A Study on Output Voltage of a Three-phase Inverter using LMI-based Robust Control

This thesis describes a method of robust control to determine controller gain. The robust control techniques applied for three-phase dc-ac inverter with an output LC filter. The control law, which employs state feedback and integration of the tracking error, and described in a synchronous 𝑑𝑞 frame and designed approach in discrete-time state space. The gains of controller determine by a linear matrix inequality (LMI)-based optimization. In addition, the implemented of switching states, IGBT are use sine pules width modulation (SPWM) technique. The uncertainties of the system express as the possible ranges of the capacitor and inductor values. The simulation test on resistive load, RL load, and nonlinear load on the output three-phase inverter are used. In order to verify the robustness of the proposed method to parameter variations, the LC filter is change under the same setting of nominal control gains. In all these works, a MATLAB, Microsoft Visual Studio, and PSIM simulation is conducted to verify the control algorithms. Finally, by using robust method for three-phase inverter with an output LC filter it has a good performance with output response, stability, robustness, and low total harmonic distortion (THD). Especially, the simulation result in this paper is presented robust control method has a high efficiency and good performance than PI control method.