Аңдатпа
The article considers the problem of forming the output voltage of a multilevel inverter in order to reduce harmonic distortion and improve power quality. The object of research is the approximation of a sinusoidal voltage by a stepped waveform. A method for determining inverter switching parameters based on the integral equal-area criterion is proposed. According to the proposed approach, the areas between the reference sinusoidal voltage and the stepped output voltage are equal within each switching interval, which ensures a more accurate approximation of the sinusoidal waveform. Analytical expressions for calculating voltage levels and switching instants for a specified number of inverter levels are derived. Switching parameters are determined for 5-, 7-, 9-, 11-, and 13-level inverters. The effectiveness of the proposed method is investigated by computer simulation in the MATLAB Simulink environment using FFT analysis of the output voltage spectrum. The influence of voltage levels and switching instants on the harmonic composition of the inverter output voltage is analyzed. The simulation results demonstrate that the total harmonic distortion decreases from 17.84% for the 5-level inverter to 6.01% for the 13-level inverter without the use of output filters. It is shown that increasing the number of voltage levels leads not only to THD reduction but also to the shift of residual harmonics toward the high-frequency region, simplifying subsequent filtering. A distinctive feature of the proposed method is the equality of the RMS values of the stepped and reference sinusoidal voltages. The proposed method can be used in the design of multilevel inverters requiring high output-voltage quality under limited switching frequency conditions.