Input charge modulation of matrix converters used in direct torque control of induction machines

Direct torque and flux control of induction machines, fed by matrix converters, is part of academic research since about ten years. Improvements have been achieved and published for the main drawbacks of the control method, high torque and current ripples as well as the variable switching frequency, in particular. However, grid side control of the matrix converter is not yet fully explained. The aim of the paper is to introduce a closed description of the matrix converter input current modulation based on the charge as integral value of the current. Furthermore, the entire theory and control structure of the proposed direct torque, flux and charge control, including solutions for input oscillation damping as well as flux and torque estimation, is given and validated by means of experimental results.