A variable switching point predictive current control strategy for quasi-Z-source inverters

This paper presents a variable switching point predictive current control (VSP2CC) for the quasi-Z-source inverter (qZSI). The proposed VSP2CC aims to remove the output current error on the ac side as well as the inductor current and capacitor voltage errors of the quasi-Z-source network on the dc side of the converter. Unlike the previously presented direct model predictive control (MPC) strategies for the qZSI, the proposed control scheme can directly apply the switching signals not only at the discrete time instants, but at any time instant within the sampling interval. Consequently, the shoot-through state can be applied for a shorter time than the sampling interval, resulting in lower output and inductor currents ripples. Experimental results based on an FPGA are provided to verify the effectiveness of the introduced control method. As it is shown, the proposed method leads to lower inductor current ripples and less output current total harmonic distortion (THD) when compared with the conventional direct MPC.