Improved Design and Space Vector Modulation of a Z-Source Ultrasparse Matrix Converter: Analysis, Implementation, and Performance Evaluation

Space vector modulation (SVM) of a Z-source ultrasparse matrix converter (ZSUSMC) can be realized by either using or not using a zero state in the space vector rectification. In this paper, these two modulation schemes are investigated for a cascaded ZSUSMC. It is demonstrated that the input current under the modulation scheme without a zero state is nonsinusoidal, and its harmonics content depends on the output and impedance network inductor currents. In addition, restrictions on operation of the ZSUSMC with low voltage gains are unveiled. Next, aiming at improving the input current quality and suppressing the harmonics content to an acceptable level, an approach for design of the cascaded Z-source network is proposed. Furthermore, an optimal switching pattern, which results in minimum possible number of changes in the switching states of the ZSUSMC, is developed. Using the developed switching pattern, an approach for digital implementation of the SVM schemes on a single conventional digital signal processor (DSP) without employing an additional field programmable gate array is proposed. Hardware-in-the-loop studies of the ZSUSMC modulated under the proposed SVM schemes are carried out to verify their digital implementation feasibility on a conventional single DSP, as well as effectiveness in producing high-quality input/output currents.