Robust Control of a Three-phase Inverter under Unbalanced Load

his thesis describes a method of Linear Matrix Inequality (LMI) to determine robust gain for three-phase inverter under unbalanced loads. 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 and Positive sequence and Negative sequence make voltage output balance load. The gains of controller determine by a linear matrix inequality (LMI)-based optimization. In addition, the implemented of switching states, IGBT are 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 filterit has a good performance with output response, stability, robustness, and low total harmonic distortion (THD). Especially, the simulation result in this thesis is presented robust control with negative sequence compensator in comparison with non-negative sequence robust control.