Research And Design Of A Resonant Controller Based On Half-bridge Topology

With the development of electronic products,it is necessary to meet higher application indicators.Without increasing the volume and weight of the converter,we have to pursue a higher operating frequency to increase the power density of the switching power supply.But at the same time,high-frequency switching makes the switching loss very serious,and is accompanied by heat generation,its efficiency is not satisfactory,and this also makes electromagnetic interference stronger.In order to solve this problem,soft switching technology emerged,and its purpose is mainly to reduce the loss of the switch.The thesis first explains the development background and trend of resonant converters,and then introduces related theoretical knowledge,especially soft switching technology.On this basis,a resonant controller based on half-bridge topology is designed,which includes a control chip and peripheral circuits.The entire resonance control system adopts negative feedback adjustment.After sampling and voltage division,the output voltage is connected to the positive input terminal of the error amplifier module in the chip,and the inverting input terminal is the connected 5V reference voltage.Compare them.The difference between is Vr,and the result of the comparison is used as the input voltage of the internal voltage-controlled oscillator,so that the change in voltage is converted into a change in frequency.Then,the two output pulse signals at the adjusted frequency are used to drive the upper and lower switch tubes in the peripheral half-bridge circuit,and finally the output voltage is obtained through rectification and filtering.This thesis designs the overall architecture of the control chip and some key submodules,including startup circuit,voltage regulator circuit,under-voltage lockout,fault logic,voltage-controlled oscillator,and output driver.Based on Shanghai's advanced 4?m40V bipolar process,the thesis uses spectre simulation software to simulate and verify the internal sub-modules of the chip and the entire peripheral circuit.The simulation results show that all functions such as power-on,fault restart,and undervoltage lockout are working normally;and the simulation results of key parameters are within the set range,for example,the maximum frequency is about 500 k Hz,the minimum frequency is about 50 k Hz,and the linear adjustment rate is 0.9m V.,The load regulation rate is 17 m V,the turn-on threshold is 16.5V,and the turn-off threshold is 10.5V,etc.,which meet the design requirements.The main application areas of the chip designed in this thesis are digital TV,AC/DC adapter,multi-function printer,projector,LED lighting application,etc.It adopts the principle of pulse frequency modulation and has the characteristics of high efficiency.