Rectifier with energy return to mains - has matching transformer with input capacitors and monitors of voltage and zero crossing

摘要

Prevention of commutation short-circuits due to mains failure and elimination of switching off the supply are achieved with monitors sensing the zero crossing of the regeneration current with the supply provided by thyristors. In addition the instantaneous and effective values are sensed, while the input of the matching transformer features capacitors as energy storages. The actual value of the voltage is derived from a filter when the trigger pulse is obtained during the zero crossing for activating a one shot multivibrator switching over another multivibrator for deriving a wide pulse. This leaves the pulse within the required time slot for control of energy recovery.