JP4383431B2 - Battery pack charger - Google Patents

Description

  The present invention relates to a charging device capable of charging a plurality of rechargeable battery packs (hereinafter referred to as battery packs) such as lithium ion batteries. In particular, a charging device optimal for charging a spare battery pack carried in a portable device in addition to the device main body, such as a mobile phone or a digital camera, is provided.

  A method of attaching a plurality of battery packs to a charging device and sequentially switching and charging them has been performed since the power supply capacity of the charging device is small, and many patent applications have been filed. In addition, although the word “battery (or battery)” is used in the following documents, since the voltage per cell of this type of secondary battery is low, it is usually used as a battery pack in which several batteries are connected in series. It is common.

For example, Patent Document 1 efficiently charges a normal battery by skipping a battery that exhibits an abnormally low voltage during charging.
In Patent Document 2, a plurality of batteries are charged individually and sequentially, and an inactive battery is charged in the same manner as a normal battery by using a charge control mechanism for charge control of each battery.
Patent Document 3 is a device that sequentially switches and charges while detecting full charge of a plurality of batteries, detects that an uncharged battery is attached, returns to the initial state, and reliably charges the uncharged battery. Like that.
In Patent Document 4, when the temperature of the battery being charged exceeds a predetermined value, the charging is interrupted and the next battery is charged. When the temperature of the battery exceeds the predetermined value, charging of the previous battery is resumed. To shorten the charging time.
JP-A 56-110446 Japanese Patent Laid-Open No. 56-166731 Japanese Utility Model Publication No. 4-24759 JP 7-130399 A

In Patent Document 1 and Patent Document 2, a newly connected battery cannot be detected during charging. Therefore, after all the batteries have been charged, uncharged batteries must be mounted again to start charging.
In Patent Document 3, when an uncharged battery is attached, the charging device returns to the initial state and charging starts from the first battery again, so that the uncharged battery is charged. However, the battery that does not need to be charged is recharged. There are inconveniences.
In Patent Document 4, when all of a plurality of batteries are charged, there is an effect of shortening the charging time. However, it takes time to complete charging of the first battery as compared with charging one by one in order. Moreover, since the detection of an uncharged battery has not been performed, there is a problem in that, after charging of all the batteries is completed as in Patent Document 2, charging must be started by attaching a rechargeable battery again. .
Moreover, since the conventional charging device has all the control circuits for charging control incorporated in the charging device, the charging device itself becomes large and the cost of the device also increases.

The present invention can automatically detect an uncharged battery even when another battery is attached / detached or newly installed during charging, and can be charged until all the uncharged batteries are fully charged. Like that.
Also, it is possible to significantly reduce the control circuit in the charging device and to realize a reduction in size and cost of the charging device.

In order to solve the above-mentioned problem, in a charging device that attaches a plurality of battery packs and performs charging by switching in order,
Switch means (3) for selecting a battery pack to be charged;
A charging circuit for charging the selected battery pack;
A charge control circuit (22) for setting a charging method of constant current or constant voltage during charging by the charging circuit;
A battery pack voltage detection circuit (23) for detecting the voltage of the selected battery pack;
A charging current detection circuit (21) for detecting a current during charging;
A battery pack attachment detection circuit for monitoring the state of attachment of the battery pack during charging ;
E Bei and storage means (26) for storing the removable history of the battery pack from the mounting situation according to the battery pack attachment detecting circuit,
Charging is performed until there is no uncharged battery pack based on the information on the attachment / detachment history stored in the storage means .

  According to the present invention, since all the battery packs attached to the charging apparatus are constantly monitored even during charging, the other battery packs attached / detached during charging are automatically charged. . In the next charging, for example, an optimal charging method can be selected from the attachment / detachment information of the corresponding battery pack and the voltage value of the battery pack.

  Furthermore, if a charge control circuit is incorporated as a part of the device circuit in the device main body, the cost of the device will hardly increase, and a separate charge control circuit needs to be prepared on the charging device side. As a result, the charging device can be significantly reduced in cost and size. Furthermore, since charging with the battery inserted into the device main body is possible, charging can be performed without stopping the function of the device.

FIG. 1 shows a flowchart of an embodiment of the present invention, and FIGS. 2 and 3 show a charging method of the present invention.
The charging device 50 in FIG. 1 is an example of three battery packs (P1 to P3), and is roughly classified into a charging control FET portion 1 for controlling charging, and a charging control circuit 2 for controlling charging. Switch means 3 and 4. The power supply of the charging device 50 is supplied from an AC adapter.

  The sources of the FETs (M1 to M3) of the charge control FET1 are connected to the positive potential of the AC adapter via backflow prevention diodes (D1 to D3) and resistors (R1 to R3), respectively. The drain is connected to the positive terminal of each battery pack. The gate is connected to the charge FET control circuit 22 in the charge control circuit 2 via the switch means 3 (S21 to S23). The negative terminals of each battery pack are interconnected and connected to the GND potential of the charging device.

  The charge control circuit 2 is mounted with a charge current detection circuit 21 that detects a current during charging, and a charge FET control circuit 22 that controls the charge control FET 1 to perform constant current charging, constant voltage charging, and preliminary charging. A battery pack voltage detection circuit 23 for detecting the voltage of the battery pack, a battery pack attachment detection circuit 24 for detecting whether or not the battery pack is attached to the charging device 50, all the circuits, the switch means 3 and The battery pack attachment detection circuit 24 causes the battery pack attachment detection circuit 24 to switch the connection of the switch means 4 periodically while charging any battery pack attached to the charging device 50 and the control circuit 25 that controls the battery pack 50. The storage unit 26 is configured to constantly monitor the mounting state and store a battery pack attachment / detachment history from the monitoring state.

  The switch means 3 and 4 are constituted by mechanical switches or semiconductor switches. One end of each of the switches (S11 to S13) of the switch means 3 is connected to a connection point between the resistors (R1 to R3) and the backflow prevention diodes (D1 to D3), and the other end is connected to the charging current detection circuit 21. Has been. As described above, one end of each of the switches (S21 to S23) is connected to the gate of each FET (M1 to M3) of the charge control FET1, and the other end is interconnected and connected to the charge FET control circuit 22. One end of each of the switches (S31 to S33) is connected to the plus terminal of the battery pack, and the other end is connected to the battery pack voltage detection circuit 23.

  One end of each of the switches (S41 to S43) of the switch means 4 is connected to a terminal T that outputs a signal when the battery pack is attached to the charging device, and the other end is connected to the battery pack attachment detection circuit 24. Has been. The switches (S11), (S21), and (S31) included in the switch means 3 are simultaneously turned on / off. Similarly, the switches (S12), (S22), (S32), and the switches (S13), (S23) (S33) is also turned on / off at the same time. Further, the switches (S41 to 43) of the switch means 4 operate independently of the switch means 3.

  The control circuit 25 outputs a SW control signal A for controlling the switch means 3 and a SW control signal B for controlling the switch means 4. The SW control signal A is a signal for switching the order of charging the battery pack. When the charging of the battery pack being charged is completed, the switch means 3 is switched to charge the next battery pack. The SW control signal B is a signal for checking the battery pack attached to the charging device, and switches (S41) to (S43) are sequentially turned on regardless of whether charging is in progress or waiting for charging. The time during which the switches (S41) to (S43) are turned on is set to a time sufficiently shorter than a general time until the battery pack is removed from the charging device 50 and mounted again, for example, several tens of milliseconds.

  Next, a charging method of the charging device 50 will be described along the flowcharts of FIGS. The charging device 50 starts charging when power is supplied from the AC adapter (step S1). First, the battery pack P1 to be charged first is selected by the switch means 4, and the battery voltage of the battery pack P1 is measured (step S2). The battery pack P1 is a battery pack built in the main body of various devices, and charging is performed from the battery pack P1.

  If the voltage of the battery pack P1 is equal to or lower than the predetermined set voltage 1 (step S3), preliminary charging is performed (step S13). The preliminary charging is performed with a smaller current than the constant current charging performed thereafter. In the case of a lithium ion battery, the set voltage is set to about 2.5 V per unit cell. This is because, when the secondary battery is in an overdischarged state, it is dangerous to charge with a large current suddenly, and therefore it is necessary to perform charging while reducing the charging current. For this reason, the charging current at the time of preliminary charging is usually a current value of several mA to several tens mA.

  When the battery pack voltage P1 increases due to the preliminary charging and reaches the set voltage 1, or when the set voltage is 1 or more from the beginning, constant current charging is performed (step S4). This constant current charging is performed with a relatively large current set according to the capacity of the battery pack, and can be rapidly charged. When the constant current charging proceeds and the battery pack voltage reaches the set voltage 2 (step S5), switching to constant voltage charging is performed (step S6).

  Lithium ion batteries are dangerous because metallic lithium is deposited inside the battery when the charging voltage is increased, and switching to constant voltage charging is usually performed when charging proceeds to some extent so that the charging voltage does not increase. In the case of a lithium ion battery, the voltage for performing constant voltage charging is set to about 4.2 V per unit cell. During constant voltage charging, the charging current is monitored (step S7), and charging is completed when the charging current becomes equal to or lower than the set current (step S8).

  After the charging of the battery pack P1 is completed, it is checked whether there is another battery pack connected from the information in the storage means 26 (step S9), and if there is, the switch means 3 is connected to that battery pack (referred to as P2). Is switched (step S10). Further, from the information from the storage means 26, it is determined whether or not the battery pack P2 is newly installed (step S11). If the battery pack P2 is newly installed, the process returns to step S3 and the set voltage is 1 or more. Judge whether it is high or low.

  If the battery pack P2 is not newly installed, the voltage of the battery pack P2 is adjusted (step S12). If the voltage is equal to or higher than the set voltage 3, the battery pack P2 is not charged and the process returns to step S9. A search is made for another mounted battery pack. On the other hand, if it is equal to or lower than the set voltage 3, the process returns to step S4, and the battery pack P2 is charged with constant current. The set voltage 3 is a voltage value that determines that charging is necessary again when the voltage of the battery pack is reduced due to spontaneous discharge, and is set to a voltage value higher than the set voltage.

  After the charging is completed (step S8), if there is no other battery pack attached, the battery voltage after charging is measured (step S14), and if the battery voltage is equal to or higher than the set voltage 3, the step Returning to S9, this loop is repeated until the battery pack is mounted. On the other hand, if the voltage is 3 or less, the process returns to step S4, and constant current charging is performed on the previously charged battery pack (in this case, P1) (step S4).

  FIG. 3 illustrates the operation of the switch means 4. When the AC adapter is connected and the charging control circuit is turned on (step S14), the battery pack P1 is obtained in order to obtain information on the battery pack attached to the charging device 50. Then, (S41) to (S42) of the switch means 4 are sequentially turned on in the order of the battery pack P2 and the battery pack P3 (steps S16 to S18). The repetition cycle is set to be sufficiently shorter than the time when the battery pack is attached and detached, and is set to several tens of milliseconds as described above.

  FIG. 4 shows another embodiment of the present invention. In this charging device 51, the resistor, backflow prevention diode, and charge control FET provided in each battery pack in FIG. 1 are made into one system, and the drain of the FET (M1) is connected via the switch means 5 (S01 to S03). Connected to one of the battery packs. In this circuit configuration, the number of parts can be reduced as compared with that in FIG. Since the circuit operation and charging method of the charging device 51 are the same as those described above, description thereof is omitted.

The circuit diagram which showed one Embodiment of the charging device of this invention The flowchart which showed the operation | movement in the charging device of FIG. Subroutine for detecting battery pack attachment status The circuit diagram which showed another embodiment of the charging device of this invention

Explanation of symbols

1 FET for charge control
2 charge control circuit 3 switch means 4 switch means 5 switch means 21 charge current detection circuit 22 charge FET control circuit 23 battery pack detection circuit 24 battery pack attachment detection circuit 25 control circuit 26 storage means 50 charging device P battery pack T terminal

Claims (1)

In a charging device that attaches a plurality of battery packs and performs charging by switching in order,
Switch means for selecting a battery pack to be charged;
A charging circuit for charging the selected battery pack;
A charge control circuit that sets a constant current or constant voltage charging method when charging by the charging circuit;
A battery pack voltage detection circuit for detecting the voltage of the selected battery pack;
A charging current detection circuit for detecting a current during charging;
A battery pack attachment detection circuit for monitoring the state of attachment of the battery pack during charging ;
E Bei and storage means for storing a detachable history of the battery pack from the mounting situation according to the battery pack attachment detecting circuit,
The battery pack charging device is characterized in that charging is performed until there is no uncharged battery pack based on information on the attachment / detachment history stored in the storage means .

Images