JP3329749B2 - Battery cell voltage detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an assembled battery voltage detecting device.

[0002]

2. Description of the Related Art Japanese Patent Laying-Open No. 5-64377 discloses a voltage detecting device for an assembled battery, in which a voltage detecting module detects the module voltages of a plurality of battery modules composed of a number of cascaded unit cells. is suggesting.

[0003]

However, individually detecting each module voltage with a large number of differential voltage detection circuits as described above requires a large-scale circuit configuration, cost, power consumption, and space. It needed to be improved in terms of reliability. The present invention has been made in view of the above problems, and an object of the present invention is to provide an assembled battery voltage detecting device that can be realized with a simple circuit configuration while suppressing a decrease in detection accuracy and safety.

[0004]

According to the voltage detecting apparatus for an assembled battery of the present invention, for example, 300
A high-voltage assembled battery such as V is formed by connecting a plurality of battery blocks formed by connecting a plurality of battery modules in series.
As a battery module, one cell may be used,
A plurality of cells may be connected in series. A block terminal consisting of the highest terminal or the lowest terminal of the battery block is individually connected to one input terminal of the module voltage detecting unit through a pair of a reference potential changeover switch and a backflow prevention diode connected in series with each other. The terminals of each battery module except the terminals are connected to the other input terminals of the module voltage detection unit through different module voltage changeover switches.

For example, when one module voltage detecting section sequentially detects the module voltages of two battery blocks, and when detecting the module voltage of the first battery block, the reference voltages connected in series with each other are used. The potential difference is detected based on the potential of the block terminal of the first battery block through the first pair of the potential changeover switch and the backflow prevention diode, and then, when the module voltage of the second battery block is detected, the potential difference is detected. A potential difference is detected based on the potential of the block terminal of the second battery block through a second pair of the reference potential changeover switch and the backflow prevention diode connected in series.

When one module voltage detecting section sequentially detects the module voltages of a plurality of battery blocks by switching the reference potential changeover switch, the module voltage detecting section is connected to the one module voltage detecting section. Of the plurality of battery blocks, the block terminal on the lowest potential side of the battery block on the lowest potential side or the block terminal on the highest potential side of the battery block on the highest potential side has only the reference potential changeover switch without going through a backflow prevention diode. Can be connected to the input terminal of the module voltage detector.

With this configuration, each module voltage output from the same battery block to the module voltage detecting section becomes a potential signal based on the common potential formed by the potential of the reference potential line. Subsequent circuit processing is simplified, and module voltage detection with few errors can be performed with a simple circuit configuration. More specifically, in one battery block, the potential of each battery module is detected with reference to the highest potential or the lowest potential of this battery block. Therefore, the terminal voltage of each battery module is the difference between the detected potentials of the battery modules. Is required. With this configuration, the power supply voltage applied to each module voltage detection unit can be shared as compared with a case where the potential difference (terminal voltage) of each battery module is individually detected, so that the power supply circuit is simplified. And the influence of the variation of the power supply voltage output from each power supply circuit is small.

Further, in this configuration, the reference potentials of a plurality of battery blocks can be supplied to the same module voltage detection section by switching the reference potential changeover switch, and the number of the module voltage detection sections can be shared. Reduction can be achieved. Furthermore, in this configuration, even if one of the above-described reference potential changeover switches causes a short-circuit failure, the backflow prevention diode is interposed. Short-circuit current circulating through the potential changeover switch and the short-circuited reference potential changeover switch can be prevented.

According to a second aspect of the present invention, in the voltage detecting apparatus for an assembled battery according to the first aspect, the module voltage detecting section is further supplied with the divided voltage of the resistance voltage dividing circuit. With this configuration, the resistance element on the battery module side can generate a short-circuit current that flows even when one of the plurality of module voltage changeover switches whose one ends are connected to each other is short-circuited and the other is turned on. It is possible to achieve an excellent effect of reducing the voltage input to the module voltage detection unit as a component of the resistance voltage dividing circuit.

In this case, the withstand voltage and the conduction resistance of the module voltage detector can be reduced. The details will be described below. In the above-described method of calculating the potential of each battery module by the potential difference from the common reference potential for each battery block and calculating the potential difference of each battery module by subtraction of the detected potential differences, the battery block is separated from the reference potential line of the battery block. The potential of the battery module becomes as high as several times the potential difference of the battery module, for example, several tens of volts, and it is necessary to increase the withstand voltage of the input part of the module voltage detecting unit in order to detect such a high voltage.

Therefore, in this configuration, since the potential of each battery module is divided by the voltage dividing circuit based on the potential of the reference potential line (reference potential), the input voltage of the module voltage detecting section is, for example, It can be a normal level such as 5 V, and the module voltage detecting section can be constituted by a general-purpose circuit element or a general-purpose integrated circuit technology. According to a third aspect of the present invention, in the voltage detecting device for an assembled battery according to the second aspect, a resistance element on a reference potential side of one of the resistance voltage dividing circuits on the first battery block side, and a second battery block. And the resistance element on the reference potential side of one of the two resistive voltage dividing circuits.

With this configuration, the number of resistance elements can be reduced, and the circuit configuration can be simplified. According to the configuration of the fourth aspect, in the voltage detecting device for an assembled battery according to the second aspect, since the resistance element on the reference potential side of each resistance voltage dividing circuit is shared, the number of resistance elements can be reduced, The circuit configuration can be simplified.

According to a fifth aspect of the present invention, in the voltage detecting device for an assembled battery according to any one of the second to fourth aspects, each of the module voltage changeover switches is connected to a battery module side of each of the resistance voltage dividing circuits. And a plurality of the modules are interposed between the resistance element of
The voltage switch is integrated in the same circuit module. With this configuration, the circuit configuration can be simplified.

That is, when each module voltage changeover switch is interposed between a plurality of resistance elements of the voltage dividing circuit,
The terminal on the anti-battery module side of each module voltage changeover switch can be connected to the terminal on the anti-battery module side of at least one other switch inside the circuit module, so that the number of external wiring lines and the connection work are reduced. It can be greatly reduced, and the switch circuit can be simplified.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the following examples. However, the present invention is not limited to the configuration of the following embodiment, and it is obvious that the present invention can be configured using a replaceable known circuit.

[0016]

[Embodiment 1] An embodiment of a voltage detecting device for an assembled battery according to the present invention will be described with reference to a partial circuit diagram shown in FIG. Reference numeral 1 denotes an assembled battery, which is formed by connecting a total of four battery blocks including the highest battery block 11 and the next highest battery block 12 in series. However, illustration of the remaining battery blocks is omitted. The battery block 11 has five battery modules B
AT01 to BAT05 are connected in series, and the battery block 12 includes five battery modules BAT06 to BAT10.
Are connected in series.

2 denotes resistance elements R1 to R11, R13, R
15, R17, and R19.
And R2, R3 and R4, R5 and R6, R7 and R
8, R9 and R10, R11 and R2, R13 and R
4, R15 and R6, R17 and R8, R19 and R1
0 constitutes a voltage dividing circuit. Resistance element R2,
One end of each of R4, R6, R8, and R10 (the reference potential side resistance element in the present invention) is connected to the lowest potential end of the battery block 11 through the reference potential line 3, the reference potential changeover switch SW21, and the backflow prevention diode D1. And reference potential line 3, reference potential changeover switch SW
22, and connected to the lowest potential terminal of the battery block 12 through the backflow prevention diode D2. The resistance element R
The other ends of R2, R4, R6, R8, and R10 (the resistance elements on the reference potential side in the present invention) are resistance elements R1, R3, R
5, R7, R9 (the resistance element on the battery module side in the present invention) and module voltage changeover switches SW1 to S
It is connected to the higher pole of each battery module of the battery block 11 through W5. Further, the resistance elements R2, R
The other ends of R4, R6, R8 and R10 (the reference potential side resistance elements in the present invention) are connected to resistance elements R11, R13 and R1.
5, R17, R19 (the resistance element on the battery module side in the present invention) and the module voltage switch SW6
To SW10, connected to the upper pole of each battery module of the battery block 12.

Each of the changeover switches SW1 to SW10, S
W21 and SW22 are composed of photo MOS transistors, and are opened and closed by being driven by light signals from the facing LEDs. Reference numeral 4 denotes a module voltage detection block, which internally includes five channels of module voltage detection units in parallel, and includes resistance elements R2, R4, R6, R8, R
Voltage drops of 10 (the resistance element on the reference potential line side in the present invention) are individually detected. Each of the module voltage detectors comprises an A / D converter, but an A / D converter of a type for sequentially switching a large number of input signals may be used.

This A / D converter converts a voltage difference between the voltage divided from each voltage dividing circuit and the reference potential VSS into a digital signal. In one example, the A / D converter includes a reference voltage generating circuit that generates various reference voltages higher than the reference voltage VSS using a reference potential VSS as a reference potential, and a plurality of comparison circuits that compare each of the generated reference voltages with an input divided voltage. And a digital signal generation circuit for converting a signal output from the comparator into a digital signal, but detailed description thereof will be omitted. Note that the reference potential VSS is
Almost to the potential of the lower pole of the battery module BAT05,
Potential drop of backflow prevention diode D1 (about 0.7V)
Is equal to the sum of

At the time of detecting the voltage of the battery module of the battery block 11, the A / D converter receives the reference potential VSS from the lower pole of the battery module BAT05 through the reference potential line 3, the changeover switch SW21, and the backflow prevention diode D1. , Changeover switch SW
Reference numeral 22 is open. Next, the changeover switch SW1
To SW5, and changeover switches SW6 to SW10
Is turned off, the potential of the high-order pole of each of the battery modules BAT01 to BAT05 of the battery block 11 is converted into a digital signal and output to a controller (not shown), and the controller performs subtraction processing on each of the battery modules BAT01 to BAT05. Detect voltage.

However, the potential difference between the input terminal CH4 and the reference potential VSS detected this time depends on the forward voltage drop of the backflow prevention diode D1 and the module voltage switch S.
Since the voltage drop due to the on-resistance of W21 is included, the above-described controller detects each of the battery modules BAT01-BA
From the potential of T05 and the current element temperature, the forward voltage drop of the backflow prevention diode D1 and the voltage drop due to the ON resistance of the module voltage changeover switch SW21 are estimated based on a map, and the total of the estimated voltage drops is detected this time. By subtracting from the potential difference between the input terminal CH4 and the reference potential VSS to obtain the terminal voltage of the battery module BAT05,
Accuracy can be further improved.

Similarly, when detecting the voltage of the battery module in the battery block 12, the A / D converter receives the reference potential VSS from the lower pole of the battery module BAT10 through the reference potential line 3, the changeover switch SW22 and the backflow prevention diode D2. At this time, the switch SW
Reference numeral 21 is open. The reference potential VSS is substantially equal to a value obtained by adding the potential drop (about 0.7 V) of the backflow prevention diode D2 to the potential of the lower pole of the battery module BAT10. Next, the changeover switches SW6 to S
By turning on W10 and turning off the changeover switches SW1 to SW5, the potential of the high-order pole of each of the battery modules BAT06 to BAT10 of the battery block 12 is converted into a digital signal and output to a controller (not shown). The voltage of each of the battery modules BAT06 to BAT10 is detected by the subtraction processing.

However, the difference between the input terminal CH4 detected this time and the reference potential VSS is determined by the forward voltage drop of the backflow prevention diode D2 and the module voltage switch S.
Since the voltage drop caused by the on-resistance of W22 is included, the above controller detects each of the detected battery modules BAT06-BA6.
From the potential of T10 and the current element temperature, the forward voltage drop of the backflow prevention diode D2 and the voltage drop due to the on-resistance of the module voltage changeover switch SW22 are estimated based on a map, and the total of the estimated voltage drops is detected this time. If the terminal voltage of the battery module BAT10 is subtracted from the potential difference between the input terminal CH4 and the reference potential VSS, the accuracy can be further improved.

According to this embodiment, even if one of the above-mentioned reference potential changeover switches SW21 and SW22 has a short-circuit fault, the reverse current prevention diodes D1 and D2 are interposed, so that the module voltage changeover switch is provided. S
Even if the other of W21 and SW22 is made conductive, a short circuit current circulating through the conductive reference potential switch and the short-circuited reference potential switch can be prevented.

Further, according to this embodiment, the module voltage signal composed of the divided voltage outputted from each voltage dividing circuit in the same battery block to the module voltage detecting section is obtained from the potential of the reference potential line. Since the potential signal is based on a common potential, the power supply voltage applied to each module voltage detection unit can be shared, so that the power supply circuit can be simplified, and in this case, Since the increase in the input signal voltage to the module voltage detection unit is reduced by employing the voltage dividing circuit, the circuit configuration can be simplified while suppressing the increase in the input voltage.

Further, in this embodiment, the resistance elements R2, R4. Since R6, R8, and R10 each constitute a part of two voltage dividing circuits, the number of resistance elements can be reduced. (Modification) A modification of the above embodiment will be described with reference to a partial circuit diagram shown in FIG.

This device is different from the device of the first embodiment shown in FIG. 1 in that a voltage dividing resistor R21 is further connected between the lowest potential terminals of the battery blocks 11 and 12 and the backflow prevention diodes D1 and D2.
R22. However, in this case, the resistance ratio between the resistance elements needs to be changed.

[0028]

Embodiment 2 Another embodiment of the present invention will be described with reference to a partial circuit diagram shown in FIG. The device of this embodiment is the same as the device of Embodiment 1 shown in FIG.
All module voltage changeover switches SW1 to SW
10. All reference potential changeover switches SW21, S
W22 and backflow prevention diodes D1, D2 are provided on a common circuit board 5, and furthermore, resistance elements R2, R4, R
6, R8 and R10 (the resistance element on the reference potential side in the present invention) are replaced with a single resistance element Rc.

When detecting the voltage of each of the battery modules BAT01 to BAT05 of the battery block 11, the module voltage changeover switches SW1 to SW5 are turned on sequentially to detect the potential at both ends of the common resistance element Rc. , Detected by a single module voltage detector. In addition, each battery module BAT06-
When detecting the voltage of the BAT 10, the module voltage changeover switches SW6 to SW10 are turned on sequentially to detect the potentials at both ends of the common resistance element Rc, which is detected by the same module voltage detection unit as described above. I do.

This arrangement has the advantage that the number of output terminals can be reduced by mounting each module voltage switch and the reference potential switch on a common circuit board or by integrating them on one chip. is there. That is, since one end of each of the module voltage changeover switches SW1 to SW10 up to their common output terminal 51 can be formed into a wiring pattern on a circuit board and further integrated into one chip to form an in-chip wiring, the circuit configuration is extremely simplified. There is an advantage that can be made.

[0031]

Third Embodiment FIG. 4 shows another example of a module voltage detecting section constituting the module voltage detecting circuit block 4. The module voltage detecting section comprises a differential voltage circuit 41 and an A / D converter 42 for A / D converting the output voltage. The configuration of the other module voltage detectors is the same. Power supply voltages VH and VL are supplied from a constant voltage power supply circuit 43 to each differential voltage circuit 41 and each A / D converter 42.

When the voltage of the battery module of the battery block 11 is detected, the negative input terminal of the differential voltage circuit 41 is connected to the reference potential VSS from the lower pole of the battery module BAT05 through the reference potential line 3, the changeover switch SW21 and the backflow prevention diode D1. At this time, the changeover switch SW22 is open. Constant voltage power supply circuit 43
Is shifted to a potential lower than the reference potential VSS, and the power supply voltage VH output from the constant voltage power supply circuit 43 is higher than the potential (divided) VCHO at the connection point between the resistance elements R1 and R2. Is also set to a high potential. Thus, by turning on the changeover switches SW1 to SW5 and turning off the changeover switches SW6 to SW10, each of the battery modules BAT of the battery block 11 is changed.
Since the potentials of the higher poles of 01 to BAT05 are input to the + input terminals of the respective differential voltage circuits 41, the differences are digitally converted and output to a controller (not shown). This controller performs the subtraction process to each battery module BAT01.
Ｂ BAT05 is detected.

Similarly, at the time of detecting the voltage of the battery module of the battery block 12, the negative input terminal of the differential voltage circuit 41 is connected from the lower pole of the battery module BAT10 through the reference potential line 3, the changeover switch SW22 and the backflow prevention diode D2. Upon receiving the reference potential VSS, the changeover switch SW21 is open at this time. The power supply voltage VL output from the constant voltage power supply circuit 43 is equal to the reference potential V
The power supply voltage VH which is shifted to a potential lower than SS and output from the constant voltage power supply circuit 43 is set to a potential higher than a potential (divided voltage) VCHO at a connection point between the resistance elements R11 and R2. Thereby, the changeover switches SW1 to S
By turning off W5 and turning on the changeover switches SW6 to SW10, the potential of the higher pole of each of the battery modules BAT06 to BAT10 of the battery block 12 is input to the + input terminal of each differential voltage circuit 41. The difference is digitally converted and output to a controller (not shown). This controller performs the subtraction process to each battery module B
The potential of AT06 to BAT10 is detected.

[0034]

[Embodiment 4] Another embodiment of the present invention will be described. In the device of this embodiment, the changeover switches SW1 to SW10, SW21, and SW22 shown in FIG. 1 are configured by ordinary MOS transistors. According to this embodiment, the control voltage for driving the changeover switches SW1 to SW10, SW21 and SW22 composed of MOS transistors can be reduced, and an element having a small withstand voltage (for example, gate withstand voltage) can be used. The effect can be achieved. This will be further described with reference to FIG.

The changeover switch SW1 has a gate potential Vg
And a control voltage Vgs which is a difference between the control voltage Vgs and the source potential Vs. When the changeover switch SW1 is off, the source voltage Vs is equal to the potential of the reference potential line 3, so that the changeover switch SW1 can be operated with a small control voltage Vgs. Since the voltage division between R1 and R2 is low, the changeover switch SW1 can be sufficiently driven even if the control voltage Vgs is small.

On the other hand, in the arrangement in which the resistance element and the changeover switch SW1 are reversed, the source voltage Vs becomes almost equal to the potential of the high-order pole of the battery module BAT01 after the conduction. It is necessary to employ a high gate voltage Vg, and the withstand voltage and channel resistance of the semiconductor switch constituting the changeover switch are significantly increased. In addition, protection of the changeover switch against static electricity and other surge voltages is insufficient. (Modification) In each of the above-described embodiments, the backflow prevention diode D1 is provided between the lower terminal (block terminal) of the battery block 11 and the common potential line 3, and the lower terminal (block terminal) of the battery block 12 Although the backflow prevention diode D2 is provided between the common potential line 3 and the common current line 3, even if the backflow prevention diode D2 is omitted, a short circuit current due to a short circuit of the changeover switch SW21 or SW22 can be prevented.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an example of a battery pack voltage detecting device according to the present invention.

FIG. 2 is a circuit diagram showing a modification of the voltage detector of the assembled battery shown in FIG.

FIG. 3 is a circuit diagram showing another example of the battery pack voltage detecting device of the present invention.

FIG. 4 is a block diagram illustrating an example of a circuit configuration of a module voltage detection unit.

FIG. 5 is a circuit diagram illustrating an example of a switch.

[Explanation of symbols]

1 is an assembled battery, 2 is a voltage dividing circuit group, 3 is a reference potential line,
R1 to R10, R11, R13, R15, R17, R1
9 is a resistance element of a voltage dividing circuit, and SW1 to SW10 are modules.
Voltage changeover switches, SW21 and SW22 are reference potential changeover switches, D1 and D2 are backflow prevention diodes

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-2000-60001 (JP, A) JP-A-11-160371 (JP, A) JP-A-11-55865 (JP, A) JP-A-9-236624 (JP, A) JP-A-5-64377 (JP, A) JP-A-2000-88898 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J ^7/ 00-7/12 H02J 7/34-7/36 G01R 19/165 G01R 31/36

Claims (5)

(57) [Claims] 1. A voltage detecting apparatus for a battery pack, comprising: a module voltage detecting section for detecting a terminal voltage of each battery module from a battery pack formed by connecting a plurality of battery blocks connected in series. A block terminal composed of one terminal of the battery block is connected to one input terminal of the module voltage detection unit through a pair of a reference potential switch and a backflow prevention diode connected in series with each other, excluding the block terminal. The terminal of each of the battery modules is connected to another input terminal of the module voltage detector through a different module voltage switch. 2. The module battery voltage detecting device according to claim 1, wherein the other input terminal of the module voltage detecting unit is connected to the one input of the module voltage detecting unit through a resistance element on a reference potential side. And connected to the respective terminals of the battery module through the resistor element on the battery module side and the module voltage changeover switch, the resistor element on the reference potential side and the resistor element on the battery module side Is a voltage detecting device for an assembled battery, which forms a resistance voltage dividing circuit. 3. The voltage detecting device for an assembled battery according to claim 2, wherein the resistance element on the reference potential side of the one resistor voltage dividing circuit on the first battery block side is connected to the second battery block side. A voltage detecting device for an assembled battery, which is common to the resistance element on the reference potential side of one resistance voltage dividing circuit. 4. The voltage detecting device for an assembled battery according to claim 2, wherein the resistance element on the reference potential side is common to each of the resistance voltage dividing circuits. 5. The voltage detecting device for an assembled battery according to claim 2, wherein each of the module voltage changeover switches is connected to a resistance element on the battery module side of each of the resistance voltage dividing circuits and the reference voltage. A voltage detecting device for an assembled battery, wherein a plurality of the module voltage changeover switches are interposed between a resistance element on a potential side and a plurality of module voltage changeover switches are integrated in the same circuit module.