A high voltage, high power (HVHP) neutral-point-clamped-flying-capacitor (NPCFC) converter comprising a series connection of first, second, third and fourth voltage sources, wherein the negative terminal of said first voltage source is connected to a negative DC terminal, the positive terminal of said first voltage source is connected to the negative terminal of said second voltage source, the positive terminal of said second voltage source is connected to a common neutral point, the negative terminal of said third voltage source is connected to said common neutral point, the positive terminal of said third voltage source is connected to the negative terminal of said fourth voltage source and the positive terminal of said fourth voltage source is connected to a positive DC terminal; first and second multi-level neutral-point-clamped-flying-capacitor (NPCFC) converter cells (92,94) stacked together by a first NPP converter cell being connected to a second NPP converter cell at an output mode, wherein the first NPP converter cell comprises a first switching transistor having a first terminal, and a second terminal connected directly to the output node, a first series connection of m, wherein m is equal or larger than 2, switching transistors connected between the positive DC terminal and the first terminal of said first switching transistor, and a first series connection of m bidirectional transistor switches connected between the negative terminal of said fourth voltage source and the first terminal of said first switching transistor, wherein a flying capacitor is connected between each connection point of two switching transistors of said first series connection of switching transistors and a corresponding connection point of two bidirectional transistor switches of said first series connection of bidirectional transistor switches; and the second NPP converter cell comprises a second switching transistor having a first terminal, and a second terminal connected directly to the output node, a second series connection of m, wherein m is equal or larger than 2, switching transistors connected between the negative DC terminal and the first terminal of said second switching transistor, and a second series connection of m bidirectional transistor switches connected between the positive terminal of said first voltage source and the first terminal of said second switching transistor, wherein a flying capacitor is connected between each connection point of two switching transistors of said second series connection of switching transistors and a corresponding connection point of two bidirectional transistor switches of said second series connection of bidirectional transistor switches; a plurality of clamping diodes (96,98) arranged in series such that a first end of the plurality of clamping diodes (96,98) is directly connected to the first terminal of the first switching transistor and a second end of the plurality of diodes (96,98) opposite the first end is directly connected to the first terminal of the second switching transistor, wherein each multi-level NPP converter cell (92,94) is connected to said common neutral point by a midpoint of the series connection of the plurality of clamping diodes (69,98).