Modeling and control of the improved Trans-Z-Source Inverter

An improved Trans-Z-Source Inverter (TZSI) shows advantages due to its high boost capability, which can overcome the mutual limitation between the shoot-through duty ratio and modulation index. This paper derives the state equations through analyzing the equivalent circuit of the TZSI, and then achieves the transfer functions through small signal analysis in detail. Based on the mathematical model, a two-stage close-loop control is presented, where a constant peak dc-link voltage control is proposed to overcome the drawback of conventional constant capacitor voltage control. Simulation and experiments were carried out and good results were achieved, which verified the effectiveness of the constructed model and the proposed control approach.