Current Stress Analysis of Passive Devices and Switching Devices of Quasi-Z-Source Inverters

To calculate the current stress of each device of the three-phase quasi Z-source inverter, this paper proposes to calculate the current stress of all devices of the Quasi-Z-source inverter model by mathematical analytic Cauchy–Schwarz inequality. Because the quasi Z-source inverter is nontraditional, the current of the device consists of two components: high frequency and low frequency, which makes the calculation of current stress relatively complex. This paper proposes to separate these two components and calculate their current stresses. The average and effective values of current in Quasi-Z source network devices and inverter bridge switching devices depend on the load current and through current. Based on this, the current stress and capacitance-voltage stress in the Z source impedance network and quasi Z-source impedance network are compared. A system simulation model is built in the MATLAB/Simulink, and the results verify the feasibility of the proposed theoretical analysis.