Power converter

A power converter, comprising:

• a DC voltage source;
• a plurality of neutral point clamped inverters connected to said DC voltage source;
• means for generating an original voltage reference and a plurality of voltage references with a phase difference therebetween;
• said voltage references including a positive voltage reference produced by shifting said original voltage reference by a positive DC bias value in a positive mode and a negative voltage reference produced by shifting said original voltage reference by a negative DC bias value in a negative mode, said phase difference being based on a number of said inverters;
• means for generating polarity switching signals for switching between said positive mode and said negative mode at a predetermined cycle rate;
• and
• gate signal generating means connected to receive said plurality of said voltage references for generating a plurality of gate signals, the gate signals being respectively supplied to control said inverters in supplying AC power to a load.

A power converter for converting DC power from a DC source to AC power to supply an AC load, the power converter comprising:

• plural neutral point inverters connected between the DC source and the AC load;
• means for generating a first voltage reference;
• means for generating a polarity signal;
• means for generating a second voltage reference based on said first voltage reference and said polarity signal;
• and
• comparing means for respectively comparing an amplitude of said first and second voltage reference to an amplitude of a carrier signal and for generating gate signals for output to control said inverters based on the comparison result.