Series-parallel battery array conversion

• US 6,430,692 B1
• Filed: 09/25/1998
• Issued: 08/06/2002
• Est. Priority Date: 09/25/1998
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Kimble, Christopher John, Steele, Steven William
• Primary Examiner(s): Wiley, David
• Assistant Examiner(s): Jean, Frantz B.
• Application Number:
  US09/160,242
• Time in Patent Office: 1,411 Days
• Field of Search: 713/300, 307/66, 307/75, 320/16, 320/120, 320/121, 320/122, 320/136, 320/139, 320/117, 320/162, 320/124, 363/21, 323/210
• US Class Current: 713/300
• CPC Class Codes: G06F 1/263 Arrangements for using multiple switchable power supplies, e.g. battery and AC G06F1/30 takes precedence
• CPC Class Codes: H02J 7/0024 Parallel/serial switching of connection of batteries to charge or load circuit

Abstract

A battery backup system has a number of batteries and number of switches interconnecting the batteries to either a high-power load or a low-power load. The batteries are selectively connected in series with each other, or in parallel with each other by the switches. When the batteries are in the parallel configuration they are also connected to power the low-power load, and when in series, to power the high-power load. Between switching from the high-power series configuration to the low-power parallel configuration, a transition phase is provided during which a transition battery powers the low-power load.

Claims

1. A battery back-up system for providing battery back-up for a first and a second load, comprising:

a plurality of batteries;

a plurality of switches for interconnecting the plurality of batteries to the first load and the second load, such that;

(a) the plurality of batteries are selectively connected to the first load in series with each other, or

(b) the plurality of batteries are selectively connected to the second load in parallel with each other; and

a transition battery to power the second load during a transition phase in which the plurality of batteries are being changed from a series to a parallel connection.

2. The system according to claim 1, wherein the plurality of switches comprise low ON resistance field effect transistors.

3. The system according to claim 1, wherein the transition battery is switched in by at least one switch of the plurality of switches.

4. The system according to claim 3, further comprising a switch controller;

wherein switching of the plurality of switches is controlled by the switch controller to provide;

a high-power back-up phase during which the plurality of batteries are connected in series to the first load;

the transition phase, during which the transition battery is connected to the second load; and

a low-power phase during which the plurality of batteries are connected in parallel to the second load.

5. The system according to claim 4, wherein the plurality of batteries comprise thirty 12-volt batteries which provide an approximately 360-volt terminal voltage at the output terminals of the battery backup system when connected in series by the plurality of switches, and provide an approximately 12-volt volt terminal voltage at the output terminals of the battery backup system when connected in parallel by the plurality of switches.

6. The system according to claim 5, wherein the plurality of batteries comprise 10 Amp-hour batteries.

7. The system according to claim 4, wherein the battery back-up system is disposed to provide back-up to a computer having a power control network, wherein the switch controller is controlled by the power control network to initiate and control battery back-up operation.

8. The system according to claim 4, wherein the plurality of switches comprise:

group A switches disposed to connect respective ones of the plurality of batteries in a series arrangement;

group B switches disposed to connect respective ones of the plurality of batteries in a parallel arrangement;

an X switch disposed to connect the plurality of batteries to the first load;

a Y switch disposed to connect the plurality of batteries to the second load; and

a Z switch disposed to connect the transition battery to the second load.

9. The system according to claim 8, wherein the plurality of switches comprise low ON resistance field effect transistors.

10. A method of switching between a series and a parallel connection of batteries comprising utilizing the system according to claim 1.

11. The system according to claim 1, wherein the first load is a relatively high-power load, and wherein the second load is a relatively low-power load.

12. The system according to claim 11, wherein the relatively high-power load comprises a computer power supply, and wherein the relatively low-power load comprises a continuously powered memory regulator.

13. The system according to claim 12, wherein the computer power supply provides power to operate a computer system including memory, and wherein the continuously powered memory regulator provides power to maintain the contents of the computer system memory during a computer system shut-down.

14. A method of providing a computer system continuously powered memory shut-down comprising utilizing the system according to claim 13.

15. A method of providing a high-power and a low-power battery back-up with a battery back-up unit having a plurality of batteries, comprising:

connecting the plurality of batteries in series with an output of the battery back-up unit to provide the high-power battery back-up; and

connecting the plurality of batteries in parallel with the output of the battery back-up unit to provide the low-power battery back-up; and

providing a transition phase between the high-power battery back-up and the low-power battery back-up, during which back-up power is supplied to a load from a transition battery.

16. The method according to claim 15, wherein the connecting the plurality of batteries in series comprises closing a first group of switches;

and

wherein the connecting the plurality of batteries in parallel comprises closing a second group of switches.

17. The method according to claim 15, wherein the low-power back-up is provided to a load comprising a regulator which provides power to a memory device;

wherein the method further comprises reducing a refresh rate of the memory device before connecting the plurality of batteries in parallel; and

wherein the high-power battery back-up is provided for a relatively short time period on the order of minutes, and wherein the low-power battery back-up can be provided for a relatively longer time period on the order of hours or days.

18. A method of providing a high-power battery back-up, a transition back-up phase, and a low-power battery back-up with a battery back-up unit having a plurality of batteries and a plurality of switches, comprising:

closing a first group of switches to configure the plurality of batteries in a series array;

closing a first load switch to connect the series array of batteries to a first load to begin the high-power battery back-up;

closing a transition battery switch to connect a transition battery to a second load;

opening the first load switch to disconnect the series array of batteries from the first load to begin the transition back-up phase and end the high-power battery back-up;

opening the first group of switches to deconfigure the plurality of batteries from the series array;

closing a second group of switches to configure the plurality of batteries in a parallel array;

closing a second load switch to connect the parallel array of batteries to the second load; and

opening the transition battery switch to disconnect the transition battery from the second load to end the transition back-up phase and begin the low-power battery back-up.

19. The method according to claim 18, wherein the second load comprises a regulator providing power to a memory device;

wherein the method further comprises reducing a refresh rate of the memory device; and

wherein the high-power battery back-up is provided for a relatively short time period on the order of minutes, and wherein the low-power battery back-up can be provided for a relatively longer time period on the order of hours or days.