Microcontrolled battery charger

• US 5,998,966 A
• Filed: 03/20/1998
• Issued: 12/07/1999
• Est. Priority Date: 03/14/1997
• Status: Expired due to Term

• Current Assignee: ICC-Nexergy, Inc
• Original Assignee: International Components Corporation (ICC-Nexergy, Inc)
• Inventors: Gaza, Brian Scott
• Primary Examiner(s): Tso, Edward H.
• Application Number:
  US09/045,381
• Time in Patent Office: 627 Days
• Field of Search: 320/116, 320/119, 320/124, 320/120, 320/132, 320/136, 320/139, 320/141, 320/144, 320/145, 320/FOR 116, 320/FOR 118, 320/FOR 120, 320/FOR 138 , 320/FOR 148
• US Class Current: 320/116
• CPC Class Codes: H01M 10/446 Initial charging measures
• CPC Class Codes: H02J 7/00036 Charger exchanging data with battery
• CPC Class Codes: H02J 7/00041 in response to measured battery parameters, e.g. voltage, current or temperature profile
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0049 Detection of fully charged condition
• CPC Class Codes: H02J 7/00712 the cycle being controlled or terminated in response to electric parameters
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A battery charger for use with different types of batteries, such as batteries requiring constant current charging, such as nickel cadmium (NiCd) and nickel metal hydride (NiMH) batteries, as well as batteries which not only require constant current charging, but also require constant voltage charging, such as lithium ion batteries. The battery charger includes a pulse width modulator circuit for controlling a power transistor to provide a constant current or a constant voltage output as a function of the battery characteristics. The battery charger may include dual pockets for charging two modular batteries on a time division multiplex basis. In the dual pocket application, power is divided between the two pockets as a function of the charging characteristics of the battery and the power dissipation of the power transistors used for supplying charging current to the pockets.

Claims

1. A battery charger connected to a predetermined power supply for providing constant current and constant voltage charging, the battery charger comprising:

a power transistor connected between the power supply and a battery to be charged;

means for controlling said power transistor, said controlling means including a microprocessor coupled to said power transistor, said microprocessor including,

a plurality of input ports coupled to said power transistor, for enabling the current and voltage of said power transistor to be sensed to enable said microprocessor to calculate the power dissipation of said power transistor; and

one or more output ports, one of said output ports coupled to said power transistor for controlling said power transistor to provide constant current and constant voltage to said battery to be charged as a function of the power dissipation of said power transistor.

2. A battery charger as recited in claim 1, wherein one of said output ports is coupled to the base of said power transistor for switching said power transistor to control the power dissipation of said power supply.

3. A battery charger as recited in claim 2, further including a pulse width modulator (PWM) coupled to the base of said power transistor, said PWM being controlled by said output ports.

4. A battery charger as recited in claim 3, wherein said pulse width modulator (PWM) includes a PWM transistor having base, collector and emitter terminals, said PWM transistor being coupled to said one of said output ports of said microprocessor via a resistor and a capacitor, said resistor and capacitor defining an RC time constant.

5. A battery charger as recited in claim 4, wherein said one of said output ports of said microprocessor is coupled to said PWM transistor and drives said PWM transistor via said resistor and said capacitor in accordance with said RC time constant, said PWM transistor being coupled to said power transistor for controlling said power transistor.

6. A battery charger as recited in claim 5, wherein said pulse width modulator (PWM) output controls the operating region of said power transistor.

7. A battery charger as recited in claim 6, wherein the collector current of said pulse width modulator (PWM) transistor controls said power transistor.

8. A battery charger as recited in claim 7, wherein the collector current of said pulse width modulator (PWM) transistor and said power transistor are controlled by said pulse width modulator (PWM) output in linear operating regions to provide either constant current or constant voltage charging.

9. A battery charger as recited in claim 3, wherein said predetermined input signal is a signal generated at predetermined time periods.

10. A battery charger as recited in claim 9, wherein said RC time constant is selected to be relatively larger than said predetermined time periods.

11. A battery charger as recited in claim 9, wherein said microprocessor continuously measures various battery parameters, such as battery voltage, current and temperature during completion of each of said predetermined time periods.

12. A battery charger as recited in claim 9, wherein said predetermined time period is an interrupt cycle of said microprocessor.

13. A battery charger as recited in claim 12, wherein said microprocessor continuously measures various battery parameters such as battery voltage, current and temperature upon completion of each of said interrupt cycles.

14. A circuit for providing current and voltage regulation, comprising:

a power transistor;

means for controlling said power transistor, said controlling means including a microprocessor coupled to said power transistor, said microprocessor including,

a plurality of input ports coupled to said power transistor, for enabling the current and voltage of said power transistor to be sensed to enable said microprocessor to calculate the power dissipation of said power transistor; and

one or more output ports, one of said output ports coupled to said power transistor for controlling said power transistor to provide constant current and constant voltage, said microprocessor driving a pulse width modulator (PWM) with said one of said output ports.

15. A circuit as recited in claim 14, further including a pulse width modulator (PWM) including a PWM transistor having base, collector and emitter terminals, said PWM transistor being coupled to said one of said output ports of said microprocessor via a resistor and a capacitor, said resistor and capacitor defining an RC time constant.

16. A circuit as recited in claim 15, wherein said one of said output ports of said microprocessor is coupled to said PWM transistor and drives said PWM transistor via said resistor and said capacitor in accordance with said RC time constant, said PWM transistor being coupled to said power transistor for controlling said power transistor.

17. A circuit as recited in claim 16, wherein said one of said input ports receives predetermined input signals generated at predetermined time periods.

18. A circuit as recited in claim 17, wherein said RC time constant is selected to be relatively larger than said predetermined time periods.

19. A circuit as recited in claim 18, wherein said predetermined time period is an interrupt cycle of said microprocessor.

20. A circuit as recited in claim 19, wherein said pulse width modulator (PWM) output controls the operating region of said power transistor.

21. A circuit as recited in claim 20, wherein the collector current of said pulse width modulator (PWM) transistor controls said power transistor.

22. A circuit as recited in claim 20, wherein the collector current of said pulse width modulator (PWM) transistor and said power transistor are controlled by said pulse width modulator (PWM) output in linear operating regions to provide either constant current or constant voltage charging.

23. A battery charger for providing current and voltage regulation, comprising:

a power supply for supplying a predetermined supply voltage;

a power transistor connected between the power supply and a battery to be charged;

a pulse width modulator (PWM) for controlling said power transistor; and

an external signal driving said pulse width modulator (PWM) and causing the predetermined supply voltage from said power supply to be connected to the battery as a function of the value of the external signal.

24. A battery charger as recited in claim 23, wherein said pulse width modulator (PWM) includes a PWM transistor having base, collector and emitter terminals, said PWM transistor being coupled to said external signal via a resistor and a capacitor, said resistor and capacitor defining an RC time constant.

25. A battery charger as recited in claim 24, wherein said external signal is coupled to said PWM transistor and drives said PWM transistor via said resistor and said capacitor in accordance with said RC time constant, said PWM transistor being coupled to said power transistor for controlling said power transistor.

26. A battery charger as recited in claim 25, wherein said pulse width modulator (PWM) output controls the operating region of said power transistor.

27. A battery charger as recited in claim 26, wherein the collector current of said pulse width modulator (PWM) transistor controls said power transistor.

28. A battery charger as recited in claim 27, wherein the collector current of said pulse width modulator (PWM) transistor and said power transistor are controlled by said pulse width modulator (PWM) output in linear operating regions to provide either constant current or constant voltage charging.

29. A battery charger as recited in claim 24, wherein said external signal is a signal generated at predetermined time periods.

30. A battery charger as recited in claim 29, wherein said RC time constant is selected to be relatively larger than said predetermined time periods.

31. A multipocket battery charger connected to a predetermined power supply, the battery charger comprising:

a first pocket for receiving a first battery;

a first power transistor connected between said power supply and said first pocket;

a second pocket for receiving a second battery;

a second power transistor connected between said power supply and said second pocket;

means for controlling said power transistors, said controlling means including a microprocessor coupled to said power transistors, said microprocessor including,

a plurality of input ports coupled to said power transistors, for enabling the current and voltage of said power transistors to be sensed to enable said microprocessor to calculate the power dissipation of said power supply; and

one or more output ports, one of said output ports coupled to said power transistors for controlling said first power transistor and said second power transistor so that the electrical power supplied to said first pocket and said second pocket is a function of the power dissipation of said power supply.

32. A battery charger as recited in claim 31, comprising a transistor having base, collector and emitter terminals, said transistor being coupled to said one of said output ports of said microprocessor via a resistor and a capacitor, said resistor and capacitor defining an RC time constant.

33. A battery charger as recited in claim 31, further including a pulse width modulator (PWM) driven by said one of said output ports, and wherein said one of said input ports receives predetermined input signals.

34. A battery charger as recited in claim 33, wherein said predetermined input signal is a signal generated at predetermined time periods.

35. A battery charger as recited in claim 33, wherein said RC time constant is selected to be relatively larger than said predetermined time periods.