JP4110858B2 - Abnormality detection device for battery pack - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an abnormality detection apparatus for an assembled battery that detects an overcharged state and an overdischarged state of the assembled battery.
[0002]
[Prior art]
In an assembled battery configured by connecting a plurality of cells in series, it is important to detect an overcharge state and an overdischarge state of the cell in order to prevent a decrease in the discharge capacity of the assembled battery. A conventional battery pack abnormality detection device includes two abnormality detection circuits, an overcharge detection circuit and an overdischarge detection circuit, to detect an overcharge state and an overdischarge state of a cell.
[0003]
[Problems to be solved by the invention]
However, in the conventional assembled battery abnormality detection device, in order to detect the overcharged state and the overdischarged state of the assembled battery, the overcharge abnormality detection circuit and the overdischarge abnormality detection circuit 2 for each cell constituting the assembled battery. Since one circuit is provided, there is a problem that the number of parts constituting the abnormality detection circuit increases.
[0004]
An object of the present invention is to provide an assembled battery abnormality detection device that detects an overcharged state and an overdischarged state of an assembled battery with a single abnormality detection circuit.
[0005]
[Means for Solving the Problems]
(1) An assembled battery abnormality detection device configured by connecting a plurality of rechargeable cells in series according to the present invention is provided for each of the plurality of cells, and the terminal voltage of the corresponding cell is the first predetermined voltage. In this case, a part of the current that flows to the corresponding cell is bypassed, and a current bypass circuit that outputs a signal indicating whether or not the current bypass function is activated, and an abnormality of the corresponding cell are provided for each of the plurality of cells. The abnormality detection circuit operates as an overcharge detection circuit that detects the overcharge state of the corresponding cell when a signal indicating that the current bypass function of the current bypass circuit is operating is input. and, by acting as over-discharge detection circuit for detecting an overdischarged state of the corresponding cell when input signals indicating that the current bypass function is not activated, us the object To.
(2) An assembled battery abnormality detection device according to the present invention is provided for each of a plurality of cells, and current bypass means for bypassing a part of the current flowing through the corresponding cell when the terminal voltage of the corresponding cell becomes equal to or higher than a predetermined voltage. A voltage comparison means provided for each of the plurality of cells and comparing the terminal voltage of the corresponding cell with a reference voltage, and a reference voltage input to the voltage comparison means based on whether or not the current bypass function of the current bypass means is activated The above object is achieved by providing a reference voltage changing means for changing the voltage and an abnormality detecting means for detecting the overcharge state and overdischarge state of the corresponding cell based on the voltage comparison result by the voltage comparison means.
[0006]
【The invention's effect】
According to the battery pack abnormality detection device of the present invention, the abnormality detection circuit operates as an overcharge detection circuit that detects an overcharge state of a corresponding cell when the current bypass function of the current bypass circuit is operating, When the current bypass function is not in operation, it operates as an overdischarge detection circuit that detects the overdischarge state of the corresponding cell, so that the overcharge and overdischarge of the cell can be detected by one abnormality detection circuit.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
-First embodiment-
FIG. 1 is a diagram showing the configuration of a first embodiment of an assembled battery abnormality detection device according to the present invention. The assembled battery abnormality detection device according to the first embodiment includes current bypass circuits a1 to an, abnormality detection circuits f1 to fn, and an OR circuit 4. The assembled battery 1 is configured by connecting a plurality of rechargeable cells s1 to sn in series. The current bypass circuits a1 to an and the abnormality detection circuits f1 to fn are provided for each of the cells s1 to sn.
[0008]
The current bypass circuits a1 to an detect that the terminal voltage of the cell has risen above the first predetermined voltage V1 and become nearly fully charged, and a part of the current flowing through the corresponding cells s1 to sn is detected. It is a circuit to bypass. That is, since the DOD (depth of discharge) is different for each cell, the current bypass function of the current bypass circuit connected to the cell charged to near full charge is activated, and the charging current flowing through the cell is reduced. By continuing to charge other cells, it is possible to suppress the capacity variation between the cells.
[0009]
The abnormality detection circuits f1 to fn detect that the cell terminal voltage has risen from the second predetermined voltage V2 during charging to cause overcharge, and the cell terminal voltage from the third predetermined voltage V3 during discharging. It detects that it has descended and overdischarged. When the overcharge state or overdischarge state of the cell is detected, an abnormality detection signal is output to the OR circuit 4. When the abnormality detection signal is output from any one of the abnormality detection circuits f1 to fn, the OR circuit 4 controls the charge / discharge of the battery pack 1 with a signal indicating that an abnormality has occurred in the cell ( (Not shown).
[0010]
Detailed configurations and operations of the current bypass circuits a1 to an and the abnormality detection circuits f1 to fn will be described. FIG. 2 shows a detailed configuration of the current bypass circuit a1 and the abnormality detection circuit f1 connected to the cell s1. The current bypass circuit a1 includes a comparator (voltage comparator) C1, resistors R1, R2, and R3, a MOS transistor Q1, and an inverter INV1. A terminal voltage Vc of the corresponding cell s1 is applied to the negative terminal of the comparator C1, and a voltage V1 (= Vcc · R3 / (R2 + R3)) obtained by dividing the power supply voltage Vcc by the resistors R2 and R3 is applied to the positive terminal. Applied. The output terminal of the comparator C1 is connected to the gate terminal of the MOS transistor Q1 via the inverter INV1. The source terminal of the MOS transistor Q1 is connected to the negative electrode of the cell s1, and the drain terminal is connected to the positive electrode of the cell s1 through the resistor R1.
[0011]
Note that the comparator C1 outputs an L (low) level signal when the terminal voltage Vc applied to the negative terminal is higher than the first voltage V1 serving as a reference applied to the positive terminal. At this time, the MOS transistor Q1 is turned on and the current bypass function of the current bypass circuit a1 is activated. That is, the first predetermined voltage V1 is a threshold voltage for bypassing the charging current flowing through the cell s1, and is obtained in advance through experiments or the like. Therefore, it is necessary to set the resistors R2 and R3 so that the voltage V1 can be realized.
[0012]
The abnormality detection circuit f1 includes a comparator C2, resistors R4, R5, and R6, a MOS transistor Q2, and an exclusive NOR EXNOR1. The gate terminal of the MOS transistor Q2 is connected to the output terminal of the comparator C1. When the output of the comparator C1 is H (high) level (when current is not bypassed), the MOS transistor Q2 is turned on, and when the output of the comparator C1 is L level (when current is bypassed), the MOS transistor Q2 is turned off. . Since the resistor R6 is connected in parallel with the MOS transistor Q2, no current flows through the resistor R6 when the MOS transistor Q2 is on.
[0013]
The terminal voltage Vc of the cell s1 is applied to the negative terminal of the comparator C2, but the voltage applied to the positive terminal of the comparator C2 varies depending on the on / off state of the MOS transistor Q2. When the MOS transistor Q2 is off (current bypass), the voltage V2 (= Vcc · (R5 + R6) / (R4 + R5 + R6) obtained by dividing the power supply voltage Vcc by the resistor R4 and the combined resistance (R5 + R6) of the resistors R5 and R6. )) Is applied. On the other hand, when the MOS transistor Q2 is on (when the current is not bypassed), a voltage V3 (= Vcc · R5 / (R4 + R5)) obtained by dividing the power supply voltage Vcc by the resistors R4 and R5 is applied.
[0014]
The third predetermined voltage V3 is a threshold voltage for detecting overdischarge of the cells s1 to sn, and the second predetermined voltage V2 is a threshold voltage for detecting overcharge of the cells s1 to sn. Voltage. The voltages V2 and V3 are obtained in advance through experiments or the like. Therefore, it is necessary to set the resistors R4, R5, and R6 so that the voltages V2 and V3 can be realized.
[0015]
One input terminal of the exclusive NOR EXNOR1 is connected to the output terminal of the comparator C2, and the other input terminal is connected to the output terminal of the comparator C1. The exclusive NOR EXNOR1 outputs an H level signal indicating overcharge or overdischarge of the cell when both the outputs of the comparators C1 and C2 are at the H level or the L level, and either one of the comparators C1 and C2 is output. When the output is at the H level, an L level signal indicating that no abnormality exists in the cell is output. A magnitude relationship of V2>V1> V3 is established between the voltages V1, V2, and V3 applied to the comparators C1 and C2.
[0016]
The operations of the current bypass circuit a1 and the abnormality detection circuit f1 will be described with reference to FIGS. 3 (a) and 3 (b). FIG. 3A is a diagram showing the relationship between the terminal voltage Vc of the cell s1 and the voltages V1, V2, and V3. FIG. 3B shows the output of the inverter INV1, the outputs of the comparators C1 and C2, and the exclusive It is an operation | movement waveform diagram which respectively shows the output state of Shibnoa EXNOR1. In the following description, it is assumed that the terminal voltage Vc of the cell s1 gradually changes (rises) from a state where the terminal voltage Vc is lower than the voltage V3 to a state where it is higher than the voltage V2.
[0017]
-Overdischarge detection-
When the terminal voltage Vc of the cell s1 is lower than the voltage V3, the output of the comparator C1 becomes H level. Accordingly, since the voltage applied to the gate terminal of the MOS transistor Q1 via the inverter INV1 is at L level, the MOS transistor Q1 is turned off and the current bypass function of the current bypass circuit a1 does not operate. On the other hand, since the H level voltage is applied to the gate terminal of the MOS transistor Q2, the MOS transistor Q2 is turned on. Therefore, since the voltage V3 obtained by dividing the power supply voltage Vcc by the resistors R4 and R5 is applied to the + terminal of the comparator C2, the output of the comparator C2 becomes H level. In this case, since the H level signal is input to the two input terminals of the exclusive NOR EXNOR1, the output of the exclusive NOR EXNOR1, that is, the output of the abnormality detection circuit f1 becomes the H level. That is, an abnormality detection signal indicating that the cell s1 is overdischarged is output.
[0018]
-When the cell is neither overcharged nor overdischarged-
A case where the terminal voltage Vc of the cell s1 exceeds the voltage V3 will be described. Since the output of the comparator C1 does not change, the reference voltage applied to the + terminal of the comparator C2 remains V3. Accordingly, the output of the comparator C2 changes from H level to L level. In this case, since the output of the comparator C1 does not change, the output of the exclusive NOR EXNOR1, that is, the output of the abnormality detection circuit f1, changes from the H level to the L level. That is, the abnormality detection signal indicating that the cell s1 is overdischarged is canceled.
[0019]
-Operation of the current bypass function-
When the terminal voltage Vc of the cell s1 further rises and becomes higher than the voltage V1, the output of the comparator C1 changes from the H level to the L level, so that the output via the inverter INV1 becomes the H level. As a result, the MOS transistor Q1 is turned on, and a bypass current flows through the resistor R1 and the MOS transistor Q1. That is, when the terminal voltage Vc of the cell s1 exceeds the voltage V1, the current bypass function operates and the charging current flowing through the cell s1 decreases.
[0020]
When the output of the comparator C1 changes to L level, the MOS transistor Q2 is turned off. As a result, since the voltage V2 obtained by dividing the power supply voltage Vcc by the resistor R4 and the combined resistor (R5 + R6) is applied to the + terminal of the comparator C2, the output of the comparator C2 changes from L level to H level. Since the signals of the H level and the L level are respectively input to the input terminals of the exclusive NOR EXNOR1, the output of the exclusive NOR EXNOR1, that is, the output of the abnormality detection circuit f1 remains at the L level. No detection signal is output.
[0021]
-Overcharge detection-
When the terminal voltage Vc of the cell s1 further rises and exceeds the voltage V2, the output of the comparator C1 does not change and the output of the comparator C2 changes from H level to L level. Therefore, since the L level signal is input to each of the two input terminals of the exclusive NOR EXNOR1, the output of the exclusive NOR EXNOR1, that is, the output of the abnormality detection circuit f1 changes from the L level to the H level. To do. Thereby, an abnormality detection signal indicating that the cell s1 is overcharged is output. As described above, since the output of the comparator C1 does not change, the current bypass function remains activated.
[0022]
According to the assembled battery abnormality detection device in the first embodiment, the abnormality detection circuit includes current bypass circuits a1 to an that suppress cell capacity variation, and abnormality detection circuits f1 to fn that detect cell abnormality. f1 to fn function as an overcharge detection circuit when the current bypass function of the current bypass circuits a1 to an is operating, and function as an overdischarge detection circuit when the current bypass function is not operating. Thereby, it is not necessary to provide two circuits of the overcharge detection circuit and the overdischarge detection circuit in order to detect the abnormality of the cells s1 to sn, the number of parts can be reduced, and the cost can be reduced.
[0023]
The abnormality detection circuits f1 to fn detect the abnormality of the cells s1 to sn by comparing the terminal voltage Vc of the corresponding cells s1 to sn with a predetermined reference voltage, but the currents of the current bypass circuits a1 to an are detected. When the bypass function is not activated, the third predetermined voltage V3 is used as the reference voltage, and when the current bypass function is activated, the second predetermined voltage V2 is used as the reference voltage. Thereby, the overdischarge state and overcharge state of a cell can be detected using one comparator.
[0024]
The current bypass circuits a1 to an bypass a part of the current flowing through the corresponding cells s1 to sn when the terminal voltage Vc of the corresponding cells s1 to sn is higher than the first predetermined voltage V1. That is, since the current bypass circuits a1 to an transmit signals indicating whether or not the current bypass function is activated to the abnormality detection circuits f1 to fn based on the terminal voltages Vc of the corresponding cells s1 to sn, the current bypass circuits are surely Whether or not the function is activated can be detected, and switching between the reference voltages V2 and V3 can be performed.
[0025]
In addition, the signal level (logic level) output from the exclusive NOR EXNOR1 when the cell is overcharged and overdischarged is H level. In the states other than the overcharge state and overdischarge state, the signal level is L level. Become. That is, since the signal level output from the abnormality detection circuit f1 is the same in the overcharge state and the overdischarge state, it is possible to accurately detect a cell abnormality with a simple configuration.
[0026]
-Second Embodiment-
The assembled battery abnormality detection device according to the second embodiment is characterized by a current bypass circuit. That is, the current bypass circuit used in the assembled battery abnormality detection device according to the second embodiment includes a Zener diode ZD1 instead of the comparator.
[0027]
FIG. 4 is a diagram showing a detailed configuration of the current bypass circuit a1 and the abnormality detection circuit f1 connected in parallel to the cell s1. Since the configurations and operations of the abnormality detection circuits f1 to fn are the same as those of the abnormality detection circuits f1 to fn of the first embodiment, description thereof is omitted. The current bypass circuit a1 includes a Zener diode ZD1, a diode D1, a bipolar transistor Q3, and resistors R7 and R8.
[0028]
The resistor R7, the Zener diode ZD1, and the diode D1 are connected in series, and are connected between the positive electrode and the negative electrode of the cell s1, and the base terminal of the bipolar transistor Q3 is connected to the connection portion of the Zener diode ZD1 and the diode D1. Has been. The emitter terminal of the bipolar transistor Q3 is connected to the negative electrode of the cell s1. The collector terminal of the bipolar transistor Q3 is connected to the power supply voltage Vcc via the resistor R8, and is also connected to the gate terminal of the MOS transistor Q2 of the abnormality detection circuit f1 and the input terminal of the exclusive NOR EXNOR1.
[0029]
The Zener voltage of the Zener diode ZD1 is set to such a voltage value that current starts to flow when the terminal voltage Vc of the cell s1 becomes equal to the reference voltage V1 described above. Hereinafter, the current bypass function of the current bypass circuit a1 and the abnormality detection method of the abnormality detection circuit f1 will be described on the assumption that the terminal voltage Vc of the cell s1 gradually changes (rises) from a state lower than the voltage V1.
[0030]
-When terminal voltage Vc is lower than voltage V1-
When the terminal voltage Vc of the cell s1 is lower than the voltage V1, the terminal voltage applied to the Zener diode ZD1 does not reach the Zener voltage, so that no current flows through the Zener diode ZD1. Accordingly, since no current flows through the resistor R7 and the diode D1, the current bypass function does not operate. In this case, since no current flows through the base terminal of the bipolar transistor Q3, the bipolar transistor Q3 is in an off state. In this case, since no current flows through the resistor R8 connected to the collector terminal of the bipolar transistor Q3, an H level signal is applied to the input terminal of the exclusive NOR EXNOR1 connected to the collector terminal of the bipolar transistor Q3. Is entered.
[0031]
The configuration of the abnormality detection circuit f1 is the same as the configuration of the abnormality detection circuit f1 of the first embodiment, and therefore the operation when the terminal voltage Vc is lower than the voltage V3 is described in the first embodiment. Is the same. That is, when the terminal voltage Vc is lower than the voltage V3, the output of the comparator C2 is at the H level, so that the output of the exclusive NOR EXNOR1 is at the H level, indicating that the cell s1 is overdischarged. Is output. When the terminal voltage Vc is higher than the voltage V3 and lower than the voltage V1, the output of the comparator C2 becomes L level, so that the output of the exclusive NOR EXNOR1 becomes L level, and the abnormality detection signal is released.
[0032]
-When terminal voltage Vc exceeds voltage V1-
When the terminal voltage Vc of the cell s1 exceeds the voltage V1, the terminal voltage applied to the Zener diode ZD1 reaches the Zener voltage, so that current starts to flow through the Zener diode ZD1. As a result, a current also flows through the resistor R7 and the diode D1, so that the current bypass function of the current bypass circuit a1 operates. In this case, since a current also flows through the base terminal of the bipolar transistor Q3, the bipolar transistor Q3 changes from an off state to an on state, and a current also flows through the resistor R8. That is, an L level signal is input to the input terminal of the exclusive NOR EXNOR1 connected to the collector terminal of the bipolar transistor Q3.
[0033]
When the bipolar transistor Q3 is turned on, an L level voltage is also applied to the gate terminal of the MOS transistor Q2, so that the MOS transistor Q2 is turned off. That is, the reference voltage applied to the + terminal of the comparator C2 changes from V3 to V2. Since the operation of the abnormality detection circuit f1 is the same as that of the first embodiment, detailed description thereof is omitted.
[0034]
According to the assembled battery abnormality detection device in the second embodiment, the current bypass circuit a1 uses the Zener diode ZD1 instead of including the comparator, whereby the assembled battery abnormality detection device in the above-described first embodiment. The same effect can be obtained. In the assembled battery abnormality detection device according to the second embodiment, a signal indicating that the current bypass function of the current bypass circuits a1 to an is activated when a current flows through the Zener diode ZD1 and the bipolar transistor Q3 is turned on. Is output to the abnormality detection circuits f1 to fn. In other words, since the current bypass circuits a1 to an output signals indicating whether or not the current bypass function is activated to the abnormality detection circuits f1 to fn based on the presence or absence of the bypass current, the operation of the current bypass function is surely performed. The presence / absence can be detected and the reference voltages V2 and V3 can be switched.
[0035]
The present invention is not limited to the embodiment described above. For example, the reference voltage applied to the + terminal of the comparator C2 of the abnormality detection circuit f1 to fn is switched based on a signal output from another external device instead of a signal from the current bypass circuit a1 to an. May be. Other external devices include, for example, a battery controller that manages charging / discharging of the assembled battery 1. Further, the reference voltage of the + terminal may be given a hysteresis by using a known technique such as inserting a resistor between the + terminal and the output terminal of the comparators C1 and C2.
[0036]
The correspondence between the constituent elements of the claims and the constituent elements of the first embodiment is as follows. That is, the current bypass circuits a1 to an constitute a current bypass circuit, and the abnormality detection circuits f1 to fn constitute an abnormality detection circuit. The comparator C2 constitutes voltage comparison means, the resistors R4, R5, R6 and the MOS transistor Q2 constitute reference voltage changing means, and the exclusive NOR EXNOR1 constitutes abnormality detection means. In addition, as long as the characteristic function of this invention is not impaired, each component is not limited to the said structure.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a first embodiment of a battery pack abnormality detection apparatus according to the present invention. FIG. 2 shows a detailed configuration of a current bypass circuit and an abnormality detection circuit according to the first embodiment. FIG. 3 (a) is a diagram showing the relationship between the cell terminal voltage Vc and the voltages V1, V2, V3, and FIG. 3 (b) shows the output of the inverter INV1 and the comparators C1, C2. FIG. 4 is a diagram showing the detailed configuration of the current bypass circuit and the abnormality detection circuit in the second embodiment.
DESCRIPTION OF SYMBOLS 1 ... Assembly battery, 4 ... OR circuit, a1-an ... Current bypass circuit, f1-fn ... Abnormality detection circuit, R1-R8 ... Resistance, C1, C2 ... Comparator, Q1, Q2 ... MOS transistor, INV1 ... Inverter, EXNOR1 ... exclusive NOR, Q3 ... bipolar transistor, D1 ... diode, ZD1 ... zener diode, s1-sn ... cell

Claims (6)

In an assembled battery abnormality detection device configured by connecting a plurality of rechargeable cells in series,
Provided for each of the plurality of cells, when a terminal voltage of the corresponding cell becomes equal to or higher than a first predetermined voltage, a signal indicating whether the current bypass function is activated and a part of the current flowing through the corresponding cell are bypassed. An output current bypass circuit;
An abnormality detection circuit that is provided for each of the plurality of cells and detects an abnormality of the corresponding cell,
The abnormality detection circuit operates as an overcharge detection circuit that detects an overcharge state of a corresponding cell when a signal indicating that the current bypass function of the current bypass circuit is operating is input, and the current bypass circuit An assembled battery abnormality detection device that operates as an overdischarge detection circuit that detects an overdischarge state of a corresponding cell when a signal indicating that the current bypass function is not activated. In the assembled battery abnormality detection device according to claim 1,
The abnormality detection circuit is a voltage comparison circuit that compares a terminal voltage of the corresponding cell with a reference voltage, and when the current bypass function of the current bypass circuit is not operating , the first voltage is used as the reference voltage . When a third predetermined voltage having a voltage value lower than the predetermined voltage is input and the current bypass function of the current bypass circuit is operating, the reference voltage is a voltage value higher than the first predetermined voltage. A battery pack abnormality detection device, wherein a second predetermined voltage is input. In the assembled battery abnormality detection device according to claim 1 or 2,
The abnormality detection device for an assembled battery , wherein the abnormality detection signal level detected by the abnormality detection circuit is the same when the overcharge state is detected and when the overdischarge state is detected . In the abnormality detection apparatus of the assembled battery in any one of Claims 1-3,
The assembled battery abnormality detection device , wherein the current bypass circuit outputs a signal indicating whether or not the current bypass function is activated to the abnormality detection circuit based on a terminal voltage of the corresponding cell . In the abnormality detecting device for a battery pack according to any one of claims 1 to 3
The assembled battery abnormality detection device , wherein the current bypass circuit outputs a signal indicating presence / absence of operation of the current bypass function to the abnormality detection circuit based on presence / absence of a bypass current . In an assembled battery abnormality detection device configured by connecting a plurality of rechargeable cells in series,
Current bypass means provided for each of the plurality of cells, and bypassing a part of the current flowing in the corresponding cell when the terminal voltage of the corresponding cell is equal to or higher than a predetermined voltage;
A voltage comparison means provided for each of the plurality of cells, for comparing a terminal voltage of the corresponding cell and a reference voltage;
A reference voltage changing means for changing a reference voltage input to the voltage comparing means based on whether or not the current bypass function of the current bypass means is activated;
An assembled battery abnormality detection device comprising: an abnormality detection unit that detects an overcharge state and an overdischarge state of the corresponding cell based on a voltage comparison result by the voltage comparison unit.

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