Harmonic Reduction by Voltage Reinjection Strategy in 12-Pulse VSI for High Power Applications

Voltage reinjection is a practical solution to improve the quality of the output voltage in the high power series inverters. In this paper, based on the voltage reinjection theory, a novel reinjection structure in the two series DC/AC converters is proposed to increase the output voltage levels. The proposed voltage reinjection structure generates a nine voltage levels waveform to inject into the main DC-link voltage of the 12-pulse VSI. The presented configuration increases the number of pulses to 108 and reduces the output voltage THD to 1.95% without any conventional filters or modulations. Also, the proposed configuration by using less number of the semiconductor elements than another structures has better output voltage quality, and the losses and stress of the reinjection switches are decreased in high power application. The simulation results approve the performance of the proposed configuration to improve the voltage harmonic condition of the two series VSIs.