Reserch And Design Of APFC System Based On One Cycle Control

Based on the consultation plenty of literature at home and abroad, The paper describes the main characteristic and development of APFC technology, analyzes the means and basal theory of PFC technologies on structure of the main circuit and control mode, and illustrates the necessary and importance of the digital PFC. Based on the work above, the paper focuses on the principle of one-cycle control technology, and analyzes the feasibility of using DSP to realize one-cycle control, then the choice of sampling frequency, the PWM signal generation, the connection between the controller and power circuit, hardware design and the software implementation of the control algorithms are described in detail.One-cycle control (OCC) strategy is a novel nonlinear control strategy which is suitable for active power factor correction system without the multiplier and AC line voltage sensing compared to the traditional APFC circuit, so one cycle control Boost-PFC converter structure is simple and have strong ability to reject the input voltage disturbance. The paper discusses the operation principle of OCC Boost-APFC and designs an APFC prototype that based on one-cycle control. The experimental results show that one-cycle control is suitable for Boost converter and can realize good APFC effect.The principle of single-phase Boost-PFC based on one-cycle control is analyzed firstly in the paper, comparative research is also done on continuous and discontinuous conduction mode of inductor current and the applicability and stability of OCC APFC are analyzed, then build a simulation model to prove correction of the analysis. In the third chapter, hardware of main circuit of power converter and peripheral circuit of400W APFC prototype are designed in detail, which contain boost inductor, Electro Magnetic Interference-EMI filter, sampling circuit, driver circuit and power component selection.The traditional APFC scheme generally uses analog control mode which is sensitive to the environmental changes and has a complicated control circuit. The paper analyzes the key problems of digital control to realize OCC scheme and improves the traditional OCC theory for digital implementation. Firstly, the features of APFC digital control chip are introduced, then analyzes the principle of digital control APFC based on OCC scheme and determine the sampling frequency and method of the measurement, and the digital controller parameter of voltage loop is designed. Finally, the paper gives the algorithm design of control system, a prototype based on the platform of TMS320F2812is described and software design process is given in detail. The experimental results on the400W prototype verify the correctness of theoretical analysis and the design.