Abstract:
Disclosed herein is a voltage detecting device including: an analog converting circuit configured to level-convert voltages of a plurality of battery cells constituting a battery into low voltages; a digital converting circuit configured to convert the low voltages output by the analog converting circuit into digital values; and a control circuit configured to be driven by a power supply provided separately to control the digital converting circuit; the analog converting circuit being driven by a first power generated from the plurality of battery cells, and the digital converting circuit being driven by a second power generated on a basis of a pulse signal generated by the control circuit.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present claims priority under 35 U.S.C. §119 to Japanese Patent Application No 2014-101330 filed in the Japan Patent Office on May 15, 2014, the entire content of which is hereby incorporated by reference. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a voltage detecting device. 
       BACKGROUND OF THE INVENTION 
       [0003]    A power supply constituted of a plurality of battery cells is used in an electric vehicle, a hybrid vehicle, and the like. 
         [0004]    Japanese Patent Laid-Open No. 2011-217606 describes, as a related technology, a technology related to the detection of voltages of battery cells. 
       SUMMARY OF THE INVENTION 
       [0005]    In general, various circuits using different power supply voltages are used in a voltage detecting device that detects the voltages of battery cells. In such a case, generating the various power supply voltages from a single power supply to supply power to the respective circuits may degrade efficiency at the time of the generation of the plurality of power supply voltages necessary for the voltage detecting device. As a result, there is a possibility of the power of current supply from the single power supply becoming insufficient, the power supply voltages necessary for the voltage detecting device being unable to be generated, and consequently the voltage detecting device being unable to detect the voltages of the battery cells. 
         [0006]    There has thus been a desire for a technology suitable for detecting the voltages of battery cells in a case where various circuits using different power supply voltages are used in a voltage detecting device. 
         [0007]    It is desirable of the present disclosure to provide a voltage detecting device that can solve the above problems. 
         [0008]    According to embodiments of the present disclosure, there is provided a voltage detecting device including: an analog converting circuit configured to level-convert voltages of a plurality of battery cells constituting a battery into low voltages; a digital converting circuit configured to convert the low voltages output by the analog converting circuit into digital values; and a control circuit configured to be driven by a power supply provided separately to control the digital converting circuit; the analog converting circuit being driven by a first power generated from the plurality of battery cells, and the digital converting circuit being driven by a second power generated on a basis of a pulse signal generated by the control circuit. 
         [0009]    In addition, according to the present disclosure, the voltage detecting device further includes a smoothing circuit configured to generate the second power by smoothing the pulse signal generated by the control circuit. 
         [0010]    In addition, according to the present disclosure, the pulse signal in the voltage detecting device is a modulated signal including control information for the digital converting circuit. 
         [0011]    In addition, according to the present disclosure, the modulated signal in the voltage detecting device is a pulse width modulation (PWM) signal indicating the control information as a duty ratio. 
         [0012]    In addition, according to the present disclosure, the pulse signal in the voltage detecting device is supplied from the control circuit to the smoothing circuit via a pulse transformer. 
         [0013]    According to the present disclosure, it is possible to provide a technology suitable for detecting the voltages of battery cells in a case where various circuits using different power supply voltages are used in a voltage detecting device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The advantages of this invention will become apparent in the following description taken in conjunction with the drawings, wherein: 
           [0015]      FIG. 1  is a diagram showing an example of a voltage detecting device according to a first embodiment of the present disclosure; 
           [0016]      FIG. 2  is a diagram showing an example of a direct current (DC)/DC converter according to the first embodiment of the present disclosure; 
           [0017]      FIG. 3  is a diagram showing an example of a voltage detecting device according to a second embodiment of the present disclosure; and 
           [0018]      FIG. 4  is a diagram showing an example of a DC/DC converter according to the second embodiment of the present disclosure. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     First Embodiment 
       [0019]      FIG. 1  is a diagram showing an example of a voltage detecting device  1  according to a first embodiment of the present disclosure. 
         [0020]    As shown in  FIG. 1 , the voltage detecting device  1  according to the first embodiment includes a battery electronic control unit (ECU) board  6 , cell voltage sensor boards  7   a ,  7   b ,  7   c , . . . , and battery cell groups (plurality of battery cells)  10   a ,  10   b ,  10   c, . . . .    
         [0021]    The cell voltage sensor board  7   a  included in the voltage detecting device  1  includes a power supply circuit  20   a , an integrated circuit  30   a , a direct current (DC)/DC converter  40   a , and an insulating element  50   a.    
         [0022]    The power supply circuit  20   a  included in the cell voltage sensor board  7   a  generates a voltage to be supplied to the power supply of a level converting section (analog converting circuit) included in the integrated circuit  30   a  with a lowest potential of the battery cell group  10   a  as a reference potential Va. For example, the power supply circuit  20   a  generates the power supply voltage for the analog converting circuit with Va as a reference potential by raising the voltage of the battery cell group  10   a.    
         [0023]    Each of the battery cell groups  10   a ,  10   b , and  10   c  is formed by a plurality of battery cells. 
         [0024]    The integrated circuit  30   a  includes a level converting section (analog converting circuit)  301   a  and an analog to digital (A/D) converting circuit (digital converting circuit)  302   a.    
         [0025]    The level converting section  301   a  converts the cell voltage of each battery cell in the battery cell group  10   a  such that a maximum voltage output by the plurality of battery cells becomes a voltage corresponding to the full scale of the A/D converting circuit  302   a . The level converting section  301   a  is a circuit operating (driven) by a power (first power) of a high voltage (for example 60 volts) because the circuit is supplied with the voltage of each battery cell in the battery cell group  10   a.    
         [0026]    The A/D converting circuit  302   a  is supplied with the cell voltage after the conversion by the level converting section  301   a , and generates a corresponding digital signal (digital value). The A/D converting circuit  302   a  is a circuit operating (driven) by a power (second power) of a low voltage (for example 5 volts). 
         [0027]    The DC/DC converter  40   a  generates a voltage to be supplied to the power supply of the A/D converting circuit (digital converting circuit)  302   a  included in the integrated circuit  30   a . For example, the DC/DC converter  40   a  generates a voltage of 5 volts with respect to the reference potential Va on the basis of a pulse width modulation (PWM) signal (pulse signal) generated by a processor (control circuit)  80 . 
         [0028]    The insulating element  50   a  transmits information indicating the voltages of the battery cells which information results from the conversion by the integrated circuit  30   a  to the processor  80  without transferring current between the cell voltage sensor board  7   a  and the battery ECU board  6 . 
         [0029]    The cell voltage sensor board  7   b  has functional sections similar to those of the cell voltage sensor board  7   a  except that the reference potential is Vb. Specifically, the cell voltage sensor board  7   b  includes a power supply circuit  20   b , an integrated circuit  30   b , a DC/DC converter  40   b , and an insulating element  50   b.    
         [0030]    Similarly, the cell voltage sensor board  7   c  has functional sections similar to those of the cell voltage sensor board  7   a  except that the reference potential is Vc. Specifically, the cell voltage sensor board  7   c  includes a power supply circuit  20   c , an integrated circuit  30   c , a DC/DC converter  40   c , and an insulating element  50   c.    
         [0031]    The battery ECU board  6  includes the DC/DC converters  40   a ,  40   b ,  40   c , . . . , the insulating elements  50   a ,  50   b ,  50   c , . . . , a power supply  60  (power supply provided separately), a power supply circuit  70 , and the processor  80 . 
         [0032]    The power supply  60  outputs a voltage to the power supply circuit  70 . For example, the power supply  60  outputs a voltage of 12 volts to the power supply circuit  70 . 
         [0033]    The power supply circuit  70  generates a power supply voltage necessary for the operation (driving) of the processor  80  on the basis of the voltage output by the power supply  60 . For example, the power supply circuit  70  generates a voltage of 5 volts from the voltage of 12 volts output by the power supply  60 . 
         [0034]    The processor  80  generates a PWM signal for the DC/DC converter  40   a  to generate the power supply voltage for the A/D converting circuit  302   a . In addition, the processor  80  obtains the information on the voltage of each battery cell which results from the conversion by the A/D converting circuit  302   a  via the insulating element  50   a . Incidentally, the processor  80  may generate a command signal indicating timing of sampling of the cell voltage of each battery cell by the A/D converting circuit  302   a.    
         [0035]    In the following, the cell voltage sensor boards  7   a ,  7   b ,  7   c , . . . will be referred to collectively as a cell voltage sensor board  7 . Similarly, the battery cell groups  10   a ,  10   b ,  10   c , . . . will be referred to collectively as a battery cell group  10 . The power supply circuits  20   a ,  20   b ,  20   c , . . . will be referred to collectively as a power supply circuit  20 . The integrated circuits  30   a ,  30   b ,  30   c , . . . will be referred to collectively as an integrated circuit  30 . The DC/DC converters  40   a ,  40   b ,  40   c , . . . will be referred to collectively as a DC/DC converter  40 . The insulating elements  50   a ,  50   b ,  50   c , . . . will be referred to collectively as an insulating element  50 . The level converting sections  301   a ,  301   b ,  301   c , . . . will be referred to collectively as a level converting section  301 . The A/D converting circuits  302   a ,  302   b ,  302   c , . . . will be referred to collectively as an A/D converting circuit  302 . 
         [0036]      FIG. 2  is a diagram showing an example of the DC/DC converter  40  according to the first embodiment of the present disclosure. 
         [0037]    As shown in  FIG. 2 , the DC/DC converter  40  according to the first embodiment includes a first communication element  25 , a second communication element  26 , a switching element  401 , a diode  402 , a capacitor  403 , and a differential buffer  404 . 
         [0038]    The DC/DC converter  40  according to the first embodiment which DC/DC converter  40  is shown in  FIG. 2  is a DC/DC converter of a configuration generally referred to as a flyback type. 
         [0039]    The first communication element  25  includes a core  27   a  and a coil  28   a . The second communication element  26  includes a core  27   b  and a coil  28   b . The coil  28   a  is a primary coil. The coil  28   b  is a secondary coil. The coil  28   a  and the coil  28   b  are arranged so as to be opposite in polarity from each other, and form a pulse transformer. 
         [0040]    When the switching element  401  is in an on state, it is difficult for the coil  28   b  to send a current because of the presence of the diode  402 . At this time, the core  27   b  is magnetized, and stores a magnetic energy. When the switching element  401  is in an off state, no current flows through the coil  28   a . At this time, the magnetic energy stored by the core  27   b  causes a current to flow from the coil  28   b  through the diode  402 . The capacitor  403  stores a charge on the basis of the current. Thus, the diode  402  performs rectification and the capacitor  403  (smoothing circuit) performs smoothing, whereby a desired voltage can be generated on the side of the cell voltage sensor board  7  on the basis of the PWM signal generated on the side of the battery ECU board  6 . In addition, for example, the pulse width, that is, the duty ratio of the PWM signal generated on the side of the battery ECU board  6 , is made to have control information desired to be transmitted to the side of the cell voltage sensor board  7 . Therefore, the PWM signal (modulated signal) can be not only used to transmit energy but also used to transmit information. 
         [0041]    Description will next be made of the processing of the voltage detecting device  1  according to the first embodiment. Incidentally, in the following, the processing of the voltage detecting device  1  will be described by taking as an example a case where the voltage detecting device  1  shown in  FIG. 1  has the DC/DC converter  40  shown in  FIG. 2 . Incidentally, in an electric vehicle, a hybrid vehicle, or the like, the cell voltages of battery cells are monitored to prevent the battery cells from being overcharged, and the voltage detecting device  1  detects the cell voltages in the battery cell group  10 . In addition, suppose that each integrated circuit  30  and the corresponding battery cell group  10  are connected to each other such that the lowest potentials of the respective integrated circuits  30  coincide with the lowest potentials of the respective corresponding battery cell groups  10 . 
         [0042]    The power supply circuit  20  generates a voltage (for example 60 volts) necessary for the operation of the level converting section  301  by raising a voltage (for example 38 volts) output by the battery cell group with the lowest potential of the corresponding battery cell group  10  as a reference. The power supply circuit  20  outputs the generated voltage to the level converting section  301 . The level converting section  301  thereby becomes operable. 
         [0043]    The power supply circuit  70  generates a voltage (for example 5 volts) necessary for the operation of the processor  80  from a voltage (for example 12 volts) output by the power supply  60 . The power supply circuit  70  outputs the generated voltage to the processor  80 . The processor  80  thereby becomes operable. 
         [0044]    When the processor  80  becomes operable, the processor  80  generates a PWM signal. The processor  80  outputs the generated PWM signal to each DC/DC converter  40 . 
         [0045]    The DC/DC converter  40  is a circuit of the flyback type shown in  FIG. 2 , for example. When the switching element  401  included in the DC/DC converter  40  is supplied with the PWM signal from the processor  80 , the switching element  401  is set in an on state to send a current through the coil  28   a  included in the first communication element  25  during the period that the PWM signal is in a High state. At this time, it is difficult for the coil  28   b  included in the second communication element  26  to send a current because of the presence of the diode  402 . Then, the core  27   b  is magnetized, and stores a magnetic energy. 
         [0046]    The switching element  401  is set in an off state during the period that the PWM signal is in a Low state. Then, no current flows through the coil  28   a . At this time, the magnetic energy stored by the core  27   b  causes a current to flow from the coil  28   b  through the diode  402 . The capacitor  403  stores a charge on the basis of the current sent by the diode  402 . 
         [0047]    A power supply terminal of the A/D converting circuit  302  is connected to the capacitor  403 . The power supply of the A/D converting circuit  302  is supplied with a voltage of 5 volts and a current from the diode  402  during the period that the diode  402  sends the current. During the period that the diode  402  does not send the current, the charge stored by the capacitor  403  is discharged, and thereby the power supply of the A/D converting circuit  302  is supplied with a voltage of 5 volts and a current. 
         [0048]    After the level converting section  301  and the A/D converting circuit  302  are supplied with the respective power supply voltages, the processor  80  generates a PWM signal including information indicating the timing of sampling of each cell voltage in the battery cell group  10 . For example, the processor  80  generates a PWM signal such that the pulse width, that is, the duty ratio of the PWM signal has control information (which PWM signal will hereinafter be referred to as a PWM information signal). The processor  80  outputs the generated PWM information signal to the DC/DC converter  40 . 
         [0049]    When the switching element  401  included in the DC/DC converter  40  is supplied with the PWM information signal, the switching element  401  switches between an on state and an off state according to the High period and the Low period indicated by the PWM information signal. A voltage corresponding to the on state and the off state of the switching element  401  is generated as voltage across the coil  28   b  included in the second communication element  26 . The differential buffer  404  is connected to both ends of the coil  28   b . The differential buffer  404  outputs a signal including information indicating the timing of sampling of each cell voltage in the battery cell group  10 , the information being based on the PWM information signal, to the corresponding A/D converting circuit  302 . 
         [0050]    At this time, the level converting section  301  is converting each cell voltage input from the battery cell group  10  into a voltage of a magnitude according to the full scale of the A/D converting circuit  302 . For example, the level converting section  301  converts the voltage of each battery cell in a ratio in which a maximum voltage output by the plurality of battery cells is converted into a voltage corresponding to the full scale of the A/D converting circuit  302 . 
         [0051]    When the A/D converting circuit  302  is supplied with the signal including the information indicating the sampling timing from the differential buffer  404 , the A/D converting circuit  302  obtains each cell voltage after the conversion by the level converting section  301  from the level converting section  301  in the sampling timing. The A/D converting circuit  302  converts each cell voltage (analog signal) obtained from the level converting section  301  into a digital signal. The A/D converting circuit  302  outputs the digital signal after the conversion to the insulating element  50 . The insulating element  50  generates a signal on the basis of the digital signal input from the A/D converting circuit  302 . When the digital signal is represented by a voltage, and the insulating element  50  is a photocoupler, for example, the photocoupler is supplied with an input current corresponding to the digital signal using a resistance. The photocoupler generates light corresponding to the input current, and emits the light from the cell voltage sensor board  7  to the battery ECU board  6  within the photocoupler. The photocoupler converts the generated light into a corresponding current on the battery ECU board  6 . 
         [0052]    The insulating element  50  outputs the current corresponding to the light to the processor  80 . The processor  80  is supplied with a signal corresponding to the current output by the insulating element  50 . For example, the processor  80  converts the current corresponding to the digital signal into a voltage by a resistance, and is supplied with a digital signal indicated by the voltage. This digital signal is generated on the basis of the digital signal output by the A/D converting circuit  302 , and includes the information on each cell voltage obtained from the level converting section  301 . 
         [0053]    The processor  80  performs control so as to prevent the battery cell group  10  from being overcharged, by outputting command signals to various circuits (not shown) managed by the processor  80  on the basis of the input digital signal. 
         [0054]    Incidentally, an example has been illustrated above in which the power supply voltage of the level converting section  301  and the power supply voltage of the A/D converting circuit  302  are two different power supply voltages. However, the power supply voltage of the level converting section  301  and the power supply voltage of the A/D converting circuit  302  are not limited to two different power supply voltages. For example, the A/D converting circuit  302  may be a circuit in which an analog circuit and a digital circuit operate on different power supply voltages, and the power supply voltage of the analog circuit may be 5 volts and the power supply voltage of the digital circuit may be 1.8 volts. In such a case, the power supply voltage of the analog circuit and the power supply voltage of the digital circuit may be generated from the voltage of 5 volts applied to the A/D converting circuit  302 . Alternatively, the 5 volts applied to the A/D converting circuit  302  may be used as the power supply voltage of the analog circuit, and the power supply voltage of the digital circuit may be supplied from another power supply. 
         [0055]    The processing of the voltage detecting device  1  according to the first embodiment of the present disclosure has been described above. According to the above-described voltage detecting device  1 , the voltage detecting device  1  includes the integrated circuit  30 . The integrated circuit  30  includes the level converting section  301  that operates on the voltage generated on the basis of the voltage output by the battery cell group  10 . The integrated circuit  30  has the A/D converting circuit  302  that operates on the voltage generated on the basis of the PWM signal generated by the processor. The integrated circuit  30  detects the cell voltages in the battery cell group  10 . 
         [0056]    Thus, it is possible to provide a technology suitable for detecting the voltages of battery cells in a case where various circuits using different power supply voltages are used in the voltage detecting device  1 . 
         [0057]    In addition, the processor  80  generates a PWM information signal including command information for the A/D converting circuit  302 . 
         [0058]    Thus, a total number of insulating elements  50  for performing communication in the voltage detecting device  1  can be reduced. 
         [0059]    In addition, the A/D converting circuit  302  outputs, to the processor  80 , a digital signal including information on each cell voltage obtained from the level converting section  301 . 
         [0060]    Thus, the processor  80  in the voltage detecting device  1  can prevent the battery cell group  10  from being overcharged, by outputting command signals to the various circuits managed by the processor  80  on the basis of the digital signal including the information on each cell voltage. 
       Second Embodiment 
       [0061]      FIG. 3  is a diagram showing an example of a voltage detecting device  1  according to a second embodiment of the present disclosure. 
         [0062]    As shown in  FIG. 3 , the voltage detecting device  1  according to the second embodiment has integrated circuits  30  and a DC/DC converter  40  that are different from those of the voltage detecting device  1  according to the first embodiment. 
         [0063]    In addition, the voltage detecting device  1  according to the second embodiment includes one cell voltage sensor board  7 , whereas the voltage detecting device  1  according to the first embodiment includes a plurality of cell voltage sensor boards  7 . 
         [0064]    Whereas each of the integrated circuits  30  according to the first embodiment outputs a digital signal to the processor  80  via the insulating element  50 , the integrated circuits  30  according to the second embodiment transmit and receive digital signals between the integrated circuits  30 , and integrate the plurality of digital signals into one digital signal. The digital signal is thereafter output to a processor  80  via an insulating element  50 . 
         [0065]    The DC/DC converter  40  includes a plurality of coils  28   b , whereas the second communication element  26  according to the first embodiment includes one coil  28   b . The plurality of coils  28   b  correspond to the respective integrated circuits  30 . 
         [0066]      FIG. 4  is a diagram showing an example of the DC/DC converter  40  according to the second embodiment of the present disclosure. 
         [0067]    As shown in  FIG. 4 , the DC/DC converter  40  according to the second embodiment includes a first communication element  25 , a second communication element  26 , a switching element  401 , a diode  402 , a capacitor  403 , and a differential buffer  404 . 
         [0068]    The DC/DC converter  40  according to the second embodiment which DC/DC converter  40  is shown in  FIG. 4  is a DC/DC converter of a configuration referred to as a flyback type. 
         [0069]    The first communication element  25  includes a core  27   a  and a coil  28   a . The second communication element  26  includes a core  27   b  and coils  28   b   1 ,  28   b   2 , and  28   b   3 . The coil  28   a  is a primary coil. The coils  28   b   1 ,  28   b   2 , and  28   b   3  are secondary coils. The coil  28   a  and the coils  28   b   1 ,  28   b   2 , and  28   b   3  are arranged so as to be opposite from each other in polarity, and form a pulse transformer. 
         [0070]    Incidentally,  FIG. 4  omits for convenience a rectifying diode, a smoothing capacitor, and a differential buffer that are connected to each of the coils  28   b   2  and  28   b   3  as in the case of the coil  28   b   1 . 
         [0071]    The operation of the DC/DC converter  40  according to the second embodiment corresponds to a case where the relation between the coil  28   a  and the coil  28   b  according to the first embodiment is applied to each of the pair of the coil  28   a  and the coil  28   b   1 , the pair of the coil  28   a  and the coil  28   b   2 , and the pair of the coil  28   a  and the coil  28   b   3 . Therefore, description of the operation of the DC/DC converter  40  according to the second embodiment will be omitted. 
         [0072]    The processing of the voltage detecting device  1  according to the second embodiment will next be described. The processing of the voltage detecting device  1  will be described in the following by taking as an example a case where the voltage detecting device  1  shown in  FIG. 3  includes the DC/DC converter  40  shown in  FIG. 4 . Incidentally, suppose that the integrated circuits  30  and corresponding battery cell groups  10  are connected to each other such that the lowest potentials of the respective integrated circuits  30  coincide with the lowest potentials of the respective corresponding battery cell groups  10 . 
         [0073]    Description in the following will be made of a part of processing of the voltage detecting device  1  according to the second embodiment which part is different from that of the voltage detecting device  1  according to the first embodiment. 
         [0074]    The processor  80  generates a PWM signal. The processor  80  outputs the generated PWM signal to the DC/DC converter  40 . 
         [0075]    The DC/DC converter  40  is a circuit of the flyback type shown in  FIG. 4 , for example. When the switching element  401  included in the DC/DC converter  40  is supplied with the PWM signal from the processor  80 , the switching element  401  is set in an on state to send a current through the coil  28   a  included in the first communication element  25  during the period that the PWM signal is in a High state. At this time, it is difficult for the coil  28   b   1  included in the second communication element  26  to send a current because of the presence of the diode  402 . Then, the core  27   b  is magnetized, and stores a magnetic energy. 
         [0076]    The switching element  401  is set in an off state during the period that the PWM signal is in a Low state. Then, no current flows through the coil  28   a . At this time, the magnetic energy stored by the core  27   b  causes a current to flow from the coil  28   b   1  through the diode  402 . The capacitor  403  stores a charge on the basis of the current sent by the diode  402 . 
         [0077]    Processing similar to the above-described processing for the coil  28   a  and the coil  28   b   1  is also performed simultaneously for each of the pair of the coil  28   a  and the coil  28   b   2  and the pair of the coil  28   a  and the coil  28   b   3 . 
         [0078]    When the switching element  401  included in the DC/DC converter  40  is supplied with the PWM information signal, the switching element  401  switches between an on state and an off state according to the High period and the Low period indicated by the PWM information signal. A voltage corresponding to the on state and the off state of the switching element  401  is generated as voltage across the coil  28   b   1  included in the second communication element  26 . The differential buffer  404  is connected to both ends of the coil  28   b   1 . The differential buffer  404  outputs a signal including information indicating the timing of sampling of each cell voltage in the battery cell group  10 , the information being based on the PWM information signal, to the corresponding A/D converting circuit  302 . 
         [0079]    Processing similar to the above-described processing for the coil  28   a  and the coil  28   b   1  is also performed simultaneously for each of the pair of the coil  28   a  and the coil  28   b   2  and the pair of the coil  28   a  and the coil  28   b   3 . 
         [0080]    A level converting section  301  provided to the cell voltage sensor board  7  is converting each cell voltage input from the battery cell group  10  into a voltage of a magnitude according to the full scale of the A/D converting circuit  302 . 
         [0081]    When the A/D converting circuit  302  is supplied with the signal including the information indicating the sampling timing from the differential buffer  404 , the A/D converting circuit  302  obtains each cell voltage after the conversion by the level converting section  301  from the level converting section  301  in the sampling timing. The A/D converting circuit  302  converts each cell voltage (analog signal) obtained from the level converting section  301  into a digital signal. The A/D converting circuit  302  transmits and receives digital signals after conversion to and from adjacent integrated circuits  30 . 
         [0082]    For example, the integrated circuit  30   a  outputs the digital signal after the conversion by the A/D converting circuit  302   a  to the integrated circuit  30   b . When the integrated circuit  30   b  is supplied with the digital signal after the conversion from the integrated circuit  30   a , the integrated circuit  30   b  generates a new digital signal obtained by linking the digital signal after the conversion by the A/D converting circuit  302   b  to the input digital signal after the conversion by the A/D converting circuit  302   a . The integrated circuit  30   b  outputs the newly generated digital signal to the integrated circuit  30   c . When the integrated circuit  30   c  is supplied with the newly generated digital signal from the integrated circuit  30   b , the integrated circuit  30   c  generates a new digital signal obtained by further linking the digital signal after the conversion by the A/D converting circuit  302   c  to the input digital signal. This linking processing is repeated for all of the integrated circuits  30 . Then, the last integrated circuit  30  (integrated circuit  30   c  in  FIG. 3 ) outputs, to the insulating element  50 , a digital signal obtained by linking together the digital signals after the conversion by the A/D converting circuits  302  included in all of the integrated circuits  30 . 
         [0083]    The insulating element  50  generates a signal on the basis of the digital signal input from the integrated circuit  30   c . When the digital signal is represented by a voltage, and the insulating element  50  is a photocoupler, for example, the photocoupler is supplied with an input current corresponding to the digital signal using a resistance. The photocoupler generates light corresponding to the input current, and emits the light from the cell voltage sensor board  7  to the battery ECU board  6  within the photocoupler. The photocoupler converts the generated light into a corresponding current on the battery ECU board  6 . 
         [0084]    The insulating element  50  outputs the current corresponding to the light to the processor  80 . The processor  80  is supplied with a signal corresponding to the current output by the insulating element  50 . For example, the processor  80  converts the current corresponding to the digital signal into a voltage by a resistance, and is supplied with a digital signal indicated by the voltage. This digital signal is generated on the basis of the digital signals output by all of the A/D converting circuits  302 , and includes the information on each cell voltage obtained from all of the level converting sections  301 . 
         [0085]    The processor  80  performs control so as to prevent the battery cell group  10  from being overcharged, by outputting command signals to various circuits (not shown) managed by the processor  80  on the basis of the input digital signal. 
         [0086]    The processing of the voltage detecting device  1  according to the second embodiment of the present disclosure has been described above. According to the above-described voltage detecting device  1 , the DC/DC converter  40  included in the voltage detecting device  1  includes the second communication element  26  having the plurality of coils. 
         [0087]    Thus, it suffices to include only one coil  28   a  in the first communication element  25  in the voltage detecting device  1 , so that the DC/DC converter  40  can be miniaturized. 
         [0088]    In addition, new digital signals obtained by linking together digital signals after the conversion by A/D converting circuits  302  are transmitted and received between the integrated circuits  30 . 
         [0089]    Thus, the digital signals after the conversion by all of the A/D converting circuits  302  can be transmitted to the processor  80  by one insulating element  50  in the voltage detecting device  1 , so that the voltage detecting device  1  can be miniaturized. 
         [0090]    Incidentally, a storage section in the present disclosure may be disposed anywhere insofar as appropriate information transmission and reception are performed. In addition, there may be a plurality of storage sections storing data in a distributed manner insofar as appropriate information transmission and reception are performed. 
         [0091]    Incidentally, the order of the processing in the embodiments of the present disclosure may be changed insofar as appropriate processing is performed. 
         [0092]    Embodiments of the present disclosure have been described above. The voltage detecting device  1  described above internally has a computer system. The processes of the above-described processing are stored on a computer readable recording medium in the form of a program. The above-described processing is performed by a computer by reading out and executing the program. The computer readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-read only memory (ROM), a DVD-ROM, a semiconductor memory, and the like. In addition, the computer program may be distributed to a computer by a communication line, and the computer that has received the distribution may execute the program. 
         [0093]    In addition, the program may be a program for implementing a part of the foregoing functions. Further, the program may be a program that enables the foregoing functions to be implemented in combination with a program already recorded in a computer system, that is, a so-called differential file (differential program). 
         [0094]    Some embodiments of the present disclosure have been described. However, these embodiments are presented as examples, and do not limit the scope of the disclosure. In addition, these embodiments are susceptible of various omissions, replacements, and changes without departing from the spirit of the disclosure.