Design and Development of a Three—Phase Matrix Converter

Abstract

This research paper presents the principle of a three—phase PWM ac—ac matrix converter, using 9—units of bi—directional, IGBT—Diode as power switching devices. The converter can directly convert three—phase utility voltages of constant frequency into a variable frequency and variable voltage having 6—pulse waveforms by adjusting the frequency and modulation index of the PWM control signals. The theoretical principle of matrix converter will be first described in terms of mathematic equations and then interpreted by means of theoretical waveforms in order to verify the concept of this converter. Moreover, the matrix converter is designed, constructed and tested in our laboratory to generate the 3—phase PWM output voltages and compared with its theoretical waveforms. In the last section of this paper, the theoretical and experimental 3—phase PWM output voltages of variable voltage and frequency which have constant voltage—to—frequency ratio are obtained which can be used in the application such as ac motor speed control.