Three-level active neutral point clamped zero voltage switching converter

摘要

A main circuit of a three-level active neutral point clamped voltage source converter having a pair of additional main switches provides two paths between an output node and a neutral point in which one of the paths involves only switches of an inner pair of switches that are operated at a high frequency. An auxiliary circuit operating at a high frequency for only a brief period during each high frequency switching cycle selects the path involving only the inner switches and provides operation with zero voltage switching and avoids reverse recovery of diodes connected antiparallel with the main and additional main switches. Accordingly, turn-on switching losses in the main switches is avoided and the voltage source converter can be operated at increased frequency to allow reduction in size of magnetic components and full potential power transfer to be achieved.

主权项

1. A three-level active neutral point clamped zero voltage switching power converter comprising a main circuit and an auxiliary circuit,
said main circuit comprising
a plurality of main switches connected in series, said plurality of switches comprising at least an inner pair of switches and an outer pair of switches, each of said switches having a diode connected anti-parallel with a respective one of said switches wherein said inner pair of switches are connected at a first node, and a clamping circuit including first and second additional main switches connected in parallel with said inner pair of switches, each of said first and second additional main switches having a diode connected anti-parallel with a respective one of said first and second additional main switches, wherein said first and second additional main switches are connected at a neutral point such that two paths are provided between said first node and said neutral point under conditions of either positive or negative current conditions at said first node, said auxiliary circuit comprising
a circuit including a resonant element for selecting between said two paths for each of said positive and negative current conditions,a pair of auxiliary switches connected in series and in parallel with said inner pair of switches, each of said auxiliary switches having a diode connected in parallel with a respective one of said auxiliary switches, said pair of auxiliary switches being connected at a second node,a pair of diodes connected in series, wherein diodes of said pair of diodes are connected at a third node, anda magnetic element comprising first and second windings magnetically coupled in opposition wherein first terminals of said first and second windings are connected together and to said first node and a second terminal of said first winding is connected to said second node and said second terminal of said second winding is connected to said third node.