Abstract

In single-phase bipolar SPWM inverter circuit, the output voltage contains high content of harmonic components. To solve this problem, we build a model of output voltage in single-phase SPWM bipolar inverter based on SPWM theory and Fourier series theory. Through theoretical analysis, calculation and plotting, we work out the distribution of harmonic in output voltage, investigate the relationship between amplitude modulation (AM) depth and harmonic components and finally determine a proper amplitude modulation depth to efficiently reduce harmonic components. To further reduce harmonic components of output voltage, we use LC low-pass filter. Then, based on the mathematical model of the filter and the distribution law of harmonics, we establish a mixed integer nonlinear programming to fully suppress harmonics and reduce switching losses. After searching for two times based on genetic algorithm, we work out the best frequency-modulation ratio and LC low-pass filter parameter. Finally in simulation, total harmonic distortion is reduced from 213.47 percent to 0.16 percent after harmonic suppression strategy implemented. The result has proved the effectiveness of the harmonic suppression strategy we applied, which can be used as a reference for output voltage harmonic elimination in single-phase SPWM inverter.

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