The Research On Pulse Frequency Modulation Technology Of Inverter Based On Chaos Mapping

The application of High-frequency inverter has been very extensive in today's society, but the harmonic electromagnetic interference caused by conventional PWM control strategy is also very serious, and then how to restrain electromagnetic interference has become a concern problem. The basic way of solving the electromagnetic interference is using advanced modulation schemes and new topological structure. By selecting the excellent modulation strategy, electromagnetic interference can be effectively suppressed.Pulse frequency modulation (PFM) technology makes use of spread spectrum energy to achieve the purpose of reducing harmonic amplitude, and it can solve the harmonic electro-magnetic interference problem from the source. Pulse frequency modulation technology based on chaos mapping uses time series chaos mapping as modulation mode. It turns the high strength discrete harmonic frequency spectrum into a continuous low intensity smooth harmonic frequency spectrum due to the spectrum broad characteristics, thus eliminate spectral peak and make the harmonic wave get a great inhibition. This strategy has a simple control, stable operation characteristic, became a kind of important ways.This article compared and explanted the principle of PWM with PFM, based on detailed Fourier analysis about the square pulse signal. It is concluded that the PFM strategy is really effective in restraining harmonic electromagnetic interference. An index, AWP-Amplitude Width Product, for measuring electromagnetic interference suppression effect is proposed on the basis of analyzing sideband spectrum. And then several time series chaotic maps are introduced.On the basis of theoretical analysis, a pulse frequency modulation experimental platform has been established. Through the experimental platform, firstly the experiment with different parameters of Lozi mapping summarized some factors to affect modulation. And draw some rules of choosing chaos mapping.Afterwards, three kinds of single chaotic modulation and two kinds of dual chaotic modulation were tested and compared with the AWP index. The index can well reflect the effect of chaotic pulse frequency modulation.Finally, the external magnetic fields of motor were measured in all sorts of different chaotic modulations, proving that chaotic pulse frequency modulation technology can really suppress electromagnetic interference effectively. And Tent-Logistic mapping is the best modulation mode for this experiment. Therefore, the rules to select proper chaotic sequence for the purpose of pulse frequency modulation have been provided according to the results of the paper.