Patent ID: 6747881
Filing Date: 2004-06-08
Classification: H02M

Abstract:
A Frequency converter for converting energy flow from a three-phase network to a three-phase consumer supply at variable frequency, current and voltage outputs, comprising:at least one cell per phase of said three-phase consumer supply; all of said cells being identical; each of said cells includes: a diode input rectifier circuit; an active harmonic filter; an intermediate-circuit capacitance; a three-point DC/AC converter on an output side; said DC/AC converter comprising NPC diodes; said active harmonic filter includes at least two input inductors, at least two series-connected controllable switches and at least two diodes for receiving sinusoidal line current input and for generating a controllable intermediate-circuit voltage for said intermediate-circuit capacitance; said intermediate-circuit capacitance has two series-connected capacitor groups; and a neutral lead of a star circuit formed from said secondary windings is connected to a central point of said series-connected controllable switches, a center point of said series-connected capacitor groups and said NPC diodes of said three-point DC/AC converter.