WSEAS Transactions on Power Systems
Print ISSN: 1790-5060, E-ISSN: 2224-350X
Volume 8, 2013
Research on a Two-level Single-phase Active Power Factor Corrector Using Gray Prediction and Repetitive Control
Authors: , , ,
Abstract: The traditional single-phase active power factor correction (APFC) has been widely used. There are two voltage levels between the output terminal of boost inductor and the negative rail of DC link, which correspond to turn-on time and turn-off time of IGBTs. IGBT is the normally used power device. One level is near zero, the other is approximately the positive Output DC voltage. Just due to this, no matter which control strategy is used, zero-crossing distortion of the mains current occurs theoretically that is inevitable. In the paper a novel two-level APFC topology is presented. It can completely eliminate the zero-crossing distortion in essence, at the time the current control strategies can be used. The two voltage levels between the output terminal of boost inductor and the negative rail of DC link are the positive Output DC voltage when IGBT is in on state and the negative Output DC voltage when IGBT is in off state, respectively. With regard to single-phase APFC’s control strategies, in order to generate the primitive driving pulse used for the next switching cycle, it is common that the data used in the current switching cycle is those measured in the previous switching cycle and the current switching cycle. It is inevitable that the method causes lagging control effects. Considering the function of gray prediction, the modulation of GM(1,1) is employed in order to achieve precise control. Thus the electrical quantities required in the next switching cycle can be accurately predicted, including the input AC voltage, the output DC voltage, the boost inductor current, the boost inductor current error and the output DC voltage error. It is also true that the single-phase APFC is powered by sinusoidal voltage, and the expected are DC voltage and sinusoidal current in phase with input voltage. It is inevitable that the method causes steady state errors, when using the traditional double loop control strategy, consisting of the voltage outer loop and the current inner loop. Therefore, the repetitive control strategy is utilized at the same time. The steady state errors can be eliminated and the dynamic characteristics can be improved by both adding voltage error in current switching cycle to the predicted current error and adding voltage error in current switching cycle to the predicted output voltage error. After analysis of the operation principle of the novel two-level APFC, a comprehensive control strategy based on gray prediction and repetitive control is designed. Then the comprehensive control strategy based two-level APFC is simulated and analyzed by means of MATLAB/SIMULINK and implemented. The obtained results are satisfactory and prove comprehensive control strategy.
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Keywords: Power factor corrector, Two voltage-level, Zero-crossing distortion, Gray predictive control, Repetitive control, comprehensive control