Direct current power supply for mission critical applications

• US 8,325,504 B2
• Filed: 09/18/2009
• Issued: 12/04/2012
• Est. Priority Date: 09/18/2009
• Status: Expired due to Fees

• Current Assignee: Power Distribution Incorporated (Eaton Corporation PLC.)
• Original Assignee: Power Distribution Incorporated (Eaton Corporation PLC.)
• Inventors: Kammeter, John B., Schlueter, Greg, Stant, Vern
• Primary Examiner(s): CAVALLARI, DANIEL J
• Application Number:
  US12/562,597
• Publication Number:
  US 20110068634A1
• Time in Patent Office: 1,173 Days
• Field of Search: 307/52, 307/151, 363/65, 363/69
• US Class Current: 363/65
• CPC Class Codes: H02J 1/102 being switching converters H02J1/108, H02J1/12 take precedence

Abstract

A DC power supply apparatus and method of supplying DC power for mission critical applications utilizes multiple power circuits in one unit, the power circuits being optimizable for efficiency as the load increases or decreases. The individual power supplies may use a multiphase topology within the power circuits, with logic phase shifts between multiphase, and two types of power management circuits arranged in parallel, or an equivalent controller, for implementing: (a) a variable linear or variable exponential precision droop algorithm, and (b) a “virtual bus” or current averaging/active current sharing circuit, the current sharing being provided by a low bandwidth communications link between droop controllers in each of the power circuits. In addition, the droop/paralleling circuitry and/or programmed components may be arranged to implement two types of arc detection and suppression, including: (a) unequal positive and negative current in each power circuit to shut down the output power, and (b) monitoring output current for an arc “signature” to protect against arcs between positive and negative.

Claims

1. A direct current power supply apparatus, comprising:

a plurality of transmutor modules;

current and voltage sensors connected to an output of each of said transmutor modules;

a droop controller connected to said output of each of said transmutor modules;

a respective compensation device connected to each droop controller for adjusting an output voltage of each transmutor module under control of said droop controller; and

a low bandwidth communications link connecting said droop controllers for sharing current data,

wherein the droop controller implements a droop algorithm for respectively adjusting said module output voltages to compensate for droop at the respective module outputs, and

said droop controller also implements a virtual bus algorithm in parallel with said droop algorithm for adjusting an output current by a correction factor calculated according to current data supplied by said low bandwidth communications link, said virtual bus algorithm being used solely for recalibration due to long term drifts.

2. A direct current power supply apparatus as claimed in claim 1, wherein said transmutor modules are multiphase transmutor modules.

5. A direct current power supply apparatus as claimed in claim 1, wherein said droop algorithm is a non-linear droop algorithm.

6. A direct current power supply apparatus as claimed in claim 1, wherein said nonlinear droop is an exponential droop such that:

Vout=Vnl−

(EXP(k*I)−

1), where;

Vout=output voltage as a function of current, I,

Vnl=No load output voltage,

I=output current, and

K=constant=[(1/I)*ln(Vnl+1+Vout)]

where the Vout value and the I value is defined at rated full load, and

wherein Vnl−

Vout (at full load) is the maximum droop voltage.

7. A direct current power supply apparatus as claimed in claim 1, wherein said controller includes a droop table that defines a load current versus load voltage function, obtained by removing modules from a shared droop system and determining an effect on the other modules as the load is varied.

8. A direct current power supply apparatus as claimed in claim 1, wherein said controller further executes arc detection and suppression.

9. A direct current power supply apparatus as claimed in claim 8, wherein said arc detection is executed by monitoring module output currents for signatures indicative of arcing between positive and negative wires connected to said output.

10. A direct current power supply apparatus as claimed in claim 9, wherein said signatures include high frequency noise or low frequency modulation with large amplitude.

11. A direct current power supply apparatus as claimed in claim 9, wherein said arc detection further comprises detection of difference between positive and negative currents that are indicative of arcing to ground.

12. A direct current power supply apparatus as claimed in claim 8, wherein said arc detection is executed by monitoring positive and negative current outputs for differences indicative of arcing to ground.

3. A direct current power supply apparatus as claimed 2, wherein said transmutor modules are three phase transmutor modules, in which a DC power input is fed to three pairs of power switching devices and the power switching device outputs are routed to a three legged, three phase transformer that outputs three square waves with a 60 degree overlap.

4. A direct current power supply apparatus as claimed in claim 3, wherein said communications link is a tri-redundant signal bus.

13. A direct current power supply method for a DC power supply that includes a plurality of transmutor modules;

a droop controller connected to an output of each of said transmutor modules;

a respective compensation device connected to each droop controller for adjusting an output voltage of each transmutor module under control of said droop controller; and

a low bandwidth communications link connecting said droop controllers for sharing current data, comprising the steps of;

the droop controller implementing a droop algorithm for respectively adjusting said module output voltages to compensate for droop at the respective module outputs, and

said droop controller also implementing a virtual bus algorithm in parallel with said droop algorithm for adjusting an output current by a correction factor calculated according to current data supplied by said low bandwidth communications link, said virtual bus algorithm being used solely for recalibration due to long term drifts.

14. A direct current power supply method as claimed in claim 13, wherein said droop algorithm is a non-linear droop algorithm.

15. A direct current power supply apparatus as claimed in claim 14, wherein said nonlinear droop is an exponential droop such that:

Vout=Vnl−

(EXP(k*I)−

1), where;

Vout=output voltage as a function of current, I,

Vnl=No load output voltage,

I=output current, and

K=constant=[(1/I)*ln(Vnl+1+Vout)]

where the Vout value and the I value is defined at rated full load, and

wherein Vnl−

Vout (at full load) is the maximum droop voltage.

16. A direct current power supply apparatus as claimed in claim 13, wherein said controller carries out said droop algorithm by referring to a droop table that defines a load current versus load voltage function, obtained by removing modules from a shared droop system and determining an effect on the other modules as the load is varied.

17. A direct current power supply apparatus as claimed in claim 13, wherein said controller further executes arc detection and suppression.

18. A direct current power supply apparatus as claimed in claim 17, wherein said arc detection is executed by monitoring module output currents for signatures indicative of arcing between positive and negative wires connected to said output.

19. A direct current power supply apparatus as claimed in claim 18, wherein said signatures include high frequency noise or low frequency modulation with large amplitude.

20. A direct current power supply apparatus as claimed in claim 17, wherein said arc detection further comprises detection of difference between positive and negative currents that are indicative of arcing to ground.

21. A direct current power supply apparatus as claimed in claim 13, wherein said arc detection is executed by monitoring positive and negative current outputs for differences indicative of arcing to ground.