A Comparative Study of Series and Cascaded Z-Source Matrix Converters

The series Z-source network, an expansion of the popular concept of the Z-source dc link, was originally proposed for boosting the output voltage of power electronic inverters. In this paper, that idea is extended on a three-phase indirect matrix converter. The converter is based on the ultrasparse matrix topology characterized by the minimum number of semiconductor switches. The series Z-source network is placed between the three-switch input rectifier stage and the six-switch output inverter stage in either the positive or the negative rail. A brief shoot-through state produces the voltage boost. An optimal pulsewidth modulation (PWM) technique is developed for higher boosting capability of the converter and minimization of switching losses. A comparison is made between the matrix converters employing series and conventional cascade Z-source networks. The inrush current and Z-source capacitor's voltage are reduced in the series Z-source matrix converter. Furthermore, the fast Fourier transform analysis of the output current of the converters suggests superiority of the series Z-source matrix converter over the cascaded Z-source matrix converter.