the electronic devices rely on,because of its advantages of wide input voltage and output voltage,high efficiency and so on.With the miniaturization of electronic devices,the efficient use of batteries has become a new demand for electronic devices.Improving efficiency and extending the life of electronic devices become the development trend of the DC-DC converter.The DC-DC converter with boost and buck functions can fully utilize the battery energy in a wide input rang and extend the life of electronic devices,which makes the DC-DC converter with boost and buck functions become a new direction for DC-DC converter.To meet the technical trend,a four-switch Buck-Boost converter system with wide input range is designed in this paper.With the traditional control method,the four-switch Buck-Boost converter can realize the input voltage and the output voltage of the same direction.However,the more switch loss is introduced in,which reduces the efficiency of the converter.In order to improve the efficiency of system transformation,the four-switch Buck-Boost converter in this paper adopts a new mode of multi-mode control that can be used to reduce switching losses.According to the input and output of the converter,the converter operates in Boost mode,transition mode and Buck mode.In addition,the PWM modulation method is used to further improve efficiency because of the high efficiency at high loads.And the current feedback control method is adopted to improve the response speed and simplify the loop compensation.In the system design,the stability of the current loop is analyzed firstly,and the slope compensation technique is introduced to prevent the occurrence of sub-harmonic shock.At the same time,the power level of the voltage loop is modeled and analyzed by the switching network method,the transfer functions of the loop is also derived and the frequency responses are verified using MATLAB simulation tool,which is used to determine the stability of the system.When designing the the block diagram of the system,the key module circuits are designed and analyzed specifically,and the simulation verification results are simulated.Finally,the characteristics of the whole system loop are simulated and verified,and the simulation results are analyzed.And all results meet the original design indicators.In this paper,0.18?m BCD process is used for the design of the four-switch Buck-Boost converter.The converter operates within a wide range of 6V~36V,and the output voltage is12 V.All the three operating modes are realized and it can switch between different modes smoothly.When the load current is more than 1A,the efficiency of the system is about 90%.