Research On Boost PEC Converters Based On Digital One-Cycle Control

In recent years, the widespread utilization of power electronic equipments has brought about increasingly serious harmonic pollution in the power grid. Power Factor Correction has become a research hot spot in the field of power electronic technology to reduce the harmonic pollution from power electronic devices and to increase the input power factor. Compared to traditional passive power factor correction, Active Power Factor Correction technology has good correction effect and stable control performance and become a gordian technique to improve the quality of electricity. With the development of high speed, cheep digital signal processor provides a new method for switching power supply. Active Power Factor Correction based on digital control represents in the development direction of power electronic field.Based on the single phase Boost rectifier, the thesis mainly focuses on digital one cycle control (OCC) strategy, the design method for Boost converter and the dynamic response performance issues of the output voltage.At first, how the OCC single phase Boost rectifier achieves high power factor is discussed, then this paper analyzes the applicability and stability of one cycle control. Based on the work above, the paper also analyzes the key problems of digital control to realize OCC scheme and the related digital arithmetic are derived.The control system model of OCC Boost converter is studied. Through the analysis of the system large signal model, the model which ignores the voltage across filter inductor, and is suitable for the application that high switching frequency is far greater than the line frequency. A equivalent current loop is gained by the built small signal model. According to the established system small signal model, the PI parameter design method for voltage controller is proposed. In addition, to improve dynamic response of the output voltage, the feedforward control of load current is adopted, and feedforward control model is established. Thus, this control scheme can ensure the converter has good input performance in the steady state and load fluctuations. Finally through the simulation and experiment, the results are given to verify the effectiveness of the above scheme.This article researches the hardware design method of Boost PFC converter. Main circuit of power converter and peripheral circuit of the experiment prototype controlled by DSP are designed in detail, which contain filter inductor, sampling circuit, driver circuit and the selection of power component. The features of digital control chip TMS320F28027are introduced.In order to validate the feasibility of digital control to realize OCC strategy and the rationality of the circuit design, the Boost PFC converter experimental prototype based on TMS320F28027is set up. And the paper gives the detailed software solutions and control flow chart. At last, simulations in PSIM and experiments have been done. The simulation and laboratory findings confirmed that, the Boost PFC converter employed digital one cycle control possesses high power factor, excellent input performance and frequent dynamic response, and meets the design requirements under the power frequency condition.