Sliding mode control of the nonminimum phase grid-connected Z-source inverter

Abstract

Summary It is well known that linear controllers are designed by using small-signal approximation around a certain operating point that cannot guarantee the stability of a nonlinear system in a wide operating range. In this paper, a hyperplane sliding mode controller (SMC) is proposed for voltage regulation across the direct current side capacitor in a single-phase grid-connected Z-source inverter. Considering nonminimum phase characteristics of the converter, capacitor voltage is indirectly controlled by regulation of current through the DC-side inductor. Moreover, another SMC is designed to control AC-side output current. The SMCs are developed by using an exact nonlinear state-space averaged model of Z-source inverter, and hence, stability and robustness of the system are maintained along a wide range of operation. It is shown that the proposed SMCs have zero steady-state error and acceptable dynamic response. Some simulations are performed in MATLAB/Simulink toolbox to verify the effectiveness and accuracy of the developed controllers. Practical response of the designed grid-connected Z-source inverter is demonstrated by using a TMS320F28335 digital signal processor in comparison with conventional linear controllers.