Power supply apparatus with chargeable battery and charge/discharge method

• US 6,204,633 B1
• Filed: 08/24/1998
• Issued: 03/20/2001
• Est. Priority Date: 02/20/1998
• Status: Expired due to Fees

• Current Assignee: Fujitsu Limited
• Original Assignee: Fujitsu Limited
• Inventors: Kitagawa, Seiya
• Primary Examiner(s): Wong, Peter S.
• Assistant Examiner(s): TOATLEY, GREGORY J
• Application Number:
  US09/139,025
• Time in Patent Office: 939 Days
• Field of Search: 320/126, 320/119, 320/162, 320/128, 320/134
• US Class Current: 320/128
• 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 which drives a load and in which a plurality of chargeable batteries are connected in parallel between the node of an external power source and the load, and the common ground of the external power source and the load, comprising:

charge state monitoring means for judging whether the external power source is in a charging state in which the external power source drives the load and the external power source outputs a sufficient voltage for charging the batteries, or in a non-charging state in which the external power source does not drive the load 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 state 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. A power supply apparatus which drives a load and in which a plurality of chargeable batteries are connected in parallel between the node of an external power source and the load, and the common ground of the external power source and the load, comprising:

charge state monitoring unit judging whether the external power source is in a charging state in which the external power source drives the load and the external power source outputs a sufficient voltage for charging the batteries, or in a discharging state in which the external power source does not drive the load and a non-charging current should be supplied from the chargeable batteries to the load;

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

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