Sliding Mode Controlled Three-Phase Two-Leg Grid-Connected T-Type qZSI

Abstract

In this paper, a sliding mode control (SMC) strategy is proposed for a three-phase two-leg grid-connected T-type quasi-Z-source inverter with LCL filter. The large dc input voltage requirement of three-phase two-leg inverter has been resolved by employing a quasi-Z-source network. The proposed SMC can achieve the control of both dc-and ac-side variables. Furthermore, the proposed SMC does not require additional active damping to remove the resonance existing due the LCL filter. The chattering is eliminated by smoothing the sliding surface functions through boundary layers. The validity of the proposed SMC strategy is investigated by computer simulations. It is shown that the dc capacitor voltages are regulated and grid currents track their references.