| With the increasing use of power electrical devices, the harmonic pollution becomes worse and worse in the distribution system. The research that how to decrease harmonic pollution becomes an important topic on the development of power supply. The whole digital control and high performance AC/DC converter have been designed by this paper. The system applied with two-stage topology. The first stage adopted Boost PFC topology by using programmable harmonic impedance control. The second stage adopted LLC full-bridge circuit, using variable-frequency control. The whole circuit control has been realized by digital controller FPGA.According to first stage, this paper has introduced the operating principle and control method and analyzed the characteristic of reducing the harmonic resonance using PHI converter. Two methods of PHI control have been introduced in detail and compared with each other. The theory analysis was validated by simulation, and the design progress of main parameters was shown in this paper. According to second stage, the equivalent circuit model of the converter was obtained by fundamental analysis, and the voltage gain characteristic curve was deduced. The small signal model of the converter is established by the piecewise-linear state-space method. The operation characteristic of the LLC converter was validated by simulation.The control system based on FPGA completed the algorithm on each module by using Verilog HDL language. The data reading control module, PI control module, serial communication module, variable-frequency control module, and so on, have been realized by using top-down design and down-top idea. The software implement and timing simulation figures are shown in this paper. The serial communication between PC and FPGA was designed in this paper. The VB was adopted on PC as program language, and there were well man-machine interface. The theory and design of software and hardware proposed in the paper were validated by experiment. |
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