Normal Diode bridge or Thyristor based rectifier systems results poor power factor and higher current harmonic injection to the input mains.

IGBT based rectifier systems can have power factor better than 0.9 or close to unity.

Also current harmonic injection can be limited to 5% so as to maintain the requirement of IEEE-519.

Transformer losses are minimum hence reduction of transformer KVA rating which is around 110% of required KW output; much lesser than the same for thyristorized systems which is around 150% of required KW output