The Study On Digital Control Method Of Single Phase PFC

Nowadays PFC (Power Factor Correction) inverters that are being used in many fields play an important role in the life. It is used in many applications. During the last decade, there has being a large interest in PFC. Many control methods are explored, including average current control, peak current control, hysteretic control, etc. Digital signal processors (DSPs) designed for closed loop control implementations have been extensively used in areas of motor control, uninterruptible power supplies(UPS), and motion control applications. Compared to traditional analog control, DSP controllers provide many distinctive advantages. With the rapidly improvement of DSP, more and more control schemas can be realized. Compared to traditional analog control, DSP controllers provide many distinctive advantages. In this dissertation, present situation and significance of the topologies,control laws,and the sample algorithms of the digital control PFC are summarized. The dissertation gives analysis and comparison of the recent developments and principles of various control strategies in digital control PFC. Based on average current mode, the dissertation introduce the design and implementation of a fully digital controlled single-phase boost power factor correction with fast response. The control-loop circuit is realized using digital control and the corrector can tend to unity power factor, low current harmonics and high transfer efficiency. The double closed-loops framework is applied in the PFC control circuit and the PI algorithm is adopted as system's control algorithm. Further more, farther research has been done in this dissertation. The duty-ratio feedforward loop was added into the normal current control loop. With this improve, the input impedance of the boost PFC converter can be regulated to approach resistive feature more. The small-signal model of PFC circuit has been researched in the dissertation and the simplified average-small-signal model of the system has been builded. The dissertation develops design method of PI regulators that are applied in double closed-loops system. Furthermore, the sampling algorithm of voltage and current variables is also analysed in this dissertation. Based on the theory analysis, design of the control programs have been done. The software system consist of a main program and a interrupt subprogram, which contained some modules to realize independent functions, such as initialization module, PI algorithm module, sampling algorithm module and interrupt module, etc. Under connection of the main program, these modules realize an integrated system. It is easier to do some management and upgrade when the program frame like this is used. All design thoughts and theoretical results are verfied by emulation and experiment. The orientation for this item was proposed at the end of this dissertation.