Bidirectional AC-DC converter with multilevel power factor correction

An AC power converter having a number of levels N, wherein N is at least 3, comprising:

• a set of switches in series, comprising (N×2) switches, having a center tap and a pair of taps after the first and before the last switches;
• (N−1) capacitors in series, the (N−1) capacitors in series being in parallel with the set of switches in series;
• and
• a clamping network communicating with nodes between the set of switches, configured to establish monotonically increasing voltages at sequential nodes between the capacitors in series,
• wherein the switches, clamping network and capacitors are configured to generate, from a first AC waveform at the center tap and a controlled sequence of switching signals, a DC voltage across the capacitors in series, and a second AC waveform from the pair of taps.

A method of power conversion, comprising:

• providing a multilevel stage of an AC power converter having at least three levels, comprising:
• a set of switches in series, comprising two switches per level, having a center tap and a pair of taps before the first and last switches;
• a set of capacitors in series, the set of capacitors in series being in parallel with the set of switches in series;
• a clamping network, interconnecting nodes between switches of the set of switches and nodes between capacitors of the set of capacitors, configured to establish different operating voltages at nodes between the set of capacitors;
• interfacing the center tap with a first AC system;
• interfacing the pair of taps with a second AC system, wherein an AC waveform of the first system is different from an AC waveform of the second AC system;
• and
• automatically controlling a sequence of switching signals for the set of switches to generate a DC voltage across the set of switches in series and the capacitors in series, and to transfer power between the first AC system and the second AC system.