JP2015083928A - Full charge capacity calculation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a full charge capacity calculation device capable of highly accurately calculating a full charge capacity of a battery mounted on a vehicle.SOLUTION: A full-charge-capacity calculation device includes: remaining-capacity calculation means detecting an open voltage of a battery cell 10a right after a starting switch is turned on and calculating a remaining capacity of the battery cell 10a on the basis of the detected open voltage; charge/discharge-amount calculation means calculating a charge/discharge amount of the battery cell 10a during one trip since a starting switch is turned on until the starting switch is turned off; and a memory 52 storing the remaining capacity of the battery cell 10a calculated by the remaining-capacity calculation means and the charge/discharge amount of the battery cell 10a calculated by the charge/discharge-amount calculation means. On condition that a difference between the remaining capacity calculated by the remaining-capacity calculation means at a time of starting a present trip and the remaining capacity at a time of starting a previous trip stored in the memory 52 is greater than a predetermined value, a full charge capacity of the battery cell 10a is calculated from the difference and the charge/discharge amount during the previous trip stored in the memory 52.

Description

  The present invention relates to an apparatus for calculating a full charge capacity of a battery mounted on a vehicle.

  In recent years, storage batteries have been required to have a large capacity, and battery packs including battery cells connected in parallel and in series, and assembled batteries in which battery packs are further connected in series are used. In such battery packs and assembled batteries, it is required to accurately detect the full charge capacity of each battery cell or each battery pack in order to avoid overcharging. However, the full charge capacity of each battery cell or each battery pack is required. Decreases gradually with the deterioration of the battery cells.

  Therefore, in Patent Document 1, the battery packs are equalized so that the most deteriorated battery pack is fully charged first, and when the most deteriorated battery pack is fully charged, charging of the assembled battery is stopped. doing. Then, discharge until the remaining capacity of the battery pack that has been most deteriorated is close to 0%, and the full charge capacity is calculated from the amount of change in the remaining capacity of each battery pack and the accumulated discharge amount. The capacity is being updated.

JP2013-51820A

  When the battery pack is applied to a vehicle, the remaining capacity of the battery cell cannot be accurately obtained because the voltage of the battery cell is not stable while the vehicle is running or immediately after it is stopped. Therefore, it is difficult to accurately detect the full charge capacity of the battery cell from the amount of change in the remaining capacity and the accumulated discharge amount during traveling.

  In view of the above circumstances, the present invention has as its main object to provide a full charge capacity calculation device capable of calculating the full charge capacity of a battery mounted on a vehicle with high accuracy.

  In order to solve the above problem, the invention according to claim 1 is a full charge capacity calculation device for calculating a full charge capacity of a battery mounted on a vehicle, immediately after the start switch of the vehicle is turned on. During one trip from when the start switch is turned on to when the start switch is turned off, and a remaining capacity calculation means for calculating the remaining capacity of the battery based on the detected open circuit voltage. A charge / discharge amount calculating means for calculating the charge / discharge amount of the battery, a remaining capacity of the battery calculated by the remaining capacity calculating means, and a charge / discharge amount of the battery calculated by the charge / discharge amount calculating means are stored. Storage means, and the difference between the remaining capacity calculated at the start of the current trip by the remaining capacity calculation means and the remaining capacity at the start of the previous trip stored in the storage means is predetermined. Condition greater than, to calculate the full charge capacity of the battery from the charging and discharging amount in the last trip are stored in the difference and the storage means.

  According to the first aspect of the present invention, immediately after the start switch of the vehicle is turned on, the open circuit voltage of the battery is detected, and the remaining capacity is calculated based on the detected open circuit voltage. Immediately after the start switch is turned on, since no current flows through the battery, the open circuit voltage can be detected. From the open circuit voltage of the battery, the remaining capacity of the battery can be calculated with high accuracy.

  Further, the charge / discharge amount of the battery is calculated during one trip from when the start switch is turned on to when it is turned off. Then, the calculated remaining capacity and charge / discharge amount of the battery are stored. Furthermore, on the condition that the difference between the remaining capacity at the start of this trip and the stored remaining capacity at the start of the previous trip is larger than a predetermined value, the difference in remaining capacity and the previous trip stored The full charge capacity is calculated from the charge / discharge amount inside.

  Therefore, since the calculated remaining capacity and charge / discharge amount are maintained even during the start switch off period, the difference between the two remaining capacities calculated with high accuracy immediately after the start switch is turned on and the charge / discharge amount are used. Thus, the full charge capacity of the battery can be calculated. At this time, since the full charge capacity is calculated only when the difference between the remaining capacities is larger than the predetermined amount, the calculation error of the full charge capacity can be suppressed. Therefore, the full charge capacity of the battery can be calculated with high accuracy.

  The invention according to claim 2 is a full charge capacity calculating device for calculating a full charge capacity of a battery including a plurality of battery cells mounted in a vehicle and connected in series to each other, wherein the start switch of the vehicle Immediately after the power is turned on, the open voltage of each battery cell is detected, and based on the detected open voltage, the remaining capacity calculation means for calculating the remaining capacity of each battery cell, and the start switch is turned on and turned off. The charge / discharge amount calculation means for calculating the charge / discharge amount of the battery, the remaining capacity of each battery cell calculated by the remaining capacity calculation means, and the charge / discharge amount calculation means Storage means for storing the charged / discharged amount of the battery, and for each battery cell, the remaining capacity calculated at the start of the current trip by the remaining capacity calculation means and stored in the storage means. On the condition that the difference from the remaining capacity at the start of the previous trip is larger than a predetermined amount, the full charge capacity is calculated from the difference and the charge / discharge amount during the previous trip stored in the storage means, A small full charge capacity is defined as the full charge capacity of the battery.

  According to the second aspect of the present invention, immediately after the start switch of the vehicle is turned on, the open voltage of each battery cell is detected, and the remaining capacity is calculated based on the detected open voltage. Immediately after the start switch is turned on, no current flows through each battery cell, so that the open voltage of each battery cell can be detected. From the open circuit voltage of each battery cell, the remaining capacity of each battery cell can be calculated with high accuracy.

  Further, the charge / discharge amount of the battery is calculated during one trip from when the start switch is turned on to when it is turned off. Since the plurality of battery cells are connected to each other in series, the charge / discharge amount is common. Then, the calculated remaining capacity of each battery cell and the charge / discharge amount of the battery are stored. Further, for each battery cell, the difference in the remaining capacity and the storage are stored on the condition that the difference between the remaining capacity at the start of the current trip and the stored remaining capacity at the start of the previous trip is larger than a predetermined value. The full charge capacity is calculated from the charge / discharge amount during the previous trip.

  Therefore, since the calculated remaining capacity and charge / discharge amount are maintained even during the start switch off period, the difference between the two remaining capacities calculated with high accuracy immediately after the start switch is turned on and the charge / discharge amount are used. Thus, the full charge capacity of each battery cell can be calculated. At this time, since the full charge capacity is calculated only when the difference between the remaining capacities is larger than the predetermined amount, the calculation error of the full charge capacity can be suppressed. Of the full charge capacities calculated for each battery cell, the smallest full charge capacity, that is, the full charge capacity of the most deteriorated battery cell is the full charge capacity of the battery including the battery cells connected in series with each other. The Therefore, the full charge capacity of the battery can be calculated with high accuracy.

The figure which shows the structure of the battery pack and battery ECU which were mounted in the vehicle. The figure which shows the relationship between SOC and charge / discharge amount, and a full charge capacity. The time chart of the output of a battery, operation | movement of battery ECU, and an equalization process. The graph which shows the change of SOC of the battery cell which concerns on 1st Embodiment. The flowchart which shows the process sequence which calculates full charge capacity. The graph which shows the change of SOC of the battery cell which concerns on 2nd Embodiment.

  Hereinafter, embodiments in which the full charge capacity calculation device is applied to calculation of the full charge capacity of a battery mounted on a plug-in hybrid vehicle will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the same reference numerals is used.

(First embodiment)
FIG. 1 shows the configuration of a battery pack 40 and a battery ECU 50 (full charge capacity calculation device) that controls the battery pack 40. The battery pack 40 includes a battery 10, an equalization circuit 20, and a monitoring IC 30. The battery 10 includes, for example, battery cells 10a to 10c such as lithium ion secondary batteries and nickel hydrogen batteries that are connected in series. In this embodiment, three battery cells are connected in series, but the number of battery cells may be any number. In addition, a plurality of battery packs 40 may be connected to the battery pack 40 in series.

  The equalization circuit 20 includes switches 21a to 21c and resistors 22a to 22c. The switch 21a and the resistor 22a are connected in series, and the switch 21a and the resistor 22a connected in series are connected in parallel to the battery cell 10a. Similarly, the directly connected switch 21b and resistor 22b are connected in parallel to the battery cell 10b, and the switch 21c and resistor 22c connected in series are connected in parallel to the battery cell 10c.

  The switches 21a to 21c are configured with switching elements such as MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) and relays, for example, and the battery ECU 50 controls opening and closing. When the battery ECU 50 equalizes the remaining capacity (SOC: State Of Charge) of the plurality of battery cells 10a to 10c, the battery ECU 50 closes a switch connected in parallel to the battery cell having a large SOC, and the battery having a large SOC Discharge the cell. The battery ECU 50 and the equalization circuit 20 constitute equalization means.

  The monitoring IC 30 includes voltage sensors 32a to 32c, and also includes circuits that drive the equalization resistance switches 21a to 21c provided outside. The current sensor 31 is connected in series to the battery 10 and detects a charge / discharge current I flowing through the battery 10. Since the battery cells 10a to 10c are connected in series with each other, the charge / discharge current I flowing through the battery cells 10a to 10c is a common current. The voltage sensors 32a to 32c detect voltages Va to Vc across the battery cells 10a to 10c, respectively. The detected voltages Va to Vc are transmitted to the battery ECU 50.

  The battery ECU 50 is configured as a computer including a CPU 51, a memory 52 (storage device), an I / O (not shown), and the like. The battery ECU 50 and the voltage sensors 32a to 32c constitute a remaining capacity calculation means, and the battery ECU 50 and the current sensor 31 constitute a charge / discharge amount calculation means.

  The remaining capacity calculating means calculates the remaining capacity of the battery cells 10a to 10c based on the open circuit voltage (OCV) of the battery cells 10a to 10c detected by the voltage sensors 32a to 32c. The OCV of the battery cells 10a to 10c is the voltage of the battery cells 10a to 10c when no current flows through the battery cells 10a to 10c, and the OCV and the SOC have a correlation. While the vehicle is traveling, the current flows through the battery cells 10a to 10c, so the OCV cannot be detected. However, immediately after the start switch of the vehicle is turned on, no current flows through the battery cells 10a to 10c. Therefore, OCV can be detected. Therefore, the remaining capacity calculation means calculates the battery from the correlation between the OCV of the battery cells 10a to 10c detected by the voltage sensors 32a to 32c and the preset OCV and SOC immediately after the start switch is turned on. The SOC of the cells 10a to 10c is calculated with high accuracy.

  The charging / discharging amount calculating means integrates the charging / discharging current I of the battery 10 detected by the current sensor 31 during one trip from when the start switch is turned on to when it is turned off, and charging / discharging the battery 10 during one trip. Calculate the amount of discharge. In the present embodiment, the battery cells 10a to 10c are not equalized during the ON period of the start switch. Therefore, the charge / discharge amounts of the battery cells 10a to 10c during one trip are equal.

  The SOC of the battery cells 10a to 10c calculated by the remaining capacity calculation unit and the charge / discharge amount during one trip calculated by the charge / discharge amount calculation unit are stored in the memory 52. Note that the CPU 51 and the memory 52 constitute storage means.

  Further, the battery ECU 50 determines the fullness of the battery cells 10a to 10c from the SOC of the battery cells 10a to 10c calculated by the remaining capacity calculation unit and the charge / discharge amount of the battery cells 10a to 10c calculated by the charge / discharge amount calculation unit. Calculate the charge capacity. Then, the battery ECU 50 sets the smallest full charge capacity as the full charge capacity of the battery 10. That is, the battery ECU 50 sets the full charge capacity of the most deteriorated battery cell as the full charge capacity of the battery 10. Thereby, overcharge of battery cell 10a-10c is prevented. The full charge capacity corresponds to the amount of charge when charging is performed from the SOC 0% state to the SOC 100% state.

  Next, a method for calculating the full charge capacity of the battery cells 10a to 10c will be described in detail with reference to FIG. Point P1 indicates the previous trip start time, and point P2 indicates the current trip start time. If the battery cells 10a to 10c are not charged / discharged between the end of the previous trip and the start of the current trip, the SOC at the start of the current trip is equal to the SOC at the end of the previous trip. Become. Therefore, the difference between the SOC at the start of the previous trip and the SOC at the start of the current trip corresponds to the charge / discharge amount during the previous trip. On the other hand, the difference between SOC 100% and SOC 0% corresponds to the full charge capacity.

  Therefore, the full charge capacity is a value obtained by dividing the charge / discharge amount during the previous trip by the difference between the SOC at the P1 point and the SOC at the P2 point, and multiplying the result by 100. However, when the difference between the SOC at the P1 point and the SOC at the P2 point is small, the calculation error of the full charge capacity becomes large. Therefore, the difference between the SOC at the P1 point and the SOC at the P2 point is larger than a predetermined amount. As a condition, the full charge capacity is calculated. Note that the SOC at the point P1 and the charge / discharge amount during the previous trip are read from the memory 52 and used to calculate the full charge capacity. Here, the charge / discharge amount during one trip is positive on the discharge side.

  Next, the operation of the battery ECU 50 will be described with reference to the time chart of FIG. When the battery 10 is charged at the time R1, the battery ECU 50 is activated when the start switch is turned on. Immediately thereafter, the voltage sensors 32a to 32c detect the OCV of the battery cells 10a to 10c, and the battery ECU 50 calculates the SOC of the battery cells 10a to 10c. Subsequently, the battery ECU 50 starts charging the battery 10 with the external power source, and ends the charging at the time point S1. As shown in FIG. 4, the SOC of the battery cell increases from the time R1 to the time S1 with charging. The battery ECU 50 calculates the charge / discharge amount from the R1 time point to the S1 time point.

  When the charging of the battery 10 ends, the battery ECU 50 stops when the start switch is turned off at the time S1. In the subsequent start switch stop period T2, equalization of the battery cells 10a to 10c is prohibited. After charging with an external power source, the SOC of the most deteriorated battery cell is high. Therefore, when equalization is performed, the battery cells that are most deteriorated may be discharged. Therefore, equalization after charging by an external power source is prohibited in order to suppress the discharge of the most deteriorated battery cell.

  Next, when the start switch is turned on at time P1, the battery ECU 50 is activated. Immediately thereafter, the voltage sensors 32a to 32c detect the OCV of the battery cells 10a to 10c, and the battery ECU 50 calculates the SOC of the battery cells 10a to 10c. Further, the battery ECU 50 calculates the full charge capacity of the battery cells 10a to 10c from the SOC at the R1 time point and the P1 time point and the charge / discharge amount from the R1 time point to the S1 time point.

  Subsequently, EV travel and HV travel are performed from time P1 to time S2, and the SOC of the battery cell decreases as shown in FIG. The battery ECU 50 calculates the charge / discharge amount from the time point P1 to the time point S2.

  When the start switch is turned off at the time S2, the battery ECU 50 stops. Since the subsequent start switch stop period T3 is a period longer than one hour, the battery ECU 50 is activated every hour. And at the time of starting of battery ECU50, voltage sensors 32a-32c detect OCV of battery cells 10a-10c. In addition, in the start switch stop period T3, the battery cells 10a to 10c are equalized. In this embodiment, on the condition that the amount of discharge during one trip from when the start switch is turned on to when it is turned off exceeds the predetermined amount by a larger amount than the charge amount, in the start switch off period after the end of one trip, The battery cells 10a to 10c are equalized. In the equalization, the cell having the lowest voltage value is not discharged, but the other cells are discharged until they match the cell voltage having the lowest voltage value. At this time, in order to prevent erroneous discharge of the lowest voltage cell due to the voltage detection error, the battery may be discharged to a voltage obtained by adding the voltage error to the lowest cell voltage. When equalization is performed in this way, at least the SOC of the most deteriorated battery cell is smaller than the SOC of the other battery cells, so that the most deteriorated battery cell is not normally discharged.

  Next, when the start switch is turned on at time P2, the battery ECU 50 is activated. Immediately thereafter, the voltage sensors 32a to 32c detect the OCV of the battery cells 10a to 10c, and the battery ECU 50 calculates the SOC of the battery cells 10a to 10c. Further, the battery ECU 50 calculates the full charge capacity of the battery cells 10a to 10c from the SOC at the P1 time point and the P2 time point, and the charge / discharge amount from the P1 time point to the S2 time point. Although equalization is performed in the start switch stop period T3, since the battery cell that has deteriorated most during the equalization is not discharged, the full charge capacity of the battery cell that has deteriorated most can be calculated with high accuracy.

  Next, a processing procedure for calculating the full charge capacity will be described with reference to the flowchart of FIG. This process is executed by the battery ECU 50.

  First, in S11, it is determined whether or not it is immediately after the start switch is turned on. If not immediately after the start switch is turned on (NO), S11 is repeatedly executed. If it is immediately after the start switch is turned on (YES), the process proceeds to S12.

  Next, in S12, it is determined whether or not an abnormality has occurred in at least one of the current sensor 31, the voltage sensors 32a to 32c, and the memory 52. If an abnormality has occurred (YES), the calculation of the full charge capacity is stopped in S13 in order to prevent erroneous calculation of the full charge capacity. In this case, the value of the full charge capacity calculated last time is held, and this process is terminated. On the other hand, if no abnormality has occurred (NO), the process proceeds to S14.

  In S14, it is determined whether or not an off period from when the start switch is turned off to when the start switch is turned on is longer than time Ta (first predetermined time). The time Ta is a time from when the start switch is turned off until the characteristics of the battery cells 10a to 10b are stabilized, for example, 15 minutes. When the start switch is turned on, off, and repeatedly turned on continuously, the characteristics of the battery cells 10a to 10b are stable when the start switch is turned on when the off period of the start switch is shorter than the time Ta (NO). Therefore, OCV is not detected. Therefore, at the start of the next trip, the SOC and the charge / discharge amount stored in the memory 52 are erased in S15 so that the old SOC and the charge / discharge amount at the trip prior to the previous trip are not used. In this case, the full charge capacity calculated last time is held, and this process is terminated.

  On the other hand, when the OFF period of the start switch is longer than the time Ta (YES), since the characteristics of the battery cells 10a to 10c are stable when the start switch is turned ON, the OCV of the battery cells 10a to 10c is determined in S16. Is detected. That is, the OCV of the battery cells 10a to 10c is detected on the condition that the time from the end of the previous trip to the start of the current trip is longer than the time Ta.

  Subsequently, in S17, the SOC of the battery cells 10a to 10c is calculated from the OCV of the battery cells 10a to 10c detected in S16 and the correlation between the OCV and the SOC. Subsequently, in S18, the SOC of the battery cells 10a to 10c calculated in S17 is stored in the memory 52.

  Subsequently, in S19, it is determined whether or not an off period from when the start switch is turned off to when the start switch is turned on is shorter than time Tb (second predetermined time). The time Tb is a time set longer than the time Ta, and is a time that can ensure the reliability of the charge / discharge amount at the previous trip stored in the memory 52, and is several days, for example. If the off period of the start switch is long, the battery cells 10a to 10c are self-discharged during the off period, and the reliability of the charge / discharge amount at the previous trip stored in the memory 52 is impaired. Therefore, when the OFF period of the start switch is longer than Tb (NO), the full charge capacity is not calculated, and the process proceeds to S24. In this case, the previously calculated full charge capacity is retained.

  On the other hand, when the OFF period of the start switch is shorter than Tb (YES), the SOC of the battery cells 10a to 10c at the start of the previous trip is read from the memory 52 in S20. Subsequently, in S21, the charge / discharge amount of the battery 10 during the previous trip is read from the memory 52.

  Subsequently, in S22, for each of the battery cells 10a to 10c, whether or not the difference between the SOC at the start of the previous trip read in S20 and the SOC at the start of the current trip calculated in S17 is greater than a predetermined amount. To determine. When the difference is smaller than the predetermined amount, the calculation error of the full charge capacity becomes large. Therefore, when the difference between any of the battery cells is smaller than the predetermined amount (NO), the process proceeds to S24 without calculating the full charge capacity. In this case, the previously calculated full charge capacity is retained.

  On the other hand, when the difference is larger than the predetermined amount (YES), the full charge capacity is calculated in S23. That is, the full charge capacity is calculated on the condition that the difference is larger than a predetermined amount. Specifically, for each of the battery cells 10a to 10b, from the difference between the SOC at the start of the previous trip read in S20 and the SOC at the start of the current trip calculated in S17, and the charge / discharge amount read in S21, The full charge capacity is calculated (see FIG. 2). The smallest full charge capacity is set as the full charge capacity of the battery 10.

  Subsequently, in S24, the charge / discharge current detected by the current sensor 31 is integrated, and the charge / discharge amount of the battery 10 during the current trip is calculated. This charge / discharge amount calculation is continuously performed during the current trip. Subsequently, in S25, the charge / discharge amount calculated in S24 is stored in the memory 52.

  Subsequently, in S26, it is determined whether or not the start switch is turned off. If the start switch is not turned off (NO), the process returns to S24 and the calculation of the charge / discharge amount of the battery 10 is repeatedly executed. On the other hand, when the start switch is turned off (YES), this process is terminated.

  According to 1st Embodiment described above, there exist the following effects.

  -Immediately after the start switch of the vehicle is turned on, the OCV of the battery cells 10a to 10c is detected, and the SOC is calculated based on the detected OCV. Immediately after the start switch is turned on, since no current flows through the battery cells 10a to 10c, the OCV of the battery cells 10a to 10c can be detected. And from the OCV of the battery cells 10a to 10c, the SOC of the battery cells 10a to 10c can be calculated with high accuracy.

  The battery charge / discharge amount is calculated during one trip from when the start switch is turned on to when it is turned off. Then, the calculated SOC and charge / discharge amount of the battery cells 10 a to 10 c are stored in the memory 52. Since the calculated SOC and charge / discharge amount are maintained even when the start switch is off, the battery cell is calculated using the difference between the two SOCs calculated with high accuracy immediately after the start switch is turned on and the charge / discharge amount. The full charge capacity of 10a to 10c can be calculated. At this time, since the full charge capacity is calculated only when the difference in SOC is larger than the predetermined amount, calculation error of the full charge capacity can be suppressed. Of the full charge capacities calculated for the battery cells 10 a to 10 c, the smallest full charge capacity, that is, the full charge capacity of the most deteriorated battery cell is set as the full charge capacity of the battery 10. Therefore, the full charge capacity of the battery 10 can be calculated with high accuracy.

  Even in the configuration in which the battery cells 10a to 10c are equalized during the off period of the start switch only when the discharge amount during one trip is larger than the charge amount, the full charge capacity of the most deteriorated battery cell, that is, the battery Can be calculated with high accuracy.

  The characteristics of the battery cells 10a to 10c are not stable until the time Ta elapses after the start switch is turned off. Therefore, the OCV of the battery cells 10a to 10c is detected immediately after the start switch is turned on only when the start switch is turned on after a time longer than the time Ta has elapsed since the start switch was turned off. Thereby, the OCV detection accuracy of the battery cells 10a to 10c can be improved, and as a result, the calculation accuracy of the full charge capacity can be improved.

  If the OCV is not detected at the start of the trip, the old SOC and charge / discharge amount stored in the memory 52 are erased. Thereby, at the start of the next trip, it is possible to prevent the full charge capacity from being calculated using the SOC and the charge / discharge amount in the trip that is older than the previous trip. As a result, the reliability of the calculated full charge capacity can be improved.

  If the time from when the start switch is turned off to when the start switch is turned on is longer than the time Tb, the calculation accuracy of the full charge capacity decreases due to self-discharge or the like during the off period of the start switch. Therefore, the full charge capacity is calculated only when the time from when the start switch is turned off to when the start switch is turned on is shorter than the time Tb. Thereby, it can suppress that the calculation precision of a full charge capacity falls.

  When the abnormality occurs in at least one of the current sensor 31, the voltage sensors 32a to 32c, and the memory 52, it is possible to prevent the full charge capacity from being erroneously calculated by stopping the calculation of the full charge capacity. Further, the full charge capacity calculated before the occurrence of the abnormality can be used until the abnormality disappears.

(Second Embodiment)
Next, a difference between the second embodiment and the first embodiment will be described. In 2nd Embodiment, equalization of battery cell 10a-10c is not prohibited in the OFF period of the start switch after charge by an external power supply. FIG. 6 shows the change in SOC of the battery cell according to the second embodiment. In the first embodiment, the full charge capacity is calculated whether the SOC at the start of the previous trip is smaller or larger than the SOC at the start of the current trip, but in the second embodiment, the SOC at the start of the previous trip is calculated. When the SOC is smaller than the SOC at the start of the current trip, the full charge capacity is not calculated.

  As shown in FIG. 6, the SOC of the battery cell is increased by external charging from the time R1 when the start switch is turned on to the time S1 when the start switch is turned off. At the S1 time point, the SOC of the most deteriorated battery cell is the largest. Thereafter, equalization is performed during the OFF period of the start switch from the time S1 to the time P1. At this time, the most deteriorated battery cell is also discharged. Therefore, if the full charge capacity of the battery 10 is calculated from the SOC at the P1 time, the SOC at the R1 time, and the charge / discharge amount from the R1 time to the S1 time, an error may occur in the full charge capacity of the battery 10.

  Next, EV and HV traveling are performed from time P1 when the start switch is turned on to time S2 when the start switch is turned off, and the SOC is reduced. At S2, the SOC of the most deteriorated battery cell is the smallest. Thereafter, equalization is performed during the OFF period of the start switch from time S2 to time P2. At this time, the most deteriorated battery cell is not discharged. Therefore, when the full charge capacity of the battery 10 is calculated from the SOC at the P2 time, the SOC at the P1 time, and the charge / discharge amount from the P1 time to the S2 time, the full charge capacity of the battery 10 is calculated with high accuracy.

  Therefore, in the second embodiment, the full charge capacity of the battery 10 is calculated on the condition that the SOC at the start of the previous trip is larger than the SOC at the start of the current trip by a predetermined amount.

  According to the second embodiment, the full charge capacity is calculated only when the SOC at the start of the previous trip is larger than the SOC at the start of the current trip by a predetermined amount. When the discharge is performed more than a predetermined amount, the SOC of the battery cell that is most deteriorated becomes smaller than the SOC of the other battery cells. Therefore, even if the battery cells are equalized during the off-period of the start switch, the battery cells that are most deteriorated during the equalization are not normally discharged. Therefore, by assuming that more than a predetermined amount of discharge has been performed during the previous trip, regardless of whether or not equalization was performed during the OFF period of the start switch, The full charge capacity, that is, the full charge capacity of the battery can be calculated with high accuracy.

(Other embodiments)
In each of the above embodiments, the full charge capacity of each of the battery cells 10a to 10c is calculated and the smallest full charge capacity is defined as the full charge capacity of the battery 10, but the full charge capacity of the battery cell (battery) that has deteriorated most It is also possible to calculate only. The battery cell that has deteriorated most is determined from, for example, the OCV at the start of the next trip after EV traveling.

  The battery ECU 50 may be applied not only to plug-in hybrid vehicles but also to EV vehicles.

  DESCRIPTION OF SYMBOLS 10 ... Battery, 10a, 10b, 10c ... Battery cell, 31 ... Current sensor, 32a, 32b, 32c ... Voltage sensor, 50 ... Battery ECU, 52 ... Memory.

Claims (8)

A full charge capacity calculation device (50) for calculating a full charge capacity of a battery mounted on a vehicle,
Immediately after the start switch of the vehicle is turned on, a remaining capacity calculation means (32a to 32c, 50) for detecting an open voltage of the battery and calculating a remaining capacity of the battery based on the detected open voltage. ,
Charge / discharge amount calculation means (31, 50) for calculating the charge / discharge amount of the battery during one trip from when the start switch is turned on to when it is turned off;
Storage means (51, 52) for storing the remaining capacity of the battery calculated by the remaining capacity calculating means and the charge / discharge amount of the battery calculated by the charge / discharge amount calculating means,
The difference is calculated on the condition that the difference between the remaining capacity calculated at the start of the current trip by the remaining capacity calculation means and the remaining capacity at the start of the previous trip stored in the storage means is larger than a predetermined amount. And a full charge capacity calculation device for calculating the full charge capacity of the battery from the charge / discharge amount during the previous trip stored in the storage means. A full charge capacity calculation device (50) for calculating a full charge capacity of a battery (10) provided with a plurality of battery cells (10a to 10c) mounted on a vehicle and connected in series with each other,
Immediately after the start switch of the vehicle is turned on, an open voltage of each battery cell is detected, and a remaining capacity calculation means (32a to 32c, 50) that calculates the remaining capacity of each battery cell based on the detected open voltage. )When,
Charge / discharge amount calculation means (31, 50) for calculating the charge / discharge amount of the battery during one trip from when the start switch is turned on to when it is turned off;
Storage means (51, 52) for storing the remaining capacity of each battery cell calculated by the remaining capacity calculation means, and the charge / discharge amount of the battery calculated by the charge / discharge amount calculation means,
For each battery cell, the difference between the remaining capacity calculated at the start of the current trip by the remaining capacity calculating means and the remaining capacity at the start of the previous trip stored in the storage means is larger than a predetermined amount. As a condition, a full charge capacity is calculated from the difference and the charge / discharge amount during the previous trip stored in the storage means, and the minimum full charge capacity is set as the full charge capacity of the battery. Capacity calculation device.   Equalization that equalizes the remaining capacity of the plurality of battery cells during a period in which the start switch is turned off after the end of the one trip, on condition that the discharge amount during the one trip is larger than the charge amount The full charge capacity calculation device according to claim 2, comprising means (20, 50).   The full charge capacity of the battery according to any one of claims 1 to 3, wherein the full charge capacity of the battery is calculated on the condition that the remaining capacity at the start of the previous trip is larger than the remaining capacity at the start of the current trip. Charge capacity calculation device.   The residual capacity calculating means detects the open circuit voltage on the condition that the time from the end of the previous trip to the start of the current trip is longer than a first predetermined time. Full charge capacity calculation apparatus of description.   The full charge capacity calculation device according to claim 5, wherein when the open circuit voltage is not detected by the remaining capacity calculation means, the remaining capacity and the charge / discharge amount stored in the storage means are erased.   The full charge capacity is calculated on the condition that the time from the end of the previous trip to the start of the current trip is shorter than a second predetermined time set longer than the first predetermined time. Item 7. The full charge capacity calculation device according to Item 5 or 6. The remaining capacity calculating means includes voltage sensors (32a to 32c) for detecting the open circuit voltage,
The charge / discharge amount calculating means includes a current sensor (31) for detecting a current flowing through the battery,
The storage means includes a storage device (52),
8. When the abnormality occurs in at least one of the voltage sensor, the current sensor, and the storage device, the calculation of the full charge capacity is stopped and the previously calculated full charge capacity is held. The full charge capacity calculation device according to any one of the above.

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