Research Of Some Issues On Matrix Converter

Matrix converter and its application in driving-motor has been attached importance to by the academic and industrial circle for more years thanks to its prominent advantage in power-transfer efficiency, high power density and flexible controllability. In recent years, there has been integrated matrix converter motor (MCM) system presented, at the same time, more and more attention has been paid to the research of independent power converter which employ technology related to matrix converter. Theoretical harmonics analysis of matrix converter and full-digital current commutation method of bi-directional switches (BDS) are systematically investigated in this dissertation, and then a new topology which employs three-phase to single-phase matrix converter to drive serial-connected resonant circuit directly has been proposed and investigated.Theoretical harmonics of the matrix converter is analysis under the condition that double line voltage modulation method is employed. Firstly, concept of fundamental period, which corresponding with the period of greatest common divisor of input frequency and output frequency has been introduced as the base of harmonic analysis using continuous Fourier method. Secondly, both the Fourier extensions of the output voltage and input current of the converter are derived from the modulation method. Thirdly, the right normal spectrums of output voltage and input current are calculated using numeric method and the zero-order component of output phase voltage has been specialized. Finally, a series of curves which can be used as correct reference to improve the matrix converter performance has been obtained using the designed harmonics-analysis-software.After the commutation method of bi-directional switches has been reviewed, the voltage commutation method of matrix converter is investigated. Firstly, the flaw of existing full-digital voltage commutation method, Mahlein method, is pointed out after the change of the critical area which switch sequence will encounter corresponding to the variety of displacement angle at the input-side of converter has been explicated in the input voltage vector space, then several rules have been presented and used to instruct detailed voltage commutation method built. Secondly, a 10KW experimental prototype of matrix converter based full-digital control has been established on which the full-digital semi-nature four step voltage-commutation method is investigated. A integrated notion to implement full-digital control, include both commutation method and algorithym of matrix converter using single high-performance FPGA chip is proposed and verified according to the assigned resource. Finally, the full-digital concept is introduced into the semi-nature two-step voltage commutation method under the condition that the improved Mahlein method is adoption. As result, both the commutation logic in critical area of input voltage and the outside hardware for voltage measurement are simplified greatly. Experimental result has been presented to verify the correctness and feasibility of proposed methods.A new topology which employed three-phase to single-phase matrix converter to drive serial-connected RLC circuit is proposed for the first time and is employed to drive the resonant induction heating power-supply used largely at present, then the fundamental modulation law for the converter is presented. The analysis to the BDS commutation process of the proposed converter follows and according to experimental result it can be concluded that the switches loss is lowest when converter operates in the capacitive condition nearby the resonant point. Two load current area distributing laws, which suit to medium frequency and high frequency induction heating power supply, respectively, are presented to improve the input power factor of converter. More attention has been paid to the area partition method which suits for medium frequency application. Simulation analysis and experimental result shows that the power current is alternative semi-trapeziform wave when the constant amplitude of resonant load current is assumed, and that the power current is alternative semi-sinusoidal wave when the variable amplitude of resonant load current is assumed. At all events, the input power factor is improved greatly when any kind of distributing law employed compare with traditional device.In the end, a summary for whole work of the dissertation is made and an expectation for future study about related work is given.