BATTERY DISCHARGE CURRENT SHARING IN A TIGHTLY REGULATED POWER SYSTEM

• US 20080258685A1
• Filed: 04/17/2007
• Published: 10/23/2008
• Est. Priority Date: 04/17/2007
• Status: Active Grant

• Current Assignee: The Boeing Co.
• Original Assignee: The Boeing Co.
• Inventors: CHOY, WINNIE
• Granted Patent: US 7,589,498 B2
• Time in Patent Office: Days
• US Class Current: 320/132
• CPC Class Codes: H02J 1/102 being switching converters H02J1/108, H02J1/12 take precedence
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/00714 in response to battery charging or discharging current

Abstract

In a high power system, plural batteries provide back-up power when primary power is unavailable. Each battery has an associated discharge controller which is controlled by a local bus control amplifier which regulates the power bus voltage set-point lower than the main bus voltage set-point. A single main bus control amplifier tightly regulates the power bus to a main bus voltage set-point and controls charging and discharging of all batteries to prevent charging of one battery at the expense (discharge) of another battery. There is one master battery discharge controller, with the remaining controllers being slave units. A local bus voltage set-point of each slave unit varies under the control of a slave unit current sharing amplifier which compares its own discharge current to the average discharge current, and an error signal modifies the reference voltage in the local bus control amplifier to allow equal discharge current from all batteries.

Claims

1. A system for regulating primary power and back-up power to a main bus, the system comprising;

a primary power source;

a primary power regulator;

a plurality of back-up power regulators each including;

a battery; and

a control amplifier configured to regulate power provided by the battery to the main power bus when the voltage on the main power bus drops below a voltage set-point;

a main control amplifier connected to the control amplifier in each of the back-up power regulators; and

a discharge current sharing amplifier for causing the discharge current of the battery of one of the back-up power regulators to be substantially equal to the average discharge current of the batteries of all of the back-up power regulators.

2. The system of claim 1 wherein said main control amplifier provides a first control signal to the control amplifier in each of the back-up power regulators for establishing a voltage set-point on the main power bus when the primary power source is not available.

3. The system of claim 2 wherein said main control amplifier is further coupled to said primary power regulator for establishing a voltage set-point on the main power bus when the primary power source is available.

4. The system of claim 3 wherein said main control amplifier provides a second control signal to said primary power regulator for establishing the voltage set-point on the main power bus when the primary power source is available and wherein said first and second control signals are of opposite sign.

5. The system of claim 4 wherein said main control amplifier compares a main power bus voltage sense signal with a main bus reference voltage signal in generating sent first and second control signals.

6. The system of claim 1 wherein each back-up power regulator further includes a local bus coupling its associated battery to the main power bus, and wherein the control amplifier of each back-up power regulator compares a main power bus voltage sense signal with a respective local bus reference voltage signal combined with said first control signal in regulating the local bus voltage to the main power bus voltage set-point.

7. The system of claim 6 wherein each back-up power regulator further include a respective discharge current sensor connecting its associated battery to a current sharing amplifier for providing an indication of battery current to the current sharing amplifier.

8. The system of claim 7 wherein each back-up power regulator further includes a discharge controller for preventing the discharge of a battery when any other battery is charging.

9. The system of claim 8 wherein each discharge controller disposed in a respective back-up power regulator is coupled to the battery and control amplifier in that back-up power regulator and is further coupled to the main power bus.

10. The system of claim 1 wherein said system powers a spacecraft.

11. The system of claim 1 wherein said system powers an aircraft.

12. A system for regulating primary power and back-up power to a main power bus, the system comprising:

a primary power source;

a primary power regulator;

a plurality of back-up power regulators each including;

a local bus;

a battery; and

a local control amplifier configured to regulate power provided by the battery via said local bus to the main power bus when the voltage on the main power bus drops below a voltage set-point;

a main control amplifier connected to the local control amplifier in each of the back-up power regulators; and

a discharge current sharing amplifier disposed in each of said back-up power regulators for comparing an output current of its associated battery with the average output current of all of the batteries for adjusting a local bus voltage set-point for causing its associated battery discharge current to be equal to the average output current of all of the batteries to equalize the load on all discharging batteries, and wherein said discharge current sharing amplifier is coupled to said local control amplifier for providing a voltage adjustment signal to said local control amplifier for adjusting the local bus voltage set-point on each of said local buses.

13. The system of claim 12 wherein said primary power regulator is coupled to said main control amplifier and responsive to a signal output by said main control amplifier for regulating voltage in the main power bus when the primary power source is available.

14. The system of claim 12 wherein said primary power regulator and each of said back-up power regulators compares a local bus sense signal with a respective local bus reference voltage signal combined with a control signal output by said main control amplifier in regulating local bus voltage provided to the main power bus.

15. The system of claim 14 wherein said control signal is a first sign for regulating voltage provided by the primary power source to the main power bus and is a second sign for regulating voltage provided by said back-up power regulators to the main power bus.

16. A system for regulating primary power and back-up power to a main power bus, the system comprising:

a primary power source;

a primary power regulator connecting the primary power source to the main power bus;

a plurality of back-up power regulators each including;

a local bus;

a battery; and

a local control amplifier configured to regulate power provided by the battery via said local bus to the main power bus when the voltage on the main power bus drops below a voltage set-point;

a main control amplifier connected to the primary power regulator and to the local control amplifier in each of the back-up power regulators for outputting a first signal for establishing a main power bus voltage when the primary power source is available and for outputting a second signal to the local control amplifiers for controlling the discharge and charge of the batteries; and

a discharge current sharing amplifier in each of the back-up power regulators for causing the discharge current of the battery in each of the back-up power regulators to be substantially equally to the average discharge current of all of the batteries.

17. The system of claim 16 further comprising means for generating a third signal representing the average discharge current of all of the batteries, and wherein the regulated power provided by each of the batteries to the main power bus is based on said second and third signals.

18. The system of claim 17 further comprising current sensing and amplification means coupling a battery and a local control amplifier in each back-up power regulator for comparing the average discharge current of the plural batteries with its associated battery discharge current and adjusting the voltage set-point of the battery discharge controller so as to match the average discharge current of the plural batteries.

19. The system of claim 18 further comprising means for generating a difference signal representing a difference between the average discharge current of the plural batteries and the discharge current one of the batteries.

20. The system of claim 19 wherein when said second signal allows all of the batteries to discharge while simultaneously preventing the charging of any of the batteries.

21. A system for regulating primary power and back-up power to a main power bus, the system comprising;

a primary power source;

a primary power regulator connecting the primary power source to the main power bus;

a plurality of back-up power regulators each including;

a local bus;

a battery; and

a local control amplifier configured to regulate power provided by the battery to the main power bus via the local bus when the voltage on the main power bus drops below a voltage set-point;

a main control amplifier for providing a first signal for establishing a main bus voltage set-point to regulate main power bus voltage and enable plural battery charging, when the primary power source is available, and for providing a second signal to allow the discharge of and inhibit the charging of the batteries when the back-up power regulators provide power to the main power bus; and

a discharge current sharing amplifier in each of the back-up power regulators for causing the discharge current of the battery in each of the back-up power regulators to be substantially equal to the average discharge current of all of the batteries.