The Development Of High Frequency Digital Switching Power Supply Based On FPGA

With the development of the power electronics industry, electrical equipments have higher requirements for power supply performance,traditional high power switching power supply commonly use hard switching and specific integrated chip, which lack of scalability and make great power loss; meanwhile, control precision becomes worse and worse with the aging of components. In recent years, digital control technology and FPGA applications in the field of power electronics have been become a new hot research area; digital control can reduce the effect of precision which components’aging and temperature drift bring about and easily make digital communication with the outside world for intelligent controlling and monitoring.In high-speed high-density low-cost FPGA,combination of internal resources can make a digital system which not only can avoid the program runaway and exception interrupt,but aslo can improve system stability.In this thesis,we take the advantages of digital control and FPGA controller, then research and develop the high frequency digital switching power supply. The research work of this thesis lies in the following areas:1. Analysed the characteristics of switching power supply topologies, converter control mode and soft switching technology, then proposed the overall design of switching power supply.2. Analysed limited double polarity zero voltage and zero current switching (LDP-ZVZCS) process. Derived the basic Buck converter model, then established the full-bridge ZVZCS converter mathematical model based on the effective duty ratio.3. According to the design objectives, in the main circuit, put forward the design method of main components which including input circuit, output circuit and full-bridge inverter; then deduced expression of the PID controller in pole placement method based on ZVZCS model; lastly, aimed at the output rectifier diode reverse recovery and narrow ZVS range of lagging-leg, this thesis proposed spike killer solutions and deduced design formula of spike killer.4. According to control requirements, in control circuit, proposed implementation method of hardware circuit which including FPGA control, voltage and current detection, driver amplifier, accessory power supply,etc;in FPGA software,designed data acquisition and processing module, digital PID module, digital pulse width modulation (DPWM) module, digital communication module, soft start module, etc; and a upper computer monitoring software which achieved upper computer monitoring and controlling function was developed in C#.Experiment had been made on a prototype platform, the results show that each FPGA program module was working properly,the effect of using spike killers to suppress rectifier reverse recovery was very good, and full-bridge converter achieved ZVZCS in a wide load range.