JP2012047520A - Battery voltage detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem in which timing of detecting voltages of battery cells Ci1-Cin tends to be displaced.SOLUTION: Each voltage of battery cells Ci1-Cin is converted into a voltage of the same reference electric potential with an electric potential converting circuit 50. A voltage of the electric potential converting circuit 50 is applied to a non-inverting input terminal of a comparator 60, and a carrier CS is applied to the non-inverting input terminal of the comparator 60. Hence, an output of the comparator 60 becomes the voltage of the electric potential converting circuit 50 on which PWM modulation is performed. The output of the comparator 60 is input into an AND circuit 64, where a signal in accordance with a minimum value of the voltages of the battery cells Ci1-Cin is generated.

Description

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

  As this type of battery voltage detection device, for example, as seen in Patent Document 1 below, one of a plurality of battery cells constituting a fuel cell is selectively connected to an A / D converter by a multiplexer. Has also been proposed.

Japanese Patent Laid-Open No. 11-345622

  By the way, when using a multiplexer as mentioned above, the shift | offset | difference of the detection timing of the voltage of a some battery cell cannot be disregarded. In addition, since the apparatus includes a plurality of A / D converters, an increase in cost cannot be ignored.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a battery voltage detection device that can suitably reduce a shift in voltage detection timing of a plurality of detection target batteries. is there.

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

  According to a first aspect of the present invention, in the battery voltage detection device for detecting the voltages of a plurality of detection target batteries, the voltage at both ends of each of the plurality of detection target batteries and their corresponding values are periodically increased or decreased 1 Comparing means for outputting a binary signal corresponding to the size of the carrier as a voltage detection signal is provided.

  In the above invention, since each of the comparison means corresponding to each of the plurality of detection target batteries outputs a voltage detection signal according to the magnitude of the common carrier, the detection timing shift of the voltages of the plurality of detection target batteries is prevented. It can reduce suitably. In particular, by using a common carrier, the demodulation method used when demodulating voltage information from the voltage detection signal can be made common.

  According to a second aspect of the invention, there is provided the first aspect of the invention, further comprising output means for selecting and outputting the voltage detection signal output from the comparison means corresponding to the minimum value of the voltage. .

  Of the information on the plurality of detection target batteries, information on the minimum value, in particular, tends to require a greater degree. In the above invention, in view of this point, by providing the output means, it is possible to reduce the number of receiving terminals of the means for receiving the output signal of the output means while reliably obtaining the required information. Can do.

  According to a third aspect of the invention, there is provided the first or second aspect of the invention, further comprising output means for selecting and outputting the voltage detection signal output from the comparison means corresponding to the maximum value of the voltage. And

  Of the information on the plurality of detection target batteries, information on the maximum value, in particular, tends to require a greater degree. In the above invention, in view of this point, by providing the output means, it is possible to reduce the number of receiving terminals of the means for receiving the output signal of the output means while reliably obtaining the required information. Can do.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the voltages at both ends of the plurality of detection target batteries are connected to both ends of the plurality of detection target batteries. Each of the above is further provided with potential conversion means for converting the voltage into a common reference potential and inputting the same to the comparison means.

  The invention according to claim 5 is the invention according to claim 4, wherein the plurality of detection target batteries constitute an assembled battery which is a series connection body of a plurality of battery cells.

  In the above invention, since the electrode potentials of the plurality of batteries to be detected are different from each other, the merit provided with the potential conversion means is particularly great.

  According to a sixth aspect of the present invention, in the fifth aspect of the present invention, each of the plurality of detection target batteries includes the same number of battery cells.

  The invention according to claim 7 is the invention according to claim 5, wherein the plurality of batteries to be detected include those in which the number of battery cells constituting the plurality of batteries is different from each other, and the potential converting means includes a plurality of objects to be detected. When each of the battery voltages is converted into the reference potential voltage, it comprises a normalizing means for normalizing the converted voltage to a voltage per the same number of battery cells.

  The invention according to claim 8 is the invention according to any one of claims 4 to 7, wherein the potential converting means includes an operational amplifier, and both ends of the plurality of detection target batteries are connected to the operational amplifier. It is directly connected to the input terminal.

  In the above invention, since the current flowing between the battery to be detected and the operational amplifier can be limited, the amount of voltage drop between them can be reduced, and thus the detection error due to the voltage drop can be reduced.

  The invention according to claim 9 is the invention according to any one of claims 5 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 conversion 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.

  The invention according to claim 10 is the invention according to any one of claims 5 to 7 and 9, wherein the assembled battery constitutes an in-vehicle high voltage system insulated from the in-vehicle low voltage system, It further comprises output means for selecting and outputting at least one of the voltage detection signal output from the comparison means corresponding to the minimum value of the voltage and the voltage detection signal corresponding to the maximum value, and the output of the output means is passed through the insulation means. Output to the low voltage system.

  Among the information on the plurality of detection target batteries, information regarding the minimum value and the maximum value in particular tends to require a greater degree. In view of this point, in the above invention, by providing the output means, it is possible to reduce the number of insulating means while reliably transmitting information with a high degree of demand.

  According to an eleventh aspect of the present invention, in the tenth aspect of the present invention, the assembled battery includes a plurality of sets of detection target batteries that are converted to a reference potential voltage by the potential converting means, and The batteries of the set are converted to different reference potential voltages by the potential converting means, and the output means is provided for each different reference potential, and the insulating means It further comprises selection means for selecting at least one of the signal corresponding to the minimum value of the voltage and the signal corresponding to the maximum value among the output signals of the respective output means output via the output means.

  In the above invention, the receiving terminals of the means for receiving the output of the selection means can be reduced.

  The invention according to claim 12 is the invention according to claim 11, further comprising synchronization means for synchronizing carriers corresponding to each set of the plurality of detection target batteries.

  In the said invention, the output of a selection means can be made into the signal which expresses at least one of the maximum value and the minimum value of all the detection object batteries with high precision.

  The invention according to claim 13 is the invention according to any one of claims 1 to 12, characterized in that the comparison means includes a hysteresis comparator.

1 is a system configuration diagram according to a first embodiment. FIG. The circuit diagram which shows the structure of the monitoring unit concerning the embodiment. The time chart which shows the voltage detection aspect concerning the embodiment. The circuit diagram which shows the structure of the monitoring unit concerning 2nd Embodiment. The time chart which shows the voltage detection aspect concerning the embodiment. The circuit diagram which shows the structure of the monitoring unit concerning 3rd Embodiment. The time chart which shows the voltage detection aspect concerning the embodiment. The circuit diagram which shows the structure of the monitoring unit concerning 4th Embodiment. The time chart which shows the voltage detection aspect concerning the embodiment. The circuit diagram which shows the structure of the monitoring unit concerning 5th Embodiment. The circuit diagram which shows the structure of the monitoring unit concerning 6th Embodiment. The circuit diagram which shows the structure of the monitoring unit concerning 7th Embodiment. The circuit diagram which shows the structure of the monitoring unit concerning the modification of the said embodiment.

<First Embodiment>
Hereinafter, a first embodiment in which a battery voltage detection device according to the present invention is applied to a voltage detection device for an assembled battery as a power source of an in-vehicle 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. A synchronization signal Syn is input to the monitoring unit Ui from the control device 22 constituting the low voltage system via the photocoupler 20. As a result, the monitoring unit Ui outputs the maximum value MAXi in the block and the minimum value MINi in the block among the voltages of the battery cells Ci1 to Cin in the block Bi to the low voltage system side via the photocouplers 24 and 28, respectively. To do. The intra-block maximum value MAXi of each block Bi is taken into the OR circuit 26, and the inter-block maximum value MAX output from the OR circuit 26 is input to the control device 22. The inter-block maximum value MAX output from the OR circuit 26 represents the maximum voltage value of the battery cells C11 to Cnm. On the other hand, the intra-block minimum value MINi of each block Bi is taken into the AND circuit 30, and the inter-block minimum value MIN output from the AND circuit 30 is input to the control device 22. The inter-block minimum value MIX output from the AND circuit 30 represents the minimum value of the voltages of the battery cells C11 to Cnm.

  The control device 22 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 illustrated, the pair of electrodes of each battery cell Ci1 to Cin is connected to the respective pair of input terminals of each potential conversion circuit 50, whereby the voltage of each battery cell Ci1 to Cin is the same potential reference. Is converted to the voltage of 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. In FIG. 2, means for setting the reference potential is not shown, but in practice, it is fixed at a predetermined potential.

  Each output of the potential conversion circuit 50 is applied to the non-inverting input terminal of the corresponding comparator 60. The carrier CS is applied to the inverting input terminal of the comparator 60. As a result, the voltage signal output from the potential conversion circuit 50 is PWM-modulated by the carrier CS.

  The output signal of the comparator 60 is input to the OR circuit 62 and the AND circuit 64, respectively. The output signal of the OR circuit 62 has a function of outputting the output signal of the n number of comparators 60 having the longest logical “H” period. For this reason, the output of the OR circuit 62 is the maximum value MAXi in the block. On the other hand, the output signal of the AND circuit 64 has a function of outputting the output signal of the n comparators 60 that has the shortest logical “H” period. For this reason, the output of the AND circuit 64 is the minimum value MINi in the block.

  The carrier CS is generated based on the synchronization signal Syn. That is, the synchronization signal Syn is taken into the rectangular wave generation circuit 70, where it is converted into a rectangular wave signal having a predetermined peak value, and then taken into the integration circuit 72. The output of the integrating circuit 72 is a triangular wave carrier CS.

  FIG. 3 shows a mode of voltage detection processing in the block according to the present embodiment. Specifically, FIG. 3A shows the transition of the synchronization signal Syn, FIG. 3B shows the transition of the output (carrier CS) of the integrating circuit 72, and FIG. Shows the transition of the input. FIG. 3D shows the transition of the output of the comparator 60 corresponding to the maximum voltage VH of the battery cells Ci1 to Cin, and FIG. 3E shows the intermediate value VM of the voltages of the battery cells Ci1 to Cin. FIG. 3F shows the transition of the output of the comparator 60 corresponding to the minimum voltage VL of the battery cells Ci1 to Cin. FIG. 3G shows the transition of the output of the OR circuit 62 (in-block maximum value MAXi), and FIG. 3H shows the transition of the output of the AND circuit 64 (in-block minimum value MINi).

  As shown in the figure, the output of the OR circuit 62 is the output of the comparator 60 that compares the maximum value VH and the carrier CS, and the output of the AND circuit 64 is the output of the comparator 60 that compares the minimum value VL and the carrier CS. It becomes. Then, by the OR circuit 26 and the AND circuit 30 shown in FIG. 1, the control device 22 can grasp the maximum value and the minimum value of the voltages of the battery cells C11 to Cmn.

  Here, as an abnormality of the battery cell Cij that occurs when power is supplied by the assembled battery 10, there is an abnormality in which the terminal voltage of the battery cell Cij decreases and eventually the electromotive force becomes zero and becomes a resistor (short state). In order to detect this abnormality when the voltage of the battery cell Cij starts to decrease, it is sufficient to detect the value of the battery cell Cij having the lowest terminal voltage. Therefore, it is possible to diagnose the presence / absence of abnormality only from the minimum value MIN between blocks.

  In addition, when the terminal voltage does not become zero in a situation where fuel is not supplied to the assembled battery 10, it is considered that an abnormal power generation occurs unintentionally. For this abnormality, it is sufficient to detect the value of the battery cell Cij having the highest terminal voltage. Therefore, it is possible to diagnose the presence / absence of abnormality only from the maximum value MAX between blocks. This diagnosis cannot be performed if the power source of the monitoring unit Ui is the block Bi itself. In this regard, according to the present embodiment, such a diagnosis process can be suitably performed by using the flyback converter 42 as a power source.

  The control device 22 can grasp the voltage value from the time ratio of the logical “H” period to one cycle of the inter-block minimum value MIN and the inter-block maximum value MAX. Therefore, the control device 22 only needs to have a time measuring operation function such as a timer measurement function or a counter function as a function for detecting the maximum value or the minimum value, and it is necessary to mount a high-precision A / D converter. There is no. Further, since the in-block minimum value MINi and the inter-block maximum value MAXi are binary signals, these are output to a low voltage system using an insulating element (photocouplers 24 and 28) that transmits a binary signal. can do. For this reason, insulation processing can also be simplified.

  Incidentally, the carrier CS is a periodic signal that periodically repeats a gradual increase period and a gradual decrease period, and the gradual increase period increases in proportion to time, and the gradual decrease period decreases in proportion to time. For this reason, the relationship between the voltage and the duty ratio is a linear relationship.

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

  (1) A binary signal corresponding to the magnitude of a voltage equivalent value at each end of each of a plurality of detection target batteries (battery cells Ci1 to Cin) and one carrier CS that periodically increases or decreases is output as a voltage detection signal. Comparator 60 is provided. Thereby, the shift | offset | difference of the detection timing of the voltage of a some detection object battery can be reduced suitably.

  (2) An AND circuit 64 that selects and outputs the voltage detection signal output from the comparator 60 corresponding to the minimum voltage value is provided. Thereby, the information regarding the presence or absence of abnormality of battery cell Cij can be acquired suitably.

  (3) An OR circuit 62 for selecting and outputting the voltage detection signal output from the comparator 60 corresponding to the maximum voltage value is provided. Thereby, the information regarding the presence or absence of abnormality of battery cell Cij can be acquired suitably.

  (4) A potential conversion circuit 50 that converts each of the voltages at both ends of the plurality of detection target batteries (battery cells Ci1 to Cin) into a common reference voltage and inputs the voltage to the comparator 60 is provided. Thereby, the signal regarding the minimum value or the maximum value can be suitably generated.

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

  (6) The battery cells Ci1 to Cin of the blocks B1 to Bm are converted to 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.

  (7) The number of input terminals of the control device 22 can be reduced by including the AND circuit 30 that takes the logical product of the in-block minimum value MINi and the OR circuit 26 that takes the logical sum of the in-block maximum value MAXi.

(8) The carriers CS of the respective blocks B1 to Bm are synchronized with each other by the synchronization signal Syn. Thereby, the minimum value MIN between blocks and the maximum value MAX between blocks can be generated with high accuracy.
<Second Embodiment>
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 4 shows a circuit configuration of the monitoring unit Ui according to the present embodiment. In FIG. 4, members corresponding to those shown in FIG. 2 are given the same reference numerals for convenience.

  As shown in the figure, in the present embodiment, the output of the integration circuit 72 is input to the inverting circuit 74 so that the carrier CS is a sawtooth wave. The inversion circuit 74 is supplied with the synchronization signal Syn so as to perform the inversion process only when the synchronization signal Syn is logic “L”.

  FIG. 5 shows an aspect of voltage detection processing in the block according to the present embodiment. Specifically, FIG. 5A and FIG. 5C to FIG. 5H correspond to FIG. 3A and FIG. 3C to FIG. 3H. 5 (b1) shows the transition of the output of the integrating circuit 72, and FIG. 5 (b2) shows the transition of the output of the inverting circuit 74.

As shown in the figure, the carrier CS according to the present embodiment is a sawtooth wave that is initialized after the gradual increase period, and is a signal that increases in proportion to the time during the gradual increase period. 62, the relationship between the output time ratio of the AND circuit 64 and the voltage value is a linear relationship.
<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, the output of the rectangular wave generation circuit 70 is taken into the low-pass filter 76 so that the output (carrier CS) is a sine wave.

  FIG. 7 shows an aspect of voltage detection processing in the block according to the present embodiment. Specifically, FIG. 7A and FIG. 7C to FIG. 7H correspond to FIG. 3A and FIG. 3C to FIG. 3H. FIG. 7B3 shows the transition of the output of the low-pass filter 76.

As shown in the figure, the carrier CS according to the present embodiment periodically repeats a gradual increase period and a gradual decrease period. However, since the gradual increase speed and the gradual decrease speed change, the comparator 60, the OR circuit 62, The relationship between the duty ratio of the output of the AND circuit 64 and the voltage value is a non-linear relationship. However, even in this case, the control device 22 can diagnose the presence or absence of abnormality of the battery cell Cij by comparing the duty ratio with the threshold value. In particular, in the case of a sine wave, the rate of change in the vicinity of the local maximum point or the local minimum point is the smallest, so that the threshold value of the output voltage of the potential conversion circuit 50 for abnormality determination is slightly smaller than the local maximum point or the local minimum point. If the carrier CS is set so as to be slightly larger than that, the voltage resolution by the control device 22 increases in the vicinity of the threshold value. For this reason, it is possible to improve the accuracy of determination as to whether or not it is greater than or equal to the threshold value.
<Fourth Embodiment>
Hereinafter, the fourth embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 8 shows a circuit configuration of the monitoring unit Ui according to the present embodiment. In FIG. 8, members corresponding to those shown in FIG. 2 are given the same reference numerals for convenience.

  As shown in the figure, in the present embodiment, the output of the low-pass filter 76 is taken into the full-wave rectifier circuit 78, so that the output (carrier CS) is a full-wave rectified sine wave.

  FIG. 9 shows an aspect of voltage detection processing in the block according to the present embodiment. Specifically, FIG. 9A and FIG. 9C to FIG. 9H correspond to FIG. 3A and FIG. 3C to FIG. 3H. 9 (b3) shows the transition of the output of the low-pass filter 76, and FIG. 9 (b4) shows the transition of the output of the full-wave rectifier circuit 78.

As shown in the figure, the carrier CS according to the present embodiment periodically repeats a gradual increase period and a gradual decrease period. However, since the gradual increase speed and the gradual decrease speed change, the comparator 60, the OR circuit 62, The relationship between the duty ratio of the output of the AND circuit 64 and the voltage value is a non-linear relationship. However, even in this case, the control device 22 can diagnose the presence or absence of abnormality of the battery cell Cij by comparing the duty ratio with the threshold value. In particular, in the case of a full-wave rectified sine wave, since the rate of change near the maximum point is the smallest, the carrier CS is set so that the threshold value of the output voltage of the potential conversion circuit 50 for abnormality determination is slightly smaller than the maximum point. If set, the resolution of the voltage by the controller 22 increases near the threshold. For this reason, it is possible to improve the accuracy of determination as to whether or not the threshold value is exceeded.
<Fifth Embodiment>
Hereinafter, a fifth embodiment will be described with reference to the drawings, focusing on differences from the first embodiment.

  FIG. 10 shows a circuit configuration of the monitoring unit Ui according to the present embodiment. In FIG. 10, members corresponding to those shown in FIG. 2 are given the same reference numerals for convenience.

  As illustrated, in the present embodiment, one voltage is detected for each of the battery cells Ci1 to Ci (n-2) in the block Bi, whereas the battery cells Ci (n in the block Bi are detected. -1) and battery cell Cin are the total voltage of these. However, the in-block maximum value MAXi is used as a voltage detection result corresponding to the maximum value of the battery cell Cij in the block Bi, and the in-block minimum value MINi is set as a voltage detection result corresponding to the minimum value of the battery cell Cij in the block Bi. Accordingly, the gain is changed between the potential conversion circuits 50 of the battery cells Ci1 to Ci (n-2) and the potential conversion circuits 50 of the battery cell Ci (n-1) and the battery cell Cin. Specifically, the resistance values R3 of the resistors 53 and 55 of the potential conversion circuit 50 of the battery cell Ci (n-1) and the battery cell Cin are set to the respective potential conversion circuits 50 of the battery cells Ci1 to Ci (n-2). The resistance value R1 of the resistors 53 and 55 is twice as large.

  Thereby, the potential conversion circuit 50 of the battery cell Ci (n-1) and the battery cell Cin is compared with the potential conversion circuit 50 of each of the battery cells Ci1 to Ci (n-2) to the output voltage of the input voltage. The conversion ratio is “½”. For this reason, each output of the potential conversion circuit 50 of the battery cell Ci (n-1) and the battery cell Cin and each of the potential conversion circuits 50 of the battery cells Ci1 to Ci (n-2) is supplied to the battery cell Cij. It can be a voltage per one.

  Incidentally, such a setting in which the number of battery cells constituting the detection target battery is not set to a constant value is effective when, for example, the probability of occurrence of an abnormality is different in a portion of the assembled battery 10. That is, the number of battery cells of the detection target battery is reduced for locations where abnormalities are likely to occur, while the number of parts is secured while ensuring the detection accuracy by increasing the number of battery cells of the detection target batteries for locations where abnormalities are unlikely to occur. Can be reduced.

  According to this embodiment described above, in addition to the effects (1) to (4) and (6) to (8) of the first embodiment, the following effects can be obtained. Become.

(9) The voltages converted by the potential conversion circuit 50 are normalized to the same number of voltages per battery cell, including those in which the number of battery cells is different from each other among the plurality of detection target batteries. Thereby, the intra-block maximum value MAXi and the intra-block minimum value MINi can be suitably generated.
<Sixth Embodiment>
Hereinafter, the sixth embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  FIG. 11 shows a circuit configuration of the monitoring unit Ui according to the present embodiment. In FIG. 11, members corresponding to those shown in FIG. 2 are given the same reference numerals for the sake of convenience.

As illustrated, in the present embodiment, the potential conversion circuit 50 includes two operational amplifiers, and both electrodes of the battery cell Cij are directly connected to an input terminal of the operational amplifier. Thereby, since no current flows between the battery cell Cij and the input terminal of the operational amplifier, the voltage drop during this period can be ignored. Therefore, as in the potential conversion circuit 50 shown in FIG. 2, it is possible to avoid a decrease in voltage detection accuracy due to a voltage drop of the resistors 53 and 55.
<Seventh Embodiment>
Hereinafter, the seventh embodiment will be described with reference to the drawings with a focus on differences from the second embodiment.

  FIG. 12 shows a circuit configuration of the monitoring unit Ui according to the present embodiment. In FIG. 12, members corresponding to those shown in FIG. 2 are given the same reference numerals for convenience.

  As shown in the figure, in the present embodiment, an open collector type is used as the comparator 60, and the output terminal is pulled up via the resistor 80 due to this. Further, a hysteresis comparator is configured by connecting a resistor 82 between the non-inverting input terminal and the output terminal of the comparator 60. Then, the output of the potential conversion circuit 50 is applied to the inverting input terminal of the comparator 60 via the resistor 84, and the carrier CS is applied to the non-inverting input terminal via the resistor 86.

  As described above, by providing the hysteresis comparator, it is possible to increase resistance to noise of the intra-block maximum value MAXi and the intra-block minimum value MINi. That is, the hysteresis comparator suitably suppresses the hunting phenomenon in which the output frequently goes back and forth between the logic “H” and the logic “L” because the threshold value that becomes the logic “H” is different from the threshold value that becomes the logic “L”. be able to.

  In particular, in this embodiment, an open collector type comparator 60 is used, and the carrier CS is applied to the non-inverting input terminal, whereby the interval between the pair of threshold values (hysteresis width) varies depending on the resistor 86 and the like. Even if this is the case, the influence on the voltage detection accuracy can be suitably avoided. This will be described below.

  Now, when the resistance values R1, R2, and R3 of the resistors 82, 84, and 86 and the voltage Vc of the carrier CS are used, when the output of the hysteresis comparator is logic “L”, the voltage V + of the non-inverting input terminal is “V +”. = Vc · R1 / (R1 + R3) ≈Vc ”. However, “R1 >> R3” was set. Therefore, when the output voltage of the potential conversion circuit 50 becomes Vc, the output of the hysteresis comparator is inverted to logic “H”.

  On the other hand, when the output of the hysteresis comparator is logic “H” (voltage Vh), the voltage V + of the non-inverting input terminal is “V + ≈Vc + Vh (R3 / R1)”. Therefore, when the output voltage of the potential conversion circuit 50 becomes this voltage “Vc + Vh (R3 / R1)”, the output of the hysteresis comparator is inverted to logic “L”. This voltage varies depending on the resistance values of the resistors 82 and 86. However, since the output of the hysteresis comparator is inverted to the logic “L” when the sawtooth wave is reset, this influence does not affect the output of the hysteresis comparator.

In the present embodiment, the output of the OR circuit 62 becomes the in-block minimum value MINi. Further, the maximum value MAXi in the block can be set to the voltage at the connection point by connecting the output terminals of the hysteresis comparator.
<Other embodiments>
Each of the above embodiments may be modified as follows.
About comparison means
In the first to sixth embodiments, the voltage equivalent signal of the detection target battery is input to the non-inverting input terminal of the comparator 60 and the carrier SC is input to the inverting input terminal.

In the seventh embodiment, the voltage equivalent signal of the detection target battery may be input to the non-inverting input terminal of the comparator 60 and the carrier SC may be input to the inverting input terminal. However, in this case, it becomes easy to be affected by variations in hysteresis due to the resistors 82 and 86.
“Hysteresis Comparator”
The hysteresis comparator is not limited to that exemplified in the seventh embodiment (FIG. 12). For example, the logic inversion may be prohibited for a predetermined period after the logic inversion of the output voltage. In this case, the same effects as those of the seventh embodiment can be obtained by using the carriers exemplified in the first to fourth embodiments. For example, an operational amplifier may be used as the comparator 60.
“About Career”
The carrier SC is not limited to those exemplified in the first to fourth embodiments. In short, any periodic voltage signal having one monotonically increasing period and one monotonically decreasing period in the detection target voltage region may be used. Here, the detection target voltage region is a region including a region connecting a normal voltage and a voltage threshold value for abnormality determination.
"About output means"
Means for outputting a signal corresponding to the minimum value of the voltage is not limited to the one configured using the AND circuit 64 or the OR circuit 62. For example, in the first embodiment, instead of the AND circuit 64, a selector that takes in each output of the comparator 60 and selectively outputs only one of the outputs is provided, and the output of the comparator 60 decreases first. It is good also as a means to select by a selector.

  Means for outputting a signal corresponding to the maximum value of the voltage is not limited to one configured using the AND circuit 64 or the OR circuit 62 or the one exemplified in the seventh embodiment. For example, in the seventh embodiment, there is provided a selector that takes in each output of the comparator 60 and selectively outputs only one of the outputs, and the selector 60 selects the one that the output of the comparator 60 falls first. Also good.

Further, the present invention is not limited to the one provided with both means for outputting a signal corresponding to the minimum value of voltage and means for outputting a signal corresponding to the maximum value of voltage.
About potential conversion means
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.
“Method for directly connecting the input terminals of an operational amplifier”
The technique of not interposing a resistor between the input terminal of the operational amplifier constituting the potential conversion circuit and the battery cell Cij is not limited to that exemplified in the sixth embodiment (FIG. 11). For example, as shown in FIG. 13, the potential conversion circuit 50 may include a measuring instrument amplifier.
"Standardization means"
In the configuration shown in FIG. 10, the normalization means may be configured by dividing the voltage across the battery cell Ci (n-1), Cin by a resistor and inputting the divided voltage to the potential conversion circuit 50. .

Further, as a normalization means, by adjusting the resistance value of the differential amplifier circuit, the magnification for converting the voltage of a large number of battery cells Cij is smaller than the magnification for converting the voltage of a small number of battery cells Cij. It is not limited to what you do. For example, the potential conversion means may be configured by providing a differential amplifier circuit for each battery cell and an average value circuit for averaging the outputs thereof.
"About synchronization means"
In the above embodiment, the synchronization signal Syn is the same signal as the output signal of the rectangular wave generation circuit 70, but is not limited thereto. For example, the pulse signal that defines the rising edge and the pulse signal that defines the falling edge of the rectangular wave generation circuit 70 may be a signal expressing the difference in the number of pulses.

Further, the synchronization means may not be provided. That is, for example, each monitoring unit Ui may be configured to include an oscillator for generating a carrier. Even in this case, the maximum value and the minimum value of the voltage of the battery cells Ci1 to Cin constituting each block Bi are grasped by storing the carrier cycle and waveform information in the control device 22 in advance. Can do. However, in this case, it is desirable to transmit the detection result to the control device 22 for each block.
“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.

Moreover, as a some detection object battery, it does not restrict to what comprises a common assembled battery. For example, they may be connected in parallel to each other. In this case, the potential conversion circuit 50 is not necessary. For this reason, you may apply the voltage of a detection object battery directly to a comparison means. Alternatively, a voltage obtained by dividing the voltage of the battery to be detected by a resistor may be applied to the comparison means.
(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.

  Each output of the comparator 60 may be output to the control device 22. However, in this case, since the number of insulating means becomes enormous, it is desirable to mount the control device 22 itself in the high voltage system.

  DESCRIPTION OF SYMBOLS 10 ... Assembly battery, 22 ... Control apparatus, 50 ... Potential conversion circuit, 60 ... Comparator, 62 ... OR circuit, 64 ... AND circuit, Ui ... Monitoring unit, Cij ... Battery cell.

Claims (13)

In the battery voltage detection device that detects the voltages of a plurality of detection target batteries,
Comparing means for outputting, as a voltage detection signal, a binary signal corresponding to the magnitude of one of the voltages at both ends of each of the plurality of detection target batteries and their corresponding values and one carrier that periodically increases or decreases. A battery voltage detection device characterized by the above.   2. The battery voltage detection apparatus according to claim 1, further comprising an output unit that selects and outputs a voltage detection signal output from the comparison unit that corresponds to a minimum value of the voltage.   3. The battery voltage detection apparatus according to claim 1, further comprising an output unit that selects and outputs a voltage detection signal output from the comparison unit that corresponds to the maximum voltage value.   A potential conversion unit that is connected to each of both ends of the plurality of detection target batteries to convert each of the voltages at both ends of the plurality of detection target batteries into a common reference potential voltage and input the voltage to the comparison unit; The battery voltage detection device according to claim 1, comprising: a battery voltage detection device according to claim 1.   The battery voltage detection device according to claim 4, wherein the plurality of batteries to be detected constitute an assembled battery that is a series connection body of a plurality of battery cells.   The battery voltage detection device according to claim 5, wherein each of the plurality of detection target batteries includes the same number of battery cells. The plurality of detection target batteries include those in which the number of battery cells constituting them is different from each other,
The potential conversion means includes a normalization means for normalizing the converted voltage to a voltage per the same number of battery cells when converting each of a plurality of detection target battery voltages to the reference potential voltage. The battery voltage detection device according to claim 5.   8. The battery according to claim 4, wherein the potential conversion unit includes an operational amplifier, and both ends of the plurality of detection target batteries are directly connected to input terminals of the operational amplifier. Voltage detection device.   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 voltage detection device according to any one of claims 5 to 7, wherein the battery voltage detection device is converted into a voltage by the potential conversion means. The assembled battery constitutes an in-vehicle high voltage system insulated from the in-vehicle low voltage system,
An output means for selecting and outputting at least one of the voltage detection signal output from the comparison means corresponding to the minimum value of the voltage and the voltage detection signal corresponding to the maximum value;
10. The battery voltage detection device according to claim 5, wherein an output of the output unit is output to the low-voltage system through an insulating unit. The assembled battery includes a plurality of detection target batteries that are converted to a reference potential voltage by the potential converting means, and each of the sets of batteries converts the potential to a different reference potential voltage. Is converted by means,
The output means is provided separately for each different reference potential.
The apparatus further comprises selection means for selecting at least one of a signal corresponding to the minimum value of the voltage and a signal corresponding to the maximum value among the output signals output from the output means via the insulating means. Item 11. The battery voltage detection device according to Item 10.   The battery voltage detection device according to claim 11, further comprising synchronization means for synchronizing carriers corresponding to each set of the plurality of detection target batteries.   The battery voltage detection device according to claim 1, wherein the comparison unit includes a hysteresis comparator.

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