High-performance predictive control of quasi-impedance source inverter

The quasi-Z-source inverter (qZSI) has attracted much attention for motor drives and renewable energy applications due to its capability to boost or buck in a single converter stage. However, this capability is associated with different challenges related to the closed-loop control of currents, control the dc capacitor voltage, produce three-phase ac output current with high dynamic performance, and obtain continuous and low ripple input current. This paper presents a predictive control strategy for a three-phase qZSI that fulfills these requirements without adding any additional layers of control loops. The proposed controller implements a discrete-time model of the qZSI to predict the future behavior of the circuit variables for each switching state, along with a set of multiobjective control variables all in one cost function. The quasi-impedance network and the ac load are considered together when designing the controller in order to obtain stability of the impedance network with a step change in the output reference. A detailed comparative investigation between the proposed controller and the conventional proportional-integral (PI) controller is presented to prove the superiority of the proposed method over the conventional control method. Simulation and experimental results are presented.