JP4270154B2 - Battery voltage detection controller - Google Patents

Description

  The present invention relates to an overcharge / discharge detection circuit and a battery voltage detection circuit for an assembled battery.

Recently, in a hybrid vehicle and an electric vehicle, it is necessary to drive a motor for driving with electric power. Therefore, a secondary battery to be used has to be set to a high voltage (about 300V), and a large number of low voltage cells are connected in series. Connected to form an assembled battery. In particular, vehicle development using a lithium battery or an electric double layer capacitor, which has a very high potential depending on applications, has been promoted recently.
However, lithium batteries are vulnerable to overcharge and overdischarge, and if they are not used within a predetermined charging voltage range, the material may decompose and the capacity may be significantly reduced, or the battery may be abnormally heated and become unusable. Therefore, when using a lithium battery, the upper limit voltage and lower limit voltage of the cell are clearly specified, and charge / discharge control is performed so that the terminal voltage of the cell is within the upper limit and lower limit voltage range, or the voltage range Generally, it is used in combination with a protection circuit that limits
For example, in patent document 1, while setting the upper limit voltage and lower limit voltage of a cell and monitoring the state of overcharge / discharge, overcharge / discharge detection for detecting a failure of an overcharge / discharge detection circuit, and voltage detection for a cell group, Is disclosed in a control system for a battery pack that is input to a control processor using a separate detection circuit.

In hybrid vehicles and electric vehicles, the high voltage system is insulated from the chassis to prevent danger such as electric shock. On the other hand, since the processor that controls charging / discharging of the assembled battery uses the chassis as a reference potential, the voltage of the high-voltage system assembled battery needs to be measured in a state insulated from the processor or the like that uses the chassis as the reference potential. is there.
For example, the invention of Patent Document 1 employs a technique of insulating and transmitting a detection signal by a photocoupler in overcharge / discharge detection.
Further, Patent Document 2 discloses voltage detection of a battery group cell group using a flying capacitor type to ensure insulation between a high voltage system and a processor, etc., and further comprising a plurality of capacitors. An assembled battery voltage detection device with improved speed is disclosed.
In the invention of Patent Document 3, the voltage detection of the cell block of the assembled battery is a flying capacitor type, and a reset circuit is provided in parallel with the capacitor to detect the voltage of the cell group in an insulating manner. It is possible to detect a disconnection failure or an off failure of a multiplexer circuit that is an input circuit to the circuit.
JP 2003-32907 A JP 2002-156392 A JP 2003-84015 A

As described in the above-described conventional example, if a flying capacitor type circuit configuration is used for voltage detection of a cell group of a battery pack of a hybrid vehicle or an electric vehicle, the voltage detection of the battery pack is performed using a chassis at the rear stage as a reference potential. It can be done in an insulating manner.
However, if the voltage detection of the assembled battery and the overcharge / discharge detection of the assembled battery are performed as separate systems as in Patent Document 1, and two detection circuits are used, wiring and elements increase and the circuit becomes complicated.
In the case of Patent Document 3, a reset circuit is provided in the voltage detection circuit so that the power consumption of the cell group can be reduced when the capacitor is charged and the disconnection failure or the off failure of the cell group voltage detection multiplexer circuit can be detected. However, when the reset circuit itself has an off failure, there is a problem that the off failure of the cell group voltage detecting multiplexer circuit cannot be detected.

  The present invention has been made in view of the above problems, and includes voltage detection of a cell group of an assembled battery, detection of overcharge / discharge of a cell, and failure and abnormality detection of an assembled battery voltage detection circuit and an overcharge / discharge detection circuit. The three functions are detected by, for example, a set of flying capacitor circuits, and an object of the present invention is to provide a battery voltage detection control device for a highly functional assembled battery with a simple circuit configuration.

In order to achieve the above object, the battery voltage detection control device according to claim 1 is provided for each of the chargeable / dischargeable single cells that are connected in series and constitute an assembled battery, and an overcharge / discharge determination signal of the single cell. A battery information output circuit comprising: an overcharge / discharge determination means for outputting a voltage; and a cell group voltage output means for outputting a voltage of a cell group obtained by grouping a plurality of the single cells in series, a voltage detection circuit, and the voltage A voltage measurement circuit for measuring a detection voltage of the detection circuit, wherein the voltage of the overcharge / discharge determination signal output by the battery information output circuit can be the cell group voltage. is set to the lowest value or less of the voltage value of the voltage range, the voltage detection circuit includes a flying capacitor circuit, an input sampling switch circuit, and an output sampling switch circuit, the polarity switching Is composed of a e switching circuit is obtained by said detecting the overdischarge determination signal and the cell group voltage.

According to the battery voltage detection control apparatus of claim 1, since both the voltage of the cell group and the overcharge / discharge determination signal of the cell are detected by the set of voltage detection circuit and voltage measurement circuit, a simple circuit is provided. It has a configuration.
Further, the cell group voltage is managed so as to operate within a certain voltage range. Therefore, by setting the voltage of the overcharge / discharge determination signal outside the range of the operating voltage of the cell group voltage, the voltage of the overcharge / discharge determination signal is stored in the flying capacitor circuit, and the remaining storage voltage of the capacitor after reading is It should be at least outside the operating voltage range of the cell group voltage. That is, by setting the voltage lower than the voltage of the normal cell group, the remaining stored voltage of the capacitor after the voltage detection of the overcharge / discharge determination signal is always lower than the voltage of the cell group. That is, the capacitor of the flying capacitor circuit has an effect equivalent to resetting by short-circuiting the storage voltage of the capacitor for detecting the cell group voltage.

Furthermore, according to the battery voltage detection control apparatus of claim 1 , the high voltage system of the assembled battery and the subsequent voltage detection circuit using the chassis as a reference voltage are electrically disconnected by a flying capacitor circuit, The overcharge / discharge determination signal of the cell can be measured in an insulating manner.

According to a second aspect of the present invention, in the battery voltage detection control device according to the first aspect, the flying capacitor circuit includes a plurality of capacitors connected in series.

According to the battery voltage detection control apparatus of the third aspect, the performance of the voltage detection circuit is improved by providing a plurality of capacitors of the flying capacitor circuit constituting the voltage detection circuit.
For example, as shown in FIG. 7, when the flying capacitor circuit is composed of two capacitors having the same capacitance connected in series, the detected voltage per capacitor stored and read in the capacitor is composed of one capacitor. Compared to the case, the voltage is halved, so that the influence of the parasitic capacitance can be reduced and more accurate voltage detection can be performed.
Further, when one capacitor is provided in parallel for each cell group constituting the assembled battery as shown in FIG. 8, the cell group voltage, the cell overcharge / discharge determination signal, Can be detected more quickly.

According to a third aspect of the present invention, in the battery voltage detection control device according to the first or second aspect , the battery voltage detection control device is sequentially connected to the flying capacitor circuit in order to detect the voltage of the overcharge / discharge determination signal and the cell group voltage. The combination of the order of connection of the output of the overcharge / discharge determination signal and the output of the cell group is sequentially changed.

When the cell group voltage is read after the voltage detection of the overcharge / discharge determination signal, the voltage remaining in the capacitor is lower than the voltage detection for each cell group continuously. The burden is heavy. Accordingly, fixing the combination of the voltage detection of the overcharge / discharge determination signal and the cell group voltage detection and repeating the reading into the capacitor in the same cycle increases the discharge amount of the specific cell group.
In the invention of claim 3 , the combination of the voltage detection of the overcharge / discharge determination signal and the cell group voltage detection is sequentially changed in each cycle, or even when the same combination is used, only when a voltage is read into a specific cell group in each cycle. The cell groups that start measurement in each cycle are changed in order so that the discharge burden is not concentrated.

  As described above, according to the present invention, the overcharge / discharge determination of the cells of the assembled battery, the voltage detection of the cell group, and the failure detection of the overcharge / discharge determination circuit and the cell group voltage detection circuit are performed as one voltage detection circuit. Therefore, a highly functional battery voltage detection control device is realized with a simple circuit configuration.

Hereinafter, an embodiment of a battery voltage detection control device for a battery pack according to the present invention will be described based on Example 1 and Example 2.
Example 1
FIG. 1 is a circuit diagram showing an outline of one embodiment of a battery voltage detection control apparatus of the present invention, where 1 is a battery information output circuit (CMUi), 2 is a voltage detection circuit, 3 is a voltage measurement circuit, and 4 is an AD The converter 5 is a micro computer (CPU), and 6 is a memory. The output of the battery information output circuit (CMUi) 1 is connected to the voltage detection circuit 2, and the output of the voltage detection circuit 2 is connected to the voltage measurement circuit 3.
The voltage detection circuit 2, the voltage measurement circuit 3, the AD converter 4, the CPU 5, and the memory 6 constitute an assembled battery controller (BCU) 70. The battery information output circuit (CMUi) 1 and the assembled battery controller (BCU) 70 Is a battery voltage detection control device of the present invention.
Reference numeral 10 denotes an assembled battery controlled by the battery voltage detection control device.

A circuit diagram of the battery information output circuit (CMUi) 1 is shown in FIG. The battery information output circuit 1 is an overcharge / discharge circuit connected to each single cell constituting a cell group (in the embodiment of FIG. 2, one cell group is composed of n single cells Ci1 to Cin). Determination circuits (ULi1 to ULin) 11, photocoupler 13, inversion OR circuit 14 as logical sum operation means, inversion AND circuit 15 as logical product operation means, output of inversion OR circuit 14 and inversion AND circuit 15 And a constant current circuit 12 for generating and outputting an overcharge / discharge determination analog signal to the voltage detection circuit 2 and resistors R1 and R2 for outputting the voltage of the cell group to the voltage detection circuit 2. . A switch circuit 7 for controlling on / off of the photocoupler 13 is provided in the BCU 70.
As shown in FIG. 3, the overcharge / discharge determination circuit (ULin) 11 includes a voltage dividing circuit 16 that divides the voltage (VCij) of a single cell, a constant voltage circuit 18 that includes a resistor Rc and a voltage generation source DU. And a comparator 19.

  Next, as shown in FIG. 1, the circuit diagram of the voltage detection circuit 2 includes a current limiting resistor 21 (R10 to Rnn), an input sampling switch 22 (SSR10 to SSRnn), and a polarity changeover switch 23 (SSR00). To SSR03), a capacitor 24 (C), and an output sampling switch 25 (SSR21 to SSR22).

(Basic Operation) The basic operation of the first embodiment will be described with reference to FIGS.
First, the overcharge / discharge determination circuit (ULi1 to ULin) 11 inverts a determination signal using an upper limit value and a lower limit value set from the usable range of the cell voltage as threshold values according to on / off of the photocoupler 13, and an inversion OR circuit 14 And output to the inverting AND circuit 15.
That is, the overcharge / discharge determination circuit (ULi1 to ULin) 11 uses the cell voltage when the photocoupler 13 is on by selecting the values of the resistors Ra, Rb, and Rx of the voltage dividing circuit 16 of FIG. Using the lower limit of the possible range as a threshold value, a determination signal is output that is low level when the cell voltage (VCij) is smaller and high level when the cell voltage (VCij) is larger.
Further, when the photocoupler 13 is off, the upper limit value of the usable range of the cell voltage is set as a threshold value. When the cell voltage (VCij) is smaller, the low level is set. When the cell voltage (VCij) is larger, the high level is set. A determination signal is output.

  As shown in FIG. 2, the inverting OR circuit 14 and the inverting AND circuit 15 are connected to the cell group (CGi) based on the determination signal of the cell voltage (VCij) input from the overcharge / discharge determination circuit (ULi1 to ULin) 11. A low-level or high-impedance (Z) signal representing the charging status is output (output of the inverting OR circuit 14: OOi output, output of the inverting AND circuit 15: OAi output). The two output signals (OOi output and OAi output) are input to a constant current circuit 12 as an output interface, converted to an analog value, synthesized, and output as an OCDS signal. At this time, the OCDS output signal is supplied to the OCDS output terminal OCDSi as one of three analog voltage values of high level, middle level, and low level depending on the charging state of the cell group (CGi) or the state of the overcharge / discharge determination circuit 11. Output.

At this time, FIG. 4 is an explanatory diagram showing the relationship between the output of the inverting OR circuit 14 (OOi output), the output of the inverting AND circuit 15 (OAi output), and the OCDS output signal (output of the constant current circuit 12).
In FIG. 4, the horizontal axis represents time, and the vertical axis represents the threshold of the overcharge / discharge determination circuit (ULin), the output of the inverting OR circuit 14 (OOi output), and the output of the inverting AND circuit 15 (OAi output). The voltage levels of the OCDS output signal (the output of the constant current circuit 12) are displayed so as to be compared with each other.
For example, in the period T1, the threshold value is set to the lower limit value (the switch circuit 7 is on and the photocoupler 13 is on), and if both the OOi output and the OAi output are at the low level (L), the OCDS output Becomes a high level (H).
In the period T2, the threshold value is set to the upper limit value (the switch circuit 7 is in the off state and the photocoupler 13 is off). If both the OOi output and the OAi output are high impedance (Z), the OCDS output is This represents that the level is low (L).
Further, in the period T3, the threshold value is set to the upper limit value, but the OOi output is low level (L), and the OAi output is high impedance (Z). At this time, the OCDS output becomes the middle level (M). In the present invention, the middle level (M) of the OCDS output signal represents a circuit failure or abnormality.

  The cell group (CGi) voltage output of the battery information output circuit (CMUi) 1 is between the output terminals VSi and OCDSi of the battery information output circuit (CMUi) 1 and the output terminals OCDSi as shown in FIG. It is divided between VSi + 1 and output as an analog voltage value.

  Note that the voltage of the OCDS output signal, which is a cell overcharge / discharge determination signal, is set to be outside the range of output voltages that can be taken by the cell group (CGi). Specifically, if the voltage is set to 50% or less of the normal voltage of the cell group (this voltage value is set to be equal to or lower than the minimum voltage that can be taken by the cell group), the output voltage that can be taken by the cell group (CGi). When a voltage in the range is detected, it can be determined that some abnormality has occurred.

Next, the operation of the voltage detection circuit 2 for detecting the cell overcharge / discharge determination signal output from the battery information output circuit (CMUi) 1 and the cell group voltage output will be described with reference to FIG.
The input sampling switch 22, the polarity switching switch 23, and the output sampling switch 25 are based on the off state (the switch is open). Here, assuming that the battery information of the cell group CG1 is to be detected, first, when the input sampling switches SSR10 and SSR11 and the polarity changeover switches SSR00 and SSR03 are turned on, the input terminals VS1 and OCDS1 are input from the battery information output circuit CMU1. The voltage representing the battery information (in this case, the overcharge / discharge determination signal) sent via is stored in the capacitor 24.
Next, when the input sampling switches SSR10 and SSR11 and the polarity changeover switches SSR00 and SSR03 are turned off and the output sampling switches SSR21 and SSR22 are turned on, the voltage stored in the capacitor 24 is read out to the voltage measuring circuit 3 and differential. Measured with an amplifier.
Next, the battery information detection of the cell group CG2 is sequentially repeated in such a manner that the input sampling switches SSR12 and SSR13 and the polarity changeover switches SSR00 and SSR03 are turned on to store the capacitor 24 and perform voltage detection.

The cell group voltage detection which is another battery information output from the battery information output circuit (CMUi) 1 is as follows.
For example, when the battery voltage of the cell group CG1 is detected, first, the input sampling switches SSR10 and SSR11 and the polarity changeover switches SSR00 and SSR03 are turned on to store the capacitor 24. Next, the input sampling switches SSR10 and SSR11 and the polarity changeover switches SSR00 and SSR03 are turned off, the output sampling switches SSR21 and SSR22 are turned on, and the voltage stored in the capacitor 24 is read to the differential amplifier of the voltage measuring circuit 3 and measured. The measured voltage is the voltage across the resistor R1 in FIG. 1, and the voltage value is sent to the CPU 5 via the AD converter 4 and stored.
Next, the input sampling switches SSR11 and SSR12 and the polarity changeover switches SSR01 and SSR02 are turned on while the output sampling switches SSR21 and SSR22 are turned off, and the capacitor 24 is charged. In this state, the input sampling switches SSR11 and SSR12 and the polarity changeover switches SSR01 and SSR02 are turned off, the output sampling switches SSR21 and SSR22 are turned on, and the voltage stored in the capacitor 24 is read to the differential amplifier of the voltage measuring circuit 3 and measured. . The measured voltage indicates the voltage across the resistor R2 in FIG. Therefore, if the voltage across the resistor R1 measured earlier and the voltage across the resistor R2 measured this time are added, the voltage value is the battery voltage of the cell group CG1.

(Combination of overcharge / discharge detection and cell group voltage detection)
The cell overcharge / discharge detection of each cell group (CG1 to CGm) is sequentially performed, and after the cell overcharge / discharge detection is completed, the cell group voltage detection is sequentially performed to complete one cycle of the detection operation. This is because the voltage level of the signal at the time of overcharge / discharge detection and the voltage level at the time of cell group voltage detection are set to different voltage ranges, so that the flying capacitor is stored and the stored voltage is stored in the voltage measurement circuit. This is because in the present invention in which reading and voltage are measured, it is more efficient to repeat the detection operation in the same voltage range, and the burden on the cell group due to capacitor storage is small.

(Overcharge detection and overcharge detection circuit error detection)
As described above, in the cell overcharge / discharge detection operation, data as an overcharge / discharge determination signal (OCDS signal) of each cell group is output to the input terminal OCDSi of the BCU 70 as an analog voltage value. Abnormality detection of the battery information output circuit (CMUi) 1 can be performed based on this data.
FIG. 5 is a table showing specific failure locations and failure details that can be determined by the OCDS signal.
As shown in the table, when the detection voltage level of the OCDS signal is at the middle level (M), it is estimated that some abnormality has occurred, and further, by combining with the information of the OOi output and the OAi output, It is possible to further narrow down the failure location and failure details.

(Abnormality detection of cell group voltage detection circuit)
Abnormality detection of the cell group voltage detection circuit can be performed by performing cell group voltage detection immediately after performing overcharge / discharge detection. Since the voltage level of the OCDS signal at the time of overcharge / discharge detection is set lower than the voltage value that can be taken by the cell group, the voltage value stored in the capacitor is read into the measurement circuit, and the measured voltage value is abnormally low. If it is outside the range of voltage values that can be taken), it is estimated that the input sampling switch 22 and the polarity changeover switch 23 are in an abnormal state such as an off failure or a disconnection failure.

(Modification of Example 1)
The combination of the voltage detection of the overcharge / discharge determination signal and the detection order of the cell group voltage detection is performed by sequentially detecting the voltage of the overcharge / discharge determination signal and then sequentially performing the cell group voltage detection. Voltage detection is performed to perform a one-cycle voltage detection operation.
In contrast, in this modification, the number of voltage detections in one cycle is set to exceed the number of cell groups. For example, when the number of cell groups is 10 (CG1 to CG10), the overcharge / discharge determination signal The voltage detection is performed sequentially from CG1 to CG10, and further, the voltage detection of CG1 is performed, and then the process proceeds to cell group voltage detection. At this time, the cell group voltage detection is started from CG2. In this way, each time the voltage detection cycle is repeated, the cell group that shifts from the voltage detection of the overcharge / discharge determination signal to the cell group voltage detection shifts, so that the burden of capacitor storage is concentrated on a specific cell group. You can avoid it.

(Example 2)
Another embodiment of the present invention will be described with reference to FIG.
In this embodiment, in the battery voltage control apparatus of Embodiment 1 shown in FIG. 1, the wiring and polarity of the input part to the capacitor 24 of the voltage detection circuit 2 for detecting the voltage of the output signal of the battery information output circuit (CMUi) 1 The configuration of the changeover switch 23 is changed to improve the efficiency of cell group voltage detection.
The characteristic of this circuit is that in the first embodiment, the cell group voltage detection is performed by dividing the voltage of the cell group into two (for example, if voltage detection of the cell group CG1 is performed, between the input terminals VS1 and OCDS1 and the input terminals OCDS1 and VS2). The voltage of the cell group is calculated by adding the two voltages.
In contrast, in the second embodiment, if the voltage of the cell group CG1 is detected, the input sampling switches SSR10 and SSR12 and the polarity changeover switches SSR00 and SSR03 are turned on, and the capacitor 24 stores the voltage of the cell group CG1 once. Thus, voltage detection is possible (see FIG. 6).
Other configurations and operations relating to voltage detection of the overcharge / discharge determination signal and abnormality detection of the battery information output circuit are the same as those in the first embodiment.

(Example 3)
Example 3 is shown in FIG. Example 3 is a circuit of Example 1 shown in FIG. 1 in which the capacitor 24 of the voltage detection circuit 2 is composed of two capacitors C3 and C3 ′ connected in series, and voltage detection is performed with one capacitor. Compared with the first embodiment, the stored voltage per capacitor is only ½ of the voltage. Therefore, the influence of the parasitic capacitance of the circuit from the capacitor to the differential amplifier 31 can be reduced.
The operations relating to voltage detection of the overcharge / discharge determination signal, cell group voltage detection, and abnormality detection of the battery information output circuit are the same as in the first embodiment.

(Example 4)
As shown in FIG. 8, the fourth embodiment has a configuration in which one capacitor is connected to each cell group. That is, the capacitor C1 is included in the cell group CG1, and the capacitor C2 is included in the cell group CG2. The capacitor Cm is connected to the cell group CGm via an input sampling switch. On the output side of the capacitors C1 to Cm, an output sampling switch is provided for each capacitor, and is connected to a differential amplifier via a polarity changeover switch 25.
The feature of this detection circuit is that when the number of capacitors is one or two as in the first to third embodiments, it is necessary to read the cell group voltage by power storage in the capacitor when detecting the cell group voltage in time sequence. However, in the case of the fourth embodiment, since parallel processing in which all cell group voltages are read simultaneously becomes possible, the voltage detection time can be shortened. In the present embodiment, parallel processing can be performed in the same manner even when the voltage of the overcharge / discharge determination signal is detected.
Other configurations and operations relating to voltage detection of the overcharge / discharge determination signal, cell group voltage detection, and abnormality detection of the battery information output circuit are the same as those in the first embodiment.

It is explanatory drawing which shows the schematic whole structure in embodiment of this invention. It is explanatory drawing of the battery information output circuit of Example 1. FIG. 3 is a circuit diagram of an overcharge / discharge determination circuit according to Embodiment 1. FIG. It is explanatory drawing of the OCDS signal for overcharge / discharge detection of Example 1. FIG. It is explanatory drawing of the abnormality detection by the OCDS signal of Example 1. 6 is a circuit diagram of Example 2. FIG. 6 is a circuit diagram of Example 3. FIG. FIG. 6 is a circuit diagram of Example 4.

Explanation of symbols

1: Battery information output circuit (CMUi) 16: Voltage dividing circuit 2: Voltage detection circuit 17: Switching transistor 3: Voltage measurement circuit 18: Constant voltage circuit 4: AD converter 19: Comparator 5: Microcomputer (CPU) 21: Current Limiting resistor 6: Memory 22: Input sampling switch 7: Switch circuit 23: Polarity changeover switch 10: Battery assembly 24: Flying capacitor 11: Overcharge / discharge determination circuit 25: Output sampling switch 12: Constant current circuit 31: Differential amplifier 13 : Photocoupler 32: Reference power supply 14: Inverting OR circuit 70: Battery controller (BCU)
15: Inversion AND circuit

Claims (3)

A plurality of single cells connected in series with an overcharge / discharge determination means for outputting an overcharge / discharge determination signal of the single cell, provided for each single cell that can be charged / discharged to constitute an assembled battery by connecting in series. Battery voltage detection comprising: a battery information output circuit comprising a cell group voltage output means for outputting a grouped cell group voltage; a voltage detection circuit; and a voltage measurement circuit for measuring a detection voltage of the voltage detection circuit. In the control device,
The voltage of the overcharge / discharge determination signal output by the battery information output circuit is set to a voltage value equal to or lower than the lowest value of the voltage range that the cell group voltage can take,
The voltage detection circuit includes a flying capacitor circuit, an input sampling switch circuit, an output sampling switch circuit, and a polarity switching switch circuit, and detects the voltage of the overcharge / discharge determination signal and the cell group voltage. A battery voltage detection control device.   The battery voltage detection control device according to claim 1, wherein the flying capacitor circuit includes a plurality of capacitors connected in series.   In order to detect the voltage of the overcharge / discharge determination signal and the cell group voltage, the combination of the order of connection of the output of the overcharge / discharge determination signal and the output of the cell group sequentially connected to the flying capacitor circuit is The battery voltage detection control device according to claim 1, which is sequentially changed.

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