Power supply apparatus with chargeable battery and charge/discharge method

• US 20020057073A1
• Filed: 01/11/2002
• Published: 05/16/2002
• Est. Priority Date: 02/20/1998
• Status: Active Grant

• Current Assignee: Seiya Kitagawa
• Original Assignee: Seiya Kitagawa
• Inventors: Kitagawa, Seiya
• Granted Patent: US 6,624,613 B2
• Time in Patent Office: Days
• US Class Current: 320/135
• CPC Class Codes: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0068 Battery or charger load switching, e.g. concurrent charging and load supply H02J7/0013 takes precedence
• CPC Class Codes: H02J 7/34 Parallel operation in networks using both storage and other dc sources, e.g. providing buffering H02J7/14 takes precedence

Abstract

The present invention provides a battery charging/discharging method for effectively using the battery energy of a power supply apparatus with a plurality of chargeable batteries. The power supply apparatus in which batteries are connected in parallel to the node of an external power source and a load comprises a charge/discharge monitor unit for judging whether the external power source is in a state where a load is driven and sufficient voltage to charge the batteries is outputted or in a state where sufficient voltage is not outputted and a discharge current should be supplied from the batteries to the load, switches inserted in series with each of the batteries, and an on/off control unit for controlling the on/off operation of the switches according to the output of the charge/discharge monitor unit and the charging/discharging state of each battery.

Claims

1. A power supply apparatus in which a plurality of chargeable batteries are connected in parallel between the node of an external power source and a load, and the common ground of the external power source and the load, comprising:

charge/discharge monitoring means for judging whether the external power source is in a charging state when the load is driven and a sufficient voltage for charging the batteries is outputted, or in a discharging state when a sufficient voltage is not outputted and a discharging current should be supplied from the chargeable batteries to the load;

switch means connected in series to each of the plurality of batteries; and

on/off controlling means for controlling the on/off operation of the switches according to the output of the charge/discharge monitoring means and the charging/discharging state of each of the plurality of batteries.

2. The power supply apparatus according to claim 1, further comprising:

current detecting means for detecting the current flowing in each of said plurality of batteries; and

charge completion detecting means for detecting the charge completion state of each of said plurality of batteries from the output of the current detecting means,

wherein when said charge/discharge monitoring means judges that said external power source is in a charging state,

said on/off controlling means performs a first control of switching on only said switch corresponding to one of said plurality of batteries,

then, when the charge completion detecting means detects the charging completion of one of the batteries, said on/off controlling means performs a second control of switching off the switched-on switch and a third control of switching on only said switch corresponding to one each of the remaining batteries of which the charging completion is not detected by the charge completion detecting means out of said plurality of batteries, and

then, every time the charge completion detecting means detects the charge completion of one of the batteries, said on/off controlling means repeats the second and third control processes.

3. The power supply apparatus according to claim 1, further comprising:

current detecting means for detecting the current flowing in each of said plurality of batteries;

charge completion detecting means for detecting the charging completion state of each of said plurality of batteries from the output of the current detecting means; and

voltage comparing means for comparing the voltages of said plurality of batteries, and

wherein when said charge/discharge monitoring means judges that said external power source is in a charging state,

said on/off controlling means performs a first control of switching on only said switch corresponding to a battery with a voltage judged to be the lowest by the voltage comparing means,

then, when the charge completion detecting means detects the charge completion of said battery with the lowest voltage, said on/off controlling means performs a second control of switching off the switched-on switch and a third control of switching on only said switch corresponding to a battery with a voltage judged to be the lowest by the voltage comparing means of the remaining batteries of which the charging completion is not detected out of said plurality of batteries, and

then, every time the charge completion detecting means detects the charging completion of said battery with the lowest voltage, said on/off controlling means repeats the second and third control processes.

4. The power supply apparatus according to claim 1, further comprising:

voltage equivalence detecting means for detecting the equivalence of the voltages between said plurality of batteries;

current detecting means for detecting a current flowing in each of said plurality of batteries; and

battery current direction judging means for judging from the output of the current detecting means whether a current flowing in each of said plurality of batteries is in a charging direction or in a discharging direction,

wherein when said charge/discharge monitoring means judges that said external power source is in a charging state,

said on/off controlling means performs a control of switching off said switches corresponding to the batteries of which the current flows in a discharging direction and charging only the batteries of which the current flows in a charging direction, and

then, every time a voltage equivalence is detected between batteries corresponding to the switched-off switches and the batteries during charging by the voltage equivalence detecting means, said on/off controlling means performs a control of switching on the switched-off switches corresponding to the batteries of which the voltage equivalence is detected by the voltage equivalence detecting means.

5. The power supply apparatus according to claim 1, further comprising:

current detecting means for detecting a current flowing in each of said plurality of batteries; and

battery current direction judging means for judging from the output of the current detecting means whether the current flowing in each of said plurality of batteries is in a charging direction or in a discharging direction,

wherein when said charge/discharge monitoring means judges that said external power source is in a charging state,

said on/off controlling means performs a first control of switching off said switches corresponding to the batteries in which the current is judged to flow in a discharging direction at that moment by the battery current direction judging means and charging only the batteries in which the current is judged to flow in a charging direction, and

then, every time a predetermined charge time of the batteries elapses, said on/off controlling means repeats the first control process.

6. The power supply apparatus according to claim 1, further comprising;

a direct current-direct current (DC-DC) converter, provided between the node of said external power source and said load, and the parallel node of said plurality of batteries, and controlled by pulse width modulation (PWM) when charging said plurality of batteries, for composing a direct discharging route from said plurality of batteries to said load when said plurality of batteries discharge current to said load;

constant voltage/constant current judging means for judging whether the DC-DC converter is constant-voltage-controlled so that the output voltage may become constant, or constant-current-controlled so that the output current may become constant;

voltage comparing means for comparing the voltages of said plurality of batteries;

voltage equivalence detecting means for detecting the equivalence of the voltages between said plurality of batteries;

current detecting means for detecting the current flowing in each of said plurality of batteries; and

battery current direction judging means judging from the output of the current detecting means whether the current flowing in each of said plurality of batteries is in a charging direction or in a discharging direction,

wherein when said charge/discharge monitoring means judges that said external power source is in a charging state,

if the constant voltage/constant current judging means judges that the DC-DC converter is constant-voltage-controlled,

said on/off controlling means performs a control of switching off said switches corresponding to the batteries in which the current is judged to flow in a discharging direction by the battery current direction judging means and charging only the batteries in which the current is judged to flow in a charging direction, and

then, every time a voltage equivalence is detected between the batteries corresponding to the switched-off switches and the batteries during charging by the voltage equivalence detecting means, said on/off controlling means performs a control of switching on the switched-off switches corresponding to the batteries of which the voltage equivalence is detected by the voltage equivalence detecting means, and

if the constant voltage/constant current judging means judges that the DC-DC converter is constant-current-controlled,

said on/off controlling means performs a control of switching on only said switches corresponding to the batteries with voltages judged to be the lowest by the voltage comparing means, and

then, every time a voltage equivalence is detected between the batteries during charge and the other batteries by the voltage equivalence detecting means, said on/off controlling means performs a control of switching on the switched-off switches corresponding to the batteries of which the voltage equivalence is detected by the voltage equivalence detecting means.

7. The power supply apparatus according to claim 6, wherein said DC-DC converter comprises:

a voltage error amplifier for outputting a signal to constant-voltage-control said DC-DC converter;

a current error amplifier for outputting a signal to constant-current-control said DC-DC converter,

wherein said constant voltage/constant current judging means comprises comparing means for comparing the output of the voltage error amplifier and the output of the current error amplifier.

8. The power supply apparatus according to claim 6, wherein

said constant voltage/constant current judging means comprises voltage comparing means for comparing the output voltage of said DC-DC converter and a predetermined reference voltage.

9. The power supply apparatus according to claim 1, further comprising discharge completion detecting means for detecting a state where each of said plurality of batteries completes discharging, wherein when said charge/discharge monitoring means judges that said external power source is in a discharging state,

said on/off controlling means performs a first control of switching on only said switch corresponding to one battery out of said plurality of batteries,

then, when the discharge completion detecting means detects the discharge of one battery, said on/off controlling means performs a second control of switching off the switched-on switch and a third control of switching on only said switch corresponding to one battery out of the remaining batteries in which the discharging completion is not detected by the discharge completion detecting means, and

then, every time the discharging completion of one battery is detected by the discharge completion detecting means, said on/off controlling means repeats the second and third control process.

10. The power supply apparatus according to claim 1, further comprising discharge completion detecting means for detecting a state where each of said plurality of batteries completes discharging, wherein when said charge/discharge monitoring means detects that a status of said external power source charges from a charging state to a discharging state,

said on/off controlling means maintains the on/off operation of said switch in the charging state,

then, every time the discharging completion detecting means detects the discharging completion of any of the batteries in which the corresponding switch is switched on, said on/off controlling means performs a control of switching off switches corresponding to the batteries in which discharging completion is detected by the discharge completion detecting means,

then, when the discharging completion of batteries corresponding to all the switches switched on in the charge state is detected by the discharge completion detecting means, said on/off controlling means performs a control of switching on the switches switched off in the charging state.

11. The power supply apparatus according to claim 1, further comprising:

discharge completion detecting means for detecting a state where each of said plurality of batteries completes discharging;

current detecting means for detecting the current flowing in each of said plurality of batteries; and

battery current direction judging means for judging from the output of the current detecting means whether the current flowing in each of said plurality of batteries is in a charging direction or in a discharging direction,

wherein when said charge/discharge monitoring means detects that a status of said external power source charges from a charging state to a discharging state,

said on/off controlling means performs a first control of switching off said switches corresponding to the batteries in which the current is judged to flow in a charging direction at that moment by the battery current direction judging means and discharging only the batteries in which the current is judged to flow in a discharging direction, and

then, every time the predetermined discharge times of the batteries elapse, said on/off controlling means repeats the first control process.

12. The power supply apparatus according to claim 1, further comprising:

current detecting means for detecting the current flowing in each of said plurality of batteries;

battery current direction judging means for judging from the output of the current detecting means whether the current flowing in each of said plurality of batteries is in a charging direction or in a discharging direction, and

voltage equivalence detecting means for detecting the equivalence of the voltages between said plurality of batteries,

wherein when said charge/discharge monitoring means judges that a status of said external power source charges from a charging state to a discharging state,

said on/off controlling means performs a control of switching off said switches corresponding to the batteries in which the current is judged to flow in a charging direction at that moment by the battery current direction judging means and discharging only the batteries in which the current is judged to flow in a discharging direction, and

then, every time a voltage equivalence is detected between the batteries corresponding to the switched-off switches and the batteries during discharge by the voltage equivalence detecting means, said on/off controlling means performs a control of switching on the switched-off switches corresponding to the batteries of which the voltage equivalence is detected by the voltage equivalence detecting means.

13. The power supply apparatus according to claim 1, further comprising current detecting means for detecting the current flowing in each of said plurality of batteries,

wherein said switch means is inserted between said plurality of batteries and the current detecting means for detecting the current of said plurality of batteries.

14. The power supply apparatus according to claim 1, wherein said switch means is inserted between each of said plurality of batteries and said common ground.

15. The power supply apparatus according to claim 1, further comprising a direct current-direct current (DC-DC) converter, provided between the node of said external power source and said load, and the parallel node of said plurality of batteries and controlled by a pulse width modulation (PWM) when charging said plurality of batteries, for composing a direct discharging route from said plurality of batteries to said load when said plurality of batteries discharge current to said load.

16. A method for charging the plurality of batteries in a power supply apparatus with a plurality of chargeable batteries, comprising the steps of:

(a) charging one battery out of the plurality of batteries;

(b) judging whether or not the charging of the battery during charging is completed;

(c) when the charging of the battery is judged to be completed in step (b), charging one battery out of the plurality of remaining batteries other than a battery in which the charging is completed; and

(d) repeating steps (b) and (c).

17. A method for charging the plurality of batteries in a power supply apparatus with a plurality of chargeable batteries, comprising the steps of:

(a) charging a battery with the lowest voltage among the plurality of batteries;

(b) judging whether or not the charging of the battery during charging is completed;

(c) when the charging of the battery is judged to be completed in step (b), charging a battery with the lowest voltage among the plurality of remaining batteries other than the battery in which the charging is completed; and

(d) repeating steps (b) and (c).

18. A method for charging the plurality of batteries in a power supply apparatus with a plurality of chargeable batteries, comprising the steps of:

(a) charging only the batteries out of the plurality of batteries in which the current flows in a charge direction when starting to charge;

(b) detecting batteries of which the voltages become equal to the voltages of the batteries during charging from the plurality of batteries, except for those during charging;

(c) charging the batteries detected in step (b); and

(d) repeating steps (b) and (c).

19. A method for charging the plurality of batteries in a power supply apparatus with a plurality of chargeable batteries, comprising the steps of:

(a) charging only the batteries out of the plurality of batteries in which the current flows in a charging direction when starting to charge;

(b) when the predetermined charging times of the batteries during charging elapse, detecting the direction of the current flowing in each of the plurality of batteries;

(c) charging only the batteries in which the current detected in step (b) flows in a charging direction; and

(d) repeating steps (b) and (c).

20. A method for charging a plurality of batteries in a power supply apparatus comprising a plurality of chargeable batteries and a direct current-direct current (DC-DC) converter, provided between the node of an external power source and a load, and the parallel node of the plurality of batteries and controlled by a pulse width modulation (PWM) when charging the plurality of batteries, for composing a direct discharging route from the plurality of batteries to the load when the plurality of batteries discharge current to the load, comprising the steps of:

(a) when charging said plurality of batteries, the DC-DC converter judges whether the converter is constant-voltage-controlled so that the output voltage may become constant, or constant-current-controlled so that the output current may become constant;

(b) if it is judged in step (a) that the DC-DC converter is constant-voltage-controlled, executing the following steps;

(c) charging only the batteries out of the plurality of batteries in which the current flows in a charge direction when starting to charge;

(d) detecting batteries of which the voltages become equal to the voltages of the batteries during charging from the plurality of batteries, except for those during charging;

(e) charging the batteries detected in step (d); and

(f) repeating steps (d) and (e), and

(g) if it is judged in step (a) that the DC-DC converter is constant-current-controlled, executing the following steps;

(h) charging a battery with the lowest voltage among the plurality of batteries;

(i) detecting batteries of which the voltages become equal to the voltages of the batteries during charging from the plurality of batteries, except for those during charging;

(j) charging the batteries detected in step (i); and

(k) repeating steps (i) and (j).

21. A method for discharging the plurality of batteries in a power supply apparatus with a plurality of chargeable batteries, comprising the steps of:

(a) when the status of the power supply apparatus charges from a charging state of the batteries to a discharging state, making charged batteries discharge;

(b) judging whether or not the discharging of the batteries during discharging is completed;

(c) when in step (b) it is judged that the discharging of the batteries is completed, making one battery out of the plurality of remaining batteries other than a battery in which the discharging is completed, discharge; and

(d) repeating steps (b) and (c).

22. A method for discharging the plurality of batteries in a power supply apparatus with a plurality of chargeable batteries, comprising the steps of:

(a) making one battery out of the plurality of batteries discharge;

(b) judging whether or not the discharging of the battery during discharging is completed;

(c) when in step (b) it is judged that the discharging of the battery is completed, making one battery out of the plurality of remaining batteries other than a battery in which the discharging is completed, discharge; and

(d) repeating steps (b) and (c).

23. A method for discharging the plurality of batteries in a power supply apparatus with a plurality of chargeable batteries, comprising the steps of:

(a) discharging only the batteries out of the plurality of batteries in which the currents flow in a discharging direction when discharging is started;

(b) when the discharging time during discharging exceeds a predetermined time, detecting the current directions of each of the plurality of batteries;

(c) making only the batteries in which the current directions detected in step (b) are discharging directions discharge; and

(d) repeating steps (b) and (c).

24. A method for discharging the plurality of batteries in a power supply apparatus with a plurality of chargeable batteries, comprising the steps of:

(a) discharging only the batteries out of the plurality of batteries in which the currents flow in a discharging direction when discharging is started;

(b) detecting batteries of which the voltages become equal to the voltage of the batteries during discharging from the plurality of batteries, except for those during discharging;

(c) discharging the batteries detected in step (b); and

(d) repeating steps (b) and (c).