CONTROL SYSTEM FOR BATTERY CHARGE MAINTENANCE IN A POWER SYSTEM WITH MAIN AC GENERATOR CONTROL

• US 20110115426A1
• Filed: 11/18/2009
• Published: 05/19/2011
• Est. Priority Date: 11/18/2009
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: LAZAROVICH, DAVID, RUSAN, ILEANA, MICHALKO, RODNEY
• Granted Patent: US 8,314,588 B2
• Time in Patent Office: Days
• US Class Current: 320/107
• CPC Class Codes: B64D 2221/00 Electric power distribution systems onboard aircraft
• CPC Class Codes: H02J 2310/44 for aircrafts
• CPC Class Codes: H02J 7/1438 in combination with power supplies for loads other than batteries

Abstract

An electrical power system may comprise an AC generator and a generator control unit (GCU) for varying AC output voltage of the AC generator. A DC bus may be connected to the AC generator via a Transformer Rectifier Unit (TRU) so that DC voltage on the DC bus is directly proportional to the AC output voltage. A battery may be connected directly to the DC bus. A control loop may be connected to receive battery current information and provide control signals to vary the AC output voltage so that battery charge may be maintained without battery damage.

Claims

1. An electrical power system comprising:

an AC generator;

a generator control unit (GCU) for varying AC output voltage of the AC generator;

a DC bus connected to the AC generator so that DC voltage on the DC bus is directly proportional to the AC output voltage;

a battery connected directly to the DC bus; and

a control loop connected to receive battery current information and provide control signals to vary the AC output voltage so that battery charge is maintained without battery damage.

2. The electrical power system of claim 1 further comprising an AC bus for distributing AC power from the AC generator to the DC bus and to other AC loads.

3. The electrical power system of claim 2 further comprising a limiter for limiting variation of AC output voltage to a range that is suitable for the other AC loads.

4. The electrical power system of claim 1 wherein:

the GCU is connected to control the AC output voltage responsively to a reference voltage; and

the control loop is connected to produce signals to vary the reference voltage.

5. The electrical power system of claim 1 wherein the control loop comprises:

a DC bus voltage comparator connected to compare DC voltage on the DC bus with a reference DC voltage and to produce a DC bus voltage correction signal;

a battery adjustment comparator interconnected with the DC bus voltage comparator to compare the DC bus voltage correction signal with battery charging current data and produce a first modified DC bus voltage correction signal; and

wherein the GCU is connected to vary the AC output voltage responsively to the first modified DC bus voltage correction signal.

6. The electrical power system of claim 5 wherein the control loop further comprises:

a battery maximum charge comparator connected to compare a battery current signal with a reference battery maximum charge current and produce a first battery charging current data signal to the battery adjustment comparator;

a battery maximum discharge comparator connected to compare a battery current signal with a reference battery maximum discharge current and produce a second battery charging current data signal to the battery adjustment comparator.

7. The electrical power system of claim 6 further comprising limiters positioned between the battery maximum charge comparator and the battery adjustment comparator and between the battery maximum discharge comparator and the battery adjustment comparator.

8. The electrical power system of claim 1 wherein the control loop comprises:

a DC bus voltage comparator connected to compare DC voltage on the DC bus with a reference DC voltage and to produce a DC bus voltage correction signal;

a battery adjustment comparator interconnected with the DC bus voltage comparator to compare the DC bus voltage correction signal with battery charging current data and produce a first modified DC bus voltage correction signal;

a battery temperature comparator interconnected with the battery adjustment comparator to compare the first modified DC bus voltage correction signal with battery temperature data and produce a second modified DC bus voltage correction signal; and

wherein the GCU is connected to vary the AC output voltage responsively to the second modified DC bus voltage correction signal.

9. The electrical power system of claim 1 further wherein the DC bus is connected to DC loads other than the battery.

10. The electrical power system of claim 1 wherein:

the GCU comprises a comparator connected to receive AC output voltage information and compare the AC output voltage information with a reference voltage signal; and

the comparator is interconnected with the control loop so that the reference voltage signal is varied as a function of battery charging requirement.

11. A method for operating an electrical power system comprising the steps of:

generating AC power at a voltage that corresponds to an AC reference voltage;

converting the AC power to DC power;

applying the DC power to a DC bus;

connecting a battery directly to the DC bus;

charging the battery with a desired charging regimen; and

varying the AC reference voltage to vary DC voltage on the DC bus so that the desired charging regimen is applied to the battery.

12. The method of claim 11 further comprising the step of connecting varying DC loads to the DC bus so that DC current on the bus varies.

13. The method of claim 11 wherein the step of charging the battery with a desired regimen comprises charging the battery with a varying voltage so that a constant-current charging of the battery is performed irrespective of any changes in battery impedance.

14. The method of claim 11 further comprising the steps of:

applying the AC power to an AC bus prior to converting the AC power to DC power;

connecting AC loads to the AC bus; and

controlling variations of AC voltage on the AC bus to a range of voltages that are suitable for operation of the AC loads.

15. The method of claim 11 wherein the reference voltage is varied as a function of battery charging current.

16. The method of claim 11 wherein the reference voltage is varied as a function of temperature of the battery.

17. A method of maintaining charge on a battery in an aircraft comprising the steps of:

connecting the battery directly to a DC bus of the aircraft;

providing power to the DC bus from an AC generator of the aircraft; and

varying output voltage of the AC generator responsively to battery charging requirements.

18. The method of claim 18 wherein the step of varying the output voltage comprises varying a reference voltage of a generator control unit (GCU) of the aircraft.

19. The method of claim 18 wherein the step of varying the output voltage further comprises:

comparing DC voltage on the DC bus to a reference DC voltage; and

producing a DC bus voltage correction signal;

employing the DC bus voltage correction signal as a parameter for varying the reference voltage.

20. The method of claim 19 wherein the step of varying the output voltage further comprises:

comparing the DC bus voltage correction signal DC voltage to a battery charging current signal and producing a first modified DC bus voltage correction signal;

comparing the first modified DC bus voltage correction signal DC voltage to a battery temperature signal and producing a second modified DC bus voltage correction signal;

employing the second modified DC bus voltage correction signal as a parameter for varying the reference voltage.