Method and apparatus for medium-voltage electronic power conversion

1. A power converter comprising:

a multiple-winding transformer, the multiple-winding transformer providing an electromagnetic link between an input side and an output side of the power converter, the input side being arranged into a plurality of input phase legs, the output side being arranged into a plurality of output phase legs;

an inductor arranged on at least one of the input side or the output side of the power converter in parallel with the multiple-winding transformer;

at least one first capacitor arranged on the input side of the power converter in parallel with the multiple-winding transformer and the inductor;

at least one second capacitor arranged on the output side of the power converter in parallel with the multiple-winding transformer, the inductor, the at least one first capacitor, and the at least one second capacitor defining a parallel resonance tank;

each input phase leg of the plurality of input phase legs comprising:

a first pair of bidirectional blocking and conducting switching devices coupled to a third capacitor and a first auxiliary transformer winding;

a second pair of bidirectional blocking and conducting switching devices coupled to the first pair of bidirectional blocking and conducting switching devices, a fourth capacitor, and a second auxiliary transformer winding; and

a third pair of bidirectional blocking and conducting switching devices coupled to the second pair of bidirectional blocking and conducting switching devices, the at least one first capacitor, the inductor, and the multiple-winding transformer

each output phase leg of the plurality of output phase legs comprising:

a fourth pair of blocking and conducting switching devices coupled to a fifth capacitor and a third auxiliary transformer winding; and

a fifth pair of block and conducting switching devices coupled to the fourth pair of blocking and conducting switching devices, the at least one second capacitor, and the multiple-winding transformer.

2. The power converter of claim 1 , wherein the first pair of bidirectional blocking and conducting switching devices, the second pair of bidirectional blocking and conducting switching devices, and the third pair of bidirectional blocking and conducting switching devices comprise a semiconductor switch.

3. The power converter of claim 1 , wherein the input side and the output side are bi-directional.

4. The power converter of claim 1 , wherein the multiple-winding transformer provides galvanic isolation between the input side and the output side.

5. The power converter of claim 1 , wherein one input phase leg is associated with one input phase of a plurality of input phases.

6. The power converter of claim 1 , wherein one output phase leg is associated with one output phase of a plurality of output phases.

7. A method of power conversion, the method comprising:

charging a parallel resonance tank with current from a first pair of input phase legs, each phase leg of the first pair of input phase legs comprising:

a first pair of bidirectional blocking and conducting switching devices coupled to a third capacitor and a first auxiliary transformer winding;

a second pair of bidirectional blocking and conducting switching devices coupled to the first pair of bidirectional blocking and conducting switching devices, a fourth capacitor, and a second auxiliary transformer winding; and

a third pair of bidirectional blocking and conducting switching devices coupled to the second pair of bidirectional blocking and conducting switching devices, the at least one first capacitor, and a multiple-winding transformer;

resonating the parallel resonance tank as a voltage of the parallel resonance tank decreases in magnitude;

charging the parallel resonance tank with current from a second pair of input phase legs, each phase leg of the second pair of input phase legs comprising:

the first pair of bidirectional blocking and conducting switching devices coupled to the third capacitor and the first auxiliary transformer winding;

the second pair of bidirectional blocking and conducting switching devices coupled to the first pair of bidirectional blocking and conducting switching devices, the fourth capacitor, and the second auxiliary transformer winding; and

the third pair of bidirectional blocking and conducting switching devices coupled to the second pair of bidirectional blocking and conducting switching devices, the at least one first capacitor, and the multiple-winding transformer;

resonating the parallel resonance tank as the voltage of the parallel resonance tank changes polarity;

discharging the parallel resonance tank on a first pair of output phase legs, each phase leg of the first pair of output phase legs comprising:

a fourth pair of blocking and conducting switching devices coupled to a fifth capacitor and a third auxiliary transformer winding; and

a fifth pair of block and conducting switching devices coupled to the fourth pair of blocking and conducting switching devices, the at least one second capacitor, and the multiple-winding transformer;

resonating the parallel resonance tank as link voltage increases in magnitude; and

discharging the parallel resonance tank on a second pair of output phase legs, each phase leg of the second pair of output phase legs comprising:

the fourth pair of blocking and conducting switching devices coupled to the fifth capacitor and the third auxiliary transformer winding; and

the fifth pair of block and conducting switching devices coupled to the fourth pair of blocking and conducting switching devices, the at least one second capacitor, and the multiple-winding transformer.

8. The method of claim 7 , wherein:

the first input phase pair has a greater current reference difference than any other phase pair;

a current reference difference of the second input phase pair is less than the current reference difference of the first input phase pair; and

a current reference difference of the first output phase pair is smaller than a current reference difference of the second output phase pair.