Distributed power system

• US 6,121,693 A
• Filed: 08/20/1998
• Issued: 09/19/2000
• Est. Priority Date: 08/20/1998
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Rock, Agnes G.
• Primary Examiner(s): RIOS CUEVAS, ROBERTO JOSE
• Application Number:
  US09/137,158
• Time in Patent Office: 761 Days
• Field of Search: 307/18, 307/23, 307/29, 307/31, 307/39, 307/44, 307/147, 361/94-98, 361/78-79, 361/83
• US Class Current: 307/18
• CPC Class Codes: H02H 3/087 for dc applications
• CPC Class Codes: H02J 1/001 Hot plugging or unplugging of load or power modules to or from power distribution networks
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02J 1/14 Balancing the load in a network

Abstract

A power supply distribution comprises equipment having a shared power bus. Supply isolators isolate the supply from the shared power bus in the event of a power supply output short circuit. Load isolators isolate the supply from other loads that may short circuit, or consume excess output current. Memory and isolators are used to detect and store the occurrence of load or supply failures, and memory may be of revertive or non-revertive type.

Claims

1. A power distribution apparatus comprising:

a shared power bus;

a first plurality of current sharing power supplies, each supply coupled to said shared power bus;

a second plurality of powered equipment, each of said powered equipment comprising;

a load;

a load isolator having an isolator input coupled to said shared power bus, and an isolator output coupled to said load,

said load isolator comprising;

a load current measurement converting current in said load into a measurement voltage;

a comparator comparing said measurement voltage to a threshold voltage, said comparator having an output, said output activated when said measurement voltage exceeds said threshold voltage;

a memory activated by said comparator output and producing an activation output for an interval of time;

a switch coupled between said isolator input and said isolator output, said switch closed when said activation output is asserted;

wherein any one of said first plurality of current sharing power supplies has sufficient capacity to provide power concurrently to all of said second plurality of loads.

2. The power distribution apparatus of claim 1 wherein said load current measurement includes amplifying a voltage developed across a resistor carrying said load current to produce said measurement voltage.

3. The power distribution apparatus of either claim 1 or claim 2 wherein said load current has a maximum value, and said threshold voltage equals said measurement voltage at said load current maximum value.

4. The power distribution apparatus of either claim 1 or claim 2 wherein said switch comprises a Field Effect Transistor (FET).

5. A power distribution apparatus comprising:

a shared power bus;

a first plurality of loads coupled to said shared power bus;

a second plurality of powering equipment, each of said powering equipment comprising;

a current sharing power supply having an output;

a supply isolator having an input coupled to said current sharing power supply output and an output coupled to said shared power bus;

said supply isolator further comprising;

a supply current measurement converting current in said supply into a measurement voltage;

a comparator comparing said measurement voltage to a threshold voltage, said comparator having an output, said output activated when said measurement voltage exceeds said threshold voltage;

a memory activated by said comparator output and producing an activation output for an interval of time;

a switch coupled between said isolator input and said isolator output, said switch closed when said activation output is asserted;

wherein any one of said second plurality of current sharing power supplies has sufficient capacity to provide power concurrently to all of said first plurality of loads.

6. The power distribution apparatus of claim 5 wherein said supply current measurement includes amplifying a voltage developed across a resistor carrying said supply current to produce said measurement voltage.

7. The power distribution apparatus of either claim 5 or claim 6 wherein said supply current has a maximum value, and said threshold voltage equals said measurement voltage at said maximum value.

8. The power distribution apparatus of either claim 5 or claim 6 wherein said switch comprises a Field Effect Transistor (FET).

9. A power distribution apparatus comprising:

a shared power bus;

a first plurality of powered equipment, each of said powered equipment comprising;

a load;

a load isolator having an isolator input coupled to said shared power bus, and an isolator output coupled to said load;

said load isolator comprising;

a load current measurement converting current in said load into a load measurement voltage;

a load comparator comparing said load measurement voltage to a load threshold voltage, said load comparator having an output, said output activated when said load measurement voltage exceeds said load threshold voltage;

a load memory activated by said load comparator output and producing a load activation output for an interval of time;

a load switch coupled between said load isolator input and said load isolator output, said load switch closed when said load activation output is asserted;

a second plurality of powering equipment, each of said powering equipment comprising;

a current sharing power supply having an output;

a supply isolator having an input coupled to said current sharing power supply output and an output coupled to said shared power bus;

said supply isolator further comprising;

a supply current measurement converting current in said supply output into a supply measurement voltage;

a supply comparator comparing said supply measurement voltage to a supply threshold voltage, said supply comparator having an output, said output activated when said supply measurement voltage exceeds said supply threshold voltage;

a supply memory activated by said supply comparator output and producing a supply activation output for an interval of time;

a supply switch coupled between said supply isolator input and said supply isolator output, said supply switch closed when said supply activation output is asserted;

wherein any one of said second plurality of current sharing power supplies has sufficient capacity to provide power concurrently to all of said first plurality of loads.

10. The power distribution apparatus of claim 9 wherein said load current measurement includes amplifying a voltage developed across a resistor carrying said load current to produce said load measurement voltage.

11. The power distribution apparatus of claim 9 wherein said supply current measurement includes amplifying a voltage developed across a resistor carrying said supply output current to produce said supply measurement voltage.

12. The power distribution apparatus of either claims 9, 10, or 11 wherein said load current has a maximum load value, and said load threshold voltage equals said load measurement voltage at said maximum load value.

13. The power distribution apparatus of either claims 9, 10, or 11 wherein said supply current has a maximum supply output value, and said supply threshold voltage equals said supply measurement voltage at said maximum supply output value.

14. The power distribution apparatus of either claims 9, 10, or 11 where at least one of said load switch or said supply switch is a Field Effect Transistor (FET).