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Quasi-Z source indirect matrix converter (IMC) combines both advantages of conventional IMC and quasi-Z source inverter, for example, no direct current (DC) link capacitor, compact all-silicon power converter, bidirectional power flow, input power factor controllable, and high voltage gain; moreover, it does not require additional input filter, because continuous quasi-Z source network integrates LC filter function. However, there is no literature to disclose common mode voltage (CMV) issue of quasi-Z source IMC. In this paper, for the first time, the CMV issue and reduction of quasi-Z source IMC are investigated. Firstly, the CMV of quasi-Z source IMC is analyzed when using current typical modulation method, which follows the brief introduction of topology and modulation method for quasi-Z source IMC, and the factors that affect the CMV are figured out; Secondly, referring to the CMV reduction methods of conventional IMC, two solutions named as Methods I and II to reduce the CMV for quasi-Z source IMC are developed, which are achieved in the inverter stage; the third CMV reduction method is proposed in the rectifier stage through redefining the six sectors of the rectifier stage, which can implement zero current commutation. Experimental bench is built to test three approaches for reducing the CMV of quasi-Z source IMC. Comparative evaluation is carried out between three methods and conventional modulation method. Experimental results verify that three methods can significantly reduce the CMV of quasi-Z source IMC, with the CMV peak value reduction of 42%, but they present different features in terms of input and output current THDs, switching loss, CMV root mean square (RMS) value, modulation index limitation, and so on. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Conventional matrix converters have a limited voltage gain less than 0.866 and also require many power switches and additional input filter that ensures a low input current harmonics to the grid. Quasi-Z source (qZS) indirect matrix converter can provide high voltage gain and ensure a sinusoidal input current without additional input filter, which requires 12 power switches in rectifier stage. In this paper, a simplified qZS indirect matrix converter is proposed to overcome aforementioned limitations and achieve (1) higher voltage gain than 0.866, (2) less power switches, and (3) LC-filter function integrated in qZS network to avoid additional filter. The new converter's operating principle and equivalent circuits are analyzed, and the modulation method is presented. The input current closed-loop control is employed to implement sinusoidal input current waveform even though the proposed converter has less power switches and without extra input filter. A test bench is used to verify the simplified qZS indirect matrix converter and control methods. Simulation and experimental results identically validate the proposed converter system with wide voltage gain range and low input current harmonics. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Conventional matrix converters (MCs) have limited voltage gain that is less than 0.866, whether for direct MC (DMC) or indirect MC (IMC). Existing Z-source (ZS)/discontinuous quasi-Z-source (qZS) DMCs and ZS IMCs achieved larger than 0.866 voltage gain; however, the former inherited the complex commutation from DMC, and the latter involved a ZS network in dc link and led to non-all-silicon solution. In this paper, ZS and discontinuous qZS networks of existing ZS/qZS DMCs are used for an IMC topology for simplifying commutation and having high voltage gain, but they require extra input filter to reduce current harmonics. A new continuous qZS IMC is proposed, where a qZS network integrates the filtering function of the grid side; hence, additional input filter is avoided in the proposed continuous qZS IMC. Three new IMCs are compared in detail, in terms of voltage gain, current ripple, voltage ripple, inductor current and capacitor voltage stresses, ZS/qZS switch current and voltage stresses, filtering function, input current total harmonic distortion (THD), output voltage THD, and efficiency. Their control and modulation methods are presented to achieve the desired performances. Experimental comparisons verify the theoretical analysis and that the proposed continuous qZS IMC is a promising topology. [ABSTRACT FROM PUBLISHER]