US Patent 6930899 N-point-converter circuit

An n-point-converter circuit with two series-connected power converter valves, each having (n−1) turn-off semiconductor switches, is disclosed. The converter circuit has a voltage intermediate circuit with (n−1) electrically series-connected capacitors. The voltage intermediate circuit is connected in parallel to DC-side terminals of the series-connected power converter valves. At least one AC-side terminal can be connected to one or more of the n potentials of the voltage intermediate circuit by means of (n−2) cross arms, each of which includes at least (n−3) turn-off semiconductor switches. The multipoint converter is easy to implement, has an improved output voltage quality, and possesses an emergency running feature.