JP2019075862A - Equalization circuit - Google Patents

Abstract

Provided is an equalizing device with improved accuracy. A differential amplifier circuit receives two terminal voltages of a plurality of cells Ce1 to Ce3, respectively, and outputs a difference between the two input terminal voltages. The changeover switch SW1 and the switch unit 12 are provided between the differential amplifier circuit 16 and the plurality of cells Ce1 to Ce3. The μCOM 19 controls the changeover switch SW1 and the switch unit 12 to switch the combination of the two cells Ce1 to Ce3 input to the differential amplifier circuit 16. Further, the μCOM 19 determines that the voltage between both ends of the plurality of cells Ce1 to Ce3 is based on the combination of the two cells Ce1 to Ce3 input to the differential amplifier circuit 16 and the difference voltage Vm of the differential amplifier circuit 16. A higher cell is obtained, and the voltage between both ends of the cell having the highest voltage is lowered to equalize the plurality of cells Ce1 to Ce3. [Selection diagram] Fig. 1

Description

  The present invention relates to an equalization device.

  EVs, PHEVs, HEVs, etc. have high voltage batteries for driving electric motors. In a high voltage battery, several tens to several hundreds of secondary batteries (hereinafter, cells) are connected in series to obtain a high voltage of several hundred volts. In the above-mentioned cell, a difference occurs in the charge amount (hereinafter, SOC) due to the battery capacity at the time of manufacture, the leakage current, and the variation in deterioration.

  For example, if the SOC of any one cell reaches 100% at the time of charging, it can not be charged further. Further, if the SOC of any one cell reaches 0% at the time of discharge, further discharge can not be performed. For this reason, if there is variation in SOC, charge and discharge efficiency will deteriorate. Therefore, a cell balance circuit has been proposed to equalize the SOC of each cell (Patent Document 1).

  The cell balance circuit (equalization device) of Patent Document 1 detects each cell voltage by a voltage detection unit, and transfers energy from a high voltage cell to a low voltage cell via an inductance.

JP, 2013-13292, A

  However, there has been a problem that the detection accuracy of the voltage detection unit of the above-described conventional equalization device can not be equalized with a accuracy of more than ± several millivolts.

  The present invention has been made in view of the above background, and it is an object of the present invention to provide an equalization apparatus with improved accuracy.

  The equalizing device according to an aspect of the present invention has two input terminals, and two end voltages of three or more secondary batteries constituting the assembled battery are respectively input to the two input terminals, and the input A differential amplifier circuit that outputs the difference between the two end-to-end voltages, a plurality of switches provided between the differential amplifier circuit and the battery pack, and the switches, which are controlled to control the differential amplifier circuit A first switch control unit that switches a combination of two of the secondary batteries input to the first, a combination of two secondary batteries input to the differential amplifier circuit, and an output of the differential amplifier circuit. And an equalization unit that performs equalization based on the obtained magnitude relationship.

  The first switch control unit uses one of the two secondary batteries input to the differential amplifier circuit as a reference secondary battery, which is one of the secondary batteries that constitute the assembled battery, The other of the secondary batteries may be sequentially switched to all secondary batteries constituting the assembled battery except the reference secondary battery.

  The first switch control unit controls the switch so as to switch the secondary battery input to the two input terminals of the differential amplifier circuit when the output of the differential amplifier circuit is 0. You may

  The first switch control unit may use, as the reference secondary battery, a secondary battery in which a voltage between both ends is determined to be the largest when the previous equalization is performed.

  A capacitor for holding a voltage across the secondary battery in the first state, a voltage across the secondary battery held by the capacitor, and a voltage across the secondary battery in the second state are input to the differential amplifier circuit A second switch control unit that controls the switch so as to input to the second switch control unit, and a state detection unit that detects the battery state of the secondary battery based on the output of the differential amplifier circuit at the time of control by the second switch control unit And may be provided.

  As described above, according to the aspect, the accuracy of equalization can be improved by performing equalization based on the difference between the voltages across the two secondary batteries.

FIG. 1 is a circuit diagram illustrating an embodiment of a cell monitoring device incorporating the equalization device of the present invention. It is a flowchart which shows the equalization process procedure of (micro) COM which comprises the cell monitoring apparatus of FIG. 1 in 1st Embodiment. It is a flowchart which shows the equalization process procedure of (mu) COM which comprises the cell monitoring apparatus of FIG. 1 in 2nd Embodiment.

First Embodiment
The cell monitoring apparatus according to the first embodiment will be described below with reference to FIG. The cell monitoring device 1 of the present embodiment is, for example, mounted on an electric vehicle, and monitors cells Ce1 to Ce3 as a plurality of secondary batteries constituting the battery assembly 2 shown in FIG. 1 provided in the electric vehicle. . The cells Ce1 to Ce3 are connected in series to one another.

  The cell monitoring device 1 executes the following three controls. First, the cell monitoring device 1 executes control to detect the internal resistances of the cells Ce1 to Ce3 and to detect the states of the cells Ce1 to Ce3. The cell monitoring device 1 also executes control to equalize the voltages across the cells Ce1 to Ce3. In addition, the cell monitoring device 1 detects the voltage across the cells Ce1 to Ce3 using the CVS 18, and stops charging if any one exceeds the threshold during charging, and stops one even below the threshold during discharging. If there is, control is performed to stop the discharge.

  As shown in FIG. 1, the cell monitoring device 1 includes an equalization circuit 11, a first capacitor C1 and a second capacitor C2, a switch SW1 and a switch unit 12, a charge / discharge unit 13, and a voltage detection unit. 14, an A / D converter 15, a differential amplifier circuit 16, an A / D converter 17, a CVS 18, and a microcomputer (hereinafter, μCOM) 19.

  The equalization circuit 11 is a circuit for performing equalization of the cells Ce1 to Ce3. The equalizing circuit 11 is, for example, a discharge type that discharges the cells Ce1 to Ce3 with high voltage across the discharge using discharge resistors, or a capacitor or the like to charge the cells Ce1 to Ce3 with high voltage across to the low cells Ce1 to Ce3. Using a known equalization circuit such as a charge pump type that moves the

  The first capacitor C1 and the second capacitor C2 are capacitors for holding the bipolar voltages of the cells Ce1 to Ce3, respectively. The first capacitor C1 and the second capacitor C2 are connected to one of the plurality of cells Ce1 to Ce3 selected by the switch unit 12 described later.

  In addition, the first capacitor C1 is connected to the + input which is one of two input terminals of a differential amplifier circuit 16 which will be described later. The second capacitor C2 is connected to the-input which is one of the two input terminals of the differential amplifier circuit 16 to be described later.

  The changeover switch SW1 is configured of a switch that switches the connection of the c terminal between the a terminal and the b terminal. The a terminal is connected to the one electrode of the first capacitor C1 and the + input of the differential amplifier circuit 16, and the b terminal is connected to the one electrode of the second capacitor C2 and the-input of the differential amplifier circuit 16 It is done. The c terminal is connected to an e + terminal of a changeover switch SW + described later. The changeover switch SW1 is a switch that selects one of the first capacitor C1 and the second capacitor C2 and connects it to the e + terminal of the changeover switch SW +.

  The switch unit 12 is composed of two changeover switches SW + and SW−. The changeover switch SW + is configured of a switch that switches the e + terminal between the a +, b +, and c + terminals. The a + to c + terminals are respectively connected to the positive electrodes of the cells Ce1 to Ce3. The changeover switch SW + connects one positive electrode selected among the plurality of cells Ce1 to Ce3 to one pole plate of the capacitors C1 and C2 selected by the changeover switch SW1.

  The changeover switch SW- is composed of a switch for switching the e- terminal between the a-, b- and c- terminals. The a- to c- terminals are respectively connected to the negative electrodes of the cells Ce1 to Ce3. The changeover switch SW- connects one negative electrode selected among the plurality of cells Ce1 to Ce3 to the other electrode plate of the capacitors C1 and C2.

  The voltage detection unit 14 is a circuit that detects the bipolar voltage of the entire assembled battery 2. The A / D converter 15 converts the bipolar voltage of the battery pack 2 detected by the voltage detection unit 14 into a digital value and supplies the digital value to the μCOM 19.

  The charge / discharge unit 13 is connected to both electrodes of the assembled battery 2 and provided so as to allow predetermined charging current Ic and discharging current Id to flow during charging and discharging of the cells Ce1 to Ce3 constituting the assembled battery 2. It is done. The charge / discharge unit 13 is connected to the μCOM 19 described later, charges the cells Ce1 to Ce3 by charging the charging current Ic in accordance with the control signal from the μCOM 19, and discharges the cells Ce1 to Ce3 by discharging Do.

  The differential amplifier circuit 16 is a known differential amplifier circuit that outputs a differential voltage Vm (= output) of the + input and the − input. The A / D converter 17 converts the differential voltage Vm (= output) output from the differential amplifier circuit 16 into a digital value and supplies the digital value to the μCOM 19.

  The CVS 18 comprises a detection circuit that detects the voltage across the cells Ce1 to Ce3, and sequentially outputs the detection result to the μCOM 19.

  The μCOM 19 is constituted by a microcomputer having a known CPU, ROM, RAM and the like. The μCOM 19 functions as a second switch control unit and a state detection unit, and controls the on / off control of the changeover switch SW1 and the switch unit 12 and controls the charge / discharge unit 13 to detect the internal resistance of the cells Ce1 to Ce3. Execute detection processing.

  In the detection processing of the internal resistance, in the first state, the μCOM 19 connects the e + terminal of the changeover switch SW + to the a + terminal and connects the e− terminal of the changeover switch SW− to the a− terminal, and c of the changeover switch SW1. Connect the terminal to the a terminal. As a result, the μCOM 19 causes the first capacitor C1 to hold the voltage across the cell Ce1 in the first state. Thereafter, in the second state, the μCOM 19 connects the c terminal of the changeover switch SW1 to the b terminal. As a result, the μCOM 19 causes the second capacitor C2 to hold the voltage across the cell Ce1 in the second state. Then, the voltage across the cell Ce1 in the first state and the second state is input to the differential amplifier circuit 16 at the + input and the − input.

  Here, the first state and the second state indicate states in which the currents flowing to the cells Ce1 to Ce3 are different. In the present embodiment, the state in which the charging current Ic is flowing is referred to as a first state, and the state in which the discharging current Id is flowing is referred to as a second state. The μCOM 19 controls the charge / discharge unit 13 based on the detection value from the voltage detection unit 14 to flow the charge current Ic and the discharge current Id to the cells Ce1 to Ce3.

Further, in the detection processing of the internal resistance, the μCOM 19 takes in the difference voltage Vm, detects the internal resistance of the cell Ce1, and detects the state of the cell Ce1. Describing in detail, in the present embodiment, the both-end voltage Vc1 of the cell Ce1 in the charged state is expressed by the following equation (1).
Vc1 = Ve1 + r1 × Ic (1)
Ve1: electromotive force of the cell Ce1, r1: internal resistance of the cell Ce1

On the other hand, the voltage Vd1 across the cell Ce1 in the discharge state is expressed by the following equation (2).
Vd1 = Ve1-r1 × Id (2)

  Therefore, the differential voltage Vm output from the differential amplifier circuit 16 has a value corresponding to Vc1−Vd1 = r1 × (Ic + Id), and if the charging current Ic and the discharging current Id are known in advance, the differential voltage Vm is The resistance r1 can be determined. The internal resistances r2 and r3 can be similarly obtained for the cells Ce2 and Ce3.

  Further, the μCOM 19 functions as a first switch control unit and equalization unit, and performs on / off control of the changeover switch SW1 and the switch unit 12 and control of the equalization circuit 11 to execute equalization processing of the cells Ce1 to Ce3. .

  Next, the details of the equalization processing procedure of the cell monitoring device 1 described above in the outline will be described below with reference to the flowchart of FIG. First, the μCOM 19 starts equalization processing before the end of charging. The μCOM 19 sets the cell Ce1 as a reference cell (reference secondary battery). The micro COM 19 connects the cell Ce1 to the first capacitor C1 and connects the cell Ce2 to the second capacitor C2 (step S1).

The step S1 will be described in detail. The μ COM 19 connects the cell Ce1 to the first capacitor C1, and waits for a predetermined time such that the voltage across the first capacitor C1 becomes equal to the voltage Vc1 across the cell Ce1, The cell Ce2 is connected to the capacitor C2. By this step S1, in the differential amplifier circuit 16, the voltage Vc1 across the cell Ce1 is input to the + input, and the voltage Vc2 across the cell Ce2 is input to the − input. At this time, the differential voltage Vm output from the differential amplifier circuit 16 is expressed by the following equation (4).
Vm = (Vc1-Vc2) x Av (4)

  Next, the μCOM 19 takes in the difference voltage Vm shown in the equation (4) (step S2). Here, if Vc1> Vc2, the differential voltage Vm shown in the equation (4) becomes larger than zero. On the other hand, if Vc1 ≦ Vc2, the differential voltage Vm shown in the equation (4) is 0, and it can not be distinguished whether Vc1 = Vc2 or Vc1 <Vc2. In addition, when Vc1 <Vc2, it can not be determined how much difference there is.

Then, after that, the μCOM 19 switches the cells Ce1 and Ce2 input to the differential amplifier circuit 16 (step S3). In step S3, the μ COM 19 connects the cell Ce2 to the first capacitor C1 and connects the cell Ce2 to the second capacitor C2 by the same procedure as in step S1. As a result, in the differential amplifier circuit 16, the voltage Vc2 across the cell Ce2 is input to the positive input, and the voltage Vc1 across the cell Ce1 is input to the negative input. At this time, the differential voltage Vm output from the differential amplifier circuit 16 is expressed by the following equation (5).
Vm = (Vc2-Vc1) * Av (5)

Next, the μCOM 19 takes in the difference voltage Vm shown in the equation (5) (step S4). After that, the μ COM 19 connects the cell Ce1 to the first capacitor C1 and connects the cell Ce3 to the second capacitor C2 by the same procedure as step S1 (step S5). As a result, in the differential amplifier circuit 16, the voltage Vc1 across the cell Ce1 is input to the positive input, and the voltage Vc3 across the cell Ce3 is input to the negative input. At this time, the differential voltage Vm output from the differential amplifier circuit 16 is expressed by the following equation (6).
Vm = (Vc1-Vc3) × Av (6)

Next, the μ COM 19 takes in the difference voltage Vm shown in the equation (6) (step S6). Thereafter, the μCOM 19 switches the cells Ce1 and Ce3 input to the differential amplifier circuit 16 (step S7). In step S7, the μ COM 19 connects the cell Ce3 to the first capacitor C1 and connects the cell Ce1 to the second capacitor C2 by the same procedure as in step S1. As a result, in the differential amplifier circuit 16, the voltage Vc3 across the cell Ce3 is input to the positive input, and the voltage Vc1 across the cell Ce1 is input to the negative input. At this time, the differential voltage Vm output from the differential amplifier circuit 16 is expressed by the following equation (7).
Vm = (Vc3-Vc1) x Av (7)

  Next, the μCOM 19 takes in the difference voltage Vm shown in the equation (7) (step S8). Thereafter, the μ COM 19 obtains the magnitude relationship of the cells Ce1 to Ce3 based on the differential voltage Vm indicated by the equations (4) to (7) (step S9). That is, the μ COM 19 can determine the magnitude relationship between Vc1 and Vc2 based on the differential voltage Vm of the equations (4) and (5) fetched at steps S2 and S4. μCOM determines that Vc1> Vc2 if the differential voltage Vm in equation (4) is greater than 0, and determines Vc1 <Vc2 if the differential voltage Vm in equation (5) is greater than 0, equation (4), If the differential voltage Vm of (5) = 0, it is determined that Vc1 = Vc2.

  Further, the μCOM 19 can determine the magnitude relationship between Vc1 and Vc3 based on the differential voltage Vm of the equations (6) and (7) captured at steps S6 and S8. μCOM determines that Vc1> Vc3 if the difference voltage Vm in equation (6) is greater than 0, and determines Vc1 <Vc3 if the difference voltage Vm in equation (7) is greater than 0, equation (6), If the differential voltage Vm of (7) = 0, it is determined that Vc1 = Vc3.

  When the microcomputer COM19 determines that Vc1> Vc2 and Vc1> Vc3, it determines the magnitude of Vc2 and Vc3 based on the magnitude of the differential voltage Vm of the equations (4) and (6) captured in steps S2 and S6. When it is determined that Vc1 <Vc2 and Vc1 <Vc3, the μ COM 19 determines the magnitude of Vc2 and Vc3 based on the magnitude of the differential voltage Vm of the equations (5) and (7) captured in steps S4 and S8.

  Next, the μ COM 19 controls the equalization circuit 11 based on the magnitude relationship of the cells Ce1 to Ce3 obtained in step S9 to perform equalization (step S10), and then ends the processing. In step S10, the μ COM 19 performs well-known equalization which discharges the cell with the highest voltage across the terminals or transfers the charge from the cell with the highest voltage across to the cell with the lowest voltage.

  According to the first embodiment described above, the differential amplifier circuit 16 receives voltages at two ends of the plurality of cells Ce1 to Ce3 and outputs a difference between the two voltages at the ends. The changeover switch SW1 and the switch unit 12 are provided between the differential amplifier circuit 16 and the plurality of cells Ce1 to Ce3. The μCOM 19 controls the changeover switch SW1 and the switch unit 12 to switch the combination of the two cells Ce1 to Ce3 input to the differential amplifier circuit 16. Further, the μCOM 19 determines the magnitude relationship of the plurality of cells Ce1 to Ce3 based on the combination of the two cells Ce1 to Ce3 input to the differential amplifier circuit 16 and the differential voltage Vm of the differential amplifier circuit 16, Equalization is performed based on the determined magnitude relation. Thus, the equalization accuracy can be improved by performing equalization based on the difference between the voltages Vc1 to Vc3 across the two cells Ce1 to Ce3. That is, since the differential voltage of the cells Ce1 to Ce3 is smaller than the voltage across the cells Ce1 to Ce3, the resolution of A / D conversion is high, and the magnitude relationship can be accurately obtained, and the accuracy of equalization is achieved. It can improve.

  Further, according to the first embodiment described above, the μ COM 19 sets one of the two cells input to the differential amplifier circuit 16 as the reference cell Ce1, and the other of the two cells in the plurality of cells Ce1 to Ce3. Among the cells Ce2 and Ce3 except the reference cell Ce1 are sequentially switched. Thus, the magnitude relationship of the plurality of cells Ce1 to Ce3 can be easily obtained.

  Further, according to the first embodiment described above, the μ COM 19 is held in the voltage across the cells Ce1 to Ce3 in the first state held in the first capacitor C1 and in the second capacitor C2 in the state detection processing. The switch SW + and the switch unit 12 are controlled so that the voltage across the cells Ce1 to Ce3 in the second state inputs an input to the differential amplifier circuit 16. The μCOM 19 detects the battery state of the cells Ce1 to Ce3 based on the difference voltage Vm of the differential amplifier circuit 16 at this time. As a result, the differential amplifier circuit 16 can be used both for equalization and for state detection, and cost reduction can be achieved.

  In the first embodiment described above, the secondary batteries Ce1 to Ce3 are controlled in the first state (the state in which the charging current Ic flows), the second state (the discharging current Id) by the control of the charge / discharge unit 13 by the μCOM 19 Flow), but it is not limited to this. A change in charge and discharge current accompanying load driving of the vehicle may be used. That is, the first state may be set before change of the charge / discharge current of the vehicle, and the second state may be set after change.

Second Embodiment
Next, a cell monitoring apparatus according to the second embodiment will be described. The configurations of the cell monitoring device of the first embodiment and the cell monitoring device of the second embodiment are the same, so detailed description of the configuration will be omitted. A significant difference between the first embodiment and the second embodiment is the equalization processing procedure executed by the μCOM 19.

  In the first embodiment, the two cells input to the differential amplifier circuit 16 are interchanged even if the differential voltage Vm acquired in steps S2 and S6 is not zero. However, if the differential voltage Vm taken in at steps S2 and S6 is not 0, the magnitude relationship between the two cells input to the differential amplifier circuit 16 can be determined, and thus there is no need to perform replacement (ie, step S5, There is no need to perform S6, S7 and S8). Therefore, in the second embodiment, when the differential voltage Vm taken in is 0, the μCOM 19 switches the two cells input to the differential amplifier circuit 16.

  Next, details of the equalization processing procedure of the cell monitoring device 1 in the second embodiment outlined above will be described below with reference to the flowchart of FIG. First, the μCOM 19 starts equalization processing before the end of charging. The μ COM 19 connects the cell Ce1 to the first capacitor C1 using the cell Ce1 as a reference cell, and connects the cell Ce2 to the second capacitor C2 (step S11), as in step S1 of the first embodiment.

At step S11, the differential voltage Vm output from the differential amplifier circuit 16 is expressed by the following equation (4).
Vm = (Vc1-Vc2) x Av (4)

Next, the μCOM 19 takes in the difference voltage Vm shown in the equation (4) (step S12). After that, the μCOM 19 determines whether the differential voltage Vm acquired in step S12 is 0 or not (step S13). When the differential voltage Vm is 0 (Y in step S13), the μ COM 19 switches the input of the differential amplifier circuit 16 (step S14). In step S14, the μCOM 19 connects the cell Ce2 to the first capacitor C1 and connects the cell Ce1 to the second capacitor C2, as in step S3 of the first embodiment. At this time, the differential voltage Vm output from the differential amplifier circuit 16 is expressed by the following equation (5).
Vm = (Vc2-Vc1) * Av (5)

  Next, after the μCOM 19 takes in the differential voltage Vm shown in the equation (5) (step S15), it proceeds to step S16. On the other hand, when the differential voltage Vm is larger than 0 (N in step S13), the μ COM 19 immediately proceeds to step S16 without proceeding to steps S14 and S15.

In step S16, the μ COM 19 connects the cell Ce1 to the first capacitor C1 and connects the cell Ce3 to the second capacitor C2, as in step S5 of the first embodiment. At this time, the differential voltage Vm output from the differential amplifier circuit 16 is expressed by the following equation (6).
Vm = (Vc1-Vc3) × Av (6)

Next, the μ COM 19 takes in the difference voltage Vm shown in the equation (6) (step S17). Thereafter, the μCOM 19 determines whether the differential voltage Vm acquired in step S17 is 0 or not (step S18). When the differential voltage Vm is 0 (Y in step S18), the μCOM 19 switches the input of the differential amplifier circuit 16 (step S19). In step S19, the μCOM 19 connects the cell Ce3 to the first capacitor C1 and connects the cell Ce1 to the second capacitor C2. At this time, the differential voltage Vm output from the differential amplifier circuit 16 is expressed by the following equation (7).
Vm = (Vc3-Vc1) x Av (7)

  Next, after the μCOM 19 takes in the difference voltage Vm shown in the equation (7) (step S20), it proceeds to step S21. On the other hand, when the differential voltage Vm is larger than 0 (N in step S18), the μ COM 19 immediately proceeds to step S21 without proceeding to steps S19 and S20. In step S21, the μCOM 19 obtains the magnitude relationship of the cells Ce1 to Ce3 based on the differential voltage Vm shown in the equations (4) to (7) fetched as in step S9 of the first embodiment.

  Next, the μ COM 19 controls the equalization circuit 11 based on the magnitude relationship of the cells Ce1 to Ce3 obtained in step S21 to perform equalization (step S22), and then ends the processing.

  According to the second embodiment described above, when the differential voltage Vm of the differential amplifier circuit 16 is 0, the μ COM 19 switches the cells Ce1 to Ce3 being input to the + input and the − input of the differential amplifier circuit 16. The switch SW + controls the switch unit 12. As a result, when the differential voltage Vm of the differential amplifier circuit 16 is larger than 0, the μ COM 19 does not replace the input of the differential amplifier circuit 16, and therefore, the processing speed can be improved.

  In the first and second embodiments described above, the cell Ce1 is used as the reference cell, but the invention is not limited to this. The reference cell may be one of the cells Ce1 to Ce3, and may be the cell Ce2 or the cell Ce3.

Third Embodiment
Next, a cell monitoring apparatus according to the third embodiment will be described. The configurations of the cell monitoring device of the second embodiment and the cell monitoring device of the third embodiment are the same, so detailed description of the configuration will be omitted.

  Further, although the cell Ce1 is used as the reference cell in the second embodiment described above, the present invention is not limited to this. The cells Ce1 to Ce3 determined to have the largest voltage at both ends by the previous equalization may be input to the positive input of the differential amplifier circuit 16 as a reference cell. As a result, the probability that the differential voltage of the differential amplifier circuit 16 becomes zero (that is, the probability that it becomes Y in steps S13 and S18) becomes low, and the probability of replacing the input of the differential amplifier circuit 16 becomes low. You can speed up.

  Further, according to the first to third embodiments described above, the differential amplifier circuit 16 is used in common for the state detection process and the equalization process, but it is not limited to this. Different differential amplifier circuits 16 may be used for the state detection process and the equalization process. In this case, the capacitors C1 and C2 are not essential for the differential amplifier circuit 16 used in the equalization process.

  Moreover, although two capacitors C1 and C2 were provided in the first to third embodiments described above, the present invention is not limited to this. As the capacitor, only one capacitor is required to hold the secondary batteries Ce1 to Ce3 in the first state, and the secondary batteries Ce1 to Ce3 in the second state may be directly input to the differential amplifier circuit 16 .

  Also, the μCOM 19 compares the differential voltage Vm taken in by the above-mentioned equalization processing with the end voltages Vc1 to Vc3 of the cells Ce1 to Ce3 detected by the CVS 18 to perform failure detection of the CVS 18. Good. For example, the μCOM 19 detects a failure of the CVS 18 when the difference voltage Vm between the cells Ce1 and Ce2 and the difference obtained from the voltages Vc1 and Vc2 of the cells Ce1 and Ce2 detected by the CVS 18 largely differ. May be

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention.

1 cell monitoring device (equalizer)
12 Switch unit (switch)
16 differential amplifier circuit 19 μCOM (first switch control unit, equalization unit)
C1 First capacitor (capacitor)
Ce1 to Ce3 cell (secondary battery)
SW + switch (switch)

Claims (5)

It has two input terminals, and the two end voltages of three or more secondary batteries constituting the assembled battery are respectively input to the two input terminals, and the difference between the two input end voltages is output. Differential amplifier circuit,
A plurality of switches provided between the differential amplifier circuit and the battery pack;
A first switch control unit that controls the switch to switch a combination of two of the secondary batteries input to the differential amplifier circuit;
Based on the combination of two secondary batteries input to the differential amplifier circuit and the output of the differential amplifier circuit, the magnitude relationship between the voltages across the secondary batteries constituting the assembled battery is determined and determined. An equalization apparatus comprising: an equalization unit that performs equalization based on a magnitude relationship.   The first switch control unit uses one of the two secondary batteries input to the differential amplifier circuit as a reference secondary battery, which is one of the secondary batteries that constitute the assembled battery, 2. The equalizing device according to claim 1, wherein the other of the secondary batteries is sequentially switched to all secondary batteries constituting the assembled battery except for the reference secondary battery.   The first switch control unit controls the switch so as to switch the secondary battery input to the two input terminals of the differential amplifier circuit when the output of the differential amplifier circuit is 0. The equalization apparatus according to claim 1 or 2, characterized by   The equalization device according to claim 2, wherein the first switch control unit sets the secondary battery whose voltage across the both ends is largest when the previous equalization is performed as the reference secondary battery. . A capacitor for holding a voltage across the secondary battery in the first state;
A second switch control unit configured to control the switch such that the voltage across the secondary battery held by the capacitor and the voltage across the secondary battery in a second state input a signal to the differential amplifier circuit;
The state detection part which detects the battery state of the said secondary battery based on the output of the said differential amplifier circuit at the time of control by the said 2nd switch control part, It was characterized by the above-mentioned. The equalization device according to claim 1.

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