Power apparatus applied in solid state transformer structure and three-phase power system having the same

A power system, the power system comprising three power apparatus assemblies, and each power apparatus assembly coupled to one phase of a three-phase AC power source, and the each power apparatus assembly comprising:

• a plurality n of power apparatuses, wherein n is a positive integer and is greater than 1, each of the plurality n of power apparatuses comprising:
• an AC-to-DC conversion unit, wherein the plurality n of AC-to-DC conversion units of the plurality n of power apparatuses are connected in series to receive one phase voltage of the three-phase AC power source, and controlled in an interleaved phase-shift manner,
• a first DC bus, coupled to the AC-to-DC conversion unit,
• a plurality m of DC-to-DC conversion units, wherein m is a positive integer and is greater than 1, the plurality m of DC-to-DC conversion units coupled to the first DC bus, and configured to convert a voltage on the first DC bus into a plurality m of DC voltages, and
• at least one second DC bus, coupled to the plurality m of DC-to-DC conversion units, and configured to receive the plurality m of DC voltages, wherein a number of the at least one second DC bus is between 1 and m,
• wherein the plurality m of DC-to-DC conversion units of each power apparatus are individually connected to a separate corresponding AC-to-DC conversion unit in the power apparatus,
• wherein the at least one second DC bus of the plurality m of DC-to-DC conversion units of the plurality n of power apparatuses of the three power apparatus assemblies are correspondingly connected in parallel.