Distributed internal fault bypass in a modular uninterruptible power supply

• US 6,292,379 B1
• Filed: 03/29/2000
• Issued: 09/18/2001
• Est. Priority Date: 03/29/2000
• Status: Expired due to Term

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Powerware Corporation (Eaton Corporation PLC.)
• Inventors: Laufenberg, Derek, Edevold, Craig, Winch, Cary, Zahrte, Donald K. Sr., Wade, Joseph R., Jungwirth, Peter
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US09/538,051
• Time in Patent Office: 538 Days
• Field of Search: 363/71, 363/144, 307/66
• US Class Current: 363/71
• CPC Class Codes: H02J 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 9/06 with automatic change-over , e.g. UPS systems

Abstract

A modular uninterruptible power supply is presented having multiple power modules installed therein. Each of the individual power modules contains an internal bypass circuit sized for its particular power module. Preferably internal bypass circuitry is sized to carry two per unit load. The system and method of the invention also includes internal control circuitry for each of the modular power modules that control transitions between the inverter and bypass modes of operation. This transition control is coordinated with the other controllers for the other modular power modules installed in the uninterruptible power supply. Both the high speed communication bus and a high level interrupt line are utilized to minimize the transfer break time between different modes of operation while ensuring that the inverter is never paralleled with the utility line voltage. To further minimize this transfer time, a solid state switching circuit is utilized to provide the initialization between operational modes. To maximize the efficiency during the bypass mode of operation, and electromechanical relay is utilized in coordinated operation with the solid state switching device to provide long-term power requirements during the bypass mode.

Claims

1. A modular uninterruptible power supply, comprising:

a chassis defining a plurality of slots adapted to accommodate a plurality of power modules therein, said chassis further providing input power lines and output power lines to each of said slots; and

at least two power modules installed in two of said plurality of slots, each of said power modules including an inverter and an inverter bypass circuit coupled in parallel thereacross, each of said power modules further including a controller operably coupled to said inverter and said inverter bypass; and

wherein said controller from each of said power modules communicate with one another to coordinate transitions between inverter operation and bypass circuit operation.

2. The modular uninterruptible power supply of claim 1, wherein said chassis further comprises a communications bus and a shared logic line among said plurality of slots, and wherein said controller in each of said power modules is operatively coupled to said communications bus and said shared logic line.

3. The modular uninterruptible power supply of claim 2, wherein one of said controllers takes control of said shared logic line, communicates state change information over said communications bus, and thereafter toggles said shared logic line to initiate a state change within each of said power modules.

4. The modular uninterruptible power supply of claim 3, wherein each of said power modules is operating in an inverter mode, and wherein each of said controllers disable operation of said inverter and thereafter enable bypass circuit operation upon detection of said toggle of said shared logic line to place each of said power modules in a bypass mode.

5. The modular uninterruptible power supply of claim 4, wherein said bypass circuit comprises a solid state switching circuit and an electromechanical switching circuit coupled in parallel, and wherein said controller commands said solid state switching circuit closed upon detection of said toggle of said shared logic line, and thereafter said controller commands said electromechanical switching element closed and said solid sate switching circuit open.

6. The modular uninterruptible power supply of claim 3, wherein each of said power modules is operating in a bypass mode, and wherein each of said controllers disable operation of said bypass circuit and thereafter enable inverter operation upon detection of said toggle of said shared logic line to place each of said power modules in an inverter mode.

7. The modular uninterruptible power supply of claim 6, wherein said bypass circuit comprises a solid state switching circuit and an electromechanical switching circuit coupled in parallel, and wherein said controller commands said solid state switching circuit closed and said electromechanical switching circuit open upon receipt of said state change information, and wherein said controller commands open said solid state switching circuit to disable operation of said bypass circuit upon detection of said toggle of said shared logic line.

8. The modular uninterruptible power supply of claim 3, wherein said toggling of said shared logic line causes said controller to execute a high level non-maskable interrupt.

9. The modular uninterruptible power supply of claim 1, wherein said bypass circuit comprises a solid state switching circuit and an electromechanical switching circuit coupled in parallel.

10. The modular uninterruptible power supply of claim 9, wherein said solid state switching circuit comprises back-to-back configured silicon controlled rectifiers (SCRs).

11. The modular uninterruptible power supply of claim 1, wherein said bypass circuit is rated to carry two times an electrical rating of said inverter.

12. The modular uninterruptible power supply of claim 1, wherein said inverter comprises a double-conversion, transformerless inverter.

13. The method of claim 2, wherein said step of executing the transition to the desired state comprises the step of:

opening the solid state switching circuit; and

thereafter initiating operation of the inverter.

14. A method of coordinating transitions between operating modes in a modular power supply having multiple power modules, each power module having an inverter and an inverter bypass circuit;

comprising the steps of;

communicating desired state information to the power modules;

preparing to execute a transition to the desired state;

transmitting an interrupt command;

executing the transition to the desired state.

15. The method of claim 14 wherein the bypass circuit in each of the power modules includes a solid state switching circuit and an electromechanical switching circuit, wherein the power modules are operating in a bypass mode with the electromechanical switching circuit closed, and wherein said step of preparing to execute a transition to the desired state comprises the steps of:

closing the solid state switching circuit; and

opening the electromechanical switching circuit.

16. The method of claim 14, wherein the bypass circuit in each of the power modules includes a solid state switching circuit and an electromechanical switching circuit, wherein the power modules are operating in an inverter mode with the solid state switching circuit and the electromechanical switching circuit open, and wherein said step of executing the transition to the desired state comprises the steps of:

ceasing inverter operation;

thereafter closing the solid state switching circuit; and

closing the electromechanical switching circuit.

17. The method of claim 16, further comprising the step of opening the solid state switching circuit after said step of closing the electromechanical switching circuit.

18. The method of claim 14, wherein said step of executing the transition to the desired state comprises the step of executing a high level non-maskable interrupt.

19. The method of claim 14, further comprising the steps of:

detecting a need for a state change; and

taking control of a shared logic line.

20. A modular uninterruptible power supply, comprising a plurality of power modules coupled in parallel, each of said power modules including an inverter, a bypass circuit, and a controller operably coupled to said inverter and said bypass circuit, said controller further communicating on a communications bus and having a shared logic line coupled to each of said controllers of said power modules capable of initiating a high level interrupt in each of said controllers.

21. The modular uninterruptible power supply of claim 20, wherein each of said bypass circuits comprises a solid state switching circuit coupled in parallel with an electromechanical switching circuit.

22. The modular uninterruptible power supply of claim 21, wherein said solid state switching circuit comprises back-to-back configured silicon controlled rectifiers (SCRs).

23. The modular uninterruptible power supply of claim 20, wherein each of said bypass circuits are rated at twice an electrical rating of each of said inverters.

24. The modular uninterruptible power supply of claim 20, wherein each of said controllers is operable to command a state change between inverter mode operation and bypass mode operation of all power modules within a single gate delay by first transmitting state change information over said communications bus followed by toggling said shared logic line, said toggling initiating a high level interrupt within each of said controllers to execute said state change.

25. The modular uninterruptible power supply of claim 24, wherein each of said bypass circuits comprises a solid state switching circuit coupled in parallel with an electromechanical switching circuit, wherein each of said power modules are operating in said inverter mode, and wherein each of said controllers commands said inverters to stop operating and thereafter commands said solid state switching circuit to close in response to said toggling of said shared logic line.

26. The modular uninterruptible power supply of claim 25, wherein said controller further commands said electromechanical switching circuit closed and thereafter commands said solid state switching circuit open.

27. The modular uninterruptible power supply of claim 24, wherein each of said bypass circuits comprises a solid state switching circuit coupled in parallel with an electromechanical switching circuit, wherein each of said power modules is operating in said bypass mode, and wherein each of said controllers commands said solid state switching circuit closed and said electromechanical switching circuit open in response to said state change information, said controller further commanding said solid state switching circuit open and thereafter commands said inverters to start operating in response to said toggling of said shared logic line.