JPH05300664A - Battery charger - Google Patents

Abstract

(57) [Summary] [Purpose] When a plurality of battery cells of the same type are connected in series and charged at the same time, an abnormal occurrence of the cells is detected and charging is stopped. [Structure] A voltage is derived via a cable 12 from a connection point at which a plurality of battery cells B ₁ ... B _n connected in series are divided by the cell numbers N ₁ and N ₂ . An inverting amplifier RA1 for inverting and amplifying this derived voltage, an adder AD for adding (actually subtracting) the result of inverting / amplifying and the battery terminal voltage, and a threshold voltage E _H (positive value) for the addition result. , E _L (negative value) is provided with a window comparator WC. The logic signal CS, which is the determination result of the comparator WC, is supplied to the diode of the charge control circuit 2, and the reverse bias and the forward bias instruct the continuous charge and the stopped charge. Comparator WC
Is connected to a light emitting diode D8 via an inverter IV1. Light emitting diode D8 when logic signal CS is logic H
Light up.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery charger for charging a secondary battery (hereinafter referred to as a battery) such as a lead storage battery or a nickel-cadmium battery, and particularly, a plurality of battery cells of the same type connected in series. , A battery charger that charges those battery cells at the same time.

[0002]

2. Description of the Related Art Conventionally, as a battery charging device for charging a plurality of battery cells of the same type in series,
The one shown in FIG. 6 is known. In the device shown in FIG. 6, a plurality of battery cells B ₁ , ..., B _n of the same type connected in series are connected to the output terminal of a charging control circuit that controls the charging voltage and the charging current. Battery cell B
₁ , ..., B _n are being charged at the same time. The control of the charging voltage in this device is performed by detecting the voltage across the battery cells connected in series.

[0003]

However, in the above-mentioned battery charger, the battery charging device is configured to detect and charge only the voltage across the battery cells connected in series.
If one cell in the battery cell group fails,
There is a risk of continuing charging without knowing this failure.In such a case, abnormal voltage is applied to other normal battery cells, which deteriorates the normal cells or internal gas. There was a risk that this could cause problems.

The present invention has been made in view of the above-mentioned problems of the prior art, and when a plurality of battery cells of the same type are simultaneously charged in series connection, the battery cells may be out of order from the beginning, or in the middle of charging. When a failure occurs in, the failure is surely detected and charging is automatically stopped.
The first purpose. A second purpose is to be able to notify the operator when charging is stopped.

[0005]

In order to achieve the first object, the battery charger according to the present invention applies a voltage across a plurality of battery cells connected in series, and a plurality of the same battery cells are connected. In a battery charger including a charging means for simultaneously charging different types of battery cells, a voltage deriving means for deriving a voltage at at least one inter-cell connection point among the plurality of battery cells, and the voltage deriving means. An abnormality determining means for determining abnormality of the battery cell based on the derived voltage of the battery and the voltage across the plurality of battery cells; and when the abnormality determining means determines abnormality of the battery cell, the charging means And a charging stop means for stopping charging.

In particular, the abnormality determining means considers the ratio of the number of cells divided by the derivation position of the voltage derivation means based on the derivation voltage of the voltage derivation means and the voltages across the plurality of battery cells. The charging means includes a calculating means for calculating the difference between the voltage across the terminal and the derived voltage, and a comparing means for comparing the calculated voltage of the calculating means with a reference voltage preset corresponding to the abnormality of the battery cell. The stopping means is means for stopping the charging by the charging means when the comparison result of the comparing means indicates an abnormality of the battery cell.

In order to achieve the first and second objects,
In particular, in the battery charging device according to the invention as defined in claim 3, alarm means for notifying the stop of charging when the charging stopping means stops charging by the charging means is added to the above configuration.

[0008]

In the battery charger according to the present invention, when one of the plurality of battery cells fails, the abnormality determining means determines the derived voltage of the voltage deriving means and the voltage across the plurality of battery cells. Based on the above, the difference between the both-end voltage and the derived voltage is calculated considering the ratio of the number of cells divided by the voltage derivation position, and this calculated voltage is compared with the reference voltage set in advance corresponding to the abnormality of the battery cell. The abnormal state of the cell is determined by performing processing such as As a result, when it is determined that there is an abnormality in the cell being charged, the charging stop means forcibly and automatically stops the charging operation of the charging means, which may adversely affect other normal cells. There is no. Particularly, according to the battery charging device of the third aspect of the present invention, when the charging stop state is reached, the alarm means notifies the operator of that fact, so that the operator can take necessary necessary measures promptly. ..

[0009]

Embodiments of the present invention will be described below with reference to the drawings.

(First Embodiment) A first embodiment will be described with reference to FIGS.

FIG. 1 shows the overall configuration of a battery charging device according to the first embodiment. The battery charger shown in FIG. 1 has a charging control circuit 2 that receives commercial AC power from an AC power supply 1, and a plurality of the same type (for example, the same type) that is connected to the output terminal of the charging control circuit 2 and is charged at the same time. Battery cell B _{1 of} lead-acid battery or nickel-cadmium battery)
, B _n, and a charging monitoring unit 3 that monitors the charging state of the battery cells B ₁ , ..., B _n and orders the charging control circuit 2 to stop charging if necessary.

Of these, the charge control circuit 2 is a battery cell B.
₁ , ..., _Bn for controlling the charging voltage and charging current, and are specifically configured as shown in FIG. The output characteristic of the charge control circuit 2 is shown in FIG. As shown in FIG. 2, the charging control circuit 2 includes a step-down transformer T connected to an AC power source 1 and having a predetermined turn ratio, a bridge rectifier D that rectifies the output of the transformer T, and a rectifier D.
And a capacitor C1 for smoothing the rectified output of the capacitor C1 and the charging output terminals OUT ⁺ , OUT.
^- and a voltage-current control circuit 10 provided between the.

The voltage / current control circuit 10 is, as shown,
It has a transistor Q1 whose collector is connected to the positive end of the capacitor C1 and whose emitter is connected to the negative end of the capacitor C1. The emitter of the transistor Q1 is connected to the plus side output terminal OUT ⁺ , its base is connected to the emitter via the resistor R10, and is connected to the collector of the transistor Q2 via the resistor R11.

The emitter of the transistor Q2 is a resistor R
The output terminal OUT ^{− of the} negative side is reached via 15. A voltage divider circuit of resistors R13 and R14 is inserted in parallel to both output terminals OUT ⁺ and OUT ^−, and an intermediate point of the voltage divider circuit is connected to a positive input terminal of a differential input type operational amplifier A3. There is. The minus input terminal of the operational amplifier A3 has a resistor R16 for dividing the voltage of + V and a zener diode ZD.
1 is connected to the midpoint of the series circuit. This operational amplifier A3 amplifies and outputs the difference between its two inputs.
The output side is connected to the base of the transistor Q2 through the diode D5 and the resistor R12 in the forward direction.

Further, the load side of the resistor R15, that is, the minus output terminal OUT ^- is connected to the ground, and the power source side of the resistor R15 also passes through an inverting amplifier RA4 composed of resistors R17, R18 and an operational amplifier A4. To the positive input terminal of the differential input type operational amplifier A5. The negative input terminal of the operational amplifier A5 is connected to the intermediate point of the series circuit of the resistor R19 and the Zener diode ZD2 that divides the voltage of + V. This operational amplifier A5 also amplifies the difference between its two inputs, and its output side has the diode D5 and the resistor R through the diode D6 in the forward direction.
It is connected to 12 midpoints.

Further, the resistor R12 and the diode D
The midpoint between 5 and D6 is connected to the charge control terminal STOP via the diode D7 in the reverse direction. As will be described later, the charge control terminal STOP is supplied with a logic level charge control signal from the charge monitoring unit 3.

As shown in FIG. 1, a plurality of battery cells B ₁ , ..., B _n having the number of cells “N1 + N2” are connected in series to the charging output terminals OUT ⁺ and OUT ⁻ . The plus side of both ends of the battery cell group connected in series is connected to the detection end IN _h of the charge monitoring unit 3 via the voltage detection cable 11. Also, the number of cells N1 and N2
The intermediate connection point between the battery cell groups divided by is connected to the other detection end IN _m of the charge monitoring unit 3 via the voltage detection cable 12. Furthermore, the negative side of both ends of the battery cell group connected in series is
It is electrically connected to the ground circuit of the charging monitoring unit 3 via the ground and has a ground potential.

Further, as shown in FIG. 1, the charge monitoring section 3 is provided with an inverting amplifier RA1 and an adder AD having two inputs and a window comparator WC in order from the input side, and further, the output side of the window comparator WC. And an inverter IV1 and a light emitting diode D8.

Of these, the inverting amplifier RA1 includes resistors R1 and R1.
2 and the operational amplifier A1 are formed as shown in the figure. The inverting input terminal of the operational amplifier A1 reaches the sensing terminal IN _m through the resistor R1 and the non-inverting input terminal reaches the ground.
The output of the inverting amplifier RA1 is supplied to the adder AD. The adder AD is formed by resistors R3, R4, R5 and an operational amplifier A2, and is provided on the inverting input end side of the operational amplifier A2.
In the input, connected resistor R3 which forms the input circuit of one of which the detection end IN _h, the resistor R4 to form a second input circuit is connected to an output terminal of the inverting amplifier RA1. The non-reverse input end of the operational amplifier A2 reaches the ground.
The output terminal of the adder AD is a window comparator WC.
Leading to.

The window comparator WC includes two comparators CMP1, CPM2 and an inverter IV as shown in the figure.
2. It has a NAND circuit ND. Both comparators CMP1, CP
The inverting input terminal of M2 is connected to the output terminal of the adder AD, and the reference voltage E _{H obtained by} dividing the positive reference voltage “+ REF” by the variable resistor VR1 is connected to the inverting input terminal of the one comparator CMP1. is applied to the inverting input terminal of the other comparator CMP2, the reference voltage E _L where negative reference voltage "-REF" divided by the variable resistor VR2 is applied. Therefore, if the output voltage of the adder AD is E _D , the output of one comparator CMP1 becomes a logic H only when E _D <E _H , and the output of the other comparator CMP2 is E _D > E
_Only when it is _H , its output becomes logic L.

The output terminal of the one comparator CMP1 is connected to one input terminal of the NAND circuit ND, and the output terminal of the other comparator CMP2 is connected to the other input terminal of the NAND circuit ND via the inverter IV2. There is. This NAND circuit ND
Has an output of logic L only when its two inputs are logic H. The output terminal of the NAND circuit ND is connected to the charging control terminal STOP of the charging control circuit 2 described above, and is also connected to the positive voltage “+ Vcc” via the inverter IV1 and the light emitting diode D8.

In the above configuration, the cable 12 forms the voltage deriving means of the present invention, the diode D7 of the charging control circuit 2 forms the charging stopping means of the present invention, and the charging control circuit 2 excluding the diode D7 is of the charging control circuit 2. The parts form the charging means of the invention. Further, the inverting amplifier RA1 and the adder AD of the charge monitoring unit 3 constitute the arithmetic means of the present invention,
The window comparator WC of the charge monitoring unit 3 constitutes the comparison means of the present invention. The calculating means and the comparing means constitute abnormality determining means. Further, the inverter IV1 and the light emitting diode D8 of the charge monitoring unit 3 constitute alarm means.

Next, the operation and effect of this embodiment will be described.

First, a plurality of battery cells B ₁ , ..., B
It is assumed that there is no abnormality in any of the _n and that it is in a normal state. At this time, the control signal CS supplied to the charging control terminal STOP of the charging control circuit 2 is a logic L (0 volt) as described later, and the diode D7 is reverse biased.
Therefore, the transistor Q2 has the diodes D5 and D6.
It is in a state of being operated by a signal supplied via.

First, at the start of charging and when the terminal voltage of the battery cells B ₁ ... B _n connected in series is low, the operating point in the output characteristic of FIG. 3 is between the points A and B. In this state, the output voltage detected by the voltage dividing circuit of the resistors R13 and R14 on the charge output side is supplied to the non-inverting input terminal of the operational amplifier A3, but is lower than the voltage of the Zener diode ZD1. Output is saturated to the logic L side. As a result, the diode D5 is reverse-biased, so that the transistors Q1 and Q2 for charging are controlled by the current passing through the diode D6.

The output (charging) current during charging is detected as a voltage value by the resistor R15. The voltage corresponding to this output current is amplified by the inverting amplifier RA4 and supplied to the non-inverting input terminal of the operational amplifier A5. Therefore, when the output current increases, the output of the inverting amplifier RA4 increases and becomes larger than the voltage of the Zener diode ZD2.
The output of 5 is saturated on the logic H side. As a result, the diode D6 becomes forward biased, the base current of the transistor Q2 increases, and the collector current also increases. As a result, the base current of the transistor Q1 connected to the collector side of the transistor Q2 decreases, so that the transistor Q1
The collector current of ₁ , that is, the output current to the batteries B ₁ , ..., B _n decreases.

On the contrary, the battery charging current decreases and the output voltage of the inverting amplifier RA4 changes to the zener diode ZD2.
When the voltage becomes smaller than the voltage of, the output voltage of the operational amplifier A5 is saturated to the logic L side, and the diode D6 is also reverse biased. Therefore, the collector current of the transistor Q2 decreases, the base current of the transistor Q1 increases, and its collector current, that is, the output (charging) current increases.

Thus, feedback control is applied according to the magnitude of the output current, and the output current holds the value I ₀ (see FIG. 3) corresponding to the Zener voltage of the Zener diode ZD2 connected to the operational amplifier A5. It is controlled to be constant. While this constant current control is being performed, charging progresses and battery cells B ₁ , ..., B connected in series are connected.
The terminal voltage of _n rises.

The battery cells B ₁ , which are connected in series,
, When the terminal voltage of B _n rises and reaches the point B in FIG. 3, this time, the input voltage of the non-inverting input terminal of the operational amplifier A3 becomes larger than the Zener voltage of the Zener diode ZD1. Is saturated on the logic H side, and the diode D5 is forward biased. On the other hand, the operational amplifier A
The input voltage of the non-inverting input terminal of 5 is the Zener diode ZD
Since it becomes lower than the Zener voltage of 2, the output is saturated to the logic L side, and the diode D6 is reverse biased. Therefore, the control of the base current of the operational amplifier A3 is effective for the transistor Q2, and in the operating region between B and C in FIG. 3, the output voltage detected by the voltage dividing circuits R13 and R14 is the Zener diode ZD1. Feedback control is applied so as to be equal to the Zener voltage, and constant voltage control of the output (charging) voltage is performed.

Next, the control of the charge monitoring unit 3 will be described.
Here, the battery cells B ₁ , ..., B _n connected in series
The voltage at the positive terminal of the cable is V _B , and the detected voltage of the cable 12 pulled out from the middle is V _C.

The voltage V _{C at the} connection point of the series-connected batteries B ₁ , ..., B _n is supplied to the inverting amplifier RA1 via the cable 12, is inverted and amplified by the inverting amplifier RA1, and then is added by the adder AD. Is supplied to one of the input terminals. on the other hand,
The positive terminal voltage V _B of the battery cells B ₁ , ..., B _n is supplied to the other input end of the adder AD via the cable 11. This adder AD adds two input voltages V _C and V _B (actually subtracts because the inter-cell voltage is inverted), and outputs the output voltage E _D to the window comparator of the next stage. Supply to WC.

The output voltage E _D of the adder AD is quantitatively expressed by the following equation.

[0033]

[Equation 1]

In the battery cells B ₁ , ..., B _n connected in series, the number of battery cells from the negative terminal to the middle cable drawing position is N ₁ , and the number of battery cells from the middle drawing position to the positive terminal is N _2. Then, the resistances R1 and R2 of the inverting amplifier RA1 and the resistance R of the adder AD
The resistance values of R3 and R4 are set so as to satisfy the following equation.

[0035]

[Equation 2] As a result, the equation 1 can be rewritten as the following equation.

[0036]

[Equation 3]

If the voltages of the battery cells B ₁ , ..., B _n are all equal,

[Equation 4] Therefore, the above equation 3 is

[Equation 5] Becomes That is, the output of the adder AD becomes 0.

The output voltage of the adder AD is the two comparators CMP1 and CP of the window comparator WC.
It becomes an inverting input of M2, and is compared with the positive limit voltage E _{H in} one comparator CMP1 and with the negative limit voltage E _L in the other comparator CMP2. Thus, when all the battery cells B ₁ , ..., B _n are in the normal state,

## EQU6 ## Since E _L <E _D <E _H (6), the output of one comparator CMP1 becomes logic H, and the output of the other comparator CMP2 becomes logic L. As a result, both inputs of the NAND circuit ND are logically high.
And its output becomes logic L. That is, the control signal CS supplied to the charge control circuit STOP is supplied to the charge control circuit 2.
Is a logic L, the charging described above is continued. Further, at this time, in the charge monitoring unit 3, the control signal CS is inverted by the inverter IV1 and becomes logic H, so that the light emitting diode D8 is reversely biased and the non-lighted state of the light emitting diode D8 is maintained.

However, it is assumed that during such charging, even one of the battery cells B ₁ , ..., B _n becomes defective and the terminal voltage of that cell becomes lower than that in the normal state. As a result, the relation of the above equation 4 is broken,

[Equation 7] Then, the output voltage E _D of the adder AD is positive, and

[Equation 8] Then, the output voltage E _D becomes negative.

As a result, if even one of the battery cells B ₁ , ..., B _n is defective,

[Equation 9] E _D > E _H or E _D <E _L .. Since Equation 9 is satisfied, the output of the NAND circuit ND becomes a logic H in any case.

That is, when an abnormality occurs in one of the cells, the charge control signal CS supplied to the charge control terminal STOP of the charge control circuit 2 becomes logic H, so the charge control circuit 2
Diode D7 is forced forward biased. Therefore, the transistor Q2 of the charge control circuit 2 is forcibly turned on, the transistor Q1 is turned off, and the charging of the battery cells B ₁ , ..., B _n is automatically stopped. At the same time, the output of the logic H of the NAND circuit ND is the inverter IV.
Since it is converted to logic L by 1, the light emitting diode D
8 is forward biased. As a result, the light emitting diode D8 is turned on, and the operator is surely notified that the cell abnormality has occurred.

In this way, when battery cells of the same type are connected in series and simultaneously charged, if an abnormality occurs in the cells during charging (including the case where the abnormality has occurred before charging), charging is performed. It is surely and automatically stopped, and it is notified. As a result, it is possible to continue charging without noticing the occurrence of such an abnormality, to deteriorate even a normal cell, and to avoid problems caused by the generation of internal gas.

Further, the lead-out position of the voltage deriving cable 12 from the battery cells connected in series can be determined at an arbitrary position in accordance with the cost of manufacturing the device for the lead-out and the probability of occurrence of cell abnormality. Even if the drawing position is changed, it is easy to adjust the variable resistors VR1 and VR2 so that the threshold values E _H and E _L corresponding to the new ratio of the numbers N ₁ and N ₂ are given to the comparators CMP1 and CMP2. Can deal with

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. Here, the same or equivalent components as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted or simplified.

The battery charger shown in FIG. 4 is suitable when the cable 12 is fixedly pulled out from a plurality of battery cells B ₁ , ..., B _n connected in series.

The positive ends of the plurality of battery cells B ₁ , ..., B _n are connected to the detection end IN of the charge monitoring unit 3 via the cable 11.
An intermediate connection point connected to _h and divided into cell number ratios N ₁ and N ₂ is connected to another detection end IN _m via a cable 12, and a negative end is further detected via a cable 13. It is connected to IN _e .

The charge monitoring unit 3 includes a voltage divider circuit of resistors R1a and R2a provided on the input side, a differential amplifier AMP and a window comparator W provided at a stage subsequent to the voltage divider circuit.
C, an inverter IV1, and a light emitting diode D8. Among them, the resistance R1a, across the sensing end IN _h of the voltage divider circuit of R2a, together are each connected to the IN _e, the voltage dividing point is connected to the inverting input terminal of the differential amplifier AMP. Further, the detection terminal IN _m is connected to the ground and is also connected to the non-inverting input terminal of the differential amplifier AMP. The output terminal of the differential amplifier AMP reaches the input terminal of the window comparator WC in the next stage.

The resistance values of the resistors R1a and R2a of the voltage dividing circuit are

## EQU10 ## (R1a / N ₁ ) = (R2a / N ₂ ) ... It is set so as to satisfy the expression 10.

Therefore, the plurality of battery cells B ₁ , ...,
If no abnormality occurs in B _n , the differential amplifier AMP 2
Among the inputs, the non-inverting side has a ground potential, and the inverting side has a voltage of plus and minus with respect to the ground potential divided by the cell number ratio, and thus has zero volts. For this reason,
The output E _D of the differential amplifier AMP also becomes zero, the charge control signal CS output from the window comparator WC holds the logic L, and the charging is continued as in the first embodiment.

However, a plurality of battery cells B ₁ , ..., B
_If an abnormality occurs in one of the _n and the cell voltage drops,
The input voltage at the inverting input terminal (-) of the differential amplifier AMP takes a certain value on the plus or minus side. Therefore, no matter which side the input voltage is, the charge control signal CS output from the window comparator WC becomes logic H, and the charging is immediately stopped, as in the first embodiment, and An alarm is issued based on the light emitting diode D8. As described above, even if the differential amplifier AMP as the adder circuit is used, it is possible to obtain substantially the same operational effect as that of the first embodiment, and the circuit can be formed relatively easily. In addition, when changing the voltage derivation position between cells, that is, when it is desired to change the cell number ratios N ₁ and N _2, by changing the values of the resistors R1a and R2a of the voltage dividing circuit so as to satisfy Expression 10, I can deal with it.

In the second embodiment, in particular, the voltage dividing circuit by the resistors R1a and R2a and the differential amplifier AMP form the arithmetic means of the present invention.

(Third Embodiment) Next, a third embodiment will be described with reference to FIG. Here, the same or equivalent components as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted or simplified.

The battery charger shown in FIG. 5 is designed to derive the voltage from two connection points of a plurality of series-connected battery cells B ₁ , ..., B _n , and is roughly shown. The inverting amplifier RA in FIG. 1 of the first embodiment.
1, two channels of an adder AD and a window comparator WC are provided (indicated by symbols a and b in FIG. 5), and the results are combined by an OR circuit OR.

First, a plurality of battery cells B ₁ , ..., B _n
Is divided into cell number ratios N ₁ , N ₂ , N ₃ as shown,
The connection point voltages V _C2 and V _C1 from the dividing points to the detection ends IN _ma and I of the charge monitoring unit 3 by the cables 12 b and 12 a.
N _mb has been derived respectively. The entire battery terminal voltage V _B is derived from the cable 11 to the detection end IN _h of the charge monitoring unit.

Further, in the charge monitoring unit 3 shown in FIG. 5, one channel a has an inverting amplifier RA1a connected to the detection terminals IN _h and IN _ma , an adder ADa, and a window comparator WCa, and the other channel a. The channel b is an inverting amplifier RA connected to the detection terminals IN _h and IN _mb.
1b, an adder ADb, and a window comparator WCb. The element configuration of each circuit of these channels a and b is the same as that of FIG. 1, but for the sake of distinction, reference numerals are divided as shown in FIG. The output signals of the window comparators WCa and WCb of both channels a and b form the charge control signal CS via the OR circuit OR.

Here, on the channel a side, N ₁₁ = N ₁
+ As _{N 2, N 12 = N 3} , the N ₁ in the above formulas 1 to 5 N
₁₁ , N ₂ to N ₁₂ , R 1 to R 11, ..., V _C to V
_It is assumed that _{C D} is replaced with E _D and E _D1 is read. Similarly, on the channel b side, N ₂₁ = N ₁ , N ₂₂ = N ₂ + N ₃ , and N ₁ in the above formulas 1 to 5 is N ₂₁ , N ₂ is N ₂₂ ,
It is assumed that R1 is read as R21, ..., V _C is read as V _C2 , and E _D is read as E _D2 (R11 ..., R21 ... Are the resistors in FIG. 5, and E _D1 and E _D2 are adders ADa. , ADb). Even in the case of detecting the voltage at two places as described above, the charging can be stopped when the cell is abnormal as in the first embodiment, and the detection accuracy for the cell abnormality is remarkably high. Can be improved.

Even when three or more connection point voltages are drawn from a plurality of series-connected battery cells B ₁ , ..., B _n , it is possible to increase the number of channels as in the second embodiment. Furthermore, the configuration of each of the above-described embodiments in the charge monitoring unit may be replaced with software of a computer.

[0058]

As described above, the battery charger of the present invention derives the voltage at at least one inter-cell connection point among a plurality of battery cells, and the derived voltage and the plurality of batteries. The battery cell is judged to be abnormal based on the voltage across the cell, and when the battery cell is judged to be abnormal, charging is stopped. It is possible to reliably eliminate the state of continuing the operation, thereby preventing the normal cell from deteriorating and the adverse effects caused by the generation of the internal gas, and significantly improving the reliability of the device.

Particularly, according to the battery charging device of the third aspect, the operator can be informed by an alarm that the charging has been stopped, so that the operator can take prompt measures to prevent the charging work from being delayed. it can.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a battery charging device according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a charge control circuit of the battery charger of FIG.

FIG. 3 is a characteristic diagram showing output characteristics of a charge control circuit.

FIG. 4 is an overall configuration diagram of a battery charger according to a second embodiment of the present invention.

FIG. 5 is an overall configuration diagram of a battery charger according to a third embodiment of the present invention.

FIG. 6 is a configuration diagram showing an example of a conventional battery charging device.

[Explanation of symbols]

1 AC power supply 2 Charging control circuit 3 Charging monitoring unit 10 Voltage / current control circuit 12, 12a, 12b Cable D7 Diode RA1 Inversion amplifier AD adder WC Window comparator RV1 Inverter D8 Light emitting diode AMP Differential amplifier R1a, R1b Resistance B ₁ ,…, B _n battery cell

Claims (3)

[Claims] 1. A battery charger comprising a charging means for simultaneously charging a plurality of battery cells of the same type by applying a voltage across a plurality of battery cells connected in series. Abnormality of the battery cell based on the voltage deriving means for deriving the voltage of at least one inter-cell connection point in the battery cell, and the derived voltage of the voltage deriving means and the voltage across the plurality of battery cells. A battery charging device, comprising: an abnormality determining unit that determines whether or not the battery cell is charged, and a charging stop unit that stops charging by the charging unit when the abnormality determining unit determines that the battery cell is abnormal. 2. The abnormality determining means considers the ratio of the number of cells divided by the derivation position of the voltage derivation means based on the derivation voltage of the voltage derivation means and the voltages across the plurality of battery cells. The charging means includes a calculating means for calculating the difference between the voltage across the terminal and the derived voltage, and a comparing means for comparing the calculated voltage of the calculating means with a reference voltage preset corresponding to the abnormality of the battery cell. 2. The battery charging device according to claim 1, wherein the stopping means is means for stopping the charging by the charging means when the comparison result of the comparing means indicates an abnormality of the battery cell. 3. The battery charging device according to claim 1, further comprising alarm means for notifying the stop of charging when the charging stopping means stops charging by the charging means.