Harmonics suppression in a power delivery device

1. A power delivery system, comprising:

two or more rectifiers electrically coupled to an AC power source and configured to generate a direct current;

a transformer coupled to the AC power source and comprising two or more output windings to convert current from the AC power source to a multiphase AC signal, wherein each of the two or more output windings is coupled to an input of one of the two or more rectifiers, and wherein phases of the multiphase AC signal are out of phase with one another by a specified displacement angle; and

two or more inverters configured to receive the direct current and generate an alternating current waveform for powering a load;

wherein the two or more rectifiers and the two or more inverters are coupled in series with each other through an inductor; and further comprising

a DC bus comprising an upper rail and a lower rail, wherein the two or more rectifiers are coupled in series with each other between the upper rail and the lower rail and the two or more inverters are coupled in series with each other between the upper rail and the lower rail;

wherein a positive output terminal of one of the rectifiers is directly coupled to a negative output terminal of a different one of the rectifiers; and wherein

a positive input terminal of one of the inverters is directly coupled to a negative input terminal of a different one of the inverters.

2. The power delivery system of claim 1 , wherein the two or more inverters are cross-linked with the two or more rectifiers.

3. The power delivery system of claim 2 , wherein:

each of the rectifiers comprises a positive output terminal and a negative output terminal and each of the inverters comprises a positive input terminal and a negative input terminal; and

each of the positive output terminals of the rectifiers is coupled to the positive input terminal of a different one of the inverters and each of the negative output terminals is coupled to a negative input terminal of a different one of the inverters.

4. The power delivery system of claim 1 , wherein the load is a multiphase motor comprising a number of windings and each inverter comprises an output terminal coupled to a respective set of the number of windings.

5. The power delivery system of claim 4 , wherein:

the two or more rectifiers and the two or more inverters are grouped into pairs, each pair comprising one of the rectifiers and one of the inverters; and

outputs of the pairs are out of phase by a specified displacement angle that depends on the number of windings of the multiphase motor; and wherein the specified displacement angle associated with the outputs of the pairs is the same as the displacement angle associated with the multiphase AC signal.

6. A system comprising:

an AC power source;

a multiphase motor; and

a power delivery device comprising:

two or more rectifiers electrically coupled to the AC power source and configured to generate a direct current;

a transformer coupled to the AC power source, wherein the transformer comprises two or more output windings, and wherein each of the two or more output windings is coupled to an input of one of the two or more rectifiers, and further wherein phases of the multiphase AC signal are out of phase with one another by a specified displacement angle; and

two or more inverters configured to receive the direct current and generate an AC waveform for powering the multiphase motor;

wherein the two or more rectifiers and the two or more inverters are coupled in series with each other through an inductor;

wherein each of the rectifiers comprises a positive output terminal and a negative output terminal and each of the inverters comprises a positive input terminal and a negative input terminal; and

wherein each of the positive output terminals of the rectifiers is coupled to the positive input terminal of a different one of the inverters and each of the negative output terminals is coupled to a negative input terminal of a different one of the inverters.

7. The system of claim 6 , comprising a DC bus comprising an upper rail and a lower rail, wherein the two or more rectifiers are coupled in series with each other between the upper rail and the lower rail and the two or more inverters are coupled in series with each other between the upper rail and the lower rail.

8. The system of claim 6 , wherein:

a positive output terminal of one of the rectifiers is directly coupled to a negative output terminal of a different one of the rectifiers; and

a positive input terminal of one of the inverters is directly coupled to a negative input terminal of a different one of the inverters.

9. The system of claim 6 , wherein the two or more inverters are cross-linked with the two or more rectifiers.

10. The system of claim 6 , wherein the multiphase motor comprises a plurality of windings and each inverter comprises an output terminal coupled to a respective one of the windings.

11. The system of claim 6 , wherein:

the two or more rectifiers and the two or more inverters are grouped into pairs, each pair comprising one of the rectifiers and one of the inverters; and

outputs of the pairs are out of phase by a specified displacement angle that depends on the number of windings of the multiphase motor, and wherein the specified displacement angle associated with the outputs of the pairs is the same as the specified displacement angle associated with the multiphase AC signal.

12. The system of claim 6 , comprising a compressor mechanically coupled to and driven by the multiphase motor.

13. The system of claim 6 , wherein the AC power source comprises a gas turbine generator or an AC power line.

14. A method of configuring a power delivery system, comprising:

coupling an input of a first inverter drive to an AC power source and coupling an output of the first inverter drive to a multiphase motor; the first inverter drive comprising a first rectifier and a first inverter;

coupling an input of a second inverter drive to the AC power source and coupling an output of the second inverter drive to the multiphase motor; the second inverter drive comprising a second rectifier and a second inverter; and

coupling the first rectifier, the second rectifier, the first inverter and the second inverter in series with each other through DC terminals corresponding to each of the first rectifier, the second rectifier, the first inverter and the second inverter;

wherein the input of the first inverter drive and the input of the second inverter drive comprise multiphase waveforms, and wherein the multiphase waveforms comprise multiple phases separated by a specified displacement angle, and

wherein the output of the first inverter drive and the output of the second inverter drive comprise multiphase waveforms, and wherein the multiphase waveforms comprise multiple phases separated by the specified displacement angle.

15. The method of claim 14 , comprising coupling an input of a subsequent inverter drive to the AC power source and coupling an output of the subsequent inverter drive to the multiphase motor; the subsequent inverter drive comprising a subsequent rectifier and a subsequent inverter.

16. The method of claim 14 , comprising coupling the first rectifier and the second rectifier to the first inverter and the second inverter using an upper rail and a lower rail of a DC bus.

17. The method of claim 14 , wherein coupling the first rectifier, the second rectifier, the first inverter and the second inverter in series comprises cross-linking the first rectifier, the second rectifier, the first inverter and the second inverter.