This paper presents novel nonlinear and linear control methods for output voltage control of a three-phase inverter. For implementation of these optimal controllers, the nonlinear and linear models of system including LC filter have been derived. Moreover, analysis of the system under the State-Dependent Riccati Equation (SDRE) and Linear Quadratic Tracking (LQT) as the nonlinear and linear optimal controllers has been done and comparison between performance of them is investigated in MATLAB.