Electro-thermal Analysis of the Coupled Inductor for Quasi-Z Source Inverters

The quasi-Z Source Inverter (qZSI) has a unique impedance network. The inductor is a significant component of the impedance network and occupies a large proportion of the qZSI. The inductor current ripple will cause the inductor core magnetize repeatedly, resulting in increased core loss. Meanwhile, high DC currents will lead to high winding loss and cause temperature rise rapidly. In this paper, the sources of inductor power losses and temperature rise in a quasi-Z source impedance network are analyzed, and quantitative calculation formulas are derived. A multi-physics joint simulation model is constructed based on ANSYS finite element software, and a qZSI prototype is established to perform comparison of the impact on inductor power losses under various modulation strategies. Simulation and experimental results conformed the theoretical analysis.