A new type of three-phase quasi-Z-source indirect matrix converter (QZS-IMC) is proposed in this paper. It uses a unique impedance network for achieving voltage-boost capability and making the input current in continuous conduction mode (CCM) to eliminate the input filter. The complete modulation strategy is proposed to operate the QZS-IMC. Meanwhile, a closed-loop DC-link peak voltage control strategy is proposed, and the DC-link peak voltage is estimated by measuring both the input and capacitor voltages. With this proposed technique, a high-performance output voltage control can be achieved with an excellent transient performance even if there are input voltage and load current variations. The controller is designed by using the small-signal model. Vector control scheme of the induction motor is combined with the QZS-IMC to achieve the motor drive. A QZS-IMC prototype is built in laboratory, and experimental results verify the operating principle and theoretical analysis of the proposed converter. The simulation tests of QZS-IMC based inductor motor drive are carried out to validate the proposed converter's application in motor drive.

SUMMARYQuasi-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.

A new space vector modulation (SVM) strategy is proposed for quasi-Z-source indirect matrix converter (QZS-IMC) to reduce common-mode voltage and to ensure a high voltage transfer ratio. QZS-IMC's common-mode voltage is analyzed, and the subdivided sectors are employed to rearrange switching sequence in the inverter stage, which can reduce common-mode voltage and power loss. The proposed modulation method mitigates the peak value of common-mode voltage by 42% and reduces the switching losses in the inverter stage. Experimental results verify the proposed method.