A Comparison of PWM Pattern for Matrix Converter

Abstract

This paper describes a comparison of PWM patterns for matrix converter. There are two PWM patterns with keeping the command of the output voltage and input current. The output voltage sequence of the pattern A is maximum-minimum-medium-minimum-maximum of each input voltage, and the pattern B is maximum-medium-minimum-medium-maximum of each input voltage in one switching period. The switching loss and the harmonics of the output voltage are analyzed for every PWM patterns. The pattern B has advantages for the low harmonics of the output voltage and reducing switching loss.
Next, an improved method of the virtual AC/DC/AC method is described in this paper. The virtual AC/DC/AC method can generates only pattern A. Thus, the improved method changes the sequence of the output pulse in order to reduce switching loss and harmonics of the output voltage. Moreover, the proposed method is very simple because it does not require a special triangular waveform. The effects of the proposed PWM generation method are confirmed by the experimental results with 22kW induction motor. The converter loss decreases by 30% and the total harmonics distortion of the input and output current are improved by 1-2points to the conventional method.