JP2005117871A - Charging device and charging method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a charging device that can always stably detects the presence of a battery to be charged and that can suppress the supply of an unnecessary charging current. <P>SOLUTION: A battery-detecting-pulse generating portion 15 generates, for example, battery detecting pulse signals S15 that have negative pulses of fixed time intervals T1. These signals are supplied to the base of a transistor Tr12. This turns on the transistor Tr12 irrespective of the pulse intervals of charging pulse signals S14 from a charging pulse generating portion 14. As a result, the charging pulse generating portion 14 can detect the presence of a battery 5 at the time intervals T1 from the potential of a junction point C. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a charging device for a secondary battery such as a lithium ion battery.

For example, there is a charging device that charges a battery that can be repeatedly used by charging, such as a lithium ion battery.
Such a charging device is, for example, whether or not a battery is installed as a charging target based on a voltage generated by a charging current flowing through a battery presence / absence detection resistor provided in parallel with the charging target battery and the battery. The charging current is intermittently supplied to the battery based on a pulse signal generated using the result of the determination.
Further, in the above-described charging device, a resistor and a transistor are connected in series between the power source serving as a charging current supply source and the battery, so that even when the battery is in a discharged state, the battery is connected between the supply source and the battery. Has a predetermined voltage. Thus, the charging current control circuit can be driven by the power source of the supply source.
By the way, in the above-described charging device, as the charging potential of the battery approaches the potential of the power source, the time interval of the pulse width of the pulse signal is increased (the time interval of supplying the charging current is increased), and the unit time The charging current supplied to the battery is reduced. That is, the period during which no charging current is supplied from the charging device to the battery is lengthened.

Japanese Patent No. 2599230

However, the above-described charging apparatus cannot determine whether or not a battery is installed as a charging target only during a period in which a charging current is flowing through the battery presence / absence detection resistor.
Therefore, if the time interval of the period for supplying the charging current is increased as described above, the period during which it is not possible to determine whether the battery is installed as the charging target becomes longer, and the charging is performed even after the battery is removed from the charging target. There is a problem that current may be continuously supplied.

  This invention is made | formed in view of this situation, and it aims at providing the charging device which can always detect the presence or absence of the battery as a charging object stably, and can suppress supply of an unnecessary charging current.

  In order to achieve the above object, a charging device according to the present invention includes a connecting unit connected to a battery to be charged, and a charging current intermittently supplied to the battery via the connecting unit during a quick charging period. 1 supply means, and, in addition to the quick charging period, the battery has a resistance through which the charging current is intermittently supplied to the battery via the connection means and the charging current is supplied to the battery. A second supply means provided in parallel to the first supply means, and a supply period in which the first supply means or the second supply means supplies the charging current to the battery. Detecting means for detecting an index value as an index for judging the voltage of the battery based on the potential of the connecting means, and the battery is connected to the connecting means based on the index value detected by the detecting means. Said second supply when it is determined that When the stage controls the charging current per unit time supplied to the battery and determines that the battery is not connected to the connecting means, the charging current is supplied to the battery by the second supplying means. First control means for stopping, and second control means for controlling the second supply means so that the supply period occurs at regular time intervals.

  In the charging device according to the present invention, preferably, the first supply means is a first transistor, and the second supply means is a second transistor, the resistor, and the charging current to the battery. The first control means and the second control means are configured to turn on / off the second transistor of the second supply means. Turn off to control the supply of the charging current to the battery.

  In the charging device of the present invention, preferably, the detection unit, the first control unit, and the second control unit are driven by a power source that supplies the charging current.

In the charging device of the present invention, preferably, the first supply unit and the second supply unit connect the current supply side and the connection unit during a period of supplying the charging current to the battery, and Switching means for bringing the current supply side and the connection means into a disconnected state during a period in which the supply of the charging current to the battery is stopped.
In the charging device of the present invention, preferably, the battery is an overcharged battery and a current flows only in a discharging direction.

  ADVANTAGE OF THE INVENTION According to this invention, the presence or absence of the battery as charging object can always be detected stably, and the charging device which can suppress supply of an unnecessary charging current can be provided.

Hereinafter, a charging device according to an embodiment of the present invention will be described.
First Embodiment FIG. 1 is a configuration diagram of a charging device 1 according to a first embodiment of the present invention.
As shown in FIG. 1, the charging device 1 charges a battery 5 that can be used repeatedly by charging a lithium ion battery or the like.
Here, the charging device 1 corresponds to the charging device of the present invention, and the battery 5 corresponds to the battery as the charging target of the second invention.

[Battery 5]
As shown in FIG. 1, the battery 5 includes, for example, a switch SW1, a diode D1, a switch SW2, a diode D2, a battery unit VAT, and resistors R5 and R6.
One end of the switch SW1 is connected to the collector C of the transistor Tr1 and the cathode of the diode D5 in the charging device 1 in a state where the battery 5 is installed in the charging device 1 as a charging target.
The other end of SW1 is connected to one end of switch SW2.
The other end of the switch SW2 is connected to the positive electrode of the battery unit VAT.
The negative electrode of the battery unit VAT is connected to the terminal T2 via the resistor R5 in the charging device 1 in a state where the battery 5 is installed in the charging device 1 as a charging target.

The diode D1 is connected in parallel to the switch SW1 so that the cathode is connected to one end of the switch SW1 and the anode is connected to the other end of the switch SW1.
The diode D2 is connected in parallel to the switch SW2 so that the anode is connected to one end of the switch SW2 and the cathode is connected to the other end of the switch SW1.

Resistors R5 and R6 connected in series are connected in parallel to the battery unit VAT.
The switches SW1 and SW2 are in one of a connected state and a non-connected state based on the potential at the junction A between the resistors R5 and R6.
Specifically, when the potential of the junction A becomes equal to or higher than a predetermined potential defined according to the overcharge voltage of the battery unit VAT, the switch SW1 is disconnected and the switch SW2 is connected. Thereby, when the battery part VAT is an overcharge state, it can avoid that charging current flows into the battery part VAT from the charging device 1 by the diode D1.
On the other hand, when the potential of the junction A is less than a predetermined potential defined according to the overcharge voltage of the battery unit VAT, the switch SW1 is connected and the switch SW2 is disconnected. Thereby, when the battery part VAT is not near full charge, it can avoid discharging to the charging device 1 to the battery part VAT by the diode D2.

[Charging device 1]
As shown in FIG. 1, the charging device 1 includes, for example, a charging control circuit 10, a transistor Tr1, resistors R1 and R2, resistors R3 and R4, a resistor R5, terminals T1 and T2, a transistor Tr12, a resistor R9, and a diode D5. .
Here, the transistor Tr1 corresponds to the supply unit of the present invention, the transistor Tr12, the resistor R9, and the diode D5 correspond to the second supply unit of the present invention, and the battery detection function unit of the charge pulse generation unit 14 shown in FIG. 21 corresponds to the detection means of the present invention, the charge control function unit 23 corresponds to the first control means of the present invention, and the battery detection pulse generation unit 15 corresponds to the second control means of the present invention.

As shown in FIG. 1, resistors R1 and R2 are connected in series between terminals T1 and T2.
A predetermined voltage is supplied between the terminals T1 and T2 from a predetermined power source (a power source that supplies the charging current).
One end of a resistor R5 is connected to the terminal T2.
The other end of the resistor R5 is connected to the negative electrode of the battery unit VAT of the battery 5 in a state where the battery 5 is installed in the charging device 1 as a charging target.

The emitter of a PNP transistor Tr1 is connected to the terminal T1.
The collector of the transistor Tr1 is connected to one terminal of the switch SW1 of the battery 5 in a state where the battery 5 is installed in the charging device 1 as a charging target.
Resistors R3 and R4 are connected in series between the collector of the transistor Tr1 and the other end of the resistor R5.

Further, the emitter of the transistor Tr12 is connected to the terminal T1.
The transistor Tr12 is provided in parallel to the transistor Tr11 on the charging current supply path from the charging side (terminal T1) to the battery 5.
Pulse signals S14 and S15 are supplied to the base of the transistor Tr12 from the charge pulse generator 14 and the battery detection pulse generator 15, respectively.
In the present embodiment, a circuit in which the transistor T12, the resistor R9, and the diode D5 are connected in series is provided in parallel with the transistor Tr11, so that even when the battery 5 that is short-circuited by the resistor is installed as a charge target, The voltage generated in the resistor R9 due to the current flowing through the resistor R9 can avoid the same potential between the power source that supplies the charging current and the battery 5. Therefore, power can be supplied to the quick charging unit 13, the charging pulse generation unit 14, and the battery detection pulse generation unit 15 from the power source that supplies the charging current.
One end of a resistor R9 is connected to the collector of the transistor Tr11.
The other end of the resistor R9 is connected to the anode of the diode D5.
The cathode of the diode D5 is connected to the collector of the transistor Tr11.

As shown in FIG. 1, the charging control circuit 10 includes, for example, a voltage control unit 11, a current control unit 12, a quick charging unit 13, a charging pulse generation unit 14, and a battery detection pulse generation unit 15.
The voltage control unit 11 is a constant voltage circuit that fixes the junction B of the resistors R1 and R2 to a predetermined potential.
The current control unit 12 is a constant current circuit that supplies a predetermined constant current.

The quick charging unit 13 supplies a control signal S13 for conducting between the emitter and the collector of the transistor Tr1 to the base of the transistor Tr1 until the voltage of the battery 5 reaches a specified voltage during the quick charging. Thus, the transistor Tr1 continuously supplies a constant charging current to the switch SW1 of the battery 5 for a predetermined period.
Further, after the voltage of the battery 5 reaches the specified voltage, the quick charging unit 13 switches to the charging control by the charging pulse generation unit 14.

FIG. 2 is a functional block diagram of the charge pulse generator 14 shown in FIG.
As illustrated in FIG. 2, the charge pulse generation unit 14 includes, for example, a potential detection function unit 21, a battery installation presence / absence detection unit 22, and a charge control function unit 23.

The potential detection function unit 21 detects the potential of the junction C between the resistors R3 and R4 (an index value serving as an index for determining the state of charge of the battery of the present invention), and the detection result is sent to the battery installation presence / absence detection unit 22. Output.
The battery installation presence / absence detection unit 22 is installed in the charging device 1 as a charging target when the potential is equal to or higher than the first potential based on the potential of the junction C input from the battery installation presence / absence detection unit 22. If the potential detected by the potential detection function unit 21 is less than the first potential, it is determined that the battery 5 is installed in the charging device 1 as a charging target.
When the transistor Tr1 or Tr12 is in the on state, the battery installation presence / absence detection unit 22 is charged with the battery 5 based on the potential at the junction C determined by whether or not the charging currents Ic1 and Ic2 flow through the resistors R3 and R4. It detects whether it is installed in the charging device 1 as. That is, the battery installation presence / absence detection unit 22 can appropriately detect whether or not the battery 5 is installed in the charging device 1 as a charging target only when the transistor Tr1 or Tr12 is in an on state.

  The charge control function unit 23 is connected to the junction C detected by the potential detection function unit 21 on the condition that the battery installation presence / absence detection unit 22 determines that the battery 5 is installed in the charging device 1 as a charge target. Based on the potential, the emitter and collector of the transistor Tr12 are intermittently connected to each other so that a predetermined charging current is supplied to the switch SW1 of the battery 5 via the resistor R9 and the diode D5 per unit time. The base potential of the transistor Tr12 is controlled. Thereby, the charging current supplied from the collector of the transistor Tr12 to the battery 5 via the resistor R5 and the diode D5 has a pulse waveform.

Specifically, the charge control function unit 23 increases the negative pulse interval of the charge pulse signal S14 as the current flowing through the resistor R9 increases based on the potential of the junction C detected by the potential detection function unit 21. Thus, the charging pulse signal S14 is generated (so that the charging current flowing through the resistor R9 decreases per unit time), and this controls the base potential of the transistor Tr12.
The charge pulse signal S14 is defined so that the base current at which the voltage Vce between the emitter and the collector of the transistor Tr12 is sufficiently saturated flows into the base of the transistor Tr12 regardless of the charging voltage of the battery 5.
When the current flowing through the resistor R9 is a predetermined value based on the potential of the junction C detected by the potential detection function unit 21, the charge control function unit 23, for example, a time interval T1 shown in FIG. A charge pulse signal S14 having a negative pulse of is generated.
As a result, a charging current Ic having a pulse waveform having a positive pulse is supplied from the collector of the transistor Tr12 to the battery 5 through the resistor R9 and the diode D5 at the time interval T1 shown in FIG.

In addition, the charge control function unit 23 is based on the potential of the junction C detected by the potential detection function unit 21 when the current flowing through the resistor R9 is larger than that in the case of FIG. As shown in FIG. 3C, a charging pulse signal S14 having a negative pulse with a time interval T2 longer than the time interval T1 shown in FIG.
As a result, the charging current Ic having a pulse waveform having a positive pulse is supplied from the collector of the transistor Tr12 to the battery 5 through the resistor R9 and the diode D5 at the time interval T2 shown in FIG.
In the present embodiment, as described above, the time interval of the positive pulse width of the charging current Ic is increased as the current flowing through the resistor R9 increases, thereby avoiding excessive energy loss in the resistor R9. .

As shown in FIG. 3E, the battery detection pulse generator 15 generates a battery detection pulse signal S15 having a negative pulse at a constant time interval T1, for example, and supplies this to the base of the transistor Tr12.
The battery detection pulse generator 15 always has a battery detection pulse signal S15 having a negative pulse at a constant time interval T2 shown in FIG. 3C regardless of the potential of the junction C detected by the potential detection function unit 21. Is generated.
Thereby, the charging current Ic having the pulse waveform shown in FIG. 3F is supplied from the collector of the transistor Tr12 to the battery 5.
That is, in the case of FIG. 3 (D), the charging current Ic has the pulses P1 and P2 shown in FIG. 3 (F) at the timing between the adjacent positive pulses of the charging current Ic shown in FIG. 3 (D). It will happen.

Here, the time interval T1 of the negative pulse of the battery detection pulse signal S15 shown in FIG. 3E is the same as the charge pulse signal S14 shown in FIG. 3A, for example.
However, the battery detection pulse signal S15 has a charging rate based on the battery detection pulse signal S15 that causes the transistor Tr12 to become conductive, and a charging rate that results from the transistor Tr12 that becomes conductive based on the charging pulse signal S14. Therefore, the pulse width of the negative pulse is specified so as to be sufficiently low.
That is, the battery detection pulse signal S15 is defined such that the voltage Vce of the transistor Tr12 is in a non-saturated state, and a base current having a sufficiently lower value than the normal saturation flows into the base of the transistor Tr12.
In the present embodiment, as described above, apart from the charge pulse signal S14, a battery detection pulse signal S15 that always generates a negative pulse at the time interval T1 shown in FIG. By supplying to the base, as shown in FIG. 3C, even when the time interval of the negative pulse of the charging pulse signal S14 becomes longer, the transistor Tr12 is connected to the emitter / collector at a constant time interval T1 shorter than that. The connection can be made between the two. Thereby, the battery installation presence / absence detection unit 22 shown in FIG. 2 can always detect the presence / absence of the battery 5 at the time interval T1.

In the charging device 1, for example, the charging pulse signal S14 shown in FIG. 4B is output from the charging pulse generator 14 to the base of the transistor Tr12, and the charging pulse signal S14 shown in FIG. 4C is output from the battery detection pulse generator 15 to the base of the transistor Tr12. The battery detection pulse S15 shown in FIG.
Thereby, the charging current Ic1 shown in FIG. 4 (E) is supplied to the battery 5, and the voltage of the battery 5 rises as shown in FIG. 4 (A).
At this time, the transistor Tr11 is turned off by the control signal S13 from the quick charging unit 13, and the charging current Ic2 becomes substantially zero as shown in FIG. 4D.

[First operation example]
In this operation example, the charging pulse generator 14 outputs the charging pulse signal S14 shown in FIG. 3C according to the potential of the junction C detected by the potential detection function unit 21 during normal charging, not during quick charging. An example of the operation in this case will be described.
In this case, as described above, the charge pulse generator 14 generates the charge pulse signal S14 having a pulse of the time interval T2, as shown in FIG. 3C, and this is applied to the base B of the transistor Tr12. Supply.
Thereby, the transistor Tr12 makes its emitter and collector conductive while the charge pulse signal S14 shown in FIG. 3C is at the low level L, and supplies the charge current Ic to the switch SW1 of the battery 5.
Further, the transistor Tr12 makes its emitter and collector non-conductive while the charge pulse signal S14 shown in FIG. Thereby, the charging current Ic is intermittently supplied from the charging device 1 to the battery 5 as shown in FIG.
In parallel with the above-described operation, the battery detection pulse generator 15 generates a battery detection pulse signal S15 having a pulse at the time interval T1, as shown in FIG. 3E, and this is generated in the base B of the transistor Tr12. Supply.
Thereby, the transistor Tr12 makes its emitter and collector conductive while the battery detection pulse signal S15 shown in FIG. 3E is at the low level L, and supplies the charging current Ic to the switch SW1 of the battery 5.
Further, the transistor Tr12 makes its emitter and collector non-conductive while the battery detection pulse signal S15 shown in FIG. As a result, the charging current Ic is intermittently supplied from the charging device 1 to the battery 5 as shown in FIG.
That is, by the battery detection pulse signal S15, the charging current Ic always flows at the time interval T1, and thus the battery installation presence / absence detecting unit 22 shown in FIG. 2 can always detect the presence / absence of the battery 5 at the time interval T1.

[Second operation example]
In this operation example, a case where the charging device 1 performs a quick charging operation will be described.
In this case, the rapid charging unit 13 supplies the control signal S13 of the low level L to the base B of the transistor Tr11 until the voltage of the battery 5 reaches the specified voltage. Thereby, the transistor Tr11 continuously supplies a constant charging current to the switch SW1 of the battery 5 for a predetermined period.
Further, after the voltage of the battery 5 reaches the specified voltage, the quick charging unit 13 switches to the charging control by the charging pulse generation unit 14.
In addition, the charge pulse generation unit 14 and the battery detection pulse generation unit 15 generate a charge pulse signal S14 and a battery detection pulse signal S15 that hold the high level H, respectively, and supply them to the base B of the transistor Tr12.
As a result, the emitter and collector of the transistor Tr12 are kept in a disconnected state.

As described above, according to the charging device 1, apart from the charging pulse signal S14, the battery detection pulse signal S15 that always generates a negative pulse at the time interval T1 shown in FIG. By supplying to the base of the transistor Tr12, as shown in FIG. 3C, even when the time interval of the negative pulse of the charging pulse signal S14 becomes longer, the transistor Tr12 is turned on at a constant time interval T1 shorter than that. The emitter and collector can be connected. Thereby, the battery installation presence / absence detection unit 22 shown in FIG. 2 can always detect the presence / absence of the battery 5 at the time interval T1.
As a result, the charge pulse generator 14 immediately disconnects the emitter and collector of the transistor Tr12 when the battery 5 is removed based on the determination result of the battery installation presence / absence detector 22. The supply of the charging current Ic can be stopped.

  Further, according to the charging device 1, as shown in FIG. 1, a battery in which a circuit in which a transistor T12, a resistor R9, and a diode D5 are connected in series is provided in parallel with the transistor Tr11, and is short-circuited by a resistor Even when 5 is installed as a charging target, it is possible to avoid the same potential between the power source that supplies the charging current and the battery 5 due to the voltage generated in the resistor R9 due to the current flowing through the resistor R9. Therefore, power can be supplied to the quick charging unit 13, the charging pulse generation unit 14, and the battery detection pulse generation unit 15 from the power source that supplies the charging current.

  Further, according to the charging device 1, the battery detection pulse signal S15 has a charging rate that is based on the battery detection pulse signal S15 and the transistor Tr12 is turned on, and the transistor Tr12 is turned on based on the charge pulse signal S14. Since the pulse width and the pulse voltage are defined so as to be sufficiently lower than the charging rate due to this, the battery 5 is not overcharged by the battery detection pulse signal S15.

  The present invention is applicable to a charging device for a secondary battery such as a lithium ion battery.

FIG. 1 is a configuration diagram of a charging apparatus according to an embodiment of the present invention. FIG. 2 is a functional block diagram of the charge pulse generator shown in FIG. FIG. 3 is a diagram for explaining an example of the waveform of each signal shown in FIG. FIG. 4 is a diagram for explaining an example of the waveform of each signal shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Charging apparatus, 5 ... Battery, 10 ... Charge control circuit, 11 ... Voltage control part, 12 ... Current control part, 13 ... Quick charge part, 14 ... Charge pulse generation part, 15 ... Battery detection pulse generation part, Tr1, Tr11, Tr12 ... Transistor, SW1, SW2 ... Switch, D1, D2, D5 ... Diode

Claims (5)

A connection means connected to the battery to be charged;
First supply means for intermittently supplying a charging current to the battery via the connection means during a quick charge period;
In addition to the quick charge period, the first supply is provided with a resistor through which the charging current is intermittently supplied to the battery via the connection means, and the charging current flows in the process of supplying the charging current to the battery. Second supply means provided in parallel to the means;
An index value serving as an index for judging the voltage of the battery based on the potential of the connecting means during a supply period in which the first supply means or the second supply means supplies the charging current to the battery. Detecting means for detecting;
The second supply means controls the charging current per unit time supplied to the battery when it is determined that the battery is connected to the connection means based on the index value detected by the detection means. First control means for stopping supply of charging current to the battery by the second supply means when it is determined that the battery is not connected to the connection means;
And a second control unit that controls the second supply unit such that the supply period occurs at a constant time interval. The first supply means is a first transistor;
The second supply means is configured by connecting in series a second transistor, the resistor, and a diode having a forward direction in which the charging current is supplied to the battery,
The first control means and the second control means control the supply of the charging current to the battery by turning on / off the second transistor of the second supply means. Charging device. The charging device according to claim 2, wherein the detection unit, the first control unit, and the second control unit are driven by a power source that supplies the charging current. The first supply means and the second supply means connect the current supply side and the connection means in a period during which the charging current is supplied to the battery, and stop supplying the charging current to the battery. The charging device according to claim 1, wherein the charging device is a switching unit that disconnects the current supply side and the connection unit during a period of time. The charging device according to claim 1, wherein the battery is an overcharged battery and a current flows only in a discharging direction.

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