Research On A Wide-input DC-DC Converter And Its Control Strategy

As the energy center of various electronic products,the power supply directly affects the overall performance of the electronic system.For example,in the automotive electronic system,when the car generator load is suddenly cut off,or the input voltage changes in a wide range due to a cold start,the internal switching power converter is required to work reliably and stably.Based on this,this article designs a two-switch BuckBoost converter with a wide input voltage range.The main work is as follows:First,use the three-mode control method of the two-switch Buck-Boost.According to the relationship between the input voltage and the output voltage of the converter and the duty cycle,the converter can work in buck,boost or transition mode,so the loss of the converter is reduced.The pulse width modulation method with constant frequency and the peak/valley current mode feedback control mode are selected,which improves the response speed of the system,and simplifies the compensation network of the system.Second,enumerate the design indicators and the overall system architecture,design the parameters of the main peripheral components,analyze the stability of the system,and design the compensation network parameters and slope compensation based on this.Use SIMPLIS software to model and simulate and verify the frequency response of the system to ensure that the system is stable in the three working modes.At the same time,based on the 0.18 μm BCD process,the design and simulation of key sub-circuits,including bandgap reference,low dropout linear regulator(Low Dropout Regulator,LDO),transconductance operational amplifier,slope compensation circuit,mode switching logic generation circuit,drive and Protection circuits such as over-temperature and under-voltage.Among them,the bandgap reference can work under the input voltage of 2.7～36 V,the temperature drift of the bandgap voltage under typical conditions is 2.274ppm/℃,the maximum output current of the LDO is 10 m A,and the operational amplifier provides a gain of 60 d B for the loop,The operational amplifier determines the main pole of the system.The ramp generation module improves the transient performance of the circuit.Third,the overall circuit simulation was carried out.Within the power supply voltage range of 2.7～36 V,the system can generate a stable 6.5 V output voltage with a maximum load current of 2 A,which meets the preset index requirements...