A current injection based twelve-pulse rectifier

A three-phase twelve-pulse rectifier that applies current injection to reduce the input current total harmonic distortion (THD) is proposed. In absence of losses, the input currents are the same as in conventional twelve-pulse rectifiers, with the THD equal to 15.22%. The current injection system applies a voltage-loaded resistance emulator, consisting of a transformer and two diodes. Piecewise linear model of the rectifier, suitable for numerical simulation, is developed. Optimization of the resistance emulator transformer turns ratio is performed. It is shown that losses in the current injection system considerably affect the input current THD and volt-ampere ratings of applied magnetic components. The results are experimentally verified on a rectifier with the rated power of 3 kW.