JPH11160367A - Apparatus for detecting voltage of battery pack for electric automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus for detecting a voltage of a battery pack for an electric automobile which can more highly accurately detect an open module voltage, a void a useless life decrease of the high-voltage battery pack, detect a module voltage stably irrespective of a large change in state in which a running power is stored. SOLUTION: A main battery 19 for storing a high-voltage, e.g. 300 V running power is divided to many battery modules 101-120. A module voltage of each battery module 101-120 is detected by a differential voltage detection circuit 201-220 and an A/D converter 5-8, and transmitted to a signal-processing circuit part 1. A circuit-driving power for the differential voltage detection circuits 201-220 and A/D converters 5-8 is supplied, not from the main battery 19, but from an auxiliary battery 301 through a DC-DC converter 300.

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 Unexamined Patent Publication No. Hei 8-140204 discloses an output voltage of a module voltage detecting circuit for individually detecting module voltages of a plurality of battery modules constituting an assembled battery through a photocoupler element. A voltage detector for a battery pack for transmitting to a low-voltage signal processing circuit has been proposed.

[0003]

However, in the above-described conventional voltage detecting apparatus for assembled batteries, each module voltage detecting circuit unit individually supplies circuit operating power from each battery module. Either an individual power supply system or a total voltage power supply system in which power for circuit operation is supplied in common from the entire assembled battery will be adopted. In the case of using the main battery, the voltage of the main battery greatly fluctuates depending on the running and charging conditions. Therefore, whichever method is adopted, there is a concern that the operation reliability at the time of low capacity is reduced.

In order to accurately measure the capacity of each battery module, it is effective to detect the terminal voltage when the charging / discharging current is 0, that is, the open terminal voltage. In the case of the former power supply method of supplying the circuit operating power to the voltage detection circuit, the discharge current does not become 0, so that it is not possible to accurately measure the open terminal voltage, and it is not easy to measure the open terminal voltage with high accuracy. There was a problem that there was no.

Further, in the case of the latter power supply system, the power for operating the circuit is supplied to each module voltage detection circuit section from the main battery, that is, the whole assembled battery, so that there is a problem that the power consumption is large. In the case of (1), there is a problem that variations in the power consumption of each module voltage detection circuit unit cause variations in the capacities of the respective battery modules and unequal battery deterioration.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and it is possible to detect the open module voltage with higher accuracy, to avoid unnecessary shortening of the life of a high-voltage assembled battery, and to further reduce the running power storage state. An object of the present invention is to provide a voltage detecting device for an assembled battery for an electric vehicle, which can stably detect a module voltage despite a large fluctuation.

[0007]

According to the voltage detecting device for an assembled battery of the present invention, for example, 300
A main battery for storing high-voltage running power such as V is divided into a number of battery modules, and the module voltage of each battery module is detected by a module voltage detection circuit section and sent to a signal processing circuit section. Transmitted.

In this configuration, the power for operating the circuit of the module voltage detection circuit which is different and processes a high potential is supplied not from the main battery but from the auxiliary battery. With this configuration, in the voltage detection device for an assembled battery for an electric vehicle, the open module voltage can be detected with higher accuracy, unnecessary shortening of the life of the high-voltage assembled battery can be avoided, and the running power storage state can be further reduced. Module voltage can be detected stably despite large fluctuations in the module voltage.

In addition, since the amount of power stored in each battery module that generates the module voltage is not consumed for detecting the module voltage, a highly accurate module voltage can be obtained.
It is possible to estimate the total voltage and the capacity based on it, and the power for operating the circuit of the module voltage detection circuit can reduce the discharge current of the battery module, so it is accurate especially when the load current is zero or small. It is possible to measure the open-circuit module voltage, thereby enabling a highly accurate capacity estimation. Incidentally, the open terminal voltage and the capacitance have a close correlation. In addition, since power is not supplied from the assembled battery even after long-distance running, when the charged amount of the assembled battery is greatly reduced, there is no need to be affected by the voltage drop or capacity shortage. The module voltage can be detected stably even when the charged amount of the battery pack decreases.

Further, the degree of consumption of each battery module is not varied due to the variation of the circuit operating power of the module voltage detecting circuit portion, and the deterioration of the battery modules does not become unequal. According to the configuration of claim 2, claim 1 is
In the above-described voltage detecting device for an assembled battery for an electric vehicle, the module voltage detecting circuit unit may further include a plurality of differential voltage detecting circuits for detecting module voltages of a plurality of battery modules adjacent to each other. I / O-isolated DC-DC converter with multiple configured voltage detection blocks
The data is provided individually for each voltage detection block.

In this way, the circuit configuration can be further simplified despite the fact that the battery modules of the assembled battery have different potentials and very high voltages. According to a third aspect of the present invention, in the voltage detecting device for an assembled battery for an electric vehicle according to the second aspect, an output of each voltage detecting block is output to a signal processing circuit unit through a photocoupler element. With this configuration, the DC levels (reference potentials) of the signal voltages can be shared and the low voltage of the signal processing circuit unit in the subsequent stage can be shared even though the output voltages of the voltage detection blocks have high voltages and different DC potentials. Driving can be realized.

[0012]

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.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a voltage detecting device for an assembled battery for an electric vehicle according to the present invention will be described with reference to FIGS. FIG.
FIG. 2 is a block circuit diagram showing an assembled battery voltage detecting device for an electric vehicle for converting each module voltage of the assembled battery 19 into a digital signal. Dynamic voltage detection circuits 201 to 220,
A / D conversion circuits 5 to 8 are illustrated. FIG. 2 is a block circuit diagram showing a signal flow of the voltage detection device of FIG.

1 is a microcomputer for controlling charging and discharging of the battery, 2
Is a selector circuit for clock signal distribution composed of a demultiplexer (hereinafter also referred to as a clock signal selector circuit), 3 is a selector circuit for distribution of control signals composed of a demultiplexer (hereinafter also referred to as a control signal selector circuit), and 4 is a multiplexer 5 to 10 are A / D converter circuits, 201 to 220 and 13 are differential voltage detection circuits, 14 is an analog amplifier circuit,
Reference numeral 15 denotes a current sensor, and reference numerals 101 to 120 denote each battery module (also simply referred to as a module) of the assembled battery 19. However, in FIG. 2, the battery modules 106 to 120,
Differential voltage detection circuits 206 to 220, A / D conversion circuit 6
8 are not shown.

In FIG. 1, reference numeral 301 denotes an auxiliary battery for supplying electric power to a control device and an electronic device of an electric vehicle; and 300, a DC power supplied from the auxiliary battery 301 to a required DC potential level and a required voltage. Power supply circuit (D
C-DC converter), 20a, 20b, 20c, 20
Reference numeral d denotes a photocoupler element that transmits the outputs of the A / D conversion circuits 5 to 8 to the microcomputer 1 while electrically insulating the outputs. Similarly,
Outputs of the A / D conversion circuits 9 and 10 are also transmitted to the microcomputer 1 by a photocoupler element (not shown).

Each of the battery modules 101 to 120 is formed by cascading 12 cells. Battery module 1
01 has the highest module voltage, and the battery module 120 has the lowest module voltage. Reference numeral 20 denotes a serial signal line group for connecting each of the selector circuits 2 to 4 and each of the A / D conversion circuits 5 to 10. In this embodiment, each of the signal lines is a photocoupler element 2 for protecting the microcomputer 1.
0a, 20b, 20c, 20d, etc.

Each of the A / D conversion circuits 5 to 10 is a switching input type A / D conversion circuit having five channel inputs.
Depending on the input switching signal, each of the A / D conversion circuits 5 to 5
Channels 10 are switched synchronously. As can be seen from FIG. 1, the module voltage of the battery module 101 is converted to a signal voltage corresponding to a predetermined reference potential 1 by a differential voltage detection circuit 201 and then A / D converted by an A / D conversion circuit 5. Is done. Similarly, the module voltage of the battery module 102 is converted to a signal voltage corresponding to a predetermined reference potential 1 by the differential voltage detection circuit 202, and then the A / D conversion circuit 5 converts the signal voltage to A.
/ D conversion, the module voltage of the battery module 103 is converted to a signal voltage corresponding to a predetermined reference potential 1 by the differential voltage detection circuit 203, and then the A / D conversion circuit 5 converts the signal voltage to an A / D signal.
The module voltage of the battery module 104 is converted to a signal voltage corresponding to a predetermined reference potential 1 by the differential voltage detection circuit 203, and then A / D converted by the A / D conversion circuit 5, and The module voltage of the module 105 is converted into a signal voltage corresponding to a predetermined reference potential 1 by the differential voltage detection circuit 205 and then A / D converted by the A / D conversion circuit 5.

Similarly, the module voltages of the battery modules 106 to 110 are input to the A / D conversion circuit 6 through the differential voltage detection circuits 206 to 210, and the battery module 1
The module voltages of 11 to 115 are applied to the differential voltage detection circuit 2.
The module voltages of the battery modules 116 to 120 are input to the A / D conversion circuit 7 through 11 to 215, and the A / D conversion circuit 8 is output to the A / D conversion circuit 8 through the differential voltage detection circuits 216 to 220.
Is input to

Further, the total voltage of the assembled battery 19 is converted into a signal voltage with respect to a predetermined common ground potential by the differential voltage detection circuit 13, and then A / D converted by the A / D conversion circuit 9. Is A / D converted by an A / D conversion circuit 19 through an amplification circuit 14 and output to the microcomputer 1 through a photocoupler element (not shown). A / D conversion circuits 5-1
The output of 0 is sequentially selected by the data selector circuit 4 and read into the microcomputer 1 as a signal SIN. A
/ D conversion circuits 5 to 10 are synchronous operation serial output type A /
In a D conversion circuit, conversion data, that is, a serial digital signal is output in synchronization with a clock pulse input after the digital signal is determined.

More specifically, the A / D conversion circuit 5 receives an analog input terminal for inputting an analog signal, a data output terminal for outputting a digital signal as a serial signal, and a control command as a serial signal. A control command input terminal, and a clock pulse input terminal to which a clock pulse for synchronization is input, and when a read command is input to the control command input terminal, an edge of the clock pulse input to the clock pulse input terminal The reading of the analog signal is performed in synchronism, and then the input of the next clock pulse outputs an 8-bit serial digital signal.
The other A / D conversion circuits 6 to 10 have the same structure.

A more detailed operation of the battery pack voltage detecting device will be described below. The microcomputer 1 outputs the clock pulse SCLK and the A / D conversion circuit selection signal SEL to the clock signal selector circuit 2, and outputs the control signal selector circuit 3
Command signals SOUT and A / D
A conversion circuit selection signal SEL is output, an A / D conversion circuit selection signal SEL is output to the data selector circuit 4, and a serial digital signal is received from the data selector circuit 4.

(Simultaneous reading) The microcomputer 1 notifies the clock signal selector circuit 2 and the control signal selector circuit 3 that all of the A / D conversion circuits 5 to 10 are selected by the A / D conversion circuit selection signal SEL. As a result, the control signal selector circuit 3 sends the read command to the A / D conversion circuits 5-1.
0, the clock signal selector circuit 2 transmits the clock pulse SCLK to all the A / D conversion circuits 5 to 10, and each of the A / D conversion circuits 5 to 10 receives the edge of the clock pulse input immediately after the input of the read command. The analog signal is read in synchronism with the analog signal, and is converted into an 8-bit digital signal and held. At this time, the A / D conversion circuit 5
A / D conversion circuit selection signal SEL for selecting all of -10
Is invalidated inside the data selector circuit 4 with respect to the data selector circuit 4.

(Sequential output) Next, the microcomputer 1 performs A / D
The selection of the A / D conversion circuit 5 is notified to the selector circuits 2 to 4 by the conversion circuit selection signal SEL, whereby the clock signal selector circuit 2 transmits the clock pulse SCLK only to the A / D conversion circuit 5, As a result, the A / D conversion circuit 5 outputs a serial digital signal to the data selector circuit 4 in synchronization with the edge of the clock pulse SCLK.
The data selector circuit 4 outputs an A / D conversion circuit selection signal SEL.
Selects the A / D conversion circuit 5, the A / D conversion circuit 5
The serial digital signal from the D conversion circuit 5 is
Sent to.

Next, the microcomputer 1 notifies the selector circuits 2 to 4 that the A / D conversion circuit 6 is to be selected by the A / D conversion circuit selection signal SEL, and thereafter performs the same operation as described above to execute A / D conversion. The serial digital signal of the D / A conversion circuit 6 is transmitted to the microcomputer 1, and similarly, each of the A / D conversion circuits 8 to 1
A serial digital signal of “0” is transmitted to the microcomputer 1.

The above series of operations is executed for the first input channels of the input switching type multi-input A / D conversion circuits 5 to 10. After that, the above series of operations is performed in the second to second stages. 5 for each channel input. Next, differential voltage detection circuits 201 to 220 for detecting each module voltage of the assembled battery 19 will be described with reference to FIG.

In this embodiment, a total of 240 cells constituting the assembled battery 19 are divided into 20 battery modules 101 to 120 which are cascaded with each other. 1, the battery modules 106 to 110 constitute a second voltage detection block, the battery modules 111 to 115 constitute a third voltage detection block, and the battery module 116
To 120 constitute a fourth voltage detection block.

The first voltage detection block has a reference potential 1 as a first reference potential, the second voltage detection block has a reference potential 2 as a second reference potential, and a third voltage detection block. Has a reference potential 3 that is a third reference potential, the fourth voltage detection block has a reference potential 4 that is a fourth reference potential, and the fifth voltage detection block has a reference potential that is a fifth reference potential. It has a potential of 5.

In this embodiment, the reference potential 1 is set to the lower terminal voltage of the battery module 103 (the higher terminal voltage of the battery module 104). 3 from the high potential side in each voltage detection block
The lower terminal voltage of the second battery module (2 from the lower side)
(The higher terminal voltage of the second battery module).

That is, in this embodiment, the reference potential (constant potential applied to one end of the input-side resistor network) of each differential voltage detection circuit in the same voltage detection block is equalized. The detection block has different reference potentials 1 to
4 is applied. Further, each of the reference potentials 1 to 4 is set to an intermediate potential (a value as close as possible to an intermediate value between the highest terminal voltage and the lowest terminal voltage) of each battery module in the voltage detection block. Battery modules as 1-4
Terminal voltage.

FIG. 3 is a circuit diagram of the differential voltage detection circuit 201. 2011 is input resistance r1, r2 and feedback resistance r
An operational amplifier having f1 and a battery module 101
The terminal voltage V1 on the high potential side and the reference potential 1 (here, the low-side terminal voltage of the battery module 103 (the battery module 1)
04 (which is set to the high-side terminal voltage of V.04).
-V4) is detected.

Similarly, reference numeral 2012 denotes an operational amplifier having input resistors r3 and r4 and a feedback resistor rf2, which is different from the terminal voltage V2 on the low potential side of the battery module 101 by (V1-V
4) and the reference potential 1 (here, the battery module 1)
The difference V1-V2 is detected by subtracting the lower terminal voltage of 03 (set to the higher terminal voltage of the battery module 104).

The positive and negative power supply voltages of the operational amplifiers 2011 and 2012 are set to the positive power supply voltage because the potentials of the positive and negative input terminals of the operational amplifier become substantially equal to the virtual ground potential, that is, the reference potential V4 in this embodiment. VH is the reference potential V4
The negative power supply voltage VL is set higher than the reference potential V4 by a predetermined voltage (7.5 V here).
5V) A low voltage may be formed.

The reference potential V1 may be an intermediate potential between the highest potential V1 and the lowest potential V6 of the voltage detection block, and may be formed by using a special voltage generating circuit. Other features of the circuit device according to the present embodiment will be described below. First, the output voltages of all the differential voltage detection circuits having the same reference potential in the same voltage detection block are input to the same sequentially switching A / D conversion circuit. Although the voltage of the A / D converter is largely different, the A / D conversion circuit can be shared and the circuit configuration can be greatly simplified.

The output signal of each A / D conversion circuit is output to the microcomputer 1 driven by a predetermined low power supply voltage through a photocoupler element (for example, 20a). In addition to eliminating the DC voltage difference between the output signal voltages of the A / D conversion circuits having different power supply voltages, a single digital signal processing circuit (usually a CPU) that operates at low voltage by cutting high voltage Can be digitally processed.

Each of the above differential type voltage detecting circuits 201 to 22
0, the power supply voltage (V) applied to the A / D conversion circuits 5 to 10
H, VL) will be described with reference to FIG. Reference numeral 301 denotes a low-voltage (12 V) auxiliary battery that supplies power to an auxiliary device of an electric vehicle. The DC power of the low-voltage (12 V) auxiliary battery is converted into an AC power by an oscillation circuit 302 through a transformer 303 having four secondary coils. Power supply power supply circuit 304 to
307. That is, the oscillation circuit 302,
Transformer 303 and power supply circuit 3 for power supply of voltage detection block
04 to 307 constitute the DC-DC converter 300.

Since the power supply circuits 304 to 307 for supplying power to the four voltage detection blocks have the same circuit configuration, the power supply circuit 3 for supplying the power supply voltage to the highest potential voltage detection block is provided.
04 will be described below. The AC voltage applied from the transformer 303 is converted into a DC voltage by the rectifying / smoothing circuit 3041 and applied to the positive and negative power supply terminals of the differential voltage detection circuits 201 to 205.

This embodiment is characterized by the following circuit configuration for generating the reference potential Vc1. More specifically, a constant voltage circuit 3042 and a Zener diode 3043 are connected in series, and a DC voltage is applied from a rectifying / smoothing circuit 3041. Then, the output voltage of the constant voltage circuit 3042 is changed to A /
The high power supply voltage VH ′ of the D conversion circuit 5 is
A / D is used to connect the connection point of the Zener diode 3043
The lower power supply voltage VL ′ of the conversion circuit 5 is used as the lower power supply voltage VL ′.
Is supplied as the reference potential 1 = Vc1. The potential difference between the output voltage of the constant voltage circuit 3042 = the higher power supply voltage VH 'of the A / D conversion circuit 5 and the reference potential 1 = Vc1 is set so that the voltage drop of the Zener diode 3043 becomes substantially equal.

In this way, A /
A constant voltage circuit 304 for applying a constant power supply voltage to the D conversion circuit 5
By simply adding one Zener diode 3043 to 2 above, it is possible to form a stable reference potential with much less potential fluctuation than using the higher terminal voltage of the battery module 104. The power supply circuit 3 for supplying voltage to the voltage detection block
04 supplies power to the differential voltage detection circuits 201 to 205 and the A / D conversion circuit 5, and the voltage detection block power supply power supply circuit 305 supplies power to the differential voltage detection circuits 206 to 211.
5 and the A / D conversion circuit 6, and the voltage detection block power supply power supply circuit 306 is provided with differential voltage detection circuits 211 to 21.
5 and the A / D conversion circuit 7 and the power supply circuit 307 for supplying voltage to the voltage detection block is provided with differential voltage detection circuits 216 to 22.
It is natural that power is supplied to the 0 and A / D conversion circuit 8.

Although the reference potentials 1 to 4 are shown using predetermined module voltages in FIG. 1, it is preferable that the reference potentials 1 to 4 have high stability in practice.
As shown in FIG. 4, the voltage detection block power supply power supply circuit 30
It is preferably created by 4-307. According to this embodiment, the following functions and effects can be obtained. A module voltage detection circuit unit (differential voltage detection circuits 201 to 220, A /
It is characterized in that the circuit operating power of the D conversion circuits 5 to 8) is supplied not from the main battery (assembled battery) 19 but from the auxiliary battery 301.

In this manner, in the voltage detecting device for an assembled battery for an electric vehicle, the open module voltage can be detected with higher accuracy, and unnecessary shortening of the life of the high-voltage assembled battery 19 can be avoided. Stable detection of the module voltage can be performed despite large fluctuations in the running power storage state. In order to detect the module voltage, each of the battery modules 101 to 12 for generating the module voltage is used.
Since the power storage amount of 0 is not consumed, it is possible to estimate the module voltage and the total voltage with high precision and the capacity estimation based on the module voltage. Since the discharge current of the modules 101 to 120 can be reduced, an accurate open module voltage can be measured particularly when the load current is zero or small, thereby enabling highly accurate capacity estimation. Incidentally, the open terminal voltage and the capacitance have a close correlation. In addition, since power is not supplied from the assembled battery even after long-distance traveling when the charged amount of the assembled battery 19 is greatly reduced, the module voltage is not affected by the voltage drop or the capacity shortage. It is possible to stably detect the module voltage even when the required charged amount of the assembled battery is low.

Further, each battery module 101 is caused by a variation in circuit operating power of the module voltage detection circuit.
The deterioration of the battery module does not become unequal due to the variation in the degree of consumption of the battery module.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an assembled battery voltage detecting device for converting each module voltage of the assembled battery 1 into a digital signal.

FIG. 2 is a block circuit diagram showing an embodiment of a battery monitoring device of the assembled battery using the voltage detecting device of the assembled battery of FIG. 1;

FIG. 3 is a block circuit diagram of the A / D conversion circuit 5 of FIG.

FIG. 4 is a block circuit diagram of a power supply circuit that supplies power to the A / D conversion circuit 5 and the differential voltage detection circuit 201 in FIG.

[Explanation of symbols]

1 is a microcomputer (signal processing circuit), 19 is an assembled battery (main battery), 101 to 120 are battery modules, 201
220 to 220 are differential voltage detection circuits (module voltage detection circuit sections), 5 to 10 are A / D conversion circuits (module voltage detection circuit sections), 20a to 20d are photocoupler elements, 30
0 is a DC-DC converter and 301 is an auxiliary battery.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // B60R 16/02 670 B60R 16/02 670S G01R 19/165 G01R 19/165 M

Claims (3)

[Claims] 1. The voltage of an assembled battery for an electric vehicle comprising a main battery for storing running power, comprising a high-voltage assembled battery in which a number of battery modules are connected in cascade with each other, and an auxiliary battery for driving auxiliary equipment. A detection device, comprising: a module voltage detection circuit unit for individually detecting a module voltage of each of the battery modules; and a signal supplied from the auxiliary battery for signal processing of each of the module voltages. An input / output insulated DC-DC converter having a processing circuit unit and a transformer, and boosting the voltage of the auxiliary battery and applying the boosted voltage to the module voltage detection circuit unit as a power supply voltage;
And a voltage detecting device for an assembled battery for an electric vehicle. 2. The voltage detecting device for an assembled battery for an electric vehicle according to claim 1, wherein the module voltage detecting circuit detects module voltages of a plurality of battery modules adjacent to each other. It has a plurality of voltage detection blocks constituted by a plurality of the differential voltage detection circuits, and the input / output insulated DC-DC converter is individually provided for each of the voltage detection blocks. A voltage detector for assembled batteries for electric vehicles. 3. The voltage detection device for an assembled battery for an electric vehicle according to claim 2, wherein an output of each of the voltage detection blocks is output to the signal processing circuit unit through a photocoupler element. A voltage detector for assembled batteries.