High frequency battery charger and method of operating same

• US 20030141845A1
• Filed: 10/15/2002
• Published: 07/31/2003
• Est. Priority Date: 01/25/2002
• Status: Active Grant

• Current Assignee: Vector Products Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Vector Products Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Vetitoe, Rov Scott, Krieger, Michael, Randolph, Bruce
• Granted Patent: US 6,822,425 B2
• Time in Patent Office: Days
• US Class Current: 320/132
• CPC Class Codes: H02J 7/00 Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
• CPC Class Codes: H02J 7/007 Regulation of charging or discharging current or voltage
• CPC Class Codes: H02J 7/342 The other DC source being a battery actively interacting with the first one, i.e. battery to battery charging with circuits for polarity protection H02J7/0034

Abstract

A high frequency charger includes a charge circuit for charging a depleted battery and a boost circuit for jump-starting a vehicle. Two separate high frequency transformers are provided for the charge and boost circuits. A selector switch selectively activates at least one of the charging circuit and the boost circuit.

Claims

1. A high frequency charger for charging a battery, comprising:

a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency;

a filter coupled to the first and second high frequency transformers for passing a DC voltage signal;

means for measuring a charge rate of the battery;

means for determining an amount of time the battery has been charging;

means for measuring a voltage of the battery; and

means for detecting an overtime fault if the charge rate is greater than a predetermined current, the battery has been charging longer than a predetermined amount of time, and the voltage of the battery is greater than or equal to a predetermined voltage.

2. The charger claim 1, further comprising a display and wherein the overtime fault is visually indicated on the display.

3. The charger claim 2, wherein the predetermined current is 2 amps, the predetermined time is 18 hours, and the predetermined voltage is 12 volts.

4. A high frequency charger for charging a battery, comprising:

a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency;

a filter coupled to the first and second high frequency transformers for passing a DC voltage signal;

means for measuring a charge rate of the battery;

means for determining an amount of time the battery has been charging;

means for measuring a voltage of the battery; and

means for detecting a shorted cell battery fault if the charge rate is greater than a predetermined current, the battery has been charging more a predetermined amount of time, and the voltage of the battery is less than or equal to a predetermined voltage.

5. The charger claim 4, further comprising a display and wherein the shorted cell fault is visually indicated on the display.

6. The charger claim 4, wherein the predetermined time is 1 hour, and the predetermined voltage is 11 volts.

7. A high frequency charger for charging a battery, comprising:

a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency;

a filter coupled to the first and second high frequency transformers for passing a DC voltage signal;

clamps for connecting the charger to the battery;

means for measuring a voltage at the clamps;

means for indicated a bad battery fault if no voltage is detected at the clamps.

8. The charger claim 7, further comprising a display and wherein the bad battery fault is visually indicated on the display.

9. A high frequency charger for charging a battery, comprising:

a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency;

a filter coupled to the first and second high frequency transformers for passing a DC voltage signal;

means for measuring a charge current of the battery;

means for determining an amount of time the battery has been charging;

means for measuring a voltage of the battery; and

means for detecting an open cell battery fault if the charge current is less than a predetermined current, the battery has been charging more a predetermined amount of time, and the voltage of the battery is greater than or equal to a predetermined voltage.

10. The charger of claim 9, further comprising a display and wherein the open cell fault is visually indicated on the display.

11. A computer-readable information storage medium for use with a computer controlling a high frequency charger comprising a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency;

a boost circuit including a second high frequency transformer;

a second switch switching the second high frequency transformer at a second frequency, and a selector for selecting one of a charge mode for charging a depleted battery and a boost mode for supplying a boosting current to start a vehicle with the depleted battery, the computer-readable information storage medium storing computer-readable program code for causing the computer to perform the steps of;

detecting a selected mode of operation;

if the boost mode is selected, controlling the boost circuit to supplying a boosting current to the depleted battery;

checking for a rapid rise in voltage after the vehicle has been started;

indicating the alternator is working properly if the rapid rise in voltage is present; and

indicating the alternator is not working properly if the rapid rise in voltage is not present.

12. The computer readable memory of claim 11 further comprising code for causing the computer to perform the step of displaying a status of the alternator on a display.

13. A computer-readable information storage medium for use with a computer controlling a high frequency charger comprising a charge circuit including a high frequency transformer;

a switch switching the high frequency transformer at a predetermined frequency, the computer-readable information storage medium storing containing software implementing a method of reducing arcing in a battery charger, the method comprising the steps of;

providing a test current that is lower than a charging current from the battery charger to a battery;

detecting if the test current is present at the battery;

indicating a fault if the test current is not detected at the battery; and

increasing the test current a predetermined amount and returning to the detecting step if the test current is detected at the battery.

14. A computer-readable information storage medium for use with a computer controlling a high frequency charger for charging a battery, comprising a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency;

a filter coupled to the first and second high frequency transformers for passing a DC voltage signal, the computer-readable information storage medium storing computer-readable program code for causing the computer to perform the steps of;

measuring a charge rate of the battery;

determining an amount of time the battery has been charging;

measuring a voltage of the battery; and

detecting an overtime fault if the charge rate is greater than a predetermined current, the battery has been charging longer than a predetermined amount of time, and the voltage of the battery is greater than or equal to a predetermined voltage.

15. The computer-readable information storage medium of claim 14 further comprising code for causing the computer to perform the step of visually indicating the overtime fault on a display.

16. The computer-readable information storage medium of claim 14, wherein the predetermined current is 2 amps, the predetermined time is 18 hours, and the predetermined voltage is 12 volts.

17. A computer-readable information storage medium for use with a computer controlling a high frequency charger for charging a battery, comprising a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency;

a filter coupled to the first and second high frequency transformers for passing a DC voltage signal, the computer-readable information storage medium storing computer-readable program code for causing the computer to perform the steps of;

measuring a charge rate of the battery;

determining an amount of time the battery has been charging;

measuring a voltage of the battery; and

detecting a shorted cell battery fault if the charge rate is greater than a predetermined current, the battery has been charging more a predetermined amount of time, and the voltage of the battery is less than or equal to a predetermined voltage.

18. The computer-readable information storage medium of claim 17 further comprising code for causing the computer to perform the step of visually indicating the shorted cell fault on a display.

19. The computer-readable information storage medium of claim 17, wherein the predetermined time is 1 hour, and the predetermined voltage is 11 volts.

20. A computer-readable information storage medium for use with a computer controlling a high frequency charger for charging a battery, comprising a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency;

a filter coupled to the first and second high frequency transformers for passing a DC voltage signal; and

clamps for coupling the filter to the battery, the computer-readable information storage medium storing computer-readable program code for causing the computer to perform the steps of;

measuring a voltage at the clamps;

indicating a bad battery fault if no voltage is detected at the clamps; and

proceeding with a charging operation if a voltage is detected at the clamps.

21. The computer-readable information storage medium of claim 20 further comprising code for causing the computer to perform the step of visually indicating the bad battery fault on a display.

22. A computer-readable information storage medium for use with a computer controlling a high frequency charger for charging a battery, comprising a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency, the charge circuit operating in at least one of a pulse mode and a charge mode; and

a selector for selecting one of the charge mode and the pulse mode, the computer-readable information storage medium storing computer-readable program code for causing the computer to perform the steps of;

measuring a charge current of the battery;

determining an amount of time the battery has been charging;

measuring a voltage of the battery; and

detecting an open cell battery fault if the charge current is less than a predetermined current, the battery has been charging more a predetermined amount of time, and the voltage of the battery is greater than or equal to a predetermined voltage.

23. The computer-readable information storage medium of claim 22 further comprising code for causing the computer to perform the step of visually indicating the open cell fault on a display.

24. A high frequency charger, comprising:

a charging circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency for producing a charging current for charging the depleted battery;

a boost circuit including a second high frequency transformer, separate from the first high frequency transformer; and

a second switch switching the second high frequency transformer at a second frequency for producing a relatively high boost current compared to the charging current for jump-starting the vehicle; and

a selector switch for selectively activating at least one of the charging circuit and the boost circuit.

25. The charger of claim 24, further comprising:

a filter coupled to the first and second high frequency transformers for passing a DC voltage signal.

26. The charger of claim 24, wherein the charging circuit has a charge mode and a pulse mode, and further comprising means for selectively activating one of the charge mode and the pulse mode.

27. The charger of claim 26, further comprising means coupled to the first switch for alternatingly enabling the first switch to switch the first transformer at the first frequency and disabling the first switch from switching the first transformer.

28. The charger of claim 24, further comprising:

a first controller providing a driving signal to the first switch; and

a second controller providing a driving signal to the second switch.

29. The charger of claim 28, wherein the selector switch is coupled to the first and second controllers for selectively activating at least one of the first and second controllers.

30. The charger of claim 29, wherein the charging circuit has a charge mode and a pulse mode and further comprising a selector coupled to the first controller for selecting between the charge mode and the pulse mode.

31. The charger of claim 30, further comprising an enable circuit coupled to the selector that selectively enables and disables the first controller at a predetermined rate when the pulse mode is selected.

32. The charger of claim 28, further comprising a feedback circuit connected between the depleted battery and the first controller for adjusting a duty cycle of the driving signal based on charging parameters of the depleted battery.

33. The charger of claim 25, wherein the DC signal output from the second high frequency transformer has a current of about 25-300 amps.

34. The charger of claim 25, wherein the DC signal output from the second high frequency transformer has a duration of about 3-35 seconds.

35. The charger of claim 26, wherein, in the pulse mode, the DC output signal of the charging circuit is a series of pulses.

36. The charger of claim 35, wherein the series of pulses has a rise time of less than 100 volts per microsecond.

37. The charger of claim 35, wherein the series of pulses has a frequency of about one pulse per second.

38. The charger of claim 25, further comprising:

a pair of connectors coupled to the filter and adapted for connection to a battery;

a switch coupled in between one of the connectors and the filter;

a polarity detection circuit coupled to the connectors for determining a polarity between the connectors and providing a polarity signal representing the polarity; and

a microprocessor receiving the polarity signal and generating a signal for opening or closing the switch in dependence on the polarity signal.

39. The charger of claim 38, wherein the polarity detection circuit includes an opto-isolator.

40. The charger of claim 38, wherein the switch includes a transistor.

41. The charger of claim 25, further comprising means for detecting disconnection of the connectors from the battery and opening the switch when disconnection is detected.

42. The charger of claim 28, further comprising a control circuit coupled to the first controller for setting a duty cycle of an output signal of the first controller.

43. The charger of claim 42, wherein the control circuit setting a duty cycle comprises:

an integrated circuit; and

at least two reference voltage circuits developing a reference voltage and coupled between the integrated circuit and the first controller, wherein the integrated circuit selectively enables at least one of the reference voltage circuits.

44. The charger of claim 43, wherein the integrated circuit comprises a counter.

45. The charger of claim 43, wherein each of the reference voltage circuits includes a switch that can be opened and closed in dependence on an output from the counter.

46. The charger of claim 42, wherein the control circuit setting a duty cycle comprises a voltage divider network dividing a voltage applied to a reference voltage input of the first controller and a control input of the first controller, wherein the duty cycle varies based on a percentage of the reference voltage applied to the control input.

47. The charger of claim 24, further comprising a computer for controlling the operation of the first and second switches.

48. The charger of claim 47, further comprising:

a display coupled to the computer for displaying output from the computer; and

input means coupled to the computer for permitting a user to select a mode operation.

49. The charger of claim 47, further comprising:

means for detecting at least one of a voltage and a current at an interface of the charger with a battery to be charged; and

a feedback circuit for providing the detected voltage or current to the computer.

50. The charger of claim 49, wherein the means for detecting comprises an opto-isolator for producing a voltage representing the voltage of the depleted battery while it is being charged by current from the charging circuit.

51. The charger of claim 47, wherein the charging circuit has a charge mode and a pulse mode, and further comprising means for selectively activating one of the charge mode and the pulse mode;

and a computer-readable information storage medium, the computer-readable information storage medium storing computer-readable program code for causing the computer to perform the steps of;

detecting a selected of mode of operation; and

when a pulse mode is selected;

a) generating a driving signal for the first switch for a first period of time;

b) disabling the first switch for a second period of time; and

c) returning to step a).

52. The charger of claim 47, and further comprising a computer-readable information storage medium coupled to the computer, the computer-readable information storage medium storing computer-readable program code for causing the computer to perform the steps of:

checking a flag indicating the depleted battery to be charged is in a bulk charge state or an absorption charge state;

if the battery is in the bulk charge state;

increasing a duty cycle of a driving signal for the first switch if a current provided by the battery charger is less than a desired current;

decreasing the duty cycle of the driving signal for the first switch if the current provided by the battery charger is greater than the desired current; and

setting the flag indicating the battery is in the absorption charge stage when a voltage of the battery is greater than or equal to a predetermined voltage and the battery has been charging for more than a predetermined time, otherwise ending the charging process; and

if the battery is in the absorption charge stage;

decreasing the duty cycle of the driving signal for the first switch if the voltage of the battery is greater than or equal to the predetermined voltage;

increasing the duty cycle of the driving signal for the first switch if the voltage of the battery is less than the predetermined voltage; and

stopping the charging process when the battery has been charging for more than a predetermined period of time.

53. A control circuit for a high frequency charger, comprising:

a pulse width modulation controller having a reference voltage input, a control input and an output for outputting a control signal;

a switch receiving the control signal and being switched on and off in response to the control signal, the switch adapted for connection to a transformer for switching the transformer;

a voltage divider network dividing a voltage applied to the reference voltage input and the control input, whereby a duty cycle of the control signal output from the pulse width modulation controller varies based on the percentage of the reference voltage applied to the control input.

54. The control circuit of claim 53, further comprising:

a transformer connected to the switch and being switched on and off via the switch.

55. The control circuit of claim 53, wherein the voltage divider network comprises:

a first resistor having a first terminal connected to the reference voltage input and a second terminal connected to the control input; and

a second resistor having a first terminal connected to second terminal of the first resistor and a second terminal that is grounded.

56. The control circuit of claim 53, wherein the voltage divider network comprises:

a first resistor having a first terminal connected to the reference voltage input and a second terminal connected to the control input; and

a plurality of second resistors each having a first terminal connected to the second terminal of the first resistor and a second terminal that is selectively grounded, wherein only one of the second resistors is selectively grounded at any time.

57. The control circuit of claim 56, further comprising a switch for selectively connecting the second resistors to ground.

58. The control circuit of claim 57, wherein the switch comprises a separate transistor for each of the second resistors providing a current path to ground when the transistor is turned on.

59. The control circuit of claim 53, wherein the voltage divider network comprises:

a first resistor having a first terminal connected to the reference voltage input and a second terminal connected to the control input; and

a plurality of second resistors each having a first terminal connected to the second terminal of the first resistor and a second terminal;

and further comprising a plurality of transistors each having a first electrode connected to the second terminal of one the second resistors, a second electrode that is grounded, and a third electrode receiving an enable signal.

60. The control circuit of claim 53, further comprising:

an integrated circuit having outputs, each output being connected to one of the third electrodes and providing the enable signal thereto, only one of the outputs being active at any time.

61. The control circuit of claim 60, wherein the integrated circuit comprises a counter.

62. A method of reducing arcing in a battery charger, comprising:

providing a test current that is lower than a charging current from the battery charger to a battery;

detecting if the test current is present at the battery;

indicating a fault if the test current is not detected at the battery; and

increasing the test current a predetermined amount and returning to the detecting step if the test current is detected at the battery.

63. The method of claim 62, further comprising providing a current lower than the test current to the battery and returning to the detecting step if the test current is not detected at the battery.

64. The method of claim 62, wherein the test current is increased according to a ramp function.

65. The method of claim 62, wherein the test current is increased according to a step function.

66. The method of claim 62, further comprising the step of using pulse width modulation to control the current provided from the battery charger.

67. The method of claim 62, further comprising the step of determining if the test current equals a selected current and, if so, continuing charging at the selected current, otherwise returning to the detecting step.

68. A computer-readable information storage medium for use with a computer controlling a high frequency charger comprising a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency, the charge circuit operating in at least one of a pulse mode and a charge mode; and

a selector for selecting one of the charge mode and the pulse mode, the computer-readable information storage medium storing computer-readable program code for causing the computer to perform the steps of;

detecting a selected of mode of operation input from the selector; and

when the pulse mode is selected;

a) generating a driving signal for the first switch for a first period of time;

b) disabling the first switch for a second period of time; and

c) returning to step a).

69. The computer useable information storage medium of claim 68, further comprising computer-readable program code for causing the computer to perform the step of ending the pulse mode if the battery charger has been operating in the pulse mode for more than a predetermined amount of time.

70. The computer useable information storage medium of claim 68, wherein the first period of time is about fifty microseconds.

71. The computer useable information storage medium of claim 68, wherein the second period of time is about one second.

72. A computer-readable information storage medium for use with a computer controlling a high frequency charger comprising a charge circuit including a high frequency transformer;

a switch switching the high frequency transformer at a predetermined frequency, the computer-readable information storage medium storing computer-readable program code for causing the computer to perform the steps of;

checking a flag indicating the battery is in a bulk charge state or an absorption charge state;

if the battery is in the bulk charge state;

increasing a duty cycle of a driving signal for the first switch if a current provided by the battery charger is less than a desired current;

decreasing the duty cycle of the driving signal for the first switch if the current provided by the battery charger is greater than the desired current; and

setting the flag indicating the battery is in the absorption charge stage when a voltage of the battery is greater than or equal to a predetermined voltage and the battery has been charging for more than a predetermined time, otherwise ending the charging process; and

if the battery is in the absorption charge stage;

decreasing the duty cycle of the driving signal for the first switch if the voltage of the battery is greater than or equal to the predetermined voltage;

increasing the duty cycle of the driving signal for the first switch if the voltage of the battery is less than the predetermined voltage; and

stopping the charging process when the battery has been charging for more than a predetermined period of time.

73. The computer-readable information storage medium of claim 72, further comprising computer-readable program code for causing a computer to perform the step of detecting a fault if the battery is in the bulk charge stage, a charge rate is greater than a predetermined current, the battery has been charging more a predetermined amount of time, and the voltage of the battery is greater than or equal to a predetermined voltage.

74. The computer-readable information storage medium of claim 72, further comprising computer-readable program code for causing a computer to perform the step of turning the battery charger off if a battery to be charged is not connected to the battery charger.

75. A high frequency charger for charging a battery, comprising:

a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency;

a filter coupled to the first and second high frequency transformers for passing a DC voltage signal;

means for coupling a resistance in parallel with the battery;

means for measuring a voltage of the battery while the battery is coupled to the resistance; and

means for correlating the measured voltage to a CCA value.

76. The charger claim 75, further comprising a display and wherein the CCA is visually indicated on the display.

77. A computer-readable information storage medium for use with a computer controlling a high frequency charger for charging a battery, comprising a charge circuit including a first high frequency transformer;

a first switch switching the first high frequency transformer at a first frequency;

a filter coupled to the first and second high frequency transformers for passing a DC voltage signal, the computer-readable information storage medium storing computer-readable program code for causing the computer to perform the steps of;

coupling a resistance in parallel with the battery;

measuring a voltage of the battery while the battery is coupled to the resistance; and

correlating the measured voltage to a CCA value.