Research On High Frequency Switching Power Supply Based On Synchronous Rectification

With the continuous development of power electronic technology,switching power supply has the advantages of small volume,light weight and high efficiency etc.It gradually replaced the linear power supply and it is widely used in various types of power electronic devices.However,in the traditional low-voltage high-current output switching power supply,the voltage drop of transformer secondary rectifier diode is large,thus resulting in transformer secondary rectifier loss is large,making the transformer secondary rectifier loss take up a large part of switching power supply total loss and secondary rectifier loss becomes the key factor of switching power supply efficiency improvement.And the synchronous rectification technology provides necessary technical support to reduce the loss of the transformer secondary rectification.In order to reduce the loss of the transformer secondary rectification and improve the efficiency of the switching power supply,the synchronous rectification technology and high frequency switching power supply were studied in this paper.The research background and significance of the high frequency switching power supply were introduced firstly in this paper.The development process of the high frequency switching power supply and the mode of the transformer secondary rectifier were analyzed and compared.And the research status of the synchronous rectification was introduced.In the aspect of main circuit topology,the working principle and operational process of the main circuit topology selected by the high frequency switching power supply was analyzed.In the research of synchronous rectification technology,it was analyzed from the introduction of synchronous rectifier,the loss of synchronous rectification,the control mode of synchronous rectifier,the design requirements of synchronous rectifier drive circuit and the advantages and disadvantages of the different type synchronous rectifier drive circuit these aspects.Then the hardware design and the software design of high frequency switching power supply system were carried out.In the aspect of main circuit hardware design,it designed the input rectifier filter circuit,high frequency transformer,output rectifier circuit and the power switch tube etc.The control circuit hardware design was based on STM32F103 as the control core,and it designed phase-shifted pulse modulation circuit,drive circuit,CPLD circuit,serial communication circuit,sampling circuit,over-under voltage protection circuit,temperature protection circuit and debugging circuit etc.In the aspect of the control system software design,it main designed the system main program,ADC sampling subroutine,DAC subroutine,incremental PI subroutine and serial communication subroutine etc.Finally,the control system and the main circuit of high frequency switching power supply were debugged,and the relevant experiments were carried out.The experimental results show that the power output waveforms was stable and the test data show that the power efficiency is approximately 90%.Therefore,the high frequency switching power supply based on the synchronous rectification technology in this paper meet the requirements.