Cell site power system management, including battery circuit management

• US 8,310,103 B2
• Filed: 03/17/2010
• Issued: 11/13/2012
• Est. Priority Date: 03/17/2010
• Status: Active Grant

• Current Assignee: T-Mobile USA, Inc. (Deutsche Telekom AG)
• Original Assignee: T-Mobile USA, Inc. (Deutsche Telekom AG)
• Inventors: Fischer, Steve
• Primary Examiner(s): AMAYA, CARLOS DAVID
• Application Number:
  US12/726,265
• Publication Number:
  US 20110227414A1
• Time in Patent Office: 972 Days
• Field of Search: 307/44, 307/66, 307/71, 307/77, 307/85, 320/116
• US Class Current: 307/85
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: G01R 31/385 Arrangements for measuring battery or accumulator variables for monitoring G01R31/382
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• CPC Class Codes: H02J 7/0014 Circuits for equalisation of charge between batteries
• CPC Class Codes: H02J 7/0019 using switched or multiplexed charge circuits
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 9/062 for AC powered loads

Abstract

Systems, apparatuses, and methods for managing battery circuits in systems such as wireless communications service base stations are disclosed. An example apparatus includes a battery circuit having multiple strings of one or more serially connected batteries. The apparatus may be configured to rotate between battery strings such that one or more strings are maintained at or near an upper threshold while other string(s) are disconnected from the maintained string(s). The apparatus may also be configured to charge the battery circuit, to test the battery circuit, and to handle power failures.

Claims

1. A cell site power management system for providing supplementary or emergency power to radio and telecommunications circuitry at a cell site, the system comprising:

a cell site battery circuit connected to a battery circuit node, wherein the battery circuit node is configured to provide battery power to the radio and telecommunications circuitry at the cell site, and wherein the battery circuit comprises—

multiple battery strings, wherein each battery string comprises;

one or more batteries coupled in a series configuration; and

at least one switch circuit configured to selectively couple the one or more batteries to the battery circuit node,

wherein the battery circuit node is configured to provide power, as needed, to the radio and telecommunications circuitry at the cell site and to receive a charging current for charging batteries when external power is available to the cell site; and

a cell site power controller configured to;

selectively couple one or more of the multiple battery strings in the battery circuit to the battery circuit node,

wherein a battery string coupled to the battery circuit node operates as an active battery string,

wherein the active battery string provides power, as needed, to the radio and telecommunications circuitry at the cell site via the battery circuit node, and

wherein the active battery string actively receives the charging current when external power is available to the cell site to maintain the active battery string at or near a full charge;

selectively decouple at least one of the one or more of the multiple battery strings in the battery circuit from the battery circuit node,

wherein a battery string decoupled from the battery circuit node operates as a parked battery string,

wherein the parked battery string does not actively receive the charging current; and

,

upon an occurrence of a battery change event, to—

(i) couple the parked battery string to the battery circuit node to provide power, as needed, to the radio and telecommunications circuitry at the cell site and to actively receive the charging current;

or

(ii) decouple the active battery string from the battery circuit node and to no longer receive the charging current;

or

(iii) both (i) and (ii); and

,

wherein the battery change event includes a specified charging event, a specified testing event, or a power failure event.

2. The cell site power management system of claim 1, wherein a current sensor is coupled to and associated with each battery string;

and

the power controller is further configured to;

monitor each of the current sensors to determine a status of an associated battery string;

monitor a particular current sensor associated with a particular battery string to determine a self-discharging rate of the particular battery string; and

evaluate whether the determined self-discharging rate is anomalous as compared to other battery strings in the battery circuit or based on empirical data.

3. The cell site power management system of claim 1, wherein a current sensor is coupled to and associated with each battery string;

and

the power controller is further configured to;

monitor each of the current sensors to determine a status of an associated battery string;

monitor a particular current sensor associated with a particular battery string to determine a charging or discharging rate of the particular battery string; and

evaluate whether the determined charging or discharging rate is anomalous as compared to other battery strings in the battery circuit or based on empirical data.

4. The cell site power management system of claim 1, further comprising:

a rectifier and switch circuit configured to charge the battery circuit and to route power from the battery circuit to a load under control of the power controller.

5. The cell site power management system of claim 1, wherein each battery string further includes an associated current sensor, and wherein the power controller is further configured to monitor each of the current sensors to determine a status of an associated battery string.

6. The cell site power management system of claim 1, wherein the cell site power management system is configured to test the battery circuit, charge the battery circuit, and provide power to the radio and telecommunications circuitry to handle power failures.

7. The cell site power management system of claim 1, wherein the power controller is further configured to select one or more of the multiple battery strings in the battery circuit to operate as active battery strings on the basis of:

a function of time;

a measured capacity of one or more battery strings;

a calculated capacity of one or more battery strings;

or

an expected capacity of one or more battery strings.

8. The cell site power management system of claim 1, wherein the power controller is configured to, during a power failure event, selectively couple one or more parked battery strings to the radio and telecommunications circuitry based on a voltage of the active battery strings and voltages of the parked battery strings.

9. The cell site power management system of claim 1, wherein the power controller is configured:

to begin charging the battery circuit at a first voltage that is based on a voltage across a parked battery string having a lowest string voltage as compared to other parked battery strings,

to apply a second, higher charging voltage to the battery circuit node, and

to repeatedly couple an additional battery string to the battery circuit node as a voltage of the coupled battery strings rises to a voltage of the additional battery string due to the second, applied charging voltage.

10. The cell site power management system of claim 1 wherein each battery string further comprises a resettable breaker configured to permit testing of the battery string.

11. A method for managing a battery circuit that has multiple battery strings and is configured to provide backup power to radio and telecommunications circuitry at a base station, the method comprising:

detecting an event that indicates that one or more actions related to management of the battery circuit is to be performed,

wherein the battery circuit comprises multiple battery strings, and wherein each battery string in the battery circuit further comprises;

two or more batteries arranged in a serial fashion and configured to provide backup power to the radio and telecommunications circuitry at the base station;

a string connection switch configured to selectively couple and decouple the battery string from a battery circuit node; and

,

a sensor configured to provide a string sense signal indicating conditions relating to at least one state of the battery string; and

wherein the detected event comprises;

a battery test event indicating that the battery circuit is to be tested;

a battery charging event indicating that the battery circuit is to be charged;

a battery rotation event indicating that at least one of the following is to be performed—

(i) rotating one or more battery strings from a parked status into an active status,

(ii) rotating one or more battery strings from an active status to a parked status, or

(iii) both (i) and (ii); and

,

a power failure event indicating that an external power failure exists;

performing a battery test process when the detected event comprises the battery test event, wherein the battery test process comprises selectively coupling one or more battery strings to the battery circuit node for testing;

performing a battery charging process when the detected event comprises the battery charging event, wherein the battery charging process comprises selectively coupling one or more battery strings to the battery circuit node for charging;

performing a battery rotation process when the detected event comprises the battery rotation event, wherein the battery rotation process comprises at least one or both of—

selectively coupling one or more battery strings to the battery circuit node and into the active status, and

selectively decoupling one or more battery strings from the battery circuit node and into the parked status; and

,

performing a power failure handling process when the detected event comprises the power failure event, wherein the power failure handling process comprises selectively coupling one or more battery strings in the parked status to the battery circuit node to provide backup power to the radio and telecommunications circuitry at the base station.

12. The method of claim 11, wherein performing a battery charging process further comprises:

selecting a target battery string;

adjusting a voltage applied to the battery circuit node so that a voltage across one or more active battery strings coupled to the battery circuit node reaches a voltage across the target battery string, wherein the voltage applied is selected based on at least one of the following;

the voltage across the target battery string,

the voltage across one or more active battery strings,

environmental conditions in or near the battery circuit, or

types of batteries in the battery circuit;

selectively coupling the target battery string to the battery circuit node when the voltage across the one or more active battery strings approximately reaches the voltage across the target battery string;

applying a charging voltage to the battery circuit node, wherein the charging voltage is selected on the basis of at least one of the following;

types of batteries in the battery circuit, or

temperature in or near the battery circuit; and

,

simultaneously topping off a charge on multiple battery strings by;

repeatedly performing the following to connect multiple battery strings to the battery circuit node;

identifying a new target battery string;

selecting and applying a voltage to the battery circuit node to cause the voltage across one or more battery strings that are coupled to the battery circuit node to reach the voltage across the new target battery string; and

selectively coupling the new target battery string to the battery circuit node when the voltage across the one or more coupled battery strings approximately reaches the voltage across the new target battery string; and

applying a float voltage simultaneously to the multiple connected battery strings.

13. The method of claim 11, wherein performing a battery charging process further comprises:

selecting a target battery string;

adjusting a voltage that is applied to the battery circuit node so that a voltage across one or more active battery strings that are coupled to the battery circuit node reaches a voltage across the target battery string, wherein the voltage applied is selected based on at least one of the following;

the voltage across the target battery string, the voltage across one or more active battery strings, environmental conditions of the battery circuit, and types of batteries in the battery circuit;

selectively coupling the target battery string to the battery circuit node when the voltage across the one or more active battery strings approximately reaches the voltage across the target battery string;

applying a charging voltage to the battery circuit node in a current limiting mode, wherein the charging voltage is selected on the basis of at least one of the following;

types of batteries in the battery circuit and temperature of the battery circuit.

14. The method of claim 11, wherein a battery test process and a battery charging process are substantially simultaneously performed, and which further comprise:

selecting a target battery string;

adjusting a voltage applied to the battery circuit node to equalize a voltage across one or more active battery strings coupled to the battery circuit node and a voltage across the target battery string, wherein the voltage applied is selected based on at least one of the following;

the voltage across the target battery string,

the voltage across one or more active battery strings,

environmental conditions near the battery circuit, or

types of batteries in the battery circuit;

selectively coupling the target battery string to the battery circuit node when the voltage across the one or more active battery strings approximately reaches the voltage across the target battery string;

applying a charging voltage to the battery circuit node, wherein the charging voltage is based on a type of battery in the battery circuit or environmental conditions at or near the battery circuit; and

utilizing the string sense signal associated with the target battery string to determine whether the target battery string experiences anomalous currents in response to the applied charging voltage.

15. The method of claim 11, wherein the detected event comprises a battery charging event, and the detected battery charging event comprises a voltage of a battery string in the battery circuit falling below a threshold value, wherein the threshold value corresponds to a particular level of estimated charge stored in the battery string.

16. The method of claim 11, wherein the detected event comprises the battery charging event, and the detected battery charging event comprises:

a current time occurring within an off-peak time period when commercial utility power rates are lower than rates for other periods; and

a voltage of a battery string in the battery circuit falling below a threshold value, wherein the threshold value corresponds to a selected level of estimated charge stored in the battery string.

17. The method of claim 11, wherein selectively coupling a battery string to the battery circuit node comprises:

adjusting a voltage across one or more other battery strings coupled to the battery circuit node to approximately equal a voltage across the battery string to be selectively coupled; and

utilizing a string connection switch to selectively couple the battery string to the battery circuit node when the voltage across the one or more other battery strings approximately equals the voltage across the battery string that is to be selectively coupled.

18. The method of claim 11, wherein performing a battery test process further comprises:

selecting a target battery string;

selectively coupling the target battery string to the battery circuit node; and

utilizing the string sense signal associated with the target battery string to determine whether the target battery string experiences anomalous currents in response to a charging source applied to the battery circuit node, and comparing currents in the target battery string to currents in other battery strings in the battery circuit.

19. The method of claim 11, wherein performing a battery test process further comprises selecting a target battery string, selectively coupling the target battery string to the battery circuit node, and utilizing the string sense signal associated with the target battery string to determine whether the target battery string has a substantially different charging, discharging, or self-discharging rate as compared to one or more other battery strings in the battery circuit.

20. The method of claim 11, wherein performing a battery test process further comprises selecting a target battery string via an electronically resettable breaker positioned in serial with the one or more batteries of the target battery string, selectively coupling the target battery string to the battery circuit node, and utilizing the electronically resettable breaker to determine whether the target battery string has failed.

21. The method of claim 11, wherein the detected event comprises a battery test event, and the detected battery test event comprises a voltage of a battery string in the battery circuit falling below a threshold value, wherein the threshold value corresponds to a particular level of estimated charge stored in the battery string.

22. The method of claim 11, wherein performing a battery rotation process further comprises selecting a battery string to rotate into an active status, wherein the battery string is selected by determining which battery string in the battery circuit has a lowest accumulated time in active status.