JP2002315202A - Battery pack for multiple and series connection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect more battery packs for multiple and series connection than the number of cells which a conventional protection IC accommodates using the protection IC. SOLUTION: A battery pack for multiple and series connection is formed by connecting two or more cells B1 to B8 in series and further connecting control elements Q9 and Q10 for charging and discharging in series. The battery pack is provided with a plurality of protection circuits U1 and U2 which monitor the cell voltage of each of a plurality of groups into which the series-connected cells are divided for the detection of overcharge/overdischarge; and logic circuits Q1 to Q7 which OR-process the detection signals of a plurality of the protection circuits, and control circuits Q8 and Q11 which control the control elements for charging and discharging according to the outputs of the logic circuits. The cell voltage is monitored on a group-by-group basis by the protection circuits U1 and U2 to detect overcharging/overdischarging by each cell B1 to B8 and control the control elements Q9 and Q10 for charging and discharging. Thus, monitoring and protection of the battery pack for multiple and series connection are accomplished by a simple constitution using a conventional protection IC.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-use battery pack in which two or more cells are connected in series, and a charge / discharge control element is connected in series.

[0002]

2. Description of the Related Art In a multi-use battery pack in which a plurality of cells are connected in series, a protection circuit is connected in parallel to each cell to perform overcharge protection and overdischarge protection. A pack has been proposed (for example, JP-A-7-22009, JP-A-000-354335).
Reference). However, in these proposals, a protection circuit is connected in parallel to each cell. Therefore, when the number of cells connected in series increases, the protection circuits are connected in parallel in accordance with the number, so that the problem becomes complicated. There is. Also,
A protection IC for multiple uses is also commercially available.
In most cases, the number of cells is usually up to four, so that there is a problem that it cannot be used for a battery pack in which a larger number of cells are connected in series.

[0003]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and uses a conventional protection IC to protect the protection IC.
This enables protection of a multiple-use battery pack having a number of cells corresponding to C or more.

[0004] For this purpose, the present invention relates to a multi-use battery pack in which two or more cells are connected in series and a charge / discharge control element is connected in series. A plurality of protection circuits for monitoring the cell voltage of each group and detecting overcharging / discharging, a logic processing circuit for OR processing detection signals of the plurality of protection circuits, and an output of the logic processing circuit. And a control circuit for controlling the charge / discharge control element.

The protection circuit detects an overcharge when the maximum cell voltage in the group is equal to or higher than a predetermined value, and detects an overdischarge when the minimum cell voltage in the group is equal to or lower than the predetermined value. The charging / discharging control element includes a charging FET and a discharging FET, and when the overcharging or overdischarging is detected in any of the plurality of protection circuits, the charging circuit or the discharging FET is controlled by the control circuit. Controlling off, connecting the base / emitter of a transistor in parallel with the discharging FET or a series circuit of the discharging FET and the charging FET, detecting overcurrent by the transistor and turning off the discharging FET The voltage drop of the charge / discharge control element is monitored by a protection circuit of a group connected to the charge / discharge control element, and an overcurrent is detected. It is intended to.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a multiple-use battery pack according to the present invention, wherein B1 to B8 are cells, U1 and U2 are protection ICs, Q1, Q2, Q11, and Q1.
2 denotes a transistor, Q3 to Q8 denote FETs, Q9 denotes a discharging FET, and Q10 denotes a charging FET.

In FIG. 1, cells B1 to B8 are connected in series, and the cells B1 to B8 are grouped into four groups as one group.
The protection IC, which is one protection circuit, monitors each voltage of a plurality of cells to detect overcharging and discharging, and is divided into two groups in total. The cells B1 to B4 are monitored by the protection ICU1, and the cells B5 to B8 are monitored by the protection ICU2.
A charging FET 10 for controlling charging and a discharging FET 9 for controlling discharging are connected in series with these cells B1 to B8. The charging FET Q10 and the discharging FET Q9 are turned on in a normal state, and the charging FET is stopped when charging is stopped.
It is the transistor Q11 that turns off Q10 and controls the on / off of the charging FET Q10. When the discharging is stopped, the transistor Q11 is turned off and the on / off of the discharging FET Q9 is controlled. Is FET
QQ8 and transistor Q12.

In this embodiment, MM1414 (IC made by MITSUMI ELECTRIC CO.), Which is a protection IC for 3 or 4 direct use, is connected to a protection ICU.
1, U2 is used, and pin 1 is fixed to Vcc and used for 4 directly. For example, the protection ICU1 or U2 compares the maximum cell voltage with a predetermined value and determines that overcharging is performed when the maximum cell voltage is higher than a predetermined value or when there is a cell voltage that is higher than a predetermined value. In addition, the minimum cell voltage is compared with a predetermined value, and if the minimum cell voltage is equal to or lower than a predetermined value, or if there is any cell voltage that is lower than or equal to a predetermined value, it is determined that overdischarge has occurred. Protection ICU1, U
2 monitors each cell voltage, and when any cell becomes overcharged from a normal state in which the output of pin 1 is at H level and the output of pin 5 is at L level, the output of pin 1 is set to L level; When any of the cells is overdischarged, the pin 5 is set to the H level.

The transistors Q1 and Q2 are connected to the protection ICU.
1 and U2 are turned on / off by the output of one pin, and when either of them is turned on, the transistor Q11 is OR-connected so that the transistor Q11 is turned on.
At the time of overcharging that has reached the level, the charging FET Q10 is turned off to stop charging. In addition, FET Q3, Q4
Is turned on / off by the output of the 5 pins of the protection ICU1 and U2, and is OR-connected via the FETs Q6 and Q7 so that when either of them is turned off, the FET Q8 is turned off.
At the time of overdischarge when the outputs of the five pins CU1 and U2 become H level, the discharge FET Q9 is turned off to stop the discharge.

In the multiple-use battery pack according to the present invention, two or more assembled cells are connected in series as described above, and a charging FET for controlling charging and a discharging FET for controlling discharging are connected in series to the assembled cells. And connect. Then, the assembled cells are divided into a plurality of groups, protection ICs corresponding to the number of the assembled cells are arranged in the assembled cells of each group, and the minimum and maximum cell voltages in the group are detected and a predetermined value is detected. It is determined whether it is below or above. By connecting all the output signals of the protection ICs whose maximum cell voltage is equal to or higher than a predetermined value, the maximum voltage of all cells becomes equal to or higher than a predetermined value, ie, equal to or higher than a predetermined value among all cells. When there is a cell having a voltage of overcharging, the charging FET Q10 is controlled to be turned off to stop charging. Similarly, by ORing all the output signals of the respective protection ICs whose minimum cell voltage is equal to or lower than a predetermined value, the minimum voltage of all cells becomes equal to or lower than a predetermined value. When there is a cell having a voltage equal to or lower than the value, the discharge FET Q9 is controlled to be turned off to stop the discharge at the time of overdischarge.

Next, the operation of the battery pack circuit having the above configuration will be described. First, in the normal state in which overcharge, overdischarge, and overcurrent are not detected, both the protection ICU1 and U2 have a high-impedance 1
Pin 5, which is the drive terminal of the discharging FET, is at the L level. In this state, in the overcharge-related circuit, the transistors Q1, Q2, and Q11 are turned off, and the charging FET Q10 is turned on. In the circuit related to overdischarge, the FETs Q3 and Q4 are turned on, the FET Q5 is turned off, and the FETs Q7, Q6 and Q8 are turned on.
The discharging FET Q9 is also turned on. In the overcurrent-related circuit, the transistor Q12 is turned off if a normal current flows, so that the discharging FET Q9 is also turned on.
As described above, in the normal state, since the discharging FET Q9 and the charging FET Q10 are on, charging and discharging are possible.

At the time of charging compared to normal time, for example, if any of cells B5 to B8 is overcharged,
Since the pin 1 of the protection ICU2 becomes L level, the transistor Q1 turns on. At this time, even if the transistor Q2 is off, the transistor Q11 is turned on, so that the charging FET Q10 is turned off to stop charging. Similarly, when any one of the cells B1 to B4 is overcharged, the pin 1 of the protection ICU1 becomes L level, so that the transistor Q2 is turned on. At this time, even if the transistor Q1 is off, the transistor Q11
Is turned on, the charging FET Q10 is turned off, and charging is stopped. However, the charging FET Q10 has
Since there is a parasitic diode, discharging is possible even if the charging FET Q10 is turned off by the parasitic diode.

At the time of discharging, for example, cell B5
-B8 is over-discharged, the protection IC
Since pin 5 of U2 is at the H level, FET Q3 is turned off. At this time, even if the FET Q7 is in the ON state,
Since the FET Q6 is turned off and the FET Q8 is also turned off,
The discharging FET Q9 is turned off to stop discharging. Similarly, when any of the cells B1 to B4 is over-discharged, the pin 5 of the protection ICU1 becomes H level.
TQ4 turns off. At this time, even if the FET Q6 is on, the FET Q7 is turned off and the FET Q8 is also turned off, so that the discharging FET Q9 is turned off to stop discharging. However, since the charging FET Q9 has a parasitic diode, the discharging diode
Even if the ETQ 9 is turned off, charging is possible.

Further, with respect to an overcurrent, a voltage drop generated in the resistor when the discharge FET Q9 is turned on by the discharge current is detected between the base and the emitter of the transistor Q12, and the transistor Q12 is turned on by the voltage drop due to the overcurrent. Therefore, the discharging FET Q9 is turned off to stop discharging.

Note that the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above-described embodiment, eight cells are connected in series, and four groups of cells are grouped into one group, and the cell voltage is monitored by the protection IC for each group. If the number of cells is different, the present invention can be similarly applied even if the number of assembled cells increases. The overcurrent was detected by detecting the voltage drop due to the discharge current in the discharge FET between the base and the emitter of the transistor, but the overcurrent was detected by the protection IC of the group of assembled cells connected to the discharge FET. The detection may be performed, or the voltage drop due to the discharge current of the series circuit with the discharge FET including the charge FET may be detected.

[0016]

As is apparent from the above description, according to the present invention, a multi-use battery pack comprising two or more cells connected in series and a charge / discharge control element connected in series. , The cells connected in series are divided into a plurality of groups, a plurality of protection circuits for monitoring the cell voltage of each group and detecting overcharge / discharge, and a logical processing for ORing detection signals of the plurality of protection circuits Circuit, and a control circuit for controlling the charge / discharge control element based on the output of the logic processing circuit, so that the protection circuit monitors the cell voltage for each group and detects overcharge / discharge for all cells. Thus, the charge / discharge control element can be controlled, and the monitoring and protection of the multiple-use battery pack can be realized with a simple configuration using a conventional protection IC.

The protection circuit detects overcharging when the maximum cell voltage in the group is equal to or higher than a predetermined value, and detects overdischarging when the minimum cell voltage in the group is equal to or lower than the predetermined value. The discharging control elements are a charging FET and a discharging FE.
T, when the control circuit detects overcharge or overdischarge in any of the plurality of protection circuits, the control circuit turns off the charging FET or the discharging FET, and the discharging FET or the discharging FET and the charging FET The base circuit and the emitter of the transistor are connected in parallel to the series circuit, and the overcurrent is detected by the transistor, and the discharging FET is controlled to be turned off. The protection circuit of the group connected to the control element side monitors and detects overcurrent, so it uses a plurality of protection ICs that can only target a limited number of commercially available assembled cells. The above-described multiple-use battery pack can be protected.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a multiple-use battery pack according to the present invention.

[Explanation of symbols]

B1 to B8: cell, U1, U2: protection IC, Q1, Q
2, Q11, Q12: transistor, Q3 to Q8: FE
T, Q9: FET for discharging, Q10: FET for charging

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02H 7/18 H02H 7/18 H02J 7/02 H02J 7/02 HF term (Reference) 5G003 BA03 CA01 CA11 DA13 FA04 GA01 5G053 AA01 AA09 BA01 BA04 CA02 EA09 EC03 5H030 AA09 BB01 BB21 DD01 DD06 FF42 FF44 5H040 AA03 AY08 DD08

Claims (6)

[Claims] 1. In a multiple-use battery pack in which two or more cells are connected in series and a charge / discharge control element is connected in series, the series-connected cells are divided into a plurality of groups. A plurality of protection circuits for monitoring cell voltages of each group and detecting overcharge / discharge; a logic processing circuit for performing an OR process on detection signals of the plurality of protection circuits; and an output of the logic processing circuit for charging / discharging. A multi-use battery pack, comprising: a control circuit for controlling a control element. 2. The multi-use battery pack according to claim 1, wherein the protection circuit detects overcharge when the maximum cell voltage in the group becomes equal to or higher than a predetermined value. 3. The multiple-use battery pack according to claim 1, wherein the protection circuit detects an overdischarge when a minimum cell voltage in the group falls below a predetermined value. 4. The charge / discharge control element is a charge FET.
And a discharge FET, wherein when the control circuit detects overcharge or overdischarge in any of the plurality of protection circuits, the control circuit turns off the charge FET or the discharge FET. 2. The multiple-use battery pack according to 1. 5. A base / emitter of a transistor is connected in parallel to the discharging FET or a series circuit of the discharging FET and the charging FET, and an overcurrent is detected by the transistor to turn off the discharging FET. The multiple-use battery pack according to claim 4, characterized in that the battery pack is configured to be controlled as follows. 6. A voltage drop of the charge / discharge control element is monitored by a protection circuit of a group connected to the charge / discharge control element,
2. The multiple-use battery pack according to claim 1, wherein an overcurrent is detected.