BATTERY CHARGING SYSTEM FOR EMERGENCY BATTERY SYSTEMS

• US 3,784,892 A
• Filed: 05/20/1971
• Issued: 01/08/1974
• Est. Priority Date: 05/20/1971
• Status: Expired due to Term

• Current Assignee: Cooper Industries, Inc. (Eaton Corporation PLC.)
• Original Assignee: William B. Zelina
• Inventors: Zelina, William B.
• Primary Examiner(s): Trammell, James D.
• Assistant Examiner(s): Hickey, Robert J.
• Application Number:
  US05/145,388
• Time in Patent Office: 964 Days
• Field of Search: 320/39,40,56,59 307/66,46 317/4A,151
• US Class Current: 320/132
• CPC Class Codes: H02J 7/007182 in response to battery voltage

Abstract

A completely static battery charging system which recognizes the battery charged state and also the battery operating temperature where a solid state valve is used to isolate the battery from the load; said valve rendered conductive instantly when the load voltage drops below a predetermined value. Means is included for decreasing the charge rate to the float voltage that will maintain full charge on the battery at all temperatures after it has been fully charged. Protective means is included to prevent either battery or system damage should an abnormal battery condition develop, said protective means including individual shorted cells, improper solution level, abnormal battery impedance, and poor electrical connections either in the individual cells or the interconnecting electrical connections.

Claims

1. In an emergency battery charging system adapted to be connected to and disconnected from a load and adapted to control the voltage and current delivered to a battery in said circuit from a power source, in combination, a battery, said battery being adapted to be connected to a load, battery charging means, a source of system voltage for said load, first electronic valve isolation means for blocking electrical current from said battery to said load, and means for triggering said first electronic valve isolation means into conductive state when said system voltage drops below a predetermined value, said first electronIc valve isolation means having means retaining it in conductive state until said source of system voltage reaches a predetermined value, said batttery charging means including second electronic valve means having a control element, said second electronic valve means connecting said battery charging means to said battery and logic means connected to said control element of said second electronic valve means for rendering said battery charging means inoperative when said first electronic valve isolation means is conductive.

2. The combination recited in claim 1 wherein said valve means comprises a silicon-controlled rectifier, and said sensing means comprises decision and logic means adapted to generate the necessary signal into said charger limiting means for controlling said battery charger.

3. The combination recited in claim 2 wherein said source of system voltage comprises a three phase stepdown transformer, and rectifier means for converting an AC voltage to said system voltage.

4. The combination recited in claim 1 wherein said battery charging means comprises a charger control means connected to said system voltage, said charger control means being capable of producing a variable output voltage, and means connected to said charger control means for varying said output voltage between a maximum voltage and a minimum voltage, said voltages being actuated by means producing a maximum phase angle and a minimum phase angle of the said AC source voltage.

5. The combination recited in claim 2 wherein a filter choke is provided connected to said battery charger and to said isolation means whereby a smoothing action of said charging current delivered to said battery is provided, said filter choke having a sensing winding connected to said battery for providing information to the charging system on the level of current demanded by the said battery under float voltage condition.

6. The combination recited in claim 5 wherein a current sensing shunt is connected in series with said choke and said battery, said sensing shunt has means sensing the charging current flowing into the said battery, said sensing shunt being connected to means to continue said charging rate to said battery for a predetermined time.

7. The combination recited in claim 6 wherein a current limiting reference and amplifier are connected to said current measuring shunt whereby the charging rate of said battery charger is limited when said battery reaches a fully charged condition.

8. The combination recited in claim 1 wherein a battery temperature sensing means is connected to said battery charging means whereby the charging rate of said battery charger is limited when the temperature of the water in said battery exceeds a predetermined amount.

9. The circuit recited in claim 8 wherein said valve means comprises a silicon control rectifier and said silicon control rectifier is connected to said sensing decision and logic circuit.

10. The circuit recited in claim 9 wherein said source of charging voltage includes means to vary the output voltage of said charging voltage source.

11. The circuit recited in claim 10 wherein said means to vary said output voltage of said charging voltage source comprises means to change the phase angle of the firing circuit to said silicon control rectifier to maintain a battery connected to said circuit at a predetermined voltage.

12. The circuit recited in claim 11 wherein a float voltage means is connected to said battery.

13. The circuit recited in claim 12 wherein said voltage sensing means is connected to said silicon control rectifier for isolating said battery from said load when said battery charging voltage is connected to said battery.

14. The circuit recited in claim 13 wherein a current sensing shunt is connected in series with said battery charging voltage and said battery, and current limiting means is connected to said current sensing shunt to connect its outpuT to a second silicon control rectifier connected in said circuit to limit the charging current when said charging voltage exceeds a predetermined value.

15. The circuit recited in claim 13 wherein said means connected to said current sensing shunt has means to control said second silicon control rectifier to deliver a constant current to said battery thereby restoring said battery charge in an optimum time.

16. The circuit recited in claim 15 wherein a temperature sensing means is provided to sense the temperature of a battery connected to said source of charging voltage, said temperature sensing means being connected to said second silicon control rectifier and adapted to reduce said charging voltage when said battery voltage exceeds a predetermined value.

17. The combination recited in claim 13 wherein a circuit means is provided to disconnect unessential loads from said power source when the voltage of said power source drops below a predetermined value. and voltage sensing means connected to said battery isolation means and to said system voltage, and charger limiting means connected to said battery charging means for shutting off said charger when said system voltage falls below a predetermined value, said battery isolation means being controlled by said voltage sensing means connecting said battery to said load means and turning off said charging means when said system voltage drops below a predetermined value and disconnecting said battery from said load means and turning on said battery charging means when said system voltage exceeds said battery voltage by a predetermined value whereby said load is protected from said battery charging voltage.

18. In an emergency battery charging system adapted to be connected to and disconnected from a load and adapted to control the voltage and current delivered to a battery in said circuit from a power source, in combination, a battery, said battery being adapted to be connected to a load, battery charging means, a source of system voltage for said load, first electronic valve isolation means for blocking electrical current from said battery to said load, and means for triggering said first electronic valve isolation means into conductive state when said system voltage drops below a predetermined value, said first electronic valve isolation means having means retaining it in conductive state until said source of system voltage reaches a predetermined value, said battery charging means including second electronic valve means having a control element, said second electronic valve means connecting said battery charging means to said battery and logic means connected to said control element of said second electronic valve means sensitive to the conductive state of said first electronic valve isolation means for rendering said battery charging means inoperative when said first electronic valve isolation means is conductive.

19. The system recited in claim 18 wherein a voltage reference means is connected to said battery charging means and said voltage reference means controlling said control circuit means and having a first portion establishing a first reference value related to a first battery voltage and a second portion establishing a second reference value related to a preselected higher battery voltage, battery voltage sensing circuit means coupled to said voltage reference means, voltage control circuit means coupled to said voltage reference means and responsive to said battery voltage sensing circuit means for coupling said second portion in effective circuit relationship in the voltage reference means whereby said control circuit means is selectively controlled at said second reference value upon the battery voltage falling below the first battery voltage value and is maintained at said second reference value until said battery attains a preselected higher voltage value.