Current-injection-based 12-pulse rectifier using a single three-phase diode bridge

A three-phase rectifier that applies current injection to reduce the input current total harmonic distortion (THD) is proposed. The rectifier injects rectangular current, which results in the waveforms of the input currents the same as in the case of 12-pulse rectifiers, with the THD equal to 15.22%. The current injection system applies a voltage-loaded resistance emulator. To simplify the rectifier analysis, an equivalent circuit of the rectifier is derived, which significantly reduces the number of nonlinear elements. Analytical optimisation of the resistance emulator transformer turns ratio is performed for the case when the losses in the current injection system can be neglected. Influence of the losses in the current injection system is analysed numerically, and it is shown that they considerably affect the rectifier performance and design. Numerical optimisation of the resistance emulator turns ratio in the presence of losses is performed. Analytical results are experimentally verified on a rectifier with a rated power of 3 kW.