Research On Direct Torque Control Of Asynchronous Motor Fed By Matrix Converter System

Matrix Converter is a kind of direct AC-AC power electric converter. Its advantages are bi-directional power flow,nearly sinusoidal input/out waveforms and a controlled input power factor.Matrix converter is a good choice to fed AC motor drive systems.Under the electric drive field,the Direct Torque control theory has the novelty control idea, direct control measure and the simple control method,it has attracted more and more attention.In this paper,the mathematical foundation,principle and evident virtue of matrix converter is explored.Deeply analysis have been to the research of the basic topology,mathematic principles and exiting modulation algorithm of the MC;such as the Venturini control methods, instantaneous value method and space vector control method.Based on many modulation techniques are compared,we decieded to use the direct space vector modulation method.Through theoretical analysis of the commutation and structure characteristic of bi-directional switch, We choosed the four-step commutation which is achieve security.The principle of DTC and the realization of it are introduced.The concept of matrix converter voltage space vector is presented.Through the combination strategy,MC-DTC switch table was given in the paper.Block diagram of system was given in the end of fourth chapter. The simulation model of main circuit and control circuit of MC-DTC system is constructed with MATLAB/SIMULINK,and a lot of simulations are carried out.The results of simuliations indicate that proposed modulation method is effective.The performances of MC-DTC system has excellent characteristics.Finally,a experimental equipment of compound control system is designed.Some valuable experience and results were got and testified,and contributed to the matrix converter's industry application.