Patent ID: 6700806
Filing Date: 2004-03-02
Classification: H02M

Abstract:
An apparatus for conversion of a three-phase voltage system to a DC voltage which is supported by an output capacitor, the negative pole of the output capacitor being connected to a negative output voltage rail, the apparatus comprising:a) a star circuit including filter capacitors, the star circuit branching off from phase input terminals; b) a controllable three-phase bridge with phase arms having an identical structure and each phase arm being formed by: an electronic control switch, which can be turned off and which governs the conductance state of the phase arm a positive input diode connected on a cathode side to the respective phase input terminal; a positive output diode to whose anode an emitter of the electronic control switch and an anode of the positive input diode are connected; a negative output diode connected on a cathode side to a collector of the electronic control switch and connected on a anode side to the negative output rail, and a negative input diode branching off from the respective phase input terminal and connected on a cathode side to the collector of the control switch; c) at a positive output of the bridge circuit a current-stabilizing inductance is connected to a cathode side of the positive output diode of the three-phase bridge; d) a step-up controller diode oriented in the direction of the output, is connected between a positive output capacitor terminal and a second terminal of the inductance, facing away from the three-phase bridge; and e) a step-up controller transistor branching off from an anode of the step-up controller diode, the step-up controller transistor being connected to the negative output voltage rail and remaining in the switched-off state in order to form an output voltage from the system which is less than the mean value of the maximum output voltage from the bridge circuit, wherein the three-phase bridge is being fully driven, via an appropriate duty ratio of the step-up controller transistor, in order to form a voltage which is above the mean value of the maximum output voltage.