Common mode voltage reduction of quasi-Z source indirect matrix converter

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.