JP6011265B2 - Battery system - Google Patents

Description

  The present invention relates to a battery system that includes an assembled battery including a plurality of single cells and calculates a full charge amount of the assembled battery.

  The battery deteriorates by repeating charge and discharge. In particular, when overcharge or overdischarge occurs, the progress of deterioration becomes faster. In order to suppress overcharge and overdischarge, the battery can be charged and discharged so that the state of charge (SOC: State of Charge) is within a predetermined range, whereby progress of battery deterioration can be suppressed. Here, the state of charge is the ratio of the current charge amount of the battery to the full charge amount (Ahf), and the full charge amount is the charge amount of the fully charged battery.

  The state of charge can be calculated using the full charge amount. Here, as the battery is repeatedly charged and discharged, the deterioration progresses, and the full charge amount decreases. By calculating the full charge amount that changes according to the deterioration of the battery and calculating the charge state of the battery using the full charge amount, the charge state of the battery can be calculated more accurately. It is possible to suppress overdischarge.

  Therefore, Patent Document 1 proposes a method for calculating the full charge amount (Ahf) as follows. The amount of current flowing through the battery is detected between the first time and the second time, and the amount of change (ΔAh) in the charge / discharge amount is calculated using the amount of current. Further, at the first time and the second time, the output voltage of the battery is detected, the state of charge at each timing is calculated using the output voltage, and the amount of change in the state of charge (ΔSOC) using the state of charge. Is calculated. The full charge amount (Ahf = ΔAh / ΔSOC) is calculated by dividing the change amount of charge / discharge amount (ΔAh) by the change amount of charge state (ΔSOC).

JP 2008-241368 A

  In addition, for example, since a high output voltage is required for a battery used in an electric vehicle or a hybrid vehicle, an assembled battery in which a plurality of single cells are connected in series is used. There are individual differences among the plurality of single cells, and the internal resistance and the like of each single cell have different values. For this reason, when charging / discharging is repeated in the assembled battery, variations in output voltage occur between the single cells. When the variation occurs, the battery charging range is detected until the overcharge of the unit cell having the highest output voltage is detected, and the battery discharge range is detected until the overdischarge of the unit cell having the lowest voltage is detected.

  For this reason, as the variation in the output voltage, which is the difference between the highest output voltage and the lowest output voltage among the output voltages of the unit cells, increases, the range in which the assembled battery can be charged and discharged becomes narrower. Accordingly, a discharge circuit is provided for each single cell, and an equalization process is performed to equalize the output voltage between the single cells by performing discharge individually based on the output voltage of the single cells.

  When the output voltage is equalized between the first time and the second time when calculating the full charge amount, the charge state is calculated based on the output voltage, and the charge state is calculated from the charge state. When the amount of change (ΔSOC) is calculated, the calculated amount of change in the charge state includes the influence of discharge accompanying the equalization of the output voltage.

  On the other hand, no current flows through the entire assembled battery in equalizing the output voltage. For this reason, when the current flowing through the battery pack is detected between the first time and the second time, and the change amount of the charge / discharge amount is calculated using the detected value, the output voltage is equalized in the calculation result. This does not include the influence of the discharge associated with, and is different from the actual amount of change in charge / discharge. For this reason, if the equalization of the output voltage is performed from the first time to the second time, the calculation accuracy of the full charge amount decreases.

  The present invention is for solving the above-described problems, and provides means capable of appropriately performing both the equalization processing of the output voltage of the unit cell included in the assembled battery and the calculation processing of the full charge amount of the unit cell. The purpose is to do.

The battery system according to this configuration includes an assembled battery (10) including a plurality of single cells (C1 to Cn) connected in series, a voltage detection means (U) for detecting output voltages of the plurality of single cells, Current detection means (60) for detecting charging / discharging current flowing in the assembled battery, and charge state calculation means for calculating the state of charge (SOC) of each of the plurality of single cells based on the voltage detected by the voltage detection means ( 50).

  Further, the full charge amount calculation period is set from the first time to the second time thereafter, and the full charge amount calculation is performed using the charge states at the first time and the second time calculated by the charge state calculation means. A first change amount calculation means (50) for calculating a change amount (ΔSOC) of the state of charge of each of the plurality of single cells in a period, and a current detected by the current detection means in the full charge amount calculation period A second change amount calculating means (50) for calculating a change amount (ΔAh) of the charge / discharge amount of each of the plurality of single cells; a charge state change amount calculated by the first change amount calculating means; Based on the change amount of the charge / discharge amount calculated by the change amount calculation means, the full charge amount calculation means (50) for calculating the full charge amounts (Ahf) of the plurality of single cells, respectively, and the voltage detection means An equalization means (50) for selectively discharging the plurality of single cells based on the detected voltage to equalize the output voltages of the plurality of single cells, the full charge amount calculation period, and the equalization And prohibiting means (50) for prohibiting duplication of the discharge period with the means.

  According to the above configuration, since the overlap between the full charge amount calculation period and the discharge execution period by the equalizing means is prohibited, it is possible to suppress a decrease in the calculation accuracy of the full charge amount caused by the equalization of the output voltage. Can do.

The system block diagram concerning one Embodiment. The figure which shows the correspondence of the variation | change_quantity of charging / discharging amount, and the variation | change_quantity of a charge condition. The figure which shows the correspondence of an open end voltage and a charge condition. The flowchart which shows the equalization process concerning the embodiment. The flowchart which shows the full charge amount calculation process concerning the embodiment. The flowchart which shows the equalization process concerning a modification. The flowchart which shows the full charge amount calculation process concerning a modification.

  Hereinafter, an embodiment in which a battery system that calculates a full charge amount for each battery cell (unit cell) of an assembled battery and performs equalized discharge of the assembled battery is applied to a hybrid vehicle will be described with reference to the drawings. .

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

  The illustrated assembled battery 10 is an assembled battery as a series connection body of battery cells C1 to Cn, and has an open end voltage (OCV) of, for example, 100 V or more. The battery cell Ci (i = 1 to n) is a secondary battery such as a lithium ion storage battery. The battery cells C1 to Cn have the same configuration except for individual differences. That is, the relationship between the OCV with respect to the SOC, the full charge amount and the internal resistance value when no deterioration has occurred, and the like are equal to each other.

  The assembled battery 10 is connected to the second motor generator 14 via the main relay MR and the inverter 12. The second motor generator 14 is an in-vehicle main machine, and its rotor is mechanically connected to the drive wheels 16.

  The assembled battery 10 is connected to the first motor generator 20 via the main relay MR and the inverter 18. The rotor of the first motor generator 20 is mechanically connected to the crankshaft of the engine 22 that is an internal combustion engine. The first motor generator 20 functions as a generator that converts the power of the crankshaft into electrical energy, and functions as an initial rotation imparting means (starter) that imparts initial rotation to the crankshaft when the engine 22 is stopped. Have

  In the present embodiment, the second motor generator 14, the first motor generator 20, and the engine 22 are controlled by a control device (not shown) that controls them, thereby stopping the HV mode for driving the engine 22 and the engine 22. The EV mode in which the vehicle travels in the state is selected as appropriate.

  A monitoring unit U that monitors the state of the battery cells C1 to Cn is connected to the assembled battery 10. The monitoring unit U includes a discharge resistor 30 and a switching element 32 connected to each of the battery cells C1 to Cn, and a discharge control unit 34 that selectively turns on the switching element 32. The monitoring unit U includes a multiplexer 36 that selectively applies one of the output voltages of the battery cells C1 to Cn to the differential amplifier circuit 38. Thereby, each output voltage of battery cell C1-Cn is input into the analog-digital converter 40 via the differential amplifier circuit 38, and is converted into digital data here.

  On the other hand, the control device 50 controls the state of the assembled battery 10 by operating the monitoring unit U. The control device 50 operates the monitoring unit U to perform equalized discharge of the output voltages of the battery cells C1 to Cn. The control device 50 is software processing means including a central processing unit and a memory. Here, the control device 50 has a function of inputting digital data (detection signal Sv) output from the analog-to-digital converter 40 and outputting a command signal Sc to the discharge control unit 34 of the monitoring unit U based on this. Here, the command signal Sc is used to command which of the battery cells C1 to Cn is discharged using the discharge resistor 30 (and whether the discharge is stopped).

  The control device 50 also has a function of opening and closing the main relay MR based on on / off of an ignition switch (hereinafter referred to as an IG switch) as a power switch and the running state of the vehicle. The control device 50 temporarily delays turning on the main relay MR when the IG switch is operated from off to on. Further, the control device 50 controls the main relay MR to be in an open state during a period in which the IG switch is off, and stops charging / discharging in the assembled battery 10.

  Based on the detection signal Sv, the control device 50 shown in FIG. 1 sends a command signal to discharge a battery cell having a high OCV when the variation width of the OCV between the battery cells C1 to Cn is equal to or greater than a specified amount. In addition to outputting Sc, a discharge stop command is output when the equalized discharge time has elapsed. Here, the variation width of the OCV is a difference between the maximum voltage value and the minimum voltage value among the OCVs of the battery cells C1 to Cn. Here, the equalizing discharge time is set to a relatively long time (for example, 1 hour or more). This is due to the fact that the discharge current using the discharge resistor 30 is relatively small.

  As shown in FIG. 1, a current sensor 60 is provided between the assembled battery 10 and the main relay MR. The current sensor 60 detects a charge / discharge current that is an output current of the battery pack 10 and outputs a detection signal Si. The control device 50 acquires the current value Ia of the charge / discharge current of the assembled battery 10 from the detection signal Si input from the current sensor 60. The control device 50 calculates the full charge amount Ahf of each of the battery cells C1 to Cn based on the detection signal Si and the detection signal Sv.

  FIG. 2 shows a relationship diagram between the SOC and the charge / discharge amount when they change. Since SOC is the ratio of the actual charge amount of the storage battery to the full charge amount Ahf, the charge / discharge amount is 0 when the SOC is 100%, and the charge / discharge amount is the full charge amount Ahf when the SOC is 0%. Hereinafter, a method for calculating the full charge amount Ahf based on the SOC change amount ΔSOC and the charge / discharge amount change amount ΔAh will be described with reference to FIG. Here, for convenience of explanation, one battery cell C will be described.

  In FIG. 2, the full charge amount calculation period is from the first time to the second time. The first time and the second time are timings at which the OCV of the battery cell C can be detected, for example, timings immediately after the IG switch is switched from the off state to the on state. At this timing, the charging / discharging current does not flow through the assembled battery 10, and the OCV can be detected.

  At the first time that is the start time of the full charge amount calculation period and the second time that is the end time, the state of charge is calculated as SOC1 and SOC2 by the OCV of the battery cell C, respectively. Here, as shown in FIG. 3, the OCV and the SOC have a one-to-one relationship, and this relationship is stored in the control device 50 as a map. Then, SOC1 and SOC2 of the battery cell C are calculated based on the relationship of FIG. Then, the SOC change ΔSOC between the first time and the second time is calculated as the difference between SOC1 and SOC2 (ΔSOC = SOC1-SOC2).

  In addition, during the period from the first time to the second time, the change amount ΔAh of the charge / discharge amount, that is, the charge amount that enters and exits the battery cell C is calculated by time-integrating the current value Ia of the output current of the assembled battery 10. (ΔAh = ∫Ia · dt).

  As described above, the first time and the second time are immediately after the IG switch is turned on, and there is a period in which the IG switch is turned off between the first time and the second time. In this case, SOC1 and ΔAh may be stored in EEPROM (registered trademark), which is a nonvolatile storage unit in control device 50, so that information on SOC1 and ΔAh is retained even when the IG switch is off.

  Since the SOC change amount ΔSOC calculated as described above and the charge / discharge amount change amount ΔAh have a relationship of Ahf × ΔSOC = ΔAh, the full charge amount Ahf is obtained as Ahf = ΔAh / ΔSOC. In FIG. 2, the slope of the straight line L1 corresponds to the full charge amount Ahf.

  However, if the equalization discharge of the battery cell C is performed between the first time and the second time, the SOC of the battery cell C is reduced at the second time due to the decrease in the OCV of the battery cell C accompanying the equalization discharge. Becomes SOC2 ′ lower than SOC2, and the amount of change in SOC is calculated as “SOC1-SOC2 ′” (ΔSOC ′ in the figure). On the other hand, regarding the change amount ΔAh of the charge / discharge amount, even if the equalization discharge is performed in the battery cell C, only a current flows through the discharge resistor 30 for each battery cell C, and the battery pack 10 is charged / discharged. No current flows, and the current value Ia detected by the current sensor 60 remains zero. For this reason, the change amount ΔAh of the charge / discharge amount does not change between when the equalized discharge is performed and when it is not performed.

  That is, when equalized discharge is performed in the full charge amount calculation period, the value of the full charge amount Ahf is different from the case where equalized discharge is not performed, and the calculation accuracy of the full charge amount Ahf is reduced. In FIG. 2, the full charge amount is calculated as the slope of the straight line L2, which is “Ahf ′”. Therefore, in the present embodiment, a decrease in the calculation accuracy of the full charge amount Ahf is suppressed by preventing an overlap between the full charge amount calculation period and the equalization discharge execution period.

  FIG. 4 shows a procedure of processing performed by the control device 50 in particular regarding the equalization processing in the present embodiment. The equalization process is performed by starting the control device 50 when the IG switch is turned off and continues for a predetermined time (for example, 1 hour) in the off state.

  First, in step S10, the OCV of each of the battery cells C1 to Cn is detected. In step S11, the variation width of the OCV between the battery cells is calculated. In step S12, it is determined whether or not the OCV variation width is equal to or greater than a first determination value K1 for determining whether or not equalization discharge is to be performed. The first determination value K1 is, for example, a value that becomes 5% when OCV is converted to SOC. If the variation width <the first determination value K1 (S12: NO), the process is terminated without performing equalization discharge.

  If an affirmative determination is made in step S12, it is determined in step S13 whether or not the full charge amount Ahf is currently being calculated. When the calculation of the full charge amount Ahf is not performed (S13: NO), the execution of the equalized discharge is permitted. That is, in step S16, the monitoring unit U is controlled to perform equalization discharge on the battery cells C1 to Cn, and then this process is terminated.

  In addition, when the full charge amount Ahf is calculated (S13: YES), priority determination processing (S14, S15) for determining which of the calculation of the full charge amount Ahf and equalization discharge has priority is performed. To do. That is, in step S14, it is determined whether or not the variation width of the OCV is equal to or greater than a second determination value K2 for determining whether equalization discharge is prioritized over calculation of the full charge amount Ahf. The second determination value K2 is a value larger than the first determination value K1, and is, for example, a value that becomes 10% when OCV is converted into SOC. When the variation width <the second determination value K2, the equalization discharge is not prioritized over the calculation of the full charge amount Ahf, and this process is terminated as it is. That is, the equalization discharge is prohibited.

  If an affirmative determination is made in step S14, it is determined in step S15 whether or not the plurality of battery cells C1 to Cn include battery cells that are in a predetermined deterioration state. Here, the deterioration determination for each of the battery cells C1 to Cn may be performed based on, for example, whether there is an overcharge or overdischarge among the battery cells C1 to Cn. More specifically, in the assembled battery 10, charge / discharge ranges in which charging / discharging is to be performed in each of the battery cells C <b> 1 to Cn are respectively determined, and the control device 50 determines each of the battery cells C <b> 1 to C <b> 1 during driving of the vehicle. Overcharge / overdischarge diagnosis is performed by sequentially determining whether the SOC of Cn is within the charge / discharge range. Then, when overcharge / overdischarge occurs in any of the battery cells (or when the overcharge / overdischarge repeatedly occurs), it is determined that the battery cell is in a predetermined deterioration state.

  When the battery cell in the predetermined deterioration state is included (S15: YES), more precise charge / discharge management is required for each of the battery cells C1 to Cn. Therefore, even if the variation width ≧ the second determination value K2, the equalization discharge is not prioritized over the calculation of the full charge amount Ahf, and this process is terminated as it is. That is, the equalization discharge is prohibited.

  If the battery cell in the predetermined deterioration state is not included (S15: NO), the monitoring unit U is controlled in step S16 to perform equalization discharge on the battery cells C1 to Cn. In other words, even when the full charge amount Ahf is being calculated, since the variation range of the OCV is equal to or greater than the second determination value K2, the equalized discharge is given priority over the calculation of the full charge amount Ahf.

  FIG. 5 shows a procedure of processing performed by the control device 50 in particular regarding the full charge amount calculation processing in the present embodiment. This process is performed at a period of Δt seconds by the control device 50 in a state where the IG switch is on.

  First, in step S20, it is determined whether there is an Ahf calculation request. Here, the Ahf calculation request is when the distance traveled by the vehicle since the full charge amount Ahf was calculated last time exceeds a predetermined value, or when overdischarge and overcharge diagnosis occur frequently in the battery pack 10. To occur. If there is no Ahf calculation request, the process ends. If an affirmative determination is made in step S20, it is determined in step S21 whether equalization discharge is currently being performed.

  If an affirmative determination is made in step S21, it is determined in step S22 whether an OCV detection condition is satisfied. Here, the OCV detection condition includes immediately after the IG switch is switched from the off state to the on state, and includes that the main relay MR is in the off state. In addition, the present embodiment includes that the main relay MR has been kept off for a predetermined time (for example, 1 hour) before the IG switch is turned on. Immediately after the IG switch is switched to the on state, no current flows through the assembled battery 10, which is a suitable state for OCV detection. Further, the fact that the main relay MR is kept off for a predetermined time or more means that no current flows through the assembled battery 10. For this reason, the influence of the polarization with respect to OCV can be suppressed and it is a suitable state for the detection of OCV. When both of these conditions are satisfied, it is determined that the OCV detection condition is satisfied.

  If a positive determination is made in step S22, the OCV of each battery cell C1 to Cn is detected in step S23. Next, in step S24, it is determined whether or not the SOC (SOC1) at the first time, which is the start time of the full charge amount calculation period, has been calculated. If a positive determination is made in step S24, SOC1 is calculated based on the OCV of each of the battery cells C1 to Cn in step S25. In step S26, the calculated SOC1 is stored in the EEPROM, and the process ends.

  If a negative determination is made in step S22, that is, if the OCV detection condition is not satisfied, it is determined in step S27 whether or not SOC1 has been calculated. If it is not after the calculation of SOC1, the process is terminated. When a positive determination is made in step S27, the current value Ia of the charge / discharge current of the assembled battery 10 is detected in step S28. In step S29, the product of the current value Ia and the full charge amount calculation process Δt is added to the change amount ΔAh (previous value) of the charge / discharge amount to calculate the current value of ΔAh. In step S26, the calculated ΔAh is stored in the EEPROM, and the process is terminated. Note that the storage of SOC1 and ΔAh in the EEPROM may not be performed for each process, but may be performed collectively when the IG switch is turned off.

  If a negative determination is made in step S24, that is, if it is determined that SOC1 has been calculated, it is determined in step S30 whether or not an Ahf calculation condition is satisfied. Here, in the Ahf calculation condition, in order to suppress an increase in the calculation error of Ahf due to the accumulation of detection errors of the current sensor 60, T_ON, which is the time when the assembled battery 10 is charged / discharged, is a predetermined value (for example, 10 Time) or less. In addition, in the assembled battery 10, in order to prevent the SOC from being reduced due to natural discharge and causing an Ahf calculation error, the time T_OFF during which the main relay MR is in the OFF state during the full charge amount calculation period. Is less than or equal to a predetermined value (for example, 3 days). Moreover, in order to suppress the influence of disturbance, it includes that (DELTA) SOC which is the variation | change_quantity of a charge condition is more than predetermined value (for example, 10%). Moreover, in order to suppress the influence of disturbance, it includes that ΔAh, which is the amount of change in the charge / discharge amount, is equal to or greater than a predetermined value (for example, 10% of Ahf in a state where the charge / discharge amount is not deteriorated). When all these conditions are satisfied, it is assumed that the Ahf calculation condition is satisfied (S30: YES).

  In step S31, the SOC (SOC2) at the second time, which is the end time of the full charge amount calculation period, is calculated based on the OCV of each of the battery cells C1 to Cn detected in the current process. Next, in step S32, the change amount ΔSOC of the SOC of each battery cell C1 to Cn is calculated (ΔSOC = SOC1-SOC2). In step S33, Ahf of each of the battery cells C1 to Cn is calculated (Ahf = ΔAh / ΔSOC), and the process is terminated.

  If the Ahf calculation condition is not satisfied (S30: NO), the calculation of Ahf is stopped in step S34, and the process ends. In step S34, the SOC1 and ΔAh values are initialized. Further, when a negative determination is made in step S21, that is, when equalization discharge is performed, the calculation of Ahf is stopped in step S34 in order to suppress duplication of the equalization process and the full charge amount calculation process. Then, the process ends.

  The effects achieved by this embodiment will be described below.

  According to the above configuration, since the overlap between the full charge amount calculation period and the equalization discharge execution period is prohibited, it is possible to suppress a decrease in the calculation accuracy of the full charge amount Ahf due to the execution of the equalization discharge. . Furthermore, even when the OCV variation width is equal to or larger than the first determination value K1 at the time of the determination in step S12 of FIG. 4, the equalization discharge is prohibited during the full charge amount calculation period. By giving priority to the full charge amount calculation process, an opportunity to calculate the full charge amount Ahf can be secured.

  Equalization discharge is implemented based on the open end voltage OCV detected in the state in which charging / discharging electric current does not flow into the assembled battery 10. FIG. Accordingly, the OCV is detected discontinuously, and when the assembled battery 10 is switched from the state where the charging / discharging current is flowing to the state where it is not flowing, the variation width of the OCV of each of the battery cells C1 to Cn is increased. It may have become too large. That is, it is considered that the variation width of the OCV is greater than or equal to the second determination value K2. In this case, it is not desirable to leave a state where the variation width of the OCV is excessively large. In this regard, in the case of variation width ≧ K2, even discharge is preferentially performed even when the full charge amount Ahf is being calculated. Therefore, it is said that the OCV variation width is excessively large. Inconvenience can be suppressed. Moreover, it is possible to suitably ensure an opportunity for performing the equalizing discharge.

  When the battery cell is in a deteriorated state, the charge / discharge speed is high, and it becomes difficult to control the SOC within a predetermined charge / discharge range. In this regard, when the battery cell C is in a deteriorated state, even if OCV variation width ≧ K2, the equalization discharge is not prioritized over the calculation of the full charge amount Ahf, and the equalization discharge is not performed. Banned. Thereby, when the battery cell is in a deteriorated state, more precise charge / discharge management of each of the battery cells C1 to Cn can be performed.

  When current flows through the battery, polarization occurs and the electromotive force fluctuates. And the fluctuation of the electromotive force continues until a predetermined time elapses after the current output is stopped. As the electromotive force varies, the OCV also varies. In the above configuration, when the IG switch is turned off and continues for a predetermined time in the off state, that is, in a state where the current output in the assembled battery 10 is stopped for a predetermined time or longer, the OCV is detected. It can be detected accurately. In the equalization process, the OCV detected with high accuracy is used to determine the variation width of the OCV and determine whether or not the equalization discharge is necessary, so that the equalization discharge can be appropriately performed. Similarly, in the full charge amount calculation process, each SOC is calculated based on the OCV detected with high accuracy. For this reason, the calculated SOC is calculated with high accuracy. Then, by calculating the full charge amount Ahf using the SOC, the full charge amount Ahf can be accurately calculated.

  When charging / discharging of the assembled battery 10 is stopped by turning off the IG switch, the charge amount of the assembled battery 10 decreases due to spontaneous discharge. Since the change in the charge amount due to the natural discharge cannot be calculated using the output current of the battery pack 10, the calculation accuracy of the change amount ΔAh in the charge / discharge amount decreases when the natural discharge increases. Therefore, in order to suppress the influence on the calculation accuracy due to spontaneous discharge, the full charge amount calculation condition includes that T_OFF is shorter than a predetermined value (for example, 3 days). Thereby, when the time for which the IG switch is in the OFF state is equal to or longer than the predetermined time, the calculation of the full charge amount Ahf is stopped and the full charge amount Ahf is prevented from being calculated with low accuracy.

  The current value Ia detected by the current sensor 60 includes an error, and the longer the integration time, the more the error is accumulated with respect to the change amount ΔAh of the charge / discharge amount calculated as the time integration of the current value Ia. It becomes. For this reason, in the full charge amount calculation period, the accuracy of the calculated full charge amount Ahf decreases as the time during which the current flows through the assembled battery 10 is longer. Therefore, the full charge amount calculation condition includes that T_ON is a predetermined value or less (for example, 10 hours). Thereby, when the error of the change amount ΔAh of the charge / discharge amount becomes large with the addition of the current value Ia for a long time, the error in the full charge amount Ahf is suppressed by not calculating the full charge amount Ahf. be able to.

  The full charge amount calculation condition includes that ΔSOC is equal to or greater than a predetermined value and ΔAh is equal to or greater than a predetermined value. Thereby, it is possible to suppress the influence of errors due to disturbances such as noise.

(Other embodiments)
In the middle of the full charge amount calculation period, when the variation range of the OCV is equal to or greater than the second determination value K2 and the equalization discharge is permitted (when both steps S13 and S14 in FIG. 4 are YES), Let the time of permission be the end time of the full charge amount calculation period, and calculate the full charge amount Ahf of each battery cell C1 to Cn based on ΔSOC and ΔAh in the period between the first time and the time of permission. It may be. Specifically, the control device 50 performs the equalization process shown in FIG. 6 and the full charge amount calculation process shown in FIG. Note that the equalization process shown in FIG. 6 is performed in place of the equalization process shown in FIG. Further, the full charge amount calculation process shown in FIG. 7 is a process performed in addition to (or in parallel with) the full charge amount calculation process shown in FIG.

  Compared with the equalization process shown in FIG. 4, the equalization process shown in FIG. 6 has step S40 added as a process after a positive determination is made in step S15. In step S40, the SOC3 of each battery cell C1 to Cn is calculated based on the OCV at this time, and the SOC3 is stored in the EEPROM. Then, equalization discharge is performed in step S16.

  In the full charge amount calculation process shown in FIG. 7, in step S50, it is determined whether or not the SOC3 is calculated and stored in the EEPROM while the IG is off, and if the determination is affirmative, the process proceeds to step S51. move on. In step S51, SOC variation ΔSOC of each battery cell C1 to Cn is calculated from SOC1 and SOC3 (ΔSOC = SOC1-SOC3). In step S52, the Ahf of each of the battery cells C1 to Cn is calculated (Ahf = ΔAh / ΔSOC), and the process ends.

  7 is performed in preference to the calculation of the full charge amount Ahf (steps S31 to S33) according to FIG. 5. When the full charge amount Ahf is calculated according to FIG. The amount of charge Ahf is not calculated.

  Note that the calculation of the full charge amount Ahf based on the SOC3 may be continued after the IG switch is turned off, that is, when the SOC3 is calculated, instead of being performed after the IG switch is turned on.

  In the middle of the full charge amount calculation period, when the OCV variation width is excessively large (greater than or equal to the second determination value K2) and equalization discharge is permitted, the calculation of the full charge amount Ahf is stopped at that time. Then, information (SOC1 and ΔAh) acquired for calculating Ahf until then is wasted. In this regard, as described above, the time of permission is the end time of the full charge amount calculation period, and the full charge of each of the battery cells C1 to Cn is based on ΔSOC and ΔAh in the period between the first time and the time of permission. Since the amount Ahf is calculated, the acquired information is not wasted, and the full charge amount Ahf can be suitably calculated according to the calculation request.

  In this case, the first time is the ON timing of the IG switch during the previous vehicle operation, the second time is the ON timing of the IG switch during the subsequent vehicle operation, and the equalization discharge is allowed to be performed during the IG OFF period therebetween. It is considered that the information for calculating Ahf has already been acquired sufficiently at the time when the discharge is permitted. Therefore, it is considered that there is no problem with the calculation of the full charge amount Ahf.

  In addition, it is determined whether or not the time between the first time and the discharge permission time is a predetermined time (for example, 1 hour) or more, and the acquired information at the time of discharge permission is used only when the time is the predetermined time or more. Thus, the full charge amount Ahf may be calculated.

  -Instead of the configuration in which the OCV is detected immediately after the IG switch is turned on, the OCV may be detected immediately after the IG switch is turned off. In this case, the polarization state of the battery cells C1 to Cn may be estimated based on the current value Ia flowing through the assembled battery 10, and the OCV may be corrected based on the estimation. Thereby, the variation width and SOC of the OCV can be accurately calculated.

  Even if the IG switch remains on, charging / discharging between the motor generators 14 and 20 may be stopped, and the battery cell C1 is opened by opening the main relay MR at that time. It is possible to detect the OCV of ~ Cn. Therefore, it is determined whether or not the main relay MR is opened (off), and the OCV is detected under the condition that the main relay MR is opened, and the equalized discharge and the full charge amount are calculated based on the OCV. You may make it do.

  -Instead of the configuration in which the equalized discharge is performed based on the variation width of the OCV of each of the battery cells C1 to Cn, the variation width of the cell output voltage detected in a state where the current flows through each of the battery cells C1 to Cn. It is good also as a structure which implements equalization discharge based on this. Moreover, it replaces with the structure which calculates SOC based on OCV of each battery cell C1-Cn, and is a structure which implements SOC based on the cell output voltage detected in the state in which the current is flowing into each battery cell C1-Cn. It is good.

  -The target of the equalization discharge process and the full charge amount calculation process is not limited to the battery cells C1 to Cn. For example, a part of the battery cells that are two or more adjacent battery cells and constitute the assembled battery 10 may be a single battery, and the single batteries may be processed. That is, even if a discharge resistor and a switching element are connected to each unit cell, and the discharge control unit 34 selectively turns on the switching element to perform equalized discharge for each unit cell. Good.

  DESCRIPTION OF SYMBOLS 10 ... Battery pack 50 ... Control device (charge state calculation means, first change amount calculation means, second change amount calculation means, full charge amount calculation means, equalization means, prohibition means), 60 ... current sensor (current detection) Means), C1 to Cn ... battery cells (single cells), U ... monitoring unit (voltage detection means), Ahf ... full charge amount, SOC ... charge state, [Delta] Ah ... charge / discharge amount change, [Delta] SOC ... charge state change. amount.

Claims (8)

An assembled battery (10) comprising a plurality of single cells (C1 to Cn) connected in series;
Voltage detection means (U) for detecting output voltages of the plurality of single cells,
Current detection means (60) for detecting charge / discharge current flowing in the assembled battery;
Charge state calculation means (50) for calculating the state of charge (SOC) of each of the plurality of single cells based on the voltage detected by the voltage detection means;
The full charge amount calculation period is from the first time to the second time thereafter, and the respective charge states at the first time and the second time calculated by the charge state calculation means are used in the full charge amount calculation period. A first change amount calculating means (50) for calculating a change amount (ΔSOC) of a charge state of each of the plurality of single cells;
Second change amount calculating means (50) for calculating change amounts (ΔAh) of charge / discharge amounts of the plurality of single cells in the full charge amount calculation period based on the current detected by the current detection means;
Full charge amounts (Ahf) of the plurality of single cells based on the change amount of the charge state calculated by the first change amount calculation unit and the change amount of the charge / discharge amount calculated by the second change amount calculation unit. A full charge amount calculating means (50) for calculating
Equalizing means (50) for selectively discharging the plurality of cells individually based on the voltage detected by the voltage detection means and equalizing output voltages of the plurality of cells;
Except for the case where priority is given to discharging by the equalization unit over calculation of the full charge amount by the full charge amount calculation unit , duplication of the full charge amount calculation period and the discharge execution period by the equalization unit is prohibited. Prohibited means (50);
A battery system comprising: The prohibiting means determines whether or not the full charge amount calculation period is reached at the time when the condition is satisfied when the execution condition based on the voltage detected by the voltage detecting means is satisfied for the equalization by the equalizing means. If the full charge amount calculation period is reached, the discharge by the equalization unit is prior to the discharge by the equalization unit over the calculation of the full charge amount by the full charge amount calculation unit . The battery system according to claim 1, wherein implementation is prohibited. The equalizing means is a first determination value in which a variation width between the cells of the open-circuit voltage (OCV) detected by the voltage detecting means in a state where no charging / discharging current flows in the assembled battery is determined in advance. (K1) In the case where it is equal to or higher, the plurality of single cells are selectively discharged,
When the discharge execution condition is satisfied when the variation range of the open-circuit voltage is equal to or greater than the first determination value, the variation of the open-circuit voltage even if the full charge amount calculation period is reached at that time. 3. The battery system according to claim 2, further comprising a unit that permits discharge by the equalizing unit when a width is equal to or greater than a second determination value (K <b> 2) that is larger than the first determination value. A deterioration determining means for determining whether or not the plurality of single cells include a predetermined deterioration state;
In the case where it is determined that the unit cell that is in the predetermined deterioration state is included, the prohibiting unit is configured to perform the equalization even if the variation width of the open-ended voltage is equal to or greater than the second determination value. The battery system according to claim 3, wherein equalization by means is prohibited.   The full charge amount calculation means, when the variation width of the open-circuit voltage is not less than the second determination value and the discharge by the equalization means is permitted during the full charge amount calculation period, The permitted time is the end time of the full charge amount calculation period, and the unit cell is based on the change amount of the charge state and the change amount of the charge / discharge amount in the period between the first time and the permission time point. 5. The battery system according to claim 3, wherein the full charge amount is calculated. The voltage detection means is for detecting an open-ended voltage of each unit cell in a state where no charge / discharge current flows through the assembled battery,
Based on the open-circuit voltage detected after a predetermined time has elapsed since charging / discharging of the assembled battery was stopped, the charge state calculation by the charge state calculation means and the discharge by the equalization means It implements, The battery system of any one of Claim 1 thru | or 5 characterized by the above-mentioned. A battery system mounted on a vehicle,
The first time is a time when the power switch of the vehicle is turned on, and the second time is a time when the power switch is subsequently turned off and then turned on again,
The full charge amount calculation is stopped when a time (T_OFF) during which the power switch is kept in an off state in the full charge amount calculation period is equal to or greater than a predetermined off time determination value. The battery system according to any one of 1 to 6. A battery system mounted on a vehicle,
The calculation of the full charge amount is stopped when a time (T_ON) during which the power switch of the vehicle is kept on in the full charge amount calculation period is equal to or greater than a predetermined on time determination value. The battery system according to any one of claims 1 to 7.

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