JP2000312442A - Series battery charging / discharging device - Google Patents

Abstract

(57) [Problem] To provide a charging / discharging device in which all batteries are fully charged and completely discharged by connecting secondary batteries in series. SOLUTION: In order to separate each of the single secondary batteries 41a, 41b from the series-connected charging / discharging circuits 100a, 100b, respectively, the single secondary batteries 41a, 41b are connected in series with respective series switches 11a, 11b. This can be achieved by providing the switches 12a and 12b. The switches 11a, 11b, 12a, 12b are operated with a certain procedure for opening and closing, and are connected in series with the charging / discharging circuits 100a, 1 safely and arbitrarily without interrupting the supply current.
00b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a serial charging / discharging apparatus for a secondary battery, and more particularly to a serial charging / discharging apparatus for safely and efficiently charging / discharging a plurality of single secondary batteries connected in series. The present invention relates to a battery charging / discharging device.

[0002]

2. Description of the Related Art An assembled battery comprising a group of cells is set in a charging device in series, and is provided adjacent to each cell, respectively.
A plurality of switches are provided for turning on and off the power supply and switching between the battery connection side and the battery bypass side while maintaining the series relationship with the power supply of each cell. All the switches are switched to the battery connection side, and all the batteries are connected in series to the constant current power supply. Next, the power is turned on, and charging starts when a constant current from the power flows into each cell. When charging is started, when the measured voltage of each voltmeter provided on each cell reaches the target voltage, a switch connected to the terminal of the cell that has reached the target voltage switches the battery bypass from the battery connection side. It is switched to the side. This operation is performed for all the cells until all switches are switched to the battery bypass side, and charging is completed. A technique related to this is disclosed in Japanese Patent Application Laid-Open No. Hei 8-115748.

[0003] A battery pack composed of a plurality of secondary batteries connected in series is provided with a DO voltage of each secondary battery based on the terminal voltage of each secondary battery.
Voltage detecting means for detecting D, a discharge switch circuit for discharging each secondary battery independently, a charging means for charging the assembled battery, and each secondary battery through the discharge switch circuit based on a detection value of the voltage detecting means. And a control means for independently discharging. Before the charging switch is turned on and charging is started, each voltage of the series-connected secondary battery pack is detected by a voltage detector. A battery whose detected voltage is equal to or higher than the discharge end voltage has a discharge switch turned on, and discharges to the discharge end voltage to equalize the depth of discharge of each battery. Thereafter, a charging voltage and a charging current are applied to the battery pack by the charger to start charging, and the charging is completed when any one of the batteries reaches a full charge. Related to this is Japanese Patent Application Laid-Open No. 7-2551.
There is a technique described in Japanese Patent Publication No. 34-34.

[0004]

As described above, in the method of charging by connecting the secondary batteries in series, a switch is connected to each battery in parallel, and the switch is opened and closed as necessary. This allows the battery to be charged safely.
However, any of these methods has a problem that power loss is large because the switch is configured by a semiconductor element such as a transistor or a diode. In addition, when there is a variation in the capacity between the batteries, there is a problem that the battery performance is limited to the battery having the smallest capacity and that all the battery capacities cannot be used sufficiently. In addition, since there is no switch provided in series with the battery, the batteries cannot be separated from each other,
If one battery is damaged, there is a problem that all the battery groups are stopped, and furthermore, when switching the parallel switches, the supply current is cut off because the circuit composed of the series-connected secondary batteries is always cut off once. was there. Further, in general, a battery has a problem that even if the charging current is increased, only the terminal voltage increases, and the battery cannot be fully charged with a large discharge capacity.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. The power loss is small, all the battery capacities can be fully utilized, the supply current can be made continuous, the full charge, the complete It is an object of the present invention to provide a series battery charging / discharging device for discharging.

[0006]

SUMMARY OF THE INVENTION A series battery charging / discharging apparatus according to the present invention comprises: a charging / discharging device; a plurality of charging / discharging circuits connected in series to the charging / discharging device; In a series battery charging / discharging device including a single secondary battery provided in the circuit and a control unit for controlling the same,
The charge / discharge circuit includes a first switch connected in series to the single secondary battery, a second switch connected in parallel to a series connection circuit of the single secondary battery and the first switch, It comprises a voltage detector for detecting the terminal voltage of the single secondary battery, and a third switch connected to both terminals of the secondary battery, and the control means uses a signal from the voltage detector to The first switch, the second switch, and the third switch are configured to be controlled.

[0007] In the series battery charging and discharging device according to the preceding paragraph,
It is characterized in that one resistance element and another resistance element connected to the second switch and the third switch, respectively, are provided. In the series battery charging and discharging device according to the preceding paragraph,
A detector for detecting a charging / discharging current is provided on a connecting line between the charging / discharging circuit and the charging / discharging device. In the series battery charging / discharging device according to the preceding paragraph, when both the first switch and the second switch are closed, the current flowing through the single secondary battery is equal to or less than the maximum current limit value of the battery. Preferably, the resistance value of the one resistance element is selected. In any one of the series battery charging / discharging devices described in the preceding paragraph, a short-circuit switch is provided for the one resistance element. In any one of the series battery charging / discharging devices described in the preceding paragraph, when performing charging by combining constant current charging and constant voltage charging, sequentially disconnect from the charging / discharging circuit from the battery that has reached the upper limit voltage at the end of constant current charging, The separated battery is connected again to perform constant-voltage charging.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 to 9, an embodiment of a series battery charging / discharging apparatus according to the present invention will be described. FIG. 1 is an explanatory diagram of a serial battery charging / discharging device according to an embodiment of the present invention, FIG. 2 is a partial explanatory diagram of a charging operation in the serial battery charging / discharging device of FIG. 1, and FIG. FIG. 4 is another partial explanatory view of the charging operation in the charging / discharging device.
FIG. 5 is still another partial explanatory view of the charging operation in the serial battery charging / discharging device of FIG. 1, FIG. 5 is still another partial explanatory diagram of the charging operation in the serial battery charging / discharging device of FIG. 1, and FIG. FIG. 7 is still another partial explanatory view of the charging operation in the battery charging / discharging device, FIG. 7 is still another partial explanatory diagram of the charging operation in the serial battery charging / discharging device of FIG. 1, and FIG. FIG. 9 is a flow sheet of the charging operation in FIG.
FIG. 2 is a charging characteristic diagram of the serial battery charging / discharging device of FIG. 1.

In brief, the present invention is provided with means for disconnecting each cell from the series circuit. The means can be achieved by providing a switch in series with the single secondary battery and a switch in parallel with the series circuit. By opening and closing the switch according to a predetermined procedure, any battery can be safely disconnected from the series circuit.

In FIG. 1, 1 is a charger / discharger, 2 is a controller, 11 (collectively), 11a, 11b,... 11n are arranged in series with batteries 41 (collectively), 41a, 41b,. First switch element, 12 (collectively), 12
a, 12b,... 12n are batteries 41 (collectively), 41a,
41b, 41n and switch elements 11 (collectively), 11
a, 11b,... 11n, second switch elements 13 (collectively), 13a,
.. 13n are batteries 41 (collectively), 41a, 41
b,... 41n are connected to resistance elements 22 (collectively), 2
, 22n, 22a, 22b,..., 22n
Are diodes 13 (collectively), 13a, 13b,.
n, 31 (collectively), 3
.. 31n are voltage detectors, 41 (collectively), 41a, 41b,... 41n are batteries, 50 is a current transformer for detecting charging current, 100 (collectively), 100a, 10a
0b,... 100n are charge / discharge circuits, 201 (collectively), 2
.. 201n are control signals.

As shown in FIG. 1, charge / discharge circuits 100a, 100a
.. 100n are connected in series, and this series connection circuit is connected to the controller 2 in parallel. Furthermore, the charge / discharge circuits 100a, 10
0b... 100n at both ends of the charge / discharge circuit 100a, 100
n is connected to the charger / discharger 1 by wirings 301 and 302, respectively. By connecting these wirings 301 and 302, the charge / discharge circuits 100a, 100b,.
Are connected to the charger / discharger 1 in series.

Charge / discharge circuits 100a, 100b,...
Since 0n has the same configuration, the charging / discharging circuit 100a will be described as an example in detail. The switch element 11a is connected to the battery 41a in series. A series circuit of the resistor 21a and the switch element 12a is connected in parallel to the series circuit of the battery 41a and the switch element 11a.

Both terminals of a series circuit of a resistor 22a and a diode element 13a are connected to a connection point between the switch element 11a and the anode side of the battery 41a and a cathode side of the battery 41a, respectively. The base of the diode element 13a is connected to the controller 2. Further, a voltage detector 31a is connected to both terminals of a series circuit of the resistor 22a and the diode element 13a, and the voltage detection signal is input to the controller 2. The switch element 11a and the switch element 12a are controlled by a control signal 201a from the controller 2.
It is controlled to be turned on and off with.

The switching element 11a and the switching element 1
2a is connected to the charge / discharger 1 and the connection line 3
01, the charging current flowing through the connection line 301 is detected by the current transformer 50, and the detected current value is input to the charger / discharger 1. The controller (not shown) in the charger / discharger 1 controls the charge / discharge current based on the input detected current value. A connection terminal between the cathode side of the battery 41a and the resistor 21a is connected to a connection terminal between the switch element 11b and the switch element 12b of the charge / discharge circuit 100b. The charge / discharge circuit 100b includes the charge / discharge circuit 10
Needless to say, the configuration is the same as 0a.

Switch element 11a and switch element 12a
Plays a role of connecting a unit cell that has been charged with a constant current to a series circuit 1
00a and disconnecting the defective unit cell from the series circuit 100a. Switch element 11
a and switch 12a are simply "on" for that purpose,
Since the switch is turned off, the switching frequency is low and the current flowing is large. Therefore, a contactor or the like having a small contact resistance is preferable, but a semiconductor switch may be used.

The role of the switch element 13a is to adjust the base of the switch element 13a by the controller 2, to adjust the on / off time of the current flowing through the switch element 13a, and to adjust the magnitude of the current. Thereby, a part of the charging current is bypassed through the switch element 13a. Therefore, the switch element 13a is
At the end of the constant voltage charging, the switch is frequently opened and closed to adjust the bypass current. Therefore, a semiconductor switch is preferable, but a contactor may be used.

The charging operation of the serial battery charging / discharging device having the above configuration will be described in detail with reference to FIGS. In order to simplify the description, in the series battery charging / discharging device of FIG.
A circuit in which two charge / discharge circuits 100a and 100b are connected in series will be described as an example. The circuit diagrams shown in FIGS. 2 to 7 correspond to specific steps of the charging operation shown in the flow sheet of FIG.

Further, two charge / discharge circuits 100 in the series battery charge / discharge device of FIG. 1 shown in FIGS.
a, 100b, a charge / discharge circuit 100 including a battery 41a
This will be described with reference to a. It is assumed that the charge / discharge circuit 100b is held in the state shown in FIG.

[0019] In FIG. 8, in S _1, initializing the controller 2, i.e., the controller 2 sets the use value of each battery. The upper limit voltage and the lower limit voltage of the use value of each of the batteries 41a and 41b are substantially the same value, and the charging current of each of the batteries is substantially the same since the batteries are connected in series. In addition, the switch element of the battery that has reached the lower limit voltage according to the capacity of each battery is turned off. Further, the base voltage of the transistor element 13a is set according to the upper limit voltage of each battery. Therefore, when the battery does not reach the upper limit voltage, the transistor element 13a is turned off.
It has become.

In S ₂ , all switch elements are turned off by the controller 2. In S _3,
The switch elements 11a and 11b are turned on. S ₄
Set the charging mode in. The charging mode includes a constant current charging mode in which a constant small current is used throughout, and a constant voltage mode in which approximately 2.3 to 2.5 V is applied to one battery and charging is performed while maintaining the voltage.

[0021] In S _5, select the constant current charging mode, in S _6, in the charge and discharge unit 1, constant current charging (hereinafter,
In this specification and in the drawings, CC charging is performed. FIG. 2 shows a case where the battery 41a and the battery 41b are connected in series to perform CC charging. In the charge / discharge circuit 100a, the switch elements 11a and 11b are closed, and the switch elements 12a, 12b, 13a and 13b are
Charging is performed in the open state. The period in the charging characteristic curve shown in FIG. 9 corresponds to the charging period. Curve 1 in FIG.
01a and 101b are the battery voltage characteristics of the batteries 41a and 41b, respectively, and as shown in the charging characteristic curve in the period of FIG. 9, the battery 41a has a characteristic in which the terminal voltage increases earlier than the battery 41b.

[0022] The terminal voltage of the battery 41a in the S ₇ (V
i) is detected by the voltage detector 31a. Terminal voltage (Vi) −Set voltage (Vs)> 0 (1) The controller 2 calculates Expression (1) to determine whether it is positive or negative. YES, that if positive, if the terminal voltage (Vi) is higher than the voltage (Vs), the process proceeds to S _9. If NO, that is, when the negative, when the setting voltage (Vs) is higher than the terminal voltage (Vi) is returned to S _6, CC charging is continued.

[0023] In S _9, the charging and discharging circuit of the battery 41a 1
By opening the switch element 12a to open the circuit from 00a, a bypass circuit is formed via the resistor 21a. The resistance value of the resistor 21a is selected so that the current flowing through the battery 41a is equal to or less than the allowable current of the battery 41a and is equal to or less than the rated current of the switch element 12a.

[0024] In S _10, opening switch element 11a as shown Figure 4. The time when the battery 41a is opened is the time when the battery 41a is opened as indicated by the charging characteristic curve shown in FIG. Through this series of operations, the battery 41a can be disconnected from the series battery charging / discharging circuit 100a without stopping power supply to the entire series battery. In S _11,
The battery 41a is left as it is until the terminal voltage of a battery having a difference in battery characteristics, for example, another battery 41b becomes constant.

Thereafter, CC charging is continued only in the battery 41b. This charging period is the period shown in FIG. When only the battery 41b is charged with the CC, the battery voltage of the battery 41a increases due to the elimination of the voltage drop due to the internal resistance of the battery and decreases due to the progress of the chemical reaction inside the battery, but as a result, the battery voltage decreases. When the battery 41b reaches the upper limit voltage of the battery voltage, the battery 41a is connected to the series charge / discharge circuit 100a again.

[0026] As shown in FIG. 5, in S _12, the battery 41
To reconnect a to the charge / discharge circuit 100a, the switch element 11a is closed. Thus, a bypass circuit to the resistor 21a is formed. As shown in FIG. 6, the switch element 12a is opened. By doing so, the battery 41a can be reconnected to the series circuit 100a without stopping power supply to the entire series battery.

The voltage of the battery 41a has a slight time delay due to a voltage drop due to the internal resistance of the battery, but is substantially equal to the voltage of the battery 41b. The value of the resistor 21a is such that the current flowing through the battery 41a is
The current is selected so as to be equal to or less than the allowable current of the battery 41a and equal to or less than the rated current of the switch element 11a.

[0028] In S _12, sets the constant voltage charging mode in the state of FIG. In S _13, the constant-voltage charge in which the above-described (referred CV charging in the specification and illustrated) is carried out in the charge and discharge unit 1. This is the period shown in FIG. 9, and it can be seen that the charging current is determined so as to be equal to or less than the allowable current of the battery 41a and equal to or less than the rated current of the switch element 11a. In this case, as shown in FIG. 6, the switch element 13a is open, so that the bypass circuit passing through the resistance element 22a is "off". In S _14, the command of the controller 2, by the voltage detector 31a, for detecting the terminal voltage of the battery 41a.

[0029] In S _15, the controller 2, the terminal voltage (Vi) - set voltage (Vs) = (ΔV)> 0 ···· (2) Equation (2) calculates a determination sign of [Delta] V, the magnitude I do. YE
For S, if ΔV is positive proceeds to S _16, If NO,
If ΔV is negative returns to S _13, CV charging is performed by the charge and discharge unit 1.

[0030] In S _16, ΔV> 0, and if not [Delta] V> C, i.e. the terminal voltage (Vi) is set voltage (Vs)
The If a little over, as shown in FIG. 7 in S ₁₆ ', the detection value of the voltage detector, by the controller 2 adjusts the base voltage of the switching element 13a, closing the switch element 13a. Then, in S ₁₆ ″, the charging is continued as it is while the charge amount of the battery 41 a is adjusted by bypassing a part of the charging current through the resistor 22 a and the switch element 13 a.

[0031] [Delta] V> 0, and [Delta] V> C, i.e., at a state where the terminal voltage of the battery 41a is largely over the upper limit voltage set by the controller 2, in S _17, the controller by the detection value of the voltage detector 31a The switch element 12a is closed by 2. In S _18, through the switch element 12a and the resistance element 21a bypassing current of the charging current.

[0032] In S _19, if greater than the charging current Ic is set charging current I, charged with S ₂₀ is completed. If smaller than the set charging current I charge current Ic is returned to S _13, C
V charging is continued. Similarly to the battery 41a, the charge of the battery 41b is adjusted. Thus, the voltage difference between the batteries can be compensated. By the above method,
The series battery can be charged with CC and CV.

It is also possible to discharge at a constant current in the same manner as during charging. That is, in the constant current discharge, the switch elements 11a, 11b,... 11n are turned on, and the switch elements 12a, 12b,. Each battery 41a, 41b,... 4 connected in series
1n. When the battery whose terminal voltage has reached the lower limit, for example, the battery 41a has reached the lower limit voltage, by closing the switch element 12a and then opening the switch element 11a, the battery 41a is cut off without interrupting the discharge current. It can be separated from the charge / discharge circuit 100a. During discharging, the switch element 13a and the resistor 22
The series circuit of FIG.
By adjusting the base voltage of a, the switch element 13a is kept "off".

Even when the number of series batteries is large, the batteries that have reached the upper limit voltage are sequentially disconnected from the series circuit at the end of CC charging. A considerable number of batteries can be disconnected from the series circuit. Reconnect the disconnected battery and CV
By charging, all the batteries can be fully charged. Here, the substantial number may be the total number, about half, or any other number.

Needless to say, when disconnecting or reconnecting the battery, the output of the charger / discharger is adjusted. However, the resistance value is set so that the potential generated across the resistor 21 according to the present invention becomes equal to the battery voltage. Is selected, the voltage adjustment range required for the charger / discharger can be narrowed, which is a great effect of the present embodiment. The period during which the current flows through the resistance element 21 causes a resistance loss, but the period is a short time with respect to the entire time, and the loss is a small amount. As shown in FIG. 1, a short-circuit switch 51 may be provided on the resistance element 21. Although the charger / discharger 1 and the controller 2 are separate bodies, the controller 2 may be built in the charger / discharger 1.

Here, an example of selection of the resistance value R21 of the resistance element 21 will be described below. Battery upper limit voltage = Vb ON resistance of switch element 12 = R12 When charging current in CC charging = Icc, R21 = (Vb / Icc) -R12. By selecting the resistance value in this manner, it is possible to prevent an excessive current from flowing through the battery when the switch element 12 is closed. Further, the breaking capacity of the switch can be reduced.

The configuration and operation of the present invention during constant current and constant voltage charging have been described above. Apart from the above-mentioned charge / discharge, by utilizing the configuration of the present invention, it is possible to disconnect an arbitrary battery during charge / discharge. This may be due to disconnection of the abnormal battery or replacement of the battery. Abnormal battery disconnection refers to the safe disconnection of a battery when abnormalities such as overcharge, overdischarge, or internal short-circuit occur during charging and discharging, and abnormalities in battery voltage or rising battery temperature are detected. And charging and discharging of other batteries can be continued. This can be performed by the operation procedure described with reference to FIGS. 3 and 4 described in the method of constant current and constant voltage charging. It goes without saying that the method of reconnecting after battery replacement follows the operation procedure described with reference to FIGS. Also,
It goes without saying that when disconnecting or reconnecting the battery, the output of the charger / discharger is adjusted.

[0038]

According to the structure of the present invention, the loss of the series battery charging / discharging circuit can be greatly reduced. Each cell can be safely opened from the series circuit, and the breaking capacity of the switch required for opening can be greatly reduced. According to the present invention, it is possible to provide a series charge / discharge device capable of fully charging and completely discharging all batteries at a low cost and safely.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a series battery charging / discharging device according to an embodiment of the present invention.

FIG. 2 is a partial explanatory view of a charging operation in the serial battery charging / discharging device of FIG. 1;

FIG. 3 is another partial explanatory view of the charging operation in the serial battery charging / discharging device of FIG. 1;

4 is still another partial explanatory view of the charging operation in the serial battery charging / discharging device of FIG. 1. FIG.

FIG. 5 is still another partial explanatory view of the charging operation in the serial battery charging / discharging device of FIG. 1;

6 is still another partial explanatory view of the charging operation in the serial battery charging / discharging device of FIG. 1. FIG.

FIG. 7 is still another partial explanatory view of the charging operation in the serial battery charging / discharging device of FIG. 1;

FIG. 8 is a flowchart showing a charging operation in the serial battery charging / discharging device of FIG. 1;

FIG. 9 is a charging characteristic diagram of the serial battery charging / discharging device of FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Charge / discharge device, 2 ... Controller, 11 (collectively), 11
a, 11b,... 11n switch elements disposed in series with the battery 41, 12 (collectively), 12a, 12b,.
n: switch elements arranged in parallel with the battery 41 and the series switch element 11, 13 (collectively), 13a, 13b,.
13n: diode elements arranged in parallel with the voltage detector 31, 22 (general name), 22a, 22b,... 22n: resistors arranged in series with the diode 13, 31 (generic name);
31n, voltage detectors, 41 (collectively), 41a, 41b,... 41n secondary batteries, 50
Current transformer for detecting charging current, 100a, 100b... 10
0n: charge / discharge circuit, 201 (collectively), 201a, 201
b ... 201n ... control signal.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenji Kubo 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Inside the Hitachi Research Laboratory, Hitachi, Ltd. (72) Inventor Akihiko Emori 7-1 Omikacho, Hitachi City, Ibaraki Prefecture No. 1 F term in Hitachi, Ltd. Hitachi Research Laboratory (reference) 5G003 AA01 BA03 CA03 CA14 CC04 DA07 5H030 AA03 AA04 AA06 BB01 BB21 DD08 FF43 FF44

Claims (6)

[Claims] 1. A charging / discharging device, a plurality of charging / discharging circuits connected in series to the charging / discharging device, a single secondary battery respectively provided in the charging / discharging circuit, and controlling these A charging / discharging circuit, wherein the charging / discharging circuit includes a first switch connected in series to the single secondary battery, and a serial connection of the single secondary battery and the first switch. A second switch connected in parallel to the connection circuit, a voltage detector for detecting a terminal voltage of the single secondary battery, and a third switch connected to both terminals of the single secondary battery, The control means is a signal from the voltage detector,
A series battery charging / discharging device, wherein the first switch, the second switch, and the third switch are controlled. 2. The series battery charging / discharging device according to claim 1, further comprising: providing one resistance element connected to the second switch and another resistance element connected to the third switch. Characteristic series battery charging / discharging device. 3. The series battery charging / discharging device according to claim 1, wherein a detector for detecting a charging / discharging current is provided on a connection line between the charging / discharging circuit and the charging / discharging device. Charge / discharge device. 4. The series battery charging / discharging device according to claim 2, wherein when both the first switch and the second switch are closed, a current flowing through the single secondary battery increases the current of the battery. A series battery charging / discharging device, wherein a resistance value of the one resistance element is selected so as to be equal to or less than a maximum current limit value. 5. The series battery charging / discharging device according to claim 2, wherein a short-circuit switch is provided in said one resistance element. 6. The battery that has reached the upper limit voltage at the end of constant current charging, when charging is performed by combining constant current charging and constant voltage charging in the series battery charging / discharging device according to any one of claims 1 to 5. From the charge / discharge circuit, and the connected batteries are connected again to perform the constant voltage charging.