基于直流侧无源电压谐波注入法的串联型24脉波整流器

In order to suppress the input current harmonics of multi-pulse rectifier, this paper proposes a voltage harmonic injection method at DC side for series-connected 12-pulse rectifier. The proposed method uses harmonic injection circuit to generate voltage harmonic, which has six times the supply frequency, so that the waveform of the input current is approximately sinusoidal. With the help of the switching function method, the formation process of the 24 step wave input voltage of isolation transformer is analyzed. The optimum turn ratio of injection transformer is designed based on the lowest THD of the input voltage of isolation transformer. Simulation and experimental results show that, after using the harmonic injection circuit, the input power factor of the rectifier is increased from 97.43% to 98.94%, thus the power quality has been improved significantly, the input voltage of isolation transformer is changed from 12 step wave to 24 step wave, its THD drops from 9.74% to 3.34%, and the THD of input current drops from 7.62% to 2.65%, the harmonic suppression performance of the rectifier has been significantly improved.