Synchronous multi-phase AC-TO-DC converter

• US 20060077602A1
• Filed: 10/12/2004
• Published: 04/13/2006
• Est. Priority Date: 10/12/2004
• Status: Active Grant

• Current Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Original Assignee: Halliburton Energy Services Incorporated (Halliburton Company)
• Inventors: Schultz, Roger L., Masino, James E.
• Granted Patent: US 7,447,051 B2
• Time in Patent Office: Days
• US Class Current: 361/84
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources

Abstract

Disclosed herein are various embodiments of power conversion systems and methods employing synchronous multi-phase AC-to-DC conversion. In one embodiment, a power converter comprises a transistor bridge and a switching controller that operates the transistor bridge in response to AC voltage threshold crossings. The switching controller may include a period counter to measure times between threshold crossings, and a delay counter to trigger a delayed state transition for the transistor bridge. One disclosed method embodiment comprises: receiving multiple phased alternating voltages; comparing each phased alternating voltage to a threshold; determining a period associated with voltage threshold crossings; triggering state transitions at some fraction of the period after each threshold crossing; and placing a transistor bridge into a configuration associated with a current state. For each state, the transistor bridge configuration is designed to couple phased alternating voltages to two output terminals in a sequence that produces a non-alternating voltage difference.

Claims

1. An alternating current (AC) to direct current (DC) converter that comprises:

a transistor bridge coupling multiple AC lines to two DC lines, each AC line being coupled to each DC line by at least one transistor; and

a switching controller that controls the transistor bridge in response to voltage threshold crossings on each AC line.

2. The converter of claim 1, further comprising:

a set of comparators that each compare a respective AC line voltage to a threshold value to generate a compare signal; and

a direction detector that processes the compare signals to generate an order signal indicating an order in which the AC line voltages cross the threshold value.

3. The converter of claim 1, further comprising:

a set of comparators that each compare a respective AC line voltage to a threshold value to generate a compare signal,

wherein the switching controller includes;

commutation state logic configured to determine a current state for the transistor bridge; and

an edge detector configured to detect a transition in a compare signal associated with the current state.

4. The converter of claim 3, wherein the switching controller further includes:

a direction selector coupled to the edge detector and configured to limit transition detection to those transitions occurring in an expected direction associated with the current state.

5. The converter of claim 3, wherein the switching controller further includes:

a period counter configured to measure each interval between adjacent transition detections.

6. The converter of claim 5, wherein the switching controller further includes:

a delay counter configured to determine a delay that is a predetermined fraction of a previous interval measured by the period counter,

wherein the commutation state logic determines a subsequent state for the transistor bridge upon expiration of said delay.

7. The converter of claim 6, wherein the switching controller further includes:

a gate coupled to the edge detector and configured to prevent transition detection during said delay.

8. The converter of claim 1, further comprising:

a frequency discriminator that disables the switching controller while the voltage on the AC lines alternates below a predetermined frequency threshold.

9. The converter of claim 8, wherein the frequency discriminator provides hysteresis.

10. The converter of claim 8, wherein the frequency discriminator includes:

an input flip-flop that is set in response to voltage threshold crossings of an AC line;

a timer that is initialized in response to voltage threshold crossings of the AC line, wherein the timer is configured to reset the input flip-flop after a delay expires; and

an output flip-flop configured to store the state of the input flip-flop in response to voltage threshold crossings of an AC line.

11. The converter of claim 1, further comprising:

a diode bridge coupling the multiple AC lines to the two DC lines, wherein the diode bridge is configured to rectify the AC voltages when the transistor bridges is not operating.

12. The converter of claim 1, wherein the switching controller is implemented in an integrated circuit operable above 185°

C.

13. The converter of claim 1, wherein the magnitude of the AC line voltages is less than two volts.

14. The converter of claim 1, wherein the switching controller is implemented in a CPLD.

15. A power generator that comprises:

a rotor with two or more magnetic poles;

a stator with three or more windings, each winding having a corresponding phase for alternating voltages induced by rotation of the rotor;

a transistor bridge that couples the windings to two nodes; and

a switching controller coupled to the transistor bridge and configured to enable and disable transistors in the transistor bridge in response to threshold crossings by the alternating voltages, thereby producing a direct current (DC) voltage difference between the two nodes.

16. The generator of claim 15, wherein the rotor is configured to be rotated by a set of vanes.

17. The generator of claim 15, wherein the set of vanes is configured to operate in a downhole fluid stream.

18. The generator of claim 15 wherein the set of vanes is configured to operate in a liquid fluid stream.

19. The generator of claim 15, wherein the switching controller is operable to enable and disable transistors in the transistor bridge in a manner designed to convert a DC voltage supplied to the two nodes into rotation of the rotor.

20. A system controller that comprises an integrated circuit having:

a switching controller configured to operate a transistor bridge in response to voltage threshold crossings in phased alternating signals so as to convert the phased alternating signals into a non-alternating voltage; and

a bus configured to couple the switching controller to a processor.

21. The controller of claim 20, wherein the integrated circuit further includes a processor coupled to the switching controller via the bus, and configured to retrieve from the switching controller a frequency value associated with the phased alternating signals.

22. A method of creating a non-alternating voltage difference between two terminals, the method comprising:

receiving multiple phased alternating voltages;

comparing each of the phased alternating voltages to a threshold;

determining a period associated with threshold crossings by the phased alternating voltages;

triggering state transitions at some fraction of the period after each threshold crossing; and

placing a transistor bridge into a configuration associated with a current state, the transistor bridge configuration being designed to couple phased alternating voltages to the two terminals in a sequence that produces the non-alternating voltage difference.

23. The method of claim 22, further comprising:

determining whether a frequency of the phased alternating voltages is below a threshold; and

inhibiting operation of the transistor bridge while the frequency is below the threshold.

24. A windmill that comprises:

a rotor with two or more magnetic poles;

a stator with three or more windings, each winding having a corresponding phase for alternating voltages induced by rotation of the rotor;

a transistor bridge that couples the windings to two nodes; and

a switching controller coupled to the transistor bridge and configured to enable and disable transistors in the transistor bridge in response to threshold crossings by the alternating voltages, thereby producing a direct current (DC) voltage difference between the two nodes,

wherein the rotor is configured to be rotated by a set of vanes.