This paper proposed a single-phase three-level inverter that has constant voltage constant frequency (CVCF) operation system. Harmonic analyses with linear and nonlinear loads have been realized to measure the robustness of the proposed technique. It has been shown that the proposed technique has 15% less harmonic distortion and better performance than the conventional inverter for the same load and switching frequency. The constant voltage and frequency used feedback PI control blocks. The system stability was analyzed with the help of Bode curves. The proposed control schema is verified by MATLAB/Simulink results and the results prove that the proposed method is able to achieve not only low harmonic distortion but constant voltage and constant frequency for various operating conditions.