A Modified Lyapunov-Function Based Control Scheme for Two-Leg Three-Level T-Type Grid-Tied Inverter with LCL Filter

Abstract

In this study, a modified Lyapunov-function based control scheme is proposed for two-leg three-phase three-level T-type grid-tied inverter with LCL filter. Proposed inverter topology has only two legs and thus it provides 1/3 reduction on the total switch count. The conventional Lyapunov-function based control is modified by adding an additional capacitor voltage feedback (CVFB) loop. This additional feedback provides better suppression of LCL filter resonance and improves the dynamic response of the system. The performance of modified Lyapunov-function based control scheme and operation of the proposed inverter are validated with MATLAB/Simulink environment. Simulation results show that the proposed inverter together with the control scheme can generate balanced three-phase voltages and currents with only two legs. Furthermore, capacitor feedback loop significantly improves the transient response of the system.