Design And EMI Analyses For Four-Quadrant Converters Based On Chaotic SPWM Control

Since Four-quadrant Convertors have the featrues of unity power factor, sinusoidal grid-connected current, and bidirectional flow of energy, it has widely employed into the fields of electric locomotive, photovoltaic power generation, wind-powered electricity generation and active power filter. But meanwhile, the application of sinusoidal pulse width modulation technology would give an abundant frequency harmonics of four-quadrant convertors, which lead to serious electromagnetic interference problem. The methods to suppress the electromagnetic interference of four-quadrant convertors effectively and fundamentally has become a hot area of research. As a consequence, Chaotic SPWM control is proposed, which can reduce the peaks of harmonic components, therefore, achieve the aim of EMI suppression of.In this thesis, the introduction of the traditional control methods and working principle of four-quadrant convertors are given firstly. After the analying theAC-side current harmonic distribution and their interference with traditional SPWM control and chaotic SPWM control. The principles of chaotic SPWM control and generation of the triangular carrier frequency of chaotic change are introduced in detail in this article. The bifurcation diagram of two types of chaotic mapping are analysed and compared carefully, and the choice of the parameters and initial data of the two mapping are discussed respectively.Based on the theoretical analyses, the simulation model of a single-phase four-quadrant converter based on Matlab/Simulink is built and simulation results under different control methods are analyzed and compared in the thesis. The influence of the chaotic control to the ripple of output voltage is studied at the same time. Finally, the EMI test of the single-phase four quadrant converter is carried out and the conducted electromagnetic interference are measured. The test results of the AC current waveform and the DC voltage waveform under different control methods are analysed. By the comparison of the spectra of the conducted electromagnetic interference, it can be concluded that the EMI test results could be correlated to the theoretical analyses and the simulation results. And the validity of the chaotic SPWM control is proved.