JP2019110708A - Buttery control device - Google Patents

Abstract

To provide a buttery control device capable of quickly and further accurately detecting voltage of a battery cell.SOLUTION: A monitoring IC 20 applied to a power supply system, includes: a storage battery 10 in which a plurality of battery cells C are connected in series; a filter circuit 31 having a capacitor 33; a connection member L connecting the battery cell C and the filter circuit 31; and a discharge circuit 34, in which there are provided a voltage detection circuit 21 provided for each battery cell C and detecting voltage of the battery cell C from which noise is removed by the filter circuit 31, a discharge determination section which determines the necessity of discharge in the discharge circuit 34 for each battery cell C, for equalization, on the basis of the voltage of the battery cells C detected by the voltage detection circuit 21, and a switch control section that opens and closes the discharge switch 22 of the battery cell C determined that the discharge is necessary by the discharge determination section a plurality of times between the detection timing at which the voltage is detected by the voltage detection section and the detection timing.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a battery control device.

  In a power supply system using a storage battery formed by connecting a plurality of battery cells in series, a voltage detection circuit for detecting a voltage of each battery cell and a voltage of each battery cell detected by the voltage detection circuit are equalized. And an equalization circuit. And, between the voltage detection circuit and each battery cell, a low pass filter circuit for removing noise contained in the voltage input from the battery cell to the voltage detection circuit is provided. And the voltage of each battery cell is detected by measuring the voltage of the capacitor | condenser of this low pass filter circuit. However, when discharging is performed from each battery cell by the equalizing circuit, the voltage of the capacitor fluctuates due to the voltage drop due to the contact resistance and the like included in the path between the battery cell and the filter circuit. It contributes to an error in detection. Therefore, in the technology of Patent Document 1, a configuration is disclosed in which the battery cell value is calculated by detecting the voltage three times after discharging by the equalizing circuit and substituting the voltage detected three times into a predetermined equation. It is done.

JP 2014-81268 A

  However, in the configuration of Patent Document 1, the voltage is detected three times after a predetermined time, and a standby time for detection is required. Therefore, extra time for waiting time is required to determine the voltage of the battery cell, and further improvement is desired.

  The present invention has been made in view of the above problems, and its main object is to provide a battery control device capable of detecting the voltage of a battery cell quickly and more accurately.

  In the first means, a filter circuit (31) having a storage battery (10) in which a plurality of battery cells (C) are connected in series, and a capacitor (33) provided for each of the battery cells and connected to the battery cells A connecting member (L) for connecting the battery cell and the filter circuit, and a discharge switch (22) provided for each battery cell and connected in series to the battery cell via the connecting member. A battery control device (20) applied to a power supply system comprising a discharge circuit (34) comprising:) and a discharge resistor (35), provided for each of the battery cells, and noise removed by the filter circuit A discharge indicator that determines the necessity of discharge in the discharge circuit for each battery cell based on the voltage detection unit (21) that detects the voltage of the battery cell and the voltage of the battery cell detected by the voltage detection unit Switch control for opening and closing the discharge switch of the battery cell determined to require discharge in the discharge determination unit between the detection unit and a detection timing when the voltage detection unit detects the voltage and the detection timing And a unit.

  The connection member between each battery cell and the filter circuit changes in internal resistance or connection resistance due to aging or the like, and when a current for discharging flows in the discharge circuit, a voltage drop in the resistance at the connection member causes The voltage of the capacitor fluctuates. Therefore, the voltage detected by the voltage detection unit after the noise is removed by the filter circuit is different from the voltage of the battery cell, which causes an error in the voltage of the battery cell. In addition, since the resistance value changes due to aging and the like, it is difficult to calculate in advance the measurement error from the difference between the voltage of the capacitor after equalization and the voltage of the battery cell.

  In this means, the discharge switch is opened and closed between the detection timing of the voltage detection unit and the detection timing of the battery cell of which the discharge determination unit determines that the discharge is necessary. By closing the discharge switch, even if the capacitor is discharged due to the voltage drop at the connection member, the discharge switch is opened and the capacitor tries to return to the voltage of the battery cell. By repeating these behaviors between the detection timing and the detection timing, the error in the voltage between the capacitor and the battery cell is reduced compared to the case where the discharge switch is kept closed between the detection timing and the detection timing. be able to. Therefore, it is possible to suppress the discharge of the capacitor due to the voltage drop at the connection member, shorten the time for waiting for the recovery of the voltage of the capacitor, and detect the value of the battery cell voltage with a small error even without special correction. it can.

  The second means includes an abnormality detection unit for detecting an abnormality in the power supply system between detection timings at which a voltage is detected by the voltage detection unit, and the abnormality detection unit is configured to detect an abnormality. During detection, the switch control unit opens / closes the discharge switch of the battery cell required to be discharged by the discharge determination unit, and performs discharge in the discharge circuit.

  When the discharge switch is opened and closed multiple times between the detection timing and the detection timing, the number of times the discharge switch is opened increases, so the time for discharging by the discharge circuit for equalization becomes short. Therefore, in addition to the discharge time originally scheduled for equalization, this means performs discharge for equalization while the abnormality detection unit detects an abnormality in the battery system. Therefore, in addition to the discharge time for equalization, the discharge required for equalization can be performed by securing the time for discharge.

  In the third means, the abnormality detection unit detects the abnormality by causing the switch control unit to close the discharge switch and detecting a result of causing a current to flow to a circuit including the discharge circuit. When the abnormality detection unit detects the abnormality, the switch control unit determines the time for which the discharge switch of the battery cell whose discharge is required to be closed by the discharge determination unit is closed. The time for which the discharge switches of the other battery cells for which discharge is unnecessary in the determination unit is set to be in the closed state is set longer.

  As abnormality detection performed by the abnormality detection unit, for example, there is one in which a current is supplied to a circuit including a discharge circuit, such as disconnection detection at a connection member, and the abnormality is detected based on the result. In the case of such an abnormality detection, discharge is implemented with respect to all the battery cells including the battery cell which does not need the discharge for equalization. At this time, the discharge time of the battery cell required to be discharged in the discharge determination unit is made longer than the discharge time of the other battery cells determined to be unnecessary in the discharge determination unit. While performing necessary detection in all the battery cells, battery cells that need to be discharged can discharge for equalization by discharging for a longer time than battery cells that do not need to be discharged.

  In the fourth means, the abnormality detection unit detects the abnormality without causing the switch control unit to close the discharge switch, and the abnormality detection unit also detects the abnormality by the abnormality detection unit. The switch control unit opens and closes the discharge switch of the battery cell for which discharge is required in the discharge determination unit.

  The abnormality detection performed by the abnormality detection unit includes, for example, measurement of the temperature of a battery cell or the like, which detects an abnormality without using a result of discharging in a discharge circuit. Also in the case of such an abnormality detection, discharge for equalization is performed in the battery cell determined to require discharge. Therefore, time to perform discharge for equalization can be increased.

  In the fifth means, the battery cells are divided into a plurality of groups such that adjacent battery cells are in different groups, and the switch control unit detects that a voltage is detected by the voltage detection unit. Between the timing and the detection timing, the discharge switch of the battery cell determined to require discharge by the discharge determination unit is continuously opened and closed for each group.

  Between the detection timing and the detection timing in the voltage detection unit, the discharge switch is continuously opened and closed for each group for the battery cells that need to be discharged. By continuing to open and close the discharge switch for each group, while another group is discharging, the discharge switch is opened in a certain group, and the time for the capacitor to return to the voltage of the battery cell become longer. Therefore, an error in voltage between the capacitor and the battery cell can be further reduced, and the value of the voltage of the battery cell can be calculated quickly with almost no error.

  In the sixth means, the battery cells are divided into a plurality of groups such that adjacent battery cells are in different groups, and the switch control unit detects that a voltage is detected by the voltage detection unit. Between the timing and the detection timing, the discharge switch of the battery cell determined to require discharging by the discharge determination unit is opened and closed multiple times for the battery cells of the certain group.

  Between the detection timing in the voltage detection unit and the detection timing, the discharge switch is opened and closed multiple times for the battery cells that need to be discharged in a certain group. By performing the discharge for each group, it becomes easy to manage the discharged battery cells.

The schematic block diagram of a power supply system. The flowchart which shows the process sequence in a battery control apparatus. The flowchart which shows the processing procedure of equalization processing. The time chart which shows change of the cell voltage at the time of equalization processing. The flowchart which shows the process sequence of the abnormality determination processing accompanied by discharge. The time chart which shows ON / OFF of the discharge switch at the time of the abnormality determination processing accompanied by discharge. The time chart which shows the change of the cell voltage in other embodiments.

  Hereinafter, an embodiment in which a battery control device according to the present invention is embodied will be described with reference to the drawings. The battery control device according to the present invention is applied to, for example, a power supply system mounted on a hybrid vehicle or an electric vehicle.

  As shown in FIG. 1, the power supply system includes a storage battery 10. The storage battery 10 is, for example, a lithium ion storage battery, and serves as a power supply source of an on-vehicle electrical load including a driving motor (not shown) of the vehicle. In addition, if it is a storage battery which connects not only a lithium ion storage battery but a several unit battery and supplies with a predetermined voltage, other storage batteries, such as a nickel hydride storage battery, may be sufficient.

  The storage battery 10 is configured of a battery module 11 configured by connecting in series battery cells C1 to Cn, which are n (n is an integer of 1 or more, approximately several to dozens of) unit batteries. The storage battery 10 may be configured by connecting a plurality of battery modules 11 in series or in parallel, or may be configured from one battery module 11. In the present embodiment, one battery module 11 is illustrated as an example of the storage battery 10. Further, in the following description, battery cells C1 to Cn are collectively referred to as battery cell C. In FIG. 1, the description of the battery cell C1 and the battery cell C9 and thereafter is omitted.

  A monitoring IC 20 for monitoring the battery state is provided for each battery module 11 while performing calculation of voltage of each battery cell C, equalization processing, and the like. The monitoring IC 20 is provided with a voltage detection circuit 21 and a discharge switch 22 for each battery cell C. In addition, the monitoring IC 20 is provided with a control unit (not shown) that calculates the voltage of each battery cell C, controls the discharge switch 22, or performs abnormality determination. In the present embodiment, the monitoring IC 20 corresponds to a "battery control device", and the voltage detection circuit 21 corresponds to a "voltage detection unit". Further, the monitoring IC 20 may monitor a plurality of battery modules 11 collectively, or may divide one battery module 11 into a plurality of monitoring ICs 20 and monitor them. The control unit may not be provided in the monitoring IC 20, but may be provided in an ECU or the like that can communicate with the monitoring IC 20.

  A voltage detection circuit 21, a filter circuit 31 and a discharge circuit 34 are provided for each battery cell C. Further, connection members L1 to L (n + 1) are provided to connect the battery cell C with the filter circuit 31 and the discharge circuit 34. The connection members L1 to L (n + 1) connect the positive electrode side of each battery cell C to one end of the filter circuit 31, and connect the negative electrode side of each battery cell C to the other end of the filter circuit 31. The connecting members L2 to Ln other than the connecting member L (n + 1) connected to the connecting member L1 on the positive electrode side of the battery cell C1 on the highest voltage side and the negative electrode of the battery cell Cn on the lowest voltage side are It is shared between adjacent battery cells C. For example, the connection member L3 connecting the positive electrode side of the battery cell C3 to one end of the filter circuit 31 is a connection member L3 connecting the negative electrode side of the battery cell C2 to the other end of the filter circuit 31. In the following description, the connection members L1 to L (n + 1) will be collectively referred to as a connection member L. In FIG. 1, the description of the connecting member L <b> 1 and the connecting member L <b> 10 and thereafter is omitted.

  The connection member L includes a wire harness 41 connecting between the battery cells C and the substrate B provided with the monitoring IC 20, the filter circuit 31, the discharge circuit 34 and the like, and a connector 42 connecting the wire harness 41 and the substrate B. The printed wiring 43 provided on the substrate B and the fuse 44 provided on the printed wiring 43 are provided. The wire harness 41 has a resistor 41a generated when a current flows, and the printed wiring 43 has a resistor 43a generated when a current flows. The connector 42 has a contact resistance, and the element connected to the printed wiring 43 or the printed wiring 43 such as the fuse 44 has the resistance and the contact resistance of the element itself. The resistances generated when current flows on the connection members L are collectively referred to as an internal resistance R. The magnitude of the internal resistance R changes with age, ambient temperature, etc., but is approximately several hundred mΩ.

  The filter circuit 31 removes noise contained in the voltage input from the battery cell C to the voltage detection circuit 21 of the monitoring IC 20. The filter circuit 31 is a low pass filter circuit called an RC circuit, and includes a filter resistor 32 and a capacitor 33. The filter resistor 32 is approximately several kΩ in size, while the capacitor 33 is several μF in size. One end of the filter resistor 32 is connected to the connection member L on the positive electrode side, and the other end is connected to the pin of the monitoring IC 20 connected to the voltage detection circuit 21. One end of the capacitor 33 is connected between the other end of the filter resistor 32 and the voltage detection circuit 21, and the other end of the capacitor 33 is connected to the connecting member L on the negative electrode side. The filter circuit 31 may be another filter circuit as long as it is a filter circuit using a capacitor, such as a low pass filter using a coil instead of the filter resistor 32.

  The discharge circuit 34 is a circuit for equalizing (balancing) the voltage of each battery cell C, and is provided in parallel with the filter circuit 31 with respect to the battery cell C. The discharge circuit 34 includes a discharge switch 22 provided in the monitoring IC 20 and a discharge resistor 35. The size of the discharge resistor 35 is approximately several tens Ω. One end of the discharge resistor 35 is connected to the connection member L together with the filter circuit 31, and the other end is connected to the pin of the monitoring IC 20 connected to the discharge switch 22. Similar to the connection member L, the discharge resistor 35 is shared between the adjacent battery cells C.

  When a current flows in the discharge circuit 34, a current flows from the positive electrode side of the battery cell C through the connection member L on the positive electrode side to the discharge resistor 35 on the positive electrode side, and a current flows to the discharge resistor 35 on the negative electrode side The negative electrode side of the battery cell C is returned through the connecting member L on the negative electrode side. Then, on this path, specifically, whether or not the discharge switch 22 is provided inside the monitoring IC 20 between the discharge resistor 35 on the positive electrode side and the discharge resistor 35 on the negative electrode side to discharge from the battery cell C It is controlled by the control unit. The discharge switch 22 is controlled by the control unit so that discharge of the battery cell C is divided into groups of odd numbered battery cells C and groups of even numbered battery cells C, and discharge is performed at different timings for each group. Ru. The discharge of the battery cell C may be performed as long as adjacent battery cells C sharing the connection member L are discharged at different timings, for example, the battery cells C may be divided into three groups to perform discharge. The battery cells C may be discharged without being divided into groups.

  The voltage detection circuit 21 is called an A / D converter, and detects the voltage of the capacitor 33. One end of the voltage detection circuit 21 is connected to the filter resistor 32, and the other end is connected to the discharge resistor 35. The voltage of each capacitor 33 matches the voltage of each battery cell C connected in parallel in the steady state, so that each voltage detection circuit 21 detects the voltage of each capacitor 33 so that each filter circuit 31 The voltage detection circuit 21 can detect the voltage of each battery cell C in a state where noise has been removed. Each voltage detection circuit 21 detects the voltage of each capacitor 33 at a constant cycle.

  FIG. 2 is a flowchart performed by the control unit (monitoring IC 20), and this process is performed by the control unit at a predetermined timing. The timing of voltage detection of each battery cell C is scheduled in advance so as to be detected at a constant cycle, and various abnormality diagnoses are also scheduled in advance to be performed at a predetermined cycle. Then, various abnormality diagnoses are performed between the voltage detection timing of the predetermined cycle and the voltage detection timing, and equalization processing is performed in advance between the voltage detection timing not performing the abnormality diagnosis and the voltage detection timing. It is scheduled.

  In step S11, the voltages of all the battery cells C are acquired. Specifically, the voltage detection circuit 21 of all the battery cells C is controlled to acquire the voltage of the capacitor 33, and the voltage detected by the voltage detection circuit 21 is acquired.

  In step S12, based on the voltage of each battery cell C acquired in step S11, a battery cell C requiring discharge for equalization is set. Specifically, when the voltage of a certain battery cell C is higher than the voltage of another battery cell C, it is determined that discharge for equalization is necessary for this battery cell C. In the present embodiment, the battery cell C3 and the battery cell C6 will be described below on the assumption that discharge for equalization is required.

  In step S13, it is determined whether it is the timing of abnormality diagnosis scheduled in advance. If it is determined in step S13 that it is not the timing of abnormality diagnosis, equalization processing is performed in step S30. FIG. 3 shows the procedure of the equalization process.

  In step S31, voltages of all the battery cells C are acquired. Specifically, as in step S11, the voltage detection circuit 21 detects the voltage of the capacitor 33 for all the battery cells C, and acquires the voltage.

  In step S32, the battery cells C that need to be discharged are discharged. Specifically, in order to discharge in the discharge circuit 34 of the battery cell C3 determined to require discharge, the corresponding discharge switch 22 is turned on (closed). Then, after the discharge switch 22 is turned on, when a predetermined time (for example, 3 milliseconds) elapses, the discharge switch 22 is turned off (opened) to end the discharge.

  When discharging of the odd-numbered battery cells C is completed, in step S33, the process waits for the switch switching time. As soon as a command to turn off the discharge switch 22 is issued, there is a possibility that current is still flowing in the discharge circuit 34, so in step S33, the process waits for a time for switching (for example, about 1 millisecond). Do.

  In step S34, the battery cells C requiring discharge of the group of the even numbered battery cells C are discharged. Specifically, in order to discharge in the discharge circuit 34 of the battery cell C6 that needs to be discharged, the corresponding discharge switch 22 is turned on (closed state). Then, after the discharge switch 22 is turned on, when a predetermined time (for example, 3 milliseconds) elapses, the discharge switch 22 is turned off (opened) to end the discharge. When discharging of the even-numbered battery cells C is completed, in step S35, as in step S33, the process waits for the switch switching time.

  Then, in steps S36 to S38, as in steps S32 to S34, discharge of the odd-numbered battery cells C and discharge of the even-numbered battery cells C are performed. When the discharge of the battery cell C ends in step S38, the process waits in a state in which the switch is turned off in step S39. It waits for, for example, about one millisecond until there is no possibility that current flows in the discharge circuit 34.

  Here, a time chart when such equalization processing is performed will be described with reference to FIG. FIG. 4 is a diagram showing the voltage of the battery cell C and the voltage of the capacitor 33 (indicated by a broken line) when discharging is performed. In FIG. 4, the horizontal axis represents time, and the vertical axis represents the level of each signal. Further, the case where the equalization process is performed twice continuously is illustrated in the present time chart.

  First, at timing t11, the voltage detection circuit 21 detects a voltage for each battery cell C. Then, when the detection by the voltage detection circuit 21 is completed, the discharge switch 22 of the odd-numbered battery cell C (for example, the battery cell C3) to be discharged is turned on (closed) at timing t12, To be implemented.

  While discharging in the discharge circuit 34, the voltage of the capacitor 33 changes due to the voltage drop due to the internal resistance R at the connection member L. Specifically, in the capacitor 33 corresponding to the battery cell C3 performing the discharge, the voltage drop of the internal resistance R of the connecting member L3 and the connecting member L4 causes the voltage of the capacitor 33 to decrease. At this time, the voltage of the capacitor 33 is lowered by the relationship determined by the time constant of the filter resistor 32 and the capacitor 33, and the value of the capacitor 33 is the value of the battery cell C3 by the value of the voltage drop due to the internal resistance R of the connection member L. Against the

  After discharge is performed for a predetermined time (for example, 3 milliseconds), the discharge switch 22 is turned off (opened) at timing t13. At this time, since the interval between the timing t12 and the timing t13 is short, the voltage of the capacitor 33 is turned back before the voltage drop by the internal resistance R of the connection member L is lowered and stabilized.

  Then, after waiting for a time (e.g., about 1 millisecond) for switching until the current does not flow reliably after the discharge switch 22 is turned off, the even numbered battery is discharged at timing t14. The discharge switch 22 of the cell C (for example, the battery cell C6) is turned on (closed), and discharge is performed. Also in the battery cell C6, the voltage of the corresponding capacitor 33 changes as in the discharge of the battery cell C3. Then, after discharging for a predetermined time (for example, 3 milliseconds), at timing t15, the discharge switch 22 corresponding to the even-numbered battery cell C is turned off (opened). Between timing t14 and timing t15, the voltage of the capacitor 33 corresponding to the discharged battery cell C decreases, and at timing t15, it returns to recovery.

  On the other hand, after the discharge switch 22 is turned off at timing t13, the voltage of the capacitor 33 of the odd-numbered battery cell C (for example, battery cell C3) that has been discharging between timing t12 and timing t13 turns off. It rises until it becomes equal to the voltage of C. After the discharge switch 22 is turned off at timing t13, the voltage of the capacitor 33 is gradually increased according to the relationship determined by the time constant of the filter resistor 32 and the capacitor 33. At this time, since the time during which the discharge is performed is short, the difference between the voltage of the capacitor 33 and the voltage of the battery cell C also decreases, and the voltage recovery becomes easy.

  Then, after waiting for a time for switching, the discharge switch 22 of the odd-numbered battery cell C is turned on again (closed state) at timing t16, and discharge is performed. After discharging for a predetermined time (for example, 3 milliseconds), at timing t17, the discharge switch 22 corresponding to the odd-numbered battery cell C is turned off (opened). Then, after waiting for a time for switching, the discharge switch 22 of the even-numbered battery cell C is turned on again (closed state) at timing t18, and discharge is performed. After a predetermined time (for example, one millisecond) has elapsed, the discharge switch 22 is turned off (opened) at timing t19.

  After the predetermined time (for example, 1 millisecond) elapses in the OFF state of the switch, the next equalization processing is performed. At timing t20, the voltage detection circuit 21 detects the voltage of each battery cell C. This voltage is a voltage after discharge after the discharge is performed at timing t12 to timing t19. At this time, although the voltage of the capacitor 33 of the even numbered battery cell C which has been discharged does not return to the voltage of the battery cell C, the voltage of the capacitor 33 is lowered because the time of discharge immediately before is short. The amount is also small, and the difference between the capacitor 33 and the battery cell C at the time of voltage detection after discharge is very small compared to the prior art. Then, after the timing t21, the discharge is performed in the same manner as the timing t12 and later.

  Between the detection timing t11 and the detection timing t20 by the voltage detection circuit 21, the discharge switch 22 is opened and closed multiple times. Therefore, the discharge by the discharge circuit 34 is performed for a shorter time than the capacitor 33 becomes steady, and the error in voltage between the capacitor 33 and the battery cell C is reduced. In addition, discharge is performed alternately (continuously) between the group of odd-numbered battery cells C and the group of even-numbered battery cells C. Therefore, for example, while discharging the group of odd numbered battery cells C, the voltage of the capacitor 33 corresponding to the group of even numbered battery cells C can be restored.

  Returning to the description of FIG. 2 above, when the equalization process is completed, in step S14, the number of times the equalization process is performed is increased by one, and the process proceeds to step S18.

  If it is determined in step S13 that it is time to perform an abnormality diagnosis, it is determined in step S15 whether the abnormality diagnosis is an abnormality diagnosis involving a discharge in the discharge circuit 34. In the case of abnormality diagnosis not involving discharge such as temperature measurement of battery cell C, the step S15 is denied, and while performing equalization processing of step S30, abnormality diagnosis not involving discharge such as temperature measurement is performed in step S16. carry out. Then, in step S17, the number of times the equalization process is performed is increased by one, and the process proceeds to step S18. As described above, by performing the equalization process also during the abnormality diagnosis not involving the discharge, the opportunity to perform the discharge for the equalization can be increased.

  On the other hand, when it is determined in step S15 that the abnormality diagnosis involves discharge such as disconnection detection, the discharge abnormality determination process is performed in step S40. In the discharge abnormality determination processing, after the discharge and the abnormality determination based on the result are performed for the odd-numbered battery cells C, the discharge and the abnormality determination based on the results are continuously performed for the even-numbered battery cells C. FIG. 5 shows the procedure of the discharge abnormality determination process.

  In step S41, voltages of all the battery cells C are acquired. Specifically, as in step S11, the voltage of the capacitor 33 in the voltage detection circuit 21 is detected for all the battery cells C, and the voltage is acquired.

  In step S42, it is determined whether or not the battery cell C determined to require discharging in step S12 for each of the odd-numbered battery cells C. In the case of battery cell C which does not require discharge (for example, in the case of battery cell C5), discharge circuit 34 discharges in step S43 for the time necessary for abnormality determination (for example, 1 to several milliseconds). In order to turn on the discharge switch 22, the discharge switch 22 is turned on (closed). Then, after the discharge switch 22 is turned on, when a predetermined time (for example, 1 to several milliseconds) elapses, the discharge switch 22 is turned off (opened) to end the discharge.

  On the other hand, in the case of the battery cell C requiring discharge (for example, in the case of the battery cell C3), the discharge switch 22 is turned on (closed) in order to discharge in the discharge circuit 34 in step S44. The discharge time is longer than the discharge time in step S43, and is about half the time until the next voltage detection timing. Then, after the discharge switch 22 is turned on, when a predetermined time (for example, several milliseconds) elapses, the discharge switch 22 is turned off (opened) to end the discharge.

  And the voltage of all the battery cells C is acquired by step S45. Specifically, as in step S11, for all the battery cells C, the voltage detection circuit 21 detects the voltage after the discharge of the capacitor 33, and acquires the voltage. In step S46, based on the voltage detected in step S45, it is determined whether or not there is a break in the connection member L by a known method.

  In steps S47 to S49, discharge is performed on the even-numbered battery cells C, as in the case of the odd-numbered battery cells C in steps S42 to S44.

  And the voltage of all the battery cells C is acquired by step S50. Specifically, as in step S11, for all battery cells C, the voltage detection circuit 21 detects the voltage of the capacitor 33, and obtains the voltage. In step S51, based on the voltage detected in step S50, it is determined whether or not the connection member L is broken by a known method.

  Here, a time chart when such a discharge abnormality determination process is performed will be described with reference to FIG. FIG. 6 is a diagram showing the on / off state of the discharge switch 22 of the battery cell C when discharging is performed. In FIG. 6, the horizontal axis represents time, and the vertical axis represents the level of each signal.

  First, at timing t41, the voltage detection circuit 21 detects a voltage for each battery cell C. Then, when the detection by the voltage detection circuit 21 ends, the discharge switch 22 of the odd-numbered battery cell C is turned on (closed state) at timing t42, and the discharge for abnormality determination processing is performed. Specifically, the discharge switches 22 of the odd-numbered battery cells C such as the battery cells C3 and C5 are turned on.

  After discharging for a predetermined time (for example, 1 to several milliseconds), at timing t43, the discharge switch 22 of the battery cell C which does not need to be discharged is turned off (opened). On the other hand, the battery cell C which needs to be discharged is continuously held in the on state (closed state). Specifically, the discharge switch 22 of the battery cell C5 not requiring discharge is turned off (opened), while the discharge switch 22 of the battery cell C3 requiring discharge is maintained on (closed). .

  Further, when a predetermined time (for example, several milliseconds) elapses from the timing t42 when the discharge switch 22 of the odd-numbered battery cell C is turned on after a lapse of time, the battery cell C which needs to be discharged at timing t44. The discharge switch 22 is also turned off (opened). Specifically, the discharge switch 22 of the battery cell C3 is turned off at timing t44. The discharge time of the battery cell C requiring discharge is preferably longer than twice the discharge time of the battery cell C not requiring discharge, and is preferably shorter than half the cycle of the detection timing by the voltage detection circuit 21. . Then, until the timing t45 of detection by the next voltage detection circuit 21, the voltage of the capacitor 33 lowered by the discharge is recovered.

  At timing t45, the voltage detection circuit 21 detects a voltage for each battery cell C. The disconnection detection is performed based on the voltage detected at the timing t45. Then, after the timing t46, discharging is performed on the even-numbered battery cells C in the same manner as the odd-numbered battery cells C (in the same manner as the timing t42 and later). Specifically, at timing t46, the discharge switch 22 of the even-numbered battery cell C is turned on. Then, the discharge switch 22 of the battery cell C4 that does not need to be discharged is turned off (opened) at timing t47. On the other hand, the discharge switch 22 of the battery cell C6 requiring discharge is turned off (opened) at timing t48.

  Then, after the voltage of the capacitor 33 lowered by the discharge is recovered, the voltage detection circuit 21 detects the voltage of each battery cell C at timing t49. The disconnection detection is performed based on the voltage detected at the timing t49.

  As described above, by discharging the battery cells C that need to be discharged for a longer time than the battery cells C that do not need to be discharged, it is possible to perform the discharge for equalization even in the abnormality determination.

  Returning to the description of FIG. 2 above, in step S18, it is determined whether the number of equalization processes exceeds a predetermined number. If the number of equalization processes does not exceed the predetermined number, the process returns to step S13, and the abnormality determination and equalization process are performed in accordance with a predetermined schedule.

  On the other hand, when the number of equalization processes exceeds the predetermined number, in step S19, the setting of the battery cell C or the like which needs the discharge set in step S12 is reset, and the process is ended.

  In this flowchart and in the flowcharts of equalization processing and discharge abnormality determination processing, the function of step S12 corresponds to the "discharge determination unit", and the functions of steps S32, S36, S42 to S44, and S47 to S49 are "switch control units. The function of steps S16 and S40 corresponds to the "abnormality detection unit".

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

  The connection resistance L between the battery cells C and the filter circuit 31 changes in internal resistance R due to aging or the like, and when a current for discharging flows through the discharge circuit 34, the internal resistance R in the connection member L Voltage of the capacitor 33 fluctuates. Therefore, the voltage detected by the voltage detection circuit 21 after the noise is removed by the filter circuit 31 is different from the voltage of the battery cell C, which causes an error in the voltage of the battery cell C. In addition, since the internal resistance R changes due to aged deterioration or the like, it is difficult to calculate in advance the measurement error from the difference between the voltage of the capacitor 33 after equalization and the voltage of the battery cell C.

  In the present embodiment, the discharge switch 22 is opened and closed between the detection timing t11 and the detection timing t20 in the voltage detection circuit 21 for the battery cell C determined to require discharge. When the discharge switch 22 is closed, even if the capacitor 33 is discharged due to a voltage drop at the connection member L, the discharge switch 22 is opened, and the capacitor 33 tries to return to the voltage of the battery cell C. Do. By repeating these behaviors between the detection timing t11 and the detection timing t20, the capacitor 33 and the battery cell C are compared with the case where the discharge switch 22 is kept closed between the detection timing t11 and the detection timing t20. The error of the voltage of can be reduced. Therefore, the discharge of capacitor 33 due to the voltage drop at connection member L can be suppressed, the time for waiting for the recovery of the voltage of capacitor 33 can be shortened, and the voltage of battery cell C is small with a small error even without special correction. The value of can be detected.

  In the case where the discharge switch 22 is opened and closed multiple times between the detection timing t11 and the detection timing t20 as in the present embodiment, the number of times the discharge switch 22 is opened increases, so the discharge circuit 34 is equalized for equalization. The time to perform discharge due to Therefore, in the present embodiment, in addition to the discharge time originally scheduled for equalization, discharge for equalization is performed while detecting an abnormality of the battery system. Therefore, in addition to the discharge time for equalization, the discharge required for equalization can be performed by securing the time for discharge.

  As the abnormality detection, for example, there is one in which a current is supplied to a circuit including the discharge circuit 34 such as disconnection detection in the connection member L, and the abnormality is detected based on the result. In the case of such an abnormality detection, discharge is implemented with respect to all the battery cells C including the battery cell C which does not need the discharge for equalization. At this time, the discharge time of the battery cell C required to be discharged is made longer than the discharge time of the other battery cells C judged to be unnecessary. The battery cell C requiring discharge is discharged for a longer time than the battery cell C not requiring discharge, while performing detection necessary for all the battery cells C, thereby enabling discharge for equalization.

  The abnormality detection includes, for example, measurement of the temperature of the battery cell C, or the like, which detects an abnormality without using a result discharged by the discharge circuit 34. In the case of such abnormality detection as well, discharge for equalization is performed in the battery cell C determined to require discharge. Therefore, time to perform discharge for equalization can be increased.

  Between the detection timing t11 and the detection timing t20 in the voltage detection circuit 21, the discharge switch 22 is continuously opened and closed for each group for the battery cells C that need to be discharged. By opening and closing the discharge switch 22 successively for each group, the discharge switch 22 is opened in a certain group while the other group is discharging, and the capacitor 33 returns to the voltage of the battery cell C. The time will be longer. Therefore, the difference in voltage between the capacitor 33 and the battery cell C can be further reduced, and the value of the voltage in the battery cell C can be calculated quickly with little error.

Other Embodiments
The present invention is not limited to the above embodiment, and may be implemented, for example, as follows.

  In the above embodiment, during the equalization process, the group of odd-numbered battery cells C and the group of even-numbered battery cells C are continuously discharged, as shown in FIG. Between the detection timing t61 and the detection timing t68, the discharge switch 22 of the battery cell C determined to require discharge in one group may be opened and closed multiple times.

  First, at timing t61, the voltage detection circuit 21 detects a voltage for each battery cell C. Then, when the detection by the voltage detection circuit 21 is completed, the discharge switch 22 of the odd-numbered battery cell C (for example, the battery cell C3) to be discharged is turned on (closed) at timing t62. To be implemented. Meanwhile, the voltage of the corresponding capacitor 33 is lower than the voltage of the battery cell C due to the voltage drop at the internal resistance R of the connection member L.

  After discharge has been performed for a predetermined time (for example, 3 milliseconds), the discharge switch 22 is turned off (opened) at timing t63. Then, after the discharge switch 22 is turned off, after waiting for a time (e.g., about 1 millisecond) for switching until the current does not flow reliably, in the odd number The discharge switch 22 of the battery cell C (for example, the battery cell C3) is turned on (closed), and discharge is performed. Thus, the open / close operation of the discharge switches 22 of the odd-numbered battery cells C is performed in a predetermined cycle at timing t65 to timing t67.

  Then, after the predetermined time (for example, 1 millisecond) has elapsed in the OFF state of the switch, the next equalization processing is performed. At timing t68, the voltage detection circuit 21 detects a voltage for each battery cell C. This voltage is a voltage after discharge after the discharge is performed at timing t62 to timing t67. Then, after timing t68, discharging is performed on the even-numbered battery cells C in the same manner as at timing t62 and thereafter.

  Between the detection timing t61 and the detection timing t68 in the voltage detection unit, the discharge switch 22 is opened and closed multiple times with respect to the battery cell C of a certain group for the battery cell C that needs to be discharged. By discharging each group, it becomes easy to manage the discharged battery cells C.

  In the above embodiment, the voltage detection circuit 21 detects the voltage at a constant cycle, but if detection is performed at a predetermined cycle scheduled in advance, the interval between the detection timing and the detection timing may not be constant. Good.

  In the above embodiment, the voltage detected by the voltage detection circuit 21 is not corrected. However, the value of the battery cell C may be calculated from the detected voltage of the capacitor 33 by a known method. .

  In the above embodiment, the discharge of the group of the odd-numbered battery cell C and the group of the even-numbered battery cell C is performed twice between the detection timing t11 and the detection timing t20, but other times May be For example, the number of times of discharging may be different for each group, such as discharging the group of odd numbered battery cells C twice and discharging the group of even numbered battery cells C once. In this case, in the equalization process after the equalization process in which a large number of groups of odd-numbered battery cells C have been discharged, the number of discharges is final, such as a large number of groups of even-numbered battery cells C being discharged. You should try to be the same.

  DESCRIPTION OF SYMBOLS 10 ... Storage battery, 20 ... Monitoring IC, 21 ... Voltage detection circuit, 22 ... Discharge switch, 31 ... Filter circuit, 32 ... Filter resistance, 33 ... Capacitor, 34 ... Discharge circuit, 35 ... Discharge resistance, C ... Battery cell, L ... connecting members.

Claims (6)

A storage battery (10) in which a plurality of battery cells (C) are connected in series; a filter circuit (31) provided for each battery cell and having a capacitor (33) connected to the battery cell; A connection member (L) for connecting to the filter circuit, and a discharge switch (22) and a discharge resistor (35) provided for each of the battery cells and connected in series to the battery cells via the connection members. A battery control device (20) applied to a power supply system comprising a discharge circuit (34) comprising
A voltage detection unit (21) provided for each of the battery cells and detecting a voltage of the battery cells from which noise has been removed by the filter circuit;
A discharge determination unit that determines necessity of discharge in the discharge circuit for each battery cell for equalization based on the voltage of the battery cell detected by the voltage detection unit;
A switch control unit that opens and closes the discharge switch of the battery cell determined to require discharging by the discharge determination unit between the detection timing and the detection timing at which the voltage is detected by the voltage detection unit; A battery control device comprising: An abnormality detection unit for detecting an abnormality in the power supply system is provided between detection timings at which a voltage is detected by the voltage detection unit, and
While the abnormality detection unit is detecting an abnormality, the switch control unit opens / closes the discharge switch of the battery cell required to be discharged by the discharge determination unit, and discharges in the discharge circuit. The battery control device according to claim 1, wherein The abnormality detection unit detects the abnormality by detecting a result of causing the switch control unit to close the discharge switch and causing a current to flow to a circuit including the discharge circuit,
At the time of detection of the abnormality by the abnormality detection unit, the switch control unit controls the time for which the discharge switch of the battery cell required to be discharged by the discharge determination unit is closed by the discharge determination unit. 3. The battery control device according to claim 2, wherein the time for which the discharge switches of the other battery cells whose discharge is not required to be closed is longer than the time for which the discharge switch is closed. The abnormality detection unit detects the abnormality without causing the switch control unit to close the discharge switch.
3. The battery control according to claim 2, wherein the switch control unit opens and closes the discharge switch of the battery cell required to be discharged by the discharge determination unit also when the abnormality detection unit detects the abnormality. apparatus. The battery cells are divided into a plurality of groups such that adjacent battery cells are in different groups.
The switch control unit is configured to open and close the discharge switch of the battery cell determined to require discharge by the discharge determination unit between detection timing and detection timing when the voltage detection unit detects a voltage. The battery control device according to any one of claims 1 to 4, which is performed successively every time. The battery cells are divided into a plurality of groups such that adjacent battery cells are in different groups.
The switch control unit is configured such that the discharge determination unit determines that the discharge determination unit needs to discharge the battery cells of a certain group between detection timings at which a voltage is detected by the voltage detection unit. The battery control device according to any one of claims 1 to 4, wherein the discharge switch of the battery cell is opened and closed plural times.

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