Input current harmonic reduction in high power AC/DC rectifiers

Specifications related to the maximum allowable amplitude of individual current harmonics generated by power converters are becoming more stringent. The authors show that if the maximum allowable amplitude is 5% or below, the widely used approach in high-power AC/DC conversion, using the typical diode and phase-controlled thyristor rectifier and harmonic filters, may not be the most economical. Therefore, they propose as an alternative a PWM (pulse-width-modulated) GTO (gate turn-off thyristor) rectifier with selective harmonic elimination of the fifth and seventh components. Additional filtering requirements, implemented through low pass filters are discussed