A five-level reinjection scheme for high pulse-voltage source conversion

A new multi-level VSC is proposed with highly reduced voltage and current harmonic distortion, without the need for filters or PWM. The multi-pulse waveform is achieved by means of two auxiliary reinjection bridges, which produce voltage pulses at six times the fundamental frequency. The proposed scheme simplifies the switching circuitry of present schemes for similar levels of waveform distortion and can operate in four quadrants without capacitor balancing problems.