Stepped-waveform power converter utilizing a summing transformer and a single inverter bridge

A summing transformer, comprising:

• first and second sets of primary windings each having a plurality of terminals wherein the windings of the first set of primary windings are connected in a phase-to-neutral configuration and the windings of the second set of primary windings are connected in a phase-to-phase configuration and wherein the terminals of the first set of primary windings are coupled to corresponding terminals of the second set of primary windings and to corresponding phase inputs;
• first and second sets of secondary windings wherein each winding of the first set of secondary windings is inductively coupled to an associated winding of the first set of primary windings and each winding of the second set of secondary windings is inductively coupled to an associated winding of the second set of primary windings wherein the windings of the first set of secondary windings are coupled to phase outputs;
• means for interconnecting the first and second sets of secondary windings;
• and
• wherein the interconnecting means comprises a neutral forming transformer having phase windings coupled between the first and second sets of secondary windings.

A power converter, comprising:

• an inverter bridge having a plurality of phase outputs;
• a summing transformer having first and second sets of primary windings each having a plurality of terminals coupled to the inverter bridge wherein the windings of the first set of primary windings are connected in a phase-to-neutral configuration and the windings of the second set of primary windings are connected in a phase-to-phase configuration, the summing transformer further including first and second sets of secondary windings wherein each winding of the first set of secondary windings is inductively coupled to an associated winding of the first set of primary windings and each winding of the second set of primary windings is inductively coupled to an associated winding of the second set of primary windings and wherein each winding of the first set of secondary windings includes an end connected to a phase output;
• a neutral forming transformer coupled to the windings of the first and second sets of secondary windings;
• and
• means for operating the inverter bridge such that a rectangular phase output waveform is produced at each phase output.

A power converter, comprising:

• a three-phase inverter bridge;
• a summing transformer having first and second sets of three-phase primary windings, each set having three terminals coupled to the inverter bridge wherein the primary windings of the first set are connected in a wye configuration and the primary windings of the second set are connected in a delta configuration and wherein each terminal of the first set of primary windings is coupled to a corresponding terminal of the second set of secondary windings, the summing transformer further including first and second sets of three-phase secondary windings wherein each winding of the first set of secondary windings is inductively coupled to an associated winding of the first set of primary windings and each winding of the second set of primary windings is inductively coupled to an associated winding of the second set of primary windings and wherein each winding of the first set of secondary windings includes a first end coupled to a phase output;
• a neutral forming transformer coupled to second ends of the windings of the first set of secondary windings and the windings of the second set of secondary windings;
• and
• means for operating the inverter bridge such that a stepped phase output waveform is produced at each phase output.