Research On Harmonic Suppression Based On Six-wave Double-variable Cycloconverter

This paper introduces the variable frequency technology, the development and trends of cycloconverter technology at home and abroad, then introduces the double-variable control theory, the basic harmonic theory in the variable-frequency system.Combining the results of previous studied, analyses the advantages of six-wave cycloconverter compared with the three-wave converter, especially on the harmonics. For the frequency bands with poor waveform symmetry,it finds a way to optimize the output waveform– according to the demand of the waveform from output speed , under the premise of meeting the conditions of positive and negative group of thyristors conduction ,uses patchwork method to give different thyristors different pulse triggering moments, analyses and calculates the load impedance angle of different frequency bands, besides the principle of selecting the trigger pulse width, to determine the pulse width of the different frequency bands in order to inhibit output signal harmonics from the converter itself especially the even harmonics component .First ,it simulates based on use MATLAB / Simulink and then does experiment based on different frequency bands .Comparing and summarizing a large number of results from the simulation and the actual experiments, gives harmonic situation of the same band with different modulated waves, the same modulation wave with different trigger timer, and points out that the trigger timer and width should be considered from the sine degrees, the symmetry and balance degree. In addition, this paper introduces the relative application of dwin HMI touch screen LCD modules, gives the waveform of voltage and motor speed showed by LCD modules , plotts the motor speed wave curve in MATLAB based on speed data picked from motor load experence .