Ascom Energy Systems Ag

Wilhelm Korb

Johann W Kolar

The invention relates to an apparatus for initial charging of the output capacitors of a three-phase three-point pulsed rectifier system. According to the invention, a thyristor is arranged in each phase between the input terminal and is connected in the current flow direction to the anode of the freewheeling diode, and an initial charging path is connected in parallel with this thyristor. The circuit for actuating the thyristor is activated after completion of the initial charging; the reference voltage is applied to the negative input of the comparator. When the potential profile which is present at the tap of the voltage divider at the input of the bridge path rises, the voltage at the positive comparator input slightly before the zero crossing of the mains voltage to positive values exceeds the reference voltage, thus initiating switching of the comparator output and/or actuation of the thyristor and, after the mean bridge branch input potential passes through zero, the actuation of the thyristor is suppressed once again. The thyristor is thus triggered only within that mains voltage half-cycle in which it is required for carrying the mains phase current.

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Möhnesee, Germany

Wilhelm Korb