Improvement of Direct Method Modulation Technique in a Three-Phase Matrix Converter

Matrix converters have received considerable interest as an alternative to the conventional AC/DC/AC converter. In a three-phase matrix converter, two control methods, known as direct and indirect methods, have been used frequently. When a high frequency output voltage is needed and the input voltage is unbalanced, it is shown that both methods can not work perfectly and output voltage THD is high. In this paper a new control method based on the direct modulation technique, which can perfectly work with input voltage unbalance, has been proposed. Theory analysis and simulation results for a three-phase matrix converter are presented in the paper to demonstrate the performance of this control method. The results confirm that the output voltages are balanced despite the input voltages are unbalanced.