Research And Implementation Of Over-modulation Technology Of Matrix Converter

Matrix converter (MC) contains many potential applications in power electronic fields because it permits frequency conversion, allows bi-directional power flow without middle DC link, and allows the input power factor freely varied regardless of the load power factor. Currently,the voltage transfer ratio of matrix converter is not high , In the ordinary way not more than 0.866. Therefore, the over-modulation strategy of MC is researched in this paper to raise the voltage transfer ratio. The corresponding researches have been investigated both simulation and prototype experiment.To begin with, this paper introduces the theory of double space vector modulation for three-phase AC-AC MC. On this basis, introduces traditional over-modulation strategy of MC and multi-orbit vector weighted over-modulation strategy of MC,analysis the over-modulation theory of the two methods, describe their time domain process, deduce the dutyfactor formula of the two over-modulation strategy of MC respectively in the"virtual rectifier"and"virtual inverter".The simulation model of over-modulation of MC is constructed by using Matlab. Respectively simulate the traditional over-modulation strategy of MC and multi-orbit vector weighted over-modulation strategy and Make a comparison to the characteristics between these two methods. The simulation results indicate that both the traditional over-modulation strategy of MC and multi-orbit vector weighted over-modulation strategy can effectually enhance the voltage transfer ratio of MC, further more, the output voltage total harmonic distortion (THD) of the multi-orbit vector weighted over-modulation strategy is lower, and it's easier to write program .therefore, it has more practical value.In the paper, a prototype of matrix converter based on over-modulation strategy of MC is built. DSP (Digital Signal Processor) and CPLD (Complex Programmable Logic Device) programs are designed, and the experiments are done for the theory of the multi-orbit vector weighted over-modulation strategy of MC. The output-voltage waveforms of the multi-orbit vector weighted over-modulation strategy of MC are given and analyzed. The experiment results further demonstrate that this method can effectually enhance the voltage transfer ratio of MC.