Design Of The High Frequency Switching Power Supply Based On MCU

With the development of power electronics, high frequency switching power supply has been widely used in the areas of computer, communication, industry porcess and aviation.It can turn strong and coarse electricity into precise and exquisite electricity, which can be used by many kinds of electricial equipments and instruments, and it is the " heart blood supply system" of modern electricial equipments. But the traditional switching power supply has low intelligence and popularity. In order to solve this problem this innovative design was made.This thesis is mainly about the research and design of high frequency switching power supply based on MCU. First, the current development of power supply and switching topology are introduced. Then bring forward some problems about switching power supply and design scheme based on theoretical analysises. By means of numerous experiments and theoretical analysises we can find that use MCU which contains PWM module to replace PWM chip in the switching power supply can solve the problem. This thesis put forward a combinatorial structure, half bridge topology make up of the main circuit, MCU and it's I/O interface circuits make up of the control circuit. Use the transaction circuit which designed by myself to sample power grid voltage and display it. This makes the power supply more intelligent, and at the same times the MCU samples and transacts the output voltage then it will export PWM wave to control the output of half bridge topology. Some keys were added into the control circuit, which can regulate the output voltage make the power supply have batter popularity. The MCU I/O interface circuit includes A/D sampling, nixie light display, the amplification of PWM wave and sampling feedback circuit. Because the object of A/D sampling is power grid, so we need a transaction circuit, whitch turn the 220V alternating voltage into 0 to 5V unipolarity changed voltage signal. This signal is transmited into A/D module of MCU and displayed by four nixie lights. The sampling feedback circuit isolates and amplifys the output voltage, then sends it to MCU for the PID compute, to control the PWM wave's duty ratio.This thesis introduces the design process of the whole switching power supply,the design of main circuit includes half bridge topology design, drive circuit design, buffer circuit design, and transformer design; the design of control circuit includes external circuit of MCU design, auxiliary power design, keyboard and display module designs. The regulating part of this thesis registers steps and processes of this power supply design, and regulating waveforms and data, which show perfect operating state of the power supply, stable output voltage, and the feasibility of the design scheme is also verified.