DC POWER SUPPLY SYSTEMS AND METHODS

1 . An AC to DC power supply system comprising:

a variable frequency drive (VFD) configured to convert AC power at a VFD input to controlled AC power at a VFD output, and the VFD is configured to control a frequency and voltage of the controlled AC power responsive to a control input;

a transformer including a primary side coupled to the VFD output and a secondary side;

a rectifier coupled to the secondary side of the transformer, the rectifier configured to rectify transformed AC power at the secondary side of the transformer to DC power at an output of the rectifier;

at least one sensor coupled to the output of the rectifier to monitor one or more characteristics of the DC power; and

a controller coupled to the at least one sensor, wherein the controller is configured to provide the control input to the VFD to adjust the controlled AC in response to changes to the one or more characteristics of the DC power.

2 . The AC to DC power supply system of claim 1 , wherein the control input to the VFD is a speed control input, and the VFD includes:

a speed-to-voltage conversion module configured to convert the speed-control input to a voltage-control-input to control the voltage of the controlled AC power at the VFD output.

3 . The AC to DC power supply system of claim 1 , wherein the VFD includes a three-phase VFD.

4 . The AC to DC power supply system of claim 3 , wherein the transformer includes a three-phase wye-delta-type transformer.

5 . The AC to DC power supply system of claim 3 , wherein the transformer includes two, 6 pulse transformers to provide as an output to the rectifier, 12 distinct phases of AC power.

6 . The AC to DC power supply system of claim 5 , wherein the 6 pulse transformers are implemented with single phase transformers.

7 . The AC to DC power supply system of claim 1 , wherein the rectifier is a passive rectifier.

8 . The AC to DC power supply system of claim 1 , wherein the at least one sensor includes voltage and current sensors.

9 . The AC to DC power supply system of claim 1 , including a filter disposed between the VFD and the transformer.

10 . A method for providing power to a load, the method comprising:

converting AC power to controlled AC power with a variable frequency drive (VFD);

transforming voltage and current of the AC power with the transformer to produce transformed AC power on a secondary side of the transformer;

rectifying the transformed AC power to produce DC power;

applying the rectified DC power to a DC load;

sensing one or more characteristics of the DC power; and

controlling, with the VFD, a frequency and voltage of the controlled AC power based upon the one or more characteristics of the DC power.

11 . The method of claim 10 , wherein controlling the VFD includes controlling the VFD with a speed control input.

12 . The method of claim 10 , wherein converting the AC power to controlled AC power includes converting three-phase AC power to three-phase controlled AC power.

13 . The method of claim 12 , wherein transforming voltage and current of the AC power includes transforming a voltage and current of the AC power with a three-phase wye-delta-type transformer.

14 . The method of claim 12 , wherein transforming voltage and current of the AC power includes transforming a voltage and current of the AC power with two, 6 pulse transformers to provide 12 distinct phases of AC power.

15 . The method of claim 10 , wherein the rectifying includes passively rectifying the transformed AC power to produce the DC power.

16 . The method of claim 10 , wherein sensing the one or more characteristics of the DC power includes sensing voltage and current of the DC power.

17 . The method of claim 10 , including filtering noise in the controlled AC power generated by the VFD during the conversion of AC power to controlled AC power.

18 . An AC to DC power supply system comprising:

means for converting AC power to controlled AC power;

means for transforming voltage and current of the AC power with the transformer to produce transformed AC power on a secondary side of the transformer;

means for rectifying the transformed AC power to produce DC power;

means for applying the rectified DC power to a DC load;

means for sensing one or more characteristics of the DC power; and

means for controlling, with the VFD, a frequency and voltage of the controlled AC power based upon the one or more characteristics of the DC power.

19 . The AC to DC power supply system of claim 18 , wherein the means for controlling the VFD includes means for controlling the VFD with a speed control input.

20 . The AC to DC power supply system of claim 18 , wherein the means for converting the AC power to controlled AC power includes means for converting three-phase AC power to three-phase controlled AC power.

21 . The AC to DC power supply system of claim 20 , wherein the means for transforming voltage and current of the AC power includes means for transforming a voltage and current of the AC power with a three-phase wye-delta-type transformer.

22 . The AC to DC power supply system of claim 20 , wherein the means for transforming voltage and current of the AC power includes means for transforming a voltage and current of the AC power with two, 6 pulse transformers to provide 12 distinct phases of AC power.

23 . The AC to DC power supply system of claim 18 , wherein the means for rectifying includes means for passively rectifying the transformed AC power to produce the DC power.

24 . The AC to DC power supply system of claim 18 , wherein the means for sensing the one or more characteristics of the DC power includes means for sensing voltage and current of the DC power.

25 . The AC to DC power supply system of claim 18 , including means for filtering noise in the controlled AC power.