JP2012047522A - Battery state monitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which it is impossible to diagnose an abnormality in a device itself for detecting a minimum value of voltages (in-block minimum value MINi) of a plurality of battery cells Ci1-Cin.SOLUTION: Each voltage of battery cells Ci1-Cin is input into an electric potential converting circuit 50 through a multiplexer MPX. An output of the electric potential converting circuit 50 is connected to a cathode of a diode 60, and anodes of the diode 60 are short-circuited. A voltage at a connection between the anodes is a minimum value of the voltages of the battery cells Ci1-Cin. In the multiplexer MPX, as an input of the electric potential converting circuit 50, a reference voltage Vref can be selected instead of a battery cell Cij. The reference voltage Vref is a value which cannot be envisaged as a voltage of the battery cell Cij in an normal use. Hence, the presence or absence of an abnormality in the electric potential converting circuit 50 can be diagnosed on the basis of the output thereof in an application of the reference voltage Vref.

Description

  The present invention relates to a battery state monitoring device that detects voltages of a plurality of detection target batteries.

  As this type of state monitoring device, for example, as seen in Patent Document 1 below, one that selectively connects one of a plurality of battery cells constituting a fuel cell to an A / D converter by a multiplexer. Proposed.

Japanese Patent Laid-Open No. 11-345622

  By the way, as a request | requirement with respect to the battery state monitoring apparatus, it is not restricted to what detects all each voltage value of several battery cell. For example, when the voltage of the battery cell decreases due to an abnormality in the battery cell, it is possible to monitor the presence / absence of abnormality of the plurality of battery cells based on the information regarding the lowest value among the voltages of the plurality of battery cells. Similarly, for example, when the battery cell is a fuel cell, an abnormality in which unintended power generation is performed when the supply of fuel gas is controlled to stop is diagnosed by information on the maximum value of the voltage of the plurality of battery cells. Can do.

  However, even in the case where the maximum value or the minimum value is detected in this way, if an abnormality occurs in the detection system, the reliability of monitoring the state of the battery cell is lowered.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a battery state monitoring apparatus that can more appropriately monitor the states of a plurality of detection target batteries.

  Hereinafter, means for solving the above-described problems and the operation and effect thereof will be described.

  The invention described in claim 1 is a battery state monitoring device that detects voltages of a plurality of detection target batteries, wherein the plurality of detection target batteries constitute an assembled battery that is a serial connection of a plurality of battery cells. A reference voltage output means for outputting a reference voltage; and potential conversion means for converting each of the plurality of input signals into a common reference potential voltage and outputting the same, and among the output voltages of the potential conversion means The voltage output means for outputting at least one detection result signal of the minimum value and the maximum value, and the input signal of the potential conversion means is set to one of the voltages at both ends of the plurality of detection target batteries and their corresponding values. And selecting means for selecting whether to use the reference voltage.

  In the above-described invention, information on the minimum value and the maximum value, which is information that is particularly required among the information on the plurality of detection target batteries, can be acquired. Can be monitored. Furthermore, by providing the selection means, it is possible to specify the value of the output signal of the voltage output means and the detection target battery corresponding to the output signal. For this reason, the presence or absence of abnormality of a battery cell, a voltage output means, etc. can also be diagnosed appropriately.

  According to a second aspect of the present invention, in the first aspect of the invention, the reference voltage is set to a voltage that cannot be assumed as one of the voltages at both ends of the plurality of detection target batteries and their corresponding values. It is characterized by that.

  In the above invention, since the output signal of the voltage output means is different depending on the detection target battery and on the reference voltage, it is easy to distinguish between them.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the selection unit may determine whether the input signal is one of voltages at both ends of the plurality of detection target batteries and their corresponding values. Is selected for each of the plurality of detection target batteries, and the reference voltage is only a voltage related to a specific one of the plurality of detection target batteries. Under the condition that the reference voltage is selected as the input of the voltage output means instead of the remaining detection target battery, the output of the voltage output means is normally the voltage of the specific detection target battery. In the above situation, the output of the voltage output means is different from the reference voltage, and the specific one and the previous one. Characterized in that it comprises a diagnostic means for the connection to the voltage output means to diagnose as normal.

  Under the above circumstances, if the connection between the voltage output means and the specific one is normal, the output of the voltage output means is considered to correspond to the specific one voltage. In the above invention, in view of this point, the diagnostic means is configured.

  According to a fourth aspect of the present invention, in the first or second aspect of the invention, the selection unit may determine whether the input signal is one of voltages at both ends of the plurality of detection target batteries and their corresponding values. Is selected for each of the plurality of detection target batteries, and the reference voltage is a specific one of the voltages related to the plurality of detection target batteries as an input of the potential output means. In the situation where only the reference voltage is selected instead of the reference voltage, the output of the voltage output means is set to correspond to the reference voltage under normal conditions. A diagnostic means for diagnosing that the voltage output means is abnormal is provided on condition that the output of the output means is different from the reference voltage.

  Under the above circumstances, if the voltage output means is normal, the output of the voltage output means is considered to correspond to the reference voltage. In the above invention, in view of this point, the diagnostic means is configured.

  According to a fifth aspect of the present invention, in the fourth aspect of the invention, when the diagnosis unit diagnoses that there is an abnormality, the learning unit learns a deviation in the output of the voltage output unit, and the plurality of detection target batteries And a correction means for correcting the output of the voltage output means based on the deviation when any one of the voltages at both ends and the corresponding value is used as the input signal.

  In the said invention, the detection accuracy of the voltage of a detection object battery can be improved by providing a learning means.

  According to a sixth aspect of the present invention, in the first or second aspect of the present invention, when a voltage related to the detection target battery is selected as an input of the voltage output means, the output of the voltage output means is the detection target battery. Diagnostic means for diagnosing whether or not it is an unexpected one depending on the voltage, and when diagnosing the unexpected thing by the diagnostic means, the input of the voltage output means is switched to the reference voltage And an identification means for identifying whether the detection target battery is abnormal or the voltage output means is abnormal depending on whether the voltage after the switching is in accordance with the reference voltage or not. Features.

  When the output of the voltage output means when the voltage of the detection target battery is selected is unexpected, the cause may be an abnormality of the voltage output means itself in addition to the abnormality of the detection target battery. In this regard, in the above-described invention, the abnormality factor can be specified by providing the identification unit.

  The invention according to claim 7 is the invention according to any one of claims 3 to 6, wherein the diagnosis means performs the diagnosis on the condition that an output current of the battery to be detected is not more than a predetermined value. It is characterized by.

  In the above-described invention, it is possible to diagnose the presence or absence of abnormality during a period in which the voltages of a plurality of detection target batteries are unlikely to vary, and as a result, diagnostic accuracy can be improved.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the assembled battery includes a plurality of detection target batteries that are converted to a voltage of one reference potential by the potential converting means. A plurality of sets are provided, and the voltages of the batteries to be detected in each set are converted into voltages having different reference potentials by the potential converting means.

  In the said invention, even if it is a case where the electrical potential difference in an assembled battery becomes large, the proof pressure requested | required of an electrical potential conversion means can be reduced.

1 is a system configuration diagram according to a first embodiment. FIG. The circuit diagram which shows the circuit structure of the monitoring unit concerning the embodiment. The flowchart which shows the procedure of the diagnostic process of the presence or absence of the connection abnormality concerning the embodiment. The flowchart which shows the procedure of a diagnostic process about the presence or absence of the detection system abnormality concerning the embodiment. The flowchart which shows the procedure of a diagnostic process about the presence or absence of abnormality concerning 2nd Embodiment. The circuit diagram which shows the circuit structure of the monitoring unit concerning 3rd Embodiment. The circuit diagram which shows the circuit structure of the monitoring unit concerning 4th Embodiment.

<First Embodiment>
Hereinafter, a first embodiment in which a battery state monitoring device according to the present invention is applied to an assembled battery state monitoring device as a power source of a vehicle-mounted main unit will be described with reference to the drawings.

  FIG. 1 shows a system configuration according to the present embodiment.

  The illustrated assembled battery 10 is a power supply source for an electric motor (not shown) as an in-vehicle main machine. The assembled battery 10 is a series connection body of battery cells Cij (i = 1 to m, j = 1 to n) constituted by fuel cells. The battery cells Cij all have the same specifications, and have the same terminal voltage except for individual differences and aging. The battery cells Cij are grouped by n adjacent ones to form a block Bi. The state of each block Bi is monitored by the monitoring unit Ui.

  The assembled battery 10 and the monitoring unit Ui constitute an in-vehicle high voltage system that is insulated from the in-vehicle low voltage system. The monitoring unit Ui outputs the minimum value (in-block minimum value MINi) of the voltages of the battery cells Ci1 to Cin in the block Bi to the control device 24 configuring the low-voltage system via the photocoupler 22, and the block The maximum value (in-block maximum value MAXi) among the voltages of the battery cells Ci <b> 1 to Cin in Bi is output to the control device 24 via the photocoupler 23. Specifically, the minimum value MINi and the maximum value MAXi in the block indicate the minimum value and the maximum value of the battery cells Ci1 to Cin in the block Bi from the control device 24 to the monitoring unit Ui via the photocoupler 20. This is when the output switching signal SSi selects all the battery cells Ci1 to Cin.

  The control device 24 uses the low voltage battery 40 as a power source. The monitoring unit Ui uses a flyback converter 42 that receives the power of the low-voltage battery 40 as a power source. That is, the flyback converter 42 includes m secondary side coils 44, and these output voltages are applied to the respective monitoring units Ui through the diodes.

  FIG. 2 shows a circuit configuration of the monitoring unit Ui according to the present embodiment.

  As shown in the figure, a pair of electrodes of each battery cell Ci1 to Cin is connected to a pair of input terminals of each potential conversion circuit 50 via a multiplexer MPX, whereby the voltage of each battery cell Ci1 to Cin. Are converted to the same potential reference voltage. The potential conversion circuit 50 is a differential amplifier circuit that includes an operational amplifier 51. That is, the resistor 53 is connected to the non-inverting input terminal, the resistor 55 is connected to the inverting input terminal, and the resistor 57 is connected between the resistor 53 and the non-inverting input terminal. A resistor 59 is connected between the inverting input terminal and the output terminal. Here, of the resistors 57, the one not on the connection side between the resistor 53 and the non-inverting input terminal is set as a reference potential. 2 illustrates the potential of the output terminal on the negative electrode side of the flyback converter 42 as the reference potential.

  Each output of the potential conversion circuit 50 is connected to the cathode of the diode 60, and the anodes of the pair of diodes 60 are connected (short-circuited). The voltage at the connection point between the anodes is the minimum value of the output voltage of the potential conversion circuit 50 (more precisely, a value that is higher than the minimum value by the voltage drop of the diode 60). The voltage at the connection point between the anodes is applied to the non-inverting input terminal of the comparator 70, and the periodic voltage signal (carrier) output from the oscillator 72 is applied to the inverting input terminal of the comparator 70. As a result, the output of the comparator 70 is obtained by PWM processing of the voltage at the connection point between the anodes with the carrier. The output of the comparator 70 is the in-block minimum value MINi.

  Each output of the potential conversion circuit 50 is connected to the anode of the diode 61, and the cathodes of the pair of diodes 61 are connected (short-circuited). The voltage at the connection point between the cathodes is the maximum value of the output voltage of the potential conversion circuit 50 (more precisely, a value lower by the voltage drop of the diode 61 than the maximum value). The voltage at the connection point between the cathodes is applied to the non-inverting input terminal of the comparator 71, and the periodic voltage signal (carrier) output from the oscillator 73 is applied to the inverting input terminal of the comparator 71. As a result, the output of the comparator 71 is obtained by PWM processing of the voltage at the connection point between the cathodes with the carrier. The output of the comparator 71 is the in-block maximum value MAXi.

  The multiplexer MPX selectively outputs one of the positive voltage of the battery cell Cij and the output voltage of the operational amplifier 86 constituting the voltage follower. At this time, the negative voltage of the battery cell Cij, the battery Either one of the negative electrode potential of the cell Cin is selectively output. Here, the multiplexer MPX is operated by the switching signal SSi. The non-inverting input terminal of the operational amplifier 86 constituting the voltage follower is applied with the voltage of the power source 80 (secondary coil 44 side of the flyback converter 42) divided by the resistors 82 and 84. . Thereby, the voltage follower outputs a voltage obtained by dividing the voltage of the power supply 80 by the resistors 82 and 84 as the reference voltage Vref. Here, in this embodiment, a value smaller than the minimum value that can be taken when the battery cell Cij is normal is set as the reference voltage Vref. In order to improve the accuracy of the reference voltage Vref, the power supply 80 may be obtained by stepping down the output voltage of the flyback converter 42 by a series regulator.

  According to such a configuration, the output voltage of the potential conversion circuit 50 can be set not only according to the battery cell Cij but also according to the reference voltage Vref. Hereinafter, a method of using the reference voltage Vref will be described.

  FIG. 3 shows a processing procedure for diagnosing whether or not the connection between the battery cell Cij and the potential conversion circuit 50 according to the present embodiment is normal. This process is repeatedly executed by the control device 24 at a predetermined cycle, for example.

  In this series of processes, first, in step S10, it is determined whether or not the output current I of the assembled battery 10 is equal to or less than the threshold current Ith. This process determines whether the voltage of the battery cell Cij is not excessively small. If an affirmative determination is made in step S10, the variable j indicating the number of the battery cell Cij in the block Bi is set to “1” in step S12. In the subsequent step S14, the battery cell Cij is selected in the multiplexer MPX, and the reference voltage Vref is selected in place of the battery cell in other cases.

  In a succeeding step S16, it is determined whether or not the intra-block maximum value MAXi is between the minimum threshold value Vmin and the maximum threshold value Vmax. Here, the minimum threshold value Vmin is set to be equal to or lower than a lower limit value that can be assumed when the battery cell Cij is normal, and the maximum threshold value Vmax is assumed to be possible when the battery cell Cij is normal. It is set above the upper limit. This process is for diagnosing whether or not the battery cell Cij is normally connected to the potential conversion circuit 50. That is, when the battery cell Cij is normally connected, the in-block maximum value MAXi is considered to be the voltage of the battery cell Cij, and thus is considered to be between the minimum threshold value Vmin and the maximum threshold value Vmax.

  When an affirmative determination is made in step S16, it is diagnosed in step S18 that the connection between the battery cell Cij and the potential conversion circuit 50 is normal. On the other hand, when a negative determination is made in step S16, it is diagnosed in step S20 that the connection between the battery cell Cij and the potential conversion circuit 50 is abnormal.

  When the processes of steps S18 and S20 are completed, the process proceeds to step S22 to determine whether or not the variable j is “n”. If a negative determination is made in step S22, the variable j is incremented in step S24, and the process returns to step S14. On the other hand, when an affirmative determination is made at step S22 or a negative determination is made at step S10, this series of processes is temporarily terminated.

  FIG. 4 shows a procedure of a diagnosis process for the presence or absence of abnormality such as gain abnormality of the potential conversion circuit 50 according to the present embodiment. This process is repeatedly executed by the control device 24 at a predetermined cycle, for example. In FIG. 4, processes corresponding to the processes shown in FIG. 3 are given the same step numbers for convenience.

  In this series of processes, after step S12, in step S30, a battery cell other than the battery cell Cij is selected by the multiplexer MPX, and the reference voltage Vref is selected instead of the battery cell Cij. In the subsequent step S32, it is determined whether or not the absolute value of the difference Δij between the in-block minimum value MINi and the reference voltage Vref is greater than or equal to a threshold value ΔthH. This process is for diagnosing whether there is an abnormality in the gain (conversion ratio of the output voltage to the input voltage) of the potential conversion circuit 50 corresponding to the battery cell Cij. Here, the threshold value ΔthH is a lower limit value of a value that is unacceptable as gain variation due to individual differences in the potential conversion circuit 50 or aging. If an affirmative determination is made in step S32, it is diagnosed in step S34 that the gain of the potential conversion circuit 50 is abnormal.

  On the other hand, when a negative determination is made in step S32, the process proceeds to step S36, and it is determined whether or not the absolute value of the difference Δij is greater than or equal to a threshold value ΔthL that is smaller than the threshold value ΔthH. Here, the threshold value ΔthL is a lower limit value for which it is desired to compensate for the gain error of the potential conversion circuit 50. This is determined based on the resolution of the voltage such as the minimum value MINi in the block by the control device 24. That is, the threshold value ΔthL is set to about the minimum resolution of the control device 24. When an affirmative determination is made in step S36, in step S38, a difference Δij is learned as an output error of the potential conversion circuit 50 for the battery cell Cij, and a storage unit (data storing the data regardless of the state of the main power supply of the control device 24). The data is stored in the EEPROM 24a) of the control device 24 shown in FIG. Thereby, when the voltage of the battery cell Cij is detected, the battery cell Cij can be detected with high accuracy by using the difference Δij. Here, the detected value of the voltage of the battery cell Cij may be, for example, the in-block maximum value MAXi at the time of processing similar to step S14 of FIG.

  In addition, when the process of said step S34, S38 is completed, or when negative determination is carried out in step S10, S36, this series of processes are once complete | finished.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The input of the potential conversion circuit 50 can be switched between the voltage of the battery cell Cij and the reference voltage Vref. Thereby, the abnormality of the detection system of the monitoring unit Ui can be detected.

  (2) The reference voltage Vref is set to a small value that cannot be assumed as the normal voltage of the battery cell Cij. Thereby, by selecting the reference voltage Vref, a voltage corresponding to the reference voltage Vref can be output as the minimum value MINi in the block.

  (3) Only the battery cell Cij is selected as the input of the potential conversion circuit 50, and the battery cell Cij and the potential conversion circuit are based on the maximum value MAXi in the block when the reference voltage Vref is selected instead of the remaining battery cells. 50 was diagnosed as to whether or not the connection was normal. Thereby, the presence or absence of connection abnormality can be diagnosed suitably.

  (4) In the situation where a battery cell other than the battery cell Cij is selected as the input of the potential conversion circuit 50 and the reference voltage Vref is selected instead of the battery cell Cij, the battery cell Cij is used based on the in-block minimum value MINi. The potential conversion circuit 50 was diagnosed for the presence or absence of gain abnormality. Thereby, the presence or absence of gain abnormality can be diagnosed suitably.

  (5) When the gain abnormality of the potential conversion circuit 50 for the battery cell Cij is small, the deviation of the output voltage of the potential conversion circuit 50 is learned. Thereby, the voltage of the battery cell Cij can be detected with high accuracy.

  (6) The diagnosis was performed on the condition that the output current I of the assembled battery 10 is equal to or less than the threshold current Ith. Thereby, diagnostic accuracy can be improved.

  (7) The plurality of batteries to be detected are all the same number of battery cells. Thereby, it is possible to appropriately generate a signal relating to the minimum value while keeping the configuration of the potential conversion circuit 50 and the like the same.

(8) The battery cells Ci1 to Cin of the blocks B1 to Bm are converted into voltages having a common reference potential by the potential conversion circuit 50, and the reference potentials are made different for each block. Thereby, the breakdown voltage required for the potential conversion circuit 50 can be reduced.
<Second Embodiment>
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In the present embodiment, the reference voltage Vref is set to a high voltage that cannot be assumed when the battery cell Cij is normal.

  FIG. 5 shows the procedure of the diagnosis process for the presence or absence of abnormality according to the present embodiment. This process is repeatedly executed by the control device 24 at a predetermined cycle, for example.

  In this series of processes, first, in step S40, it is determined whether or not the output current I of the assembled battery 10 is equal to or less than the threshold current Ith. This process is provided for the same purpose as the process of step S10 of FIG. When an affirmative determination is made in step S40, it is determined whether or not the in-block minimum value MINi is smaller than the minimum side lower limit value Vmin under the situation where all the battery cells Cij in the block Bi are selected by the multiplexer MPX. If an affirmative determination is made in step S42, a variable j indicating the number of the battery cell Cij in the block Bi is set to “1” in step S44. In the subsequent step S46, the input of the potential conversion circuit 50 for the battery cell Cij is switched to the reference voltage Vref. In step S48, it is determined whether or not the in-block minimum value MINi is smaller than the minimum side threshold value Vmin. This process is for determining whether the cause of the fact that the in-block minimum value MINi is smaller than the minimum threshold value Vmin in step S42 is an abnormality in the potential conversion circuit 50 for the battery cell Cij or an abnormality in the battery cell Cij itself. belongs to. That is, when the battery cell Cij itself is abnormal, it is considered that the in-block minimum value MINi becomes equal to or greater than the minimum threshold value Vmin by switching to the reference voltage Vref.

  When an affirmative determination is made in step S48, it is diagnosed in step S50 that there is an abnormality in the battery cell Cij. On the other hand, when a negative determination is made in step S48, it is determined in step S52 whether or not the variable j is “n”. If a negative determination is made in step S52, the variable j is incremented in step S54, and the process returns to step S46. On the other hand, when an affirmative determination is made in step S52, it is diagnosed in step S56 that the potential conversion circuit 50 is abnormal.

  In addition, when the process of step S50, S56 is completed, or when negative determination is made in step S40, S42, this series of processes is once complete | finished.

  According to this embodiment described in detail above, in addition to the effects (1), (2), (6) to (8) of the first embodiment, the following effects can be obtained. .

(9) When the in-block minimum value MINi is smaller than the minimum threshold value Vmin, the battery cell Cij is sequentially switched to the reference voltage Vref to determine whether the battery cell Cij is abnormal or the potential conversion circuit 50 is abnormal. did. Thereby, the cause of abnormality can be specified suitably.
<Third Embodiment>
Hereinafter, the third embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 6 shows a circuit configuration of the monitoring unit Ui according to the present embodiment. In FIG. 6, members corresponding to those shown in FIG. 2 are given the same reference numerals for convenience.

As shown in the figure, in this embodiment, a pair of reference voltages VrefH and VrefL input to the potential conversion circuit 50 are both divided voltage values of the power supply 80. That is, the voltage follower is configured by dividing the voltage of the power source 80 by the resistors 82 and 84 as the reference voltage VrefH and by dividing the voltage of the power source 80 by the resistors 90 and 92 as the reference voltage VrefL. Applied to the non-inverting input terminal of the operational amplifier 94.
<Fourth Embodiment>
Hereinafter, the fourth embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 7 shows a circuit configuration of the monitoring unit Ui according to the present embodiment. In FIG. 7, members corresponding to those shown in FIG. 2 are given the same reference numerals for convenience.

  In the present embodiment, the detection target battery is basically a pair of battery cells Cik, Ci (k + 1) (k = 1 to n−2). That is, the voltage between both ends of the pair of battery cells Cik and Ci (k + 1) is input to the respective potential conversion circuits 50. However, in the present embodiment, an odd number is assumed as the number of battery cells in the block Bi. Therefore, for the battery cell Cin, this becomes a detection target battery alone, and the voltage at both ends thereof is input to the potential conversion circuit 50. The

  At this time, the gain of the potential conversion circuit 50 for the pair of battery cells Cik, Ci (k + 1) is different from that of the potential conversion circuit 50 for the battery cell Cin. Specifically, the resistance value R1 of the resistors 53 and 55 of the potential conversion circuit 50 for the pair of battery cells Cik and Ci (k + 1) is set to the resistance value R3 of the resistors 53 and 55 of the potential conversion circuit 50 of the battery cell Cin. Double.

  Thus, the potential conversion circuit 50 for the pair of battery cells Cik and Ci (k + 1) has a conversion ratio of the input voltage to the output voltage of “½” compared to the potential conversion circuit 50 for the battery cell Cin. It becomes. Therefore, the respective outputs of the potential conversion circuit 50 for the pair of battery cells Cik, Ci (k + 1) and the output of the potential conversion circuit 50 for the battery cell Cin are normalized to the same number of voltages per battery cell. can do.

However, in this case, the reference voltage Vref1 input to the potential conversion circuit 50 for the pair of battery cells Cik and Ci (k + 1) is different from the reference voltage Vref2 input to the potential conversion circuit 50 for the battery cell Cin. In the figure, the reference voltage Vref1 and Vref2 are obtained by dividing the voltage of the power supply 80 by the resistors 82 and 84 and by dividing the voltage by the resistors 100 and 102 (in practice, these are voltage followers). The output when applied to the non-inverting input terminals of the operational amplifiers 86 and 106 is used as the input of the multiplexer MPX).
<Other embodiments>
Each of the above embodiments may be modified as follows.
"Voltage output means"
The voltage output means is not limited to outputting the detection result signal of both the maximum value and the minimum value of the output voltage of the potential conversion circuit, and may output only the detection result signal of the minimum value, for example.

  The means for selectively outputting the voltage signal corresponding to the minimum value or the maximum value is not limited to those exemplified in the above embodiments. For example, the configuration may include a multiplexer that takes in all the outputs of the potential conversion circuit 50 and selectively outputs any one of them. In this case, by using a plurality of comparators that compare the magnitudes of a pair of output voltages of the potential conversion circuit 50, the lowest (highest) voltage may be specified, and the multiplexer may be operated according to the specified result.

Further, for example, in FIG. 2 and the like, this analog voltage signal is modulated into a binary signal (PWM signal) of logic “H” and logic “L” based on the comparison of the output signal of the potential conversion circuit 50 and the carrier. Then, the detection result signal of the maximum value or the minimum value may be generated by logical sum or logical product of the binary signals.
"Reference voltage output means"
The setting of the reference voltage Vref is not limited to that exemplified in the above embodiments. For example, in the first embodiment, the reference voltage Vref may be larger than the upper limit Vmax of the voltage when the battery cell Cij is normal. In this case, in the process shown in FIG. 3, by changing the intra-block maximum value MAXi in step S16 to the intra-block minimum value MINi, it is possible to diagnose the presence or absence of connection abnormality of the battery cell Cij. In the process shown in FIG. 4, the presence or absence of an abnormality in the detection system can be diagnosed by changing the in-block minimum value MINi in step S32 to the in-block maximum value MAXi.

  Further, the reference voltage Vref is not limited to a value larger than the upper limit Vmax or a value smaller than the lower limit Vmin when the battery cell Cij is normal. For example, it may be a value between these. Even in this case, for example, the cause of the abnormality can be identified in the second embodiment.

Furthermore, the reference voltage Vref that can be input to one potential conversion circuit 50 may not be a single value but may be a plurality of different values. Here, it is desirable to be a pair of values of a value larger than the upper limit Vmax and a value smaller than the lower limit Vmin when the battery cell Cij is normal.
"About selection means"
The selection means is not limited to selecting for each potential conversion circuit 50 whether the input is a detection target battery or a reference voltage. For example, a selection may be made for each pair of potential conversion circuits 50, or one of the potential conversion circuits 50 may be selected uniformly in the block Bi.
About diagnosis execution conditions
The diagnosis execution conditions are not limited to those exemplified in the above embodiments. For example, in a case where a condition is assumed that the voltage variation of the battery cell Cij is small, a condition that the amount of fuel gas filled in the battery cell Cij is large may be added as this condition.
"About diagnostic tools"
The diagnostic means is not limited to those exemplified in the above embodiments. For example, after the process of step S14 of FIG. 3, the presence or absence of abnormality of the battery cell Cij itself may be diagnosed based on the in-block minimum value MINi.
"About learning means"
The learning means is not limited to storing the deviation itself. For example, the actual output value itself of the potential conversion circuit 50 may be stored.
"Insulation means"
The optical isolation element that propagates signals while maintaining insulation between the high voltage system and the low voltage system is not limited to a photocoupler, and may be a photo MOS relay or the like. Moreover, it is not limited to an optical insulating element, and may be a magnetic insulating element such as a transformer.
About potential conversion means
The reference potential of the potential conversion circuit 50 is not limited to the potential of the negative output terminal of the flyback converter 42.

  The potential conversion means is not limited to those exemplified in the above embodiments. For example, a current conversion unit that converts each voltage of the battery cells Ci1 to Ci (n-1) into a current and a voltage conversion unit such as a resistor that converts the current into a voltage based on the negative potential of the battery cell Cin are provided. It may be a thing.

The signal corresponding to the voltage of the battery cell Cij input to the potential conversion means is not limited to the terminal voltage of the battery cell Cij, and may be, for example, a voltage divided by a resistor.
“Detection target battery”
The battery to be detected is not limited to one battery cell or two battery cells connected in series. For example, three or more battery cells connected in series may be used. Moreover, as a battery cell, not only a fuel battery but a secondary battery may be sufficient, for example. Here, if a lithium ion secondary battery or the like is adopted as the secondary battery, there is a high demand for strictly monitoring the state of charge, and therefore it is particularly effective to monitor the maximum value and the minimum value of the voltage in the above manner. is there.
(others)
The power source for the monitoring unit Ui is not limited to the flyback converter 42. For example, each block Bi may be used. Even in this case, the minimum voltage or the like can be monitored after the voltage of the assembled battery 10 is stabilized. Further, when the assembled battery 10 is a secondary battery, the voltage can be constantly monitored even with such a configuration.

  DESCRIPTION OF SYMBOLS 10 ... Battery pack, 24 ... Control apparatus, 50 ... Potential conversion circuit, Ui ... Monitoring unit, Cij ... Battery cell.

Claims (8)

In the battery state monitoring device that detects the voltages of a plurality of detection target batteries,
The plurality of batteries to be detected constitute an assembled battery that is a series connection body of a plurality of battery cells,
A reference voltage output means for outputting a reference voltage;
A potential conversion unit that converts each of the plurality of input signals into a common reference potential voltage and outputs the same, and outputs a detection result signal of at least one of the minimum value and the maximum value of the output voltage of the potential conversion unit. Voltage output means for outputting;
And a selection means for selecting whether the input signal of the potential conversion means is one of the voltages at both ends of the plurality of batteries to be detected and their corresponding values or the reference voltage. Condition monitoring device.   The battery state monitoring device according to claim 1, wherein the reference voltage is set to a voltage that cannot be assumed as one of voltages at both ends of the plurality of detection target batteries and their corresponding values. The selection means selects each of the plurality of detection target batteries for selection of whether the input signal is one of the voltages at both ends of the plurality of detection target batteries and their corresponding values or the reference voltage. To do,
As for the reference voltage, only a voltage related to a specific one of the plurality of detection target batteries is selected as an input of the voltage output means, and the reference voltage is replaced by the voltage output means instead of the remaining detection target batteries. Under conditions selected as input, the output of the voltage output means is set to be in accordance with the voltage of the specific detection target battery under normal conditions,
Under the above-mentioned circumstances, it comprises diagnostic means for diagnosing that the connection between the specific one and the voltage output means is normal on condition that the output of the voltage output means is different from the reference voltage. The battery state monitoring apparatus according to claim 1 or 2, characterized in that: The selection means selects each of the plurality of detection target batteries for selection of whether the input signal is one of the voltages at both ends of the plurality of detection target batteries and their corresponding values or the reference voltage. To do,
The reference voltage is the voltage under normal circumstances when only one of the voltages related to the plurality of detection target batteries is removed as an input to the voltage output means and the reference voltage is selected instead. The output of the output means is set to be in accordance with the reference voltage,
3. A diagnostic device for diagnosing that there is an abnormality in the voltage output means under the condition that the output of the voltage output means is different from the reference voltage. The battery state monitoring device described. When the diagnosis means diagnoses that there is an abnormality, learning means for learning a shift in the output of the voltage output means;
And correcting means for correcting the output of the voltage output means based on the deviation when any of the voltages at both ends of the plurality of detection target batteries and their corresponding values is used as the input signal. The battery state monitoring device according to claim 4. When a voltage related to the detection target battery is selected as an input of the voltage output means, a diagnosis is made as to whether or not the output of the voltage output means is unexpected based on the voltage of the detection target battery. Diagnostic means;
When it is diagnosed by the diagnostic means that it is not expected, the input of the voltage output means is switched to the reference voltage, and depending on whether or not the voltage after the switching is in accordance with the reference voltage The battery state monitoring device according to claim 1, further comprising: an identification unit that identifies whether the detection target battery is abnormal or the voltage output unit is abnormal.   7. The battery state monitoring apparatus according to claim 3, wherein the diagnosis unit performs the diagnosis under a condition that an output current of the detection target battery is equal to or less than a predetermined value.   The assembled battery includes a plurality of detection target batteries that are converted to a voltage of one reference potential by the potential conversion unit, and the voltages of the detection target batteries of each set are different from each other with reference potential voltages. The battery state monitoring device according to any one of claims 1 to 7, wherein the battery state monitoring device is converted into the battery state.

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