Application of controlled flywheeling to the recovery bridge of a static Kramer drive

The input and output conditions in a naturally commutated thyristor-bridge inverter can be improved in most respects by adopting the controlled flywheeling technique. Maximum advantage is gained at low DC side voltages, and this makes the technique especially suitable for use with the static Kramer drive. Substantial improvements in reactive-power consumption, system efficiency and power factor become possible, particularly with pump-type loads. Supply-current imbalance, inevitable with single-phase recovery, can also be markedly reduced.