Three-phase power conversion using quasi Z source direct matrix converter (QZSDMC) for fixed frequency to variable frequency using direct duty ratio based pulse width modulation technique

This research article implemented a new technique for a direct ac to ac power conversion in a three-phase quasi Z-source direct matrix converter (QZSDMC). The QZSDMC is designed by connecting a quasi Z-source impedance network in series with a normal direct matrix converter. In this system, three-phase fixed voltage and supply frequency has been received from the source, whereas the variable ac voltage and frequency are fed to the stand-alone system. The bidirectional operation capability of QZSDMC provides buck-boost action with a minimum number of control switches. Here, the voltage transferring capability is controlled by its shoot-through duty ratio value. Due to the direct duty ratio pulse width modulation technique (without harmonics injection) in QZSDMC, the output voltage is doubled along with variable frequency. However, the discussion is limited here because this technique is used for an odd number of output phases. The increased output voltage from 100 V to 245 V with a minimum amount of harmonics distortions has been observed using MATLAB simulation and the same is experimentally validated. In addition to this, the converter having the capabilities of converting a fixed frequency of 50 Hz into variable frequencies like 25 Hz, 75 Hz and 100 Hz.