| With the continuing escalation of harmonic pollution in power network, the application of APF (active power filter) is more extensive. APF has gradually become the research hotspot. The quality of harmonic compensation algorithm and the size of switching loss also gradually becomes the key to determine APF performance. In order to improve above two problems, this article puts forward a kind of APF control algorithm based on virtual impedance control strategy and minimum switching loss modulation method, which can effectively reduce the control algorithm of complex and IGBT switching loss.This paper mainly studies the three-phase three-wire parallel APF system. In this paper, first of all, in view of the two big problems, which are the algorithm design complexity and the switching loss in APF, the first chapter refered to a large number of literatures at home and abroad. On the basis of understanding the research status of APF, the second chapter studies the topology structure and working principle of APF; this paper proposed improved APF topology structure, and the mathematical model of the APF is given. Without voltage or current sensor control strategy’s characteristics are studied at the end of chapter two.On the based of the analysis of the second chapter, the third chapter first summarizes the existing two kinds of control algorithm of APF, i.e., the direct current control technology and the indirect current control technology. On this basis, the combination of the application principle of virtual impedance in inverters, uninterruptible power supply and micro grid, the chapter three has designed the APF control algorithm based on virtual impedance technology. At the end of the third chapter has carried on the simulation based on MATLAB/Simulink, and the simulation experimental results show that the control algorithm designed in this paper has a lower carrier frequency and high power factor.Aiming at the problem of high switching loss of APF, due to the traditional DPWM algorithm for different inverter power factor has a different effect. In order to achieve the optimal switching loss of PWM modulation rules, the chapter four of this paper has designed a minimum switching losses DPWM control strategy. At the end of the fourth chapter gives the simulation experiment, and this results shows that in the case of the compensation effect is not affected, the minimum switching losses DPWM control strategy can reduce the switching losses and the switch frequency of inverter.At the end of the article, based on the structure and algorithm of this article, the hardware parameter of main circuit and control circuit are designed, and software algorithm is designed by Simulink mixed with C language programming method. At the end of the fifth chapter has carried on the experimental waveforms and data analysis. The experimental results show that the APF can perform effective harmonic governance, realize the function of the design and meet the design requirements. |
