A DSP-Based Dual-Loop Peak DC-link Voltage Control Strategy of the Z-Source Inverter

This paper proposes a direct dual-loop peak dc-link voltage control strategy, with outer voltage loop and inner current loop, of the Z-source inverter (ZSI). The peak dc-link 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 including input voltage and load current variations with minimized nonminimum phase characteristics caused by the right half-plane zero in the control to peak dc-link voltage transfer function. Both controllers are designed based on a third-order small-signal model of the ZSI using the direct digital control method. The performance of the proposed control strategy is verified by simulation and experimental results of a 30-kW ZSI prototype.