JP2022147323A - charging controller - Google Patents

Abstract

To provide a charging controller that avoids opportunity of rapid charging from being excessively restricted while inhibiting the rapid charging from causing reduction in battery performance.SOLUTION: A charging controller comprises: a calculation unit for calculating a damage storage amount indicating a storage amount of damage to a battery caused by rapid charging of the battery; and a charging control unit that permits rapid charging to the battery in the case that the damage storage amount is smaller than a threshold and, in the case that the damage storage amount is equal to or larger than the threshold, restricts rapid charging to the battery more than the case that the damage storage amount is smaller than the threshold. The calculation unit calculates the damage storage amount so that the damage storage amount increases more as a period in which a charging current value, a current value of the battery at the time of rapid charging, is larger than a predetermined value is longer and the damage storage amount decreases more as a period in which the charging current value is equal to or smaller than the predetermined value is longer and as a period in which the battery is not charged is longer.SELECTED DRAWING: Figure 4

Description

The present invention relates to a charging control device.

In order to suppress the deterioration of battery performance, there is known a technique of prohibiting rapid charging when the number of times of rapid charging of the battery exceeds a predetermined number (see Patent Document 1).

Japanese Patent Application Laid-Open No. 2001-218378

If rapid charging is prohibited based only on the number of times of rapid charging as described above, opportunities for rapid charging may be restricted more than necessary.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a charging control device that prevents the chances of rapid charging from being excessively restricted while suppressing deterioration in battery performance due to rapid charging.

The above object is provided by a calculating unit for calculating a damage accumulated amount indicating an accumulated amount of damage to the battery due to rapid charging of the battery, and permitting rapid charging of the battery when the damage accumulated amount is less than a threshold. and a charging control unit that restricts rapid charging of the battery when the accumulated damage amount is equal to or greater than the threshold than when the accumulated damage amount is less than the threshold; The longer the period during which the charging current value, which is the current value of the battery during charging, is greater than a predetermined value, the greater the accumulated amount of damage. This can be achieved by a charging control device that calculates the amount of accumulated damage so that the amount of accumulated damage decreases as the non-charging period of the battery increases.

Advantageous Effects of Invention According to the present invention, it is possible to provide a charging control device that avoids excessive limitation of opportunities for quick charging while suppressing degradation of battery performance due to quick charging.

FIG. 1 is a schematic configuration diagram of a vehicle. FIG. 2A is a graph showing the transition of the resistance increase rate according to the number of times the battery is rapidly charged, and FIG. 2B is a graph showing the transition of the charging current value In during rapid charging. FIG. 3A is a graph showing Δd according to the charging current value In, and FIG. 3B is a map that defines the infinite rated current value α and allowable current value β according to the SOC and temperature of the battery during charging. be. FIG. 4A is a flowchart showing an example of control for determining whether to permit or limit rapid charging, and FIG. 4B is a flowchart showing an example of control for calculating the accumulated damage amount QCd. FIG. 5 is a timing chart showing changes in the amount of accumulated damage QCd when rapid charging is performed while maintaining the charging current value In at the allowable current value β, and then the rapid charging is suspended. FIG. 6 is a timing chart showing changes in the amount of accumulated damage QCd when charging is started at a charging current value In equal to or lower than the infinite rated current value α and then rapid charging is suspended. FIG. 7 is a timing chart showing changes in the amount of accumulated damage QCd when rapid charging and discharging are repeated while maintaining the charging current value In at the allowable current value β. FIG. 8 is a timing chart showing changes in the amount of accumulated damage QCd when rapid charging and discharging are repeated while the charging current value In is maintained at the infinite rated current value α. FIG. 9 is a timing chart showing changes in the amount of accumulated damage QCd when charging is stopped after repeating rapid charging and discharging while maintaining the charging current value In at the allowable current value β. FIG. 10 is a timing chart showing changes in the amount of accumulated damage QCd when charging is stopped after repeating rapid charging and discharging while maintaining the charging current value In at the infinite rated current value α.

[Schematic configuration of vehicle 100]
FIG. 1 is a schematic configuration diagram of a vehicle 100. As shown in FIG. The vehicle 100 is an electric vehicle that is equipped with a battery 110 and can run by a motor generator (hereinafter referred to as “MG (Motor Generator)”) 130 using power stored in the battery 110 . Vehicle 100 may be a hybrid vehicle in which an engine is installed in addition to MG 130, or a fuel cell vehicle in which a fuel cell is installed in addition to battery 110, or the like.

Battery 110 is an externally chargeable battery that is charged with electric power supplied from a charger provided outside vehicle 100 . This embodiment shows a case where the battery 110 is rapidly charged using power supplied from the charging station 200 . Rapid charging is a charging method in which charging is completed in a short period of time by supplying DC power of higher power (for example, several hundred kW) than normal charging (for example, several tens of kW) to battery 110 . With the connector 280 of the charging stand 200 connected to the inlet 150 of the vehicle 100, when the vehicle 100 and the charging stand 200 are instructed to perform external charging, the battery 110 of the vehicle 100 is charged from the charging stand 200. . The charging of the battery 110 is not limited to the charging stand 200, and may be performed using a domestic commercial power source.

Specifically, vehicle 100 includes battery 110, system main relay SMR, power control unit (hereinafter referred to as "PCU (Power Control Unit)") 120, MG 130, power transmission gear 135, driving wheels 140, and , an inlet 150 , a charging relay RY, an ECU 160 , an HMI (Human Machine Interface) device 170 and a charging device 180 .

Battery 110 is configured to be chargeable and dischargeable, and is, for example, a secondary battery such as a lithium-ion battery or a nickel-metal hydride battery. In addition, the lithium ion secondary battery is a secondary battery using lithium as a charge carrier, and in addition to a general lithium ion secondary battery in which the electrolyte is a liquid, even a so-called all-solid battery using a solid electrolyte good.

Battery 110 is connected to inlet 150 via charging device 180 and externally charged by charging stand 200 connected to inlet 150 . Battery 110 supplies the stored electric power to MG 130 through PCU 120 during running. Further, battery 110 is charged by receiving power generated by MG 130 through PCU 120 when MG 130 regenerates power during vehicle braking.

System main relay SMR is provided between power lines PL1, NL1 connected to battery 110 and PCU 120, and is turned on by ECU 160 when the vehicle system is activated by a start switch or the like (not shown).

PCU 120 is a driving device that drives MG 130 and includes a power conversion device such as a converter and an inverter. PCU 120 is controlled by ECU 160 and converts DC power received from battery 110 into AC power for driving MG 130 . PCU 120 also converts AC power generated by MG 130 into DC power and outputs the DC power to battery 110 .

The MG 130 is typically an AC rotary electric machine, such as a three-phase AC synchronous electric motor with permanent magnets embedded in the rotor. MG 130 is driven by PCU 120 to generate rotational driving force, and the driving force generated by MG 130 is transmitted to drive wheels 140 through power transmission gear 135 . On the other hand, during braking of the vehicle or the like, MG 130 operates as a generator and performs regenerative power generation. Electric power generated by MG 130 is supplied to battery 110 through PCU 120 .

Charging relay RY is provided in an electric circuit between charging device 180 and battery 110 . Specifically, charging relay RY includes relays K5 and K6. Relay K5 is provided between power line DCL1 connected to inlet 150 via charging device 180 and power line PL2 connected to the positive electrode of battery 110 . Relay K6 is provided between power line DCL2 connected to inlet 150 via charging device 180 and power line NL2 connected to the negative electrode of battery 110 . Charging relay RY is turned ON/OFF by ECU 160 .

Inlet 150 receives charging power supplied from charging stand 200 when external charging is performed. Connector 280 of charging stand 200 is connected to inlet 150 . When external charging is performed, DC power output from charging stand 200 is supplied from inlet 150 to battery 110 via charging device 180, power lines DCL1 and DCL2, charging relay RY, power lines PL2 and NL2, and power lines PL1 and NL1. supplied to Charging device 180 converts the DC power output from charging stand 200 into a desired charging current to charge battery 110 . Although the details will be described later, the charging device 180 can rapidly charge the battery 110 as external charging according to a command from the ECU 160 . The ECU 160 is an example of a charging control device, and functionally implements a calculation unit and a charging control unit, which will be described later.

The ECU 160 includes a CPU (Central Processing Unit) 162, memory (RAM (Random Access Memory) and readable and writable ROM (Read Only Memory)) 164, and input/output ports (not shown) for inputting and outputting various signals. and The CPU 162 expands the program stored in the ROM into the RAM and executes it. A program stored in the ROM describes processing of the ECU 160 . When the connector 280 is connected to the inlet 150, the ECU 160 exchanges various messages with the charging stand 200 through the signal line SL to perform external charging. The ECU 160 is also electrically connected to an SOC sensor 111 that detects the SOC (State Of Charge) of the battery 110, a temperature sensor 112 that detects the temperature of the battery 110, and a current sensor 113 that detects the current value of the battery 110. there is

When the vehicle is running, ECU 160 controls the driving of MG 130 and the charging and discharging of battery 110 by turning on system main relay SMR and controlling PCU 120 . During external charging, the ECU 160 turns on the charging relay RY and exchanges various messages with the charging station 200 through the signal line SL to execute external charging. Further, when the SOC of battery 110 reaches the upper limit, ECU 160 transmits a request to stop charging to charging station 200 through signal line SL and turns off charging relay RY.

Charging station 200 is charging equipment for supplying power to vehicle 100 . The charging stand 200 is installed, for example, in a public facility, and is capable of supplying DC power (for example, several hundred kW) higher than the charging power (for example, several tens of kW) to the battery 110 for rapid charging. is. Note that when the vehicle 100 and the charging station 200 are connected, they can communicate with each other.

The HMI device 170 is a device that provides various information to the user of the vehicle 100 and receives operations by the user of the vehicle 100 . The HMI device 170 includes a display with a touch panel, a speaker, and the like.

[Details of quick charging]
Next, the rapid charging of the battery 110 and transition of the resistance increase rate of the battery 110 due to the rapid charging will be described. FIG. 2A is a graph showing changes in the resistance increase rate according to the number of times the battery 110 has been rapidly charged. FIG. 2A shows the rate of increase in resistance of the battery 110 according to the number of times of quick charging from once to four times a day. In FIG. 2A, the horizontal axis indicates the elapsed days, and the vertical axis indicates the resistance increase rate [%]. FIG. 2A shows the case where the SOC of battery 110 is rapidly charged from 0% to 100%.

As shown in FIG. 2A, as the number of times of rapid charging performed in a day increases, the rate of increase in resistance increases as the number of days elapses. That is, it indicates that the performance of the battery 110 is degraded. Therefore, since it is preferable that the number of times of rapid charging performed in one day is small, it is conceivable to limit the number of times of rapid charging. However, deterioration in the performance of battery 110 affects not only the number of times of rapid charging, but also the current value (hereinafter referred to as charging current value In) flowing through battery 110 during charging, SOC and temperature during charging. In general, the higher the charging current value In, the higher the SOC, and the lower the temperature, the lower the performance of the battery 110 is.

FIG. 2B is a graph showing changes in the charging current value In during rapid charging. The horizontal axis indicates time, and the vertical axis indicates current value [A]. FIG. 2B shows a case where rapid charging is performed from 0% to 100% of the SOC of the battery 110, and is completed in approximately 45 to 60 minutes. The charging current value In is controlled by the ECU 160 according to the SOC. Specifically, when the SOC after the start of rapid charging is low, the charging current value In is maintained at a high value. Controlled to zero, rapid charging is completed. As described above, the charging current value In is not always constant, and when the charging current value In is low, there is little effect on deterioration of the performance of the battery 110 .

Therefore, in the present embodiment, the ECU 160 calculates a damage accumulation amount QCd (Quick Charge damage), which is an index of how the rapid charging affects the deterioration of the performance of the battery 110, in consideration of the charging current value In, the SOC and the temperature, which will be described later. Then, whether to permit or restrict rapid charging of the battery 110 is determined according to the magnitude of the accumulated damage amount QCd.

The accumulated damage amount QCd is calculated as follows.
_QCdn = QCdn _-1 + Δd (1)
QCd _n indicates the current value, and QCd _n-1 indicates the previous value.
Δd is defined as follows.
Δd=(In−α)/(β−α) (2)
Δd=−E (3)
FIG. 3A is a graph showing Δd according to the charging current value In. The infinite rated current value α indicates the maximum current value that flows during charging and that has little effect on deterioration of the performance of battery 110 . The infinite rated current value α is an example of a predetermined value. Allowable current value β indicates the maximum current value that can flow to battery 110 during charging. Δd is calculated according to the equation (2) when the charging current value In is greater than the infinite rated current value α and equal to or less than the allowable current value β, and is calculated according to the equation (3) when the infinite rated current value α or less be done. For example, Δd is calculated as "D"(D>0) when the charging current value In is the allowable current value β, and is calculated as "-E" when the charging current value In is the infinite rated current value α or less. be done.

That is, the longer the period in which the charging current value In is greater than the infinite rated current value α and equal to or less than the allowable current value β, the longer the damage accumulation amount QCd is increased by adding Δd. On the other hand, the longer the period during which the charging current value In is equal to or less than the infinite rated current value α, the more the accumulated damage amount QCd is reduced by subtracting Δd. Here, in the non-charging period in which charging is not performed, the accumulated damage amount QCd is calculated based on the above equation (2) with the charging current value In set to 0. That is, in this case also, the amount of accumulated damage QCd is reduced by subtracting Δd. Note that "D" is, for example, 1, and "-E" is, for example, -0.2, but is not limited to these.

Here, the infinite rated current value α and the allowable current value β take different values depending on the SOC and temperature of the battery 110 during charging. FIG. 3B is a map that defines the infinite rated current value α and allowable current value β according to the SOC and temperature of battery 110 during charging. In FIG. 3B, two infinite rated current values α are indicated as infinite rated current values α1 and α2, and two allowable current values β are indicated as allowable current values β1 and β2, respectively. In FIG. 3B, the allowable current value β1 is indicated by a solid line, the allowable current value β2 is indicated by a dotted line, the infinite rated current value α1 is indicated by a one-dot chain line, and the infinite rated current value α2 is indicated by a two-dot chain line. Infinite rated current value α1 and allowable current value β1 indicate the case where battery 110 is at a predetermined temperature. The infinite rated current value α2 and the allowable current value β2 indicate the case where the temperature of the battery 110 is lower than the temperature of the battery 110 at the infinite rated current value α1 and the allowable current value β1. The infinite rated current value α1 when the temperature of the battery 110 is high is higher than the infinite rated current value α2 when the temperature is low, and the allowable current values β1 and β2 are the same. That is, the lower the temperature of the battery 110 is, the more likely it is that the performance of the battery 110 is degraded.

Also, as the SOC increases, the infinite rated current values α1 and α2 and the allowable current values β1 and β2 decrease. Specifically, the infinite rated current value α1 and the allowable current value β1 take constant values when the SOC is less than a predetermined value, and gradually decrease when the SOC is greater than or equal to the predetermined value. The infinite rated current value α2 and the allowable current value β2 gradually decrease as the SOC increases from a low value. Therefore, as the SOC increases, the performance of battery 110 may deteriorate.

The map in FIG. 3B shows only the infinite rated current values α1 and α2 and the allowable current values β1 and β2 at two different temperatures, but in reality the infinite rated current values α and allowable current values for each temperature are more detailed. A value β is defined and stored in memory 164 of ECU 160 in advance.

[Control executed by ECU 160]
Next, the control for determining permission or restriction of rapid charging executed by ECU 160 will be described. FIG. 4A is a flowchart showing an example of control for determining permission or restriction of quick charging. ECU 160 determines whether the temperature of battery 110 is equal to or higher than a predetermined temperature T based on the detection result of temperature sensor 112 (step S1). Predetermined temperature T is a temperature that is higher than the minimum temperature at which battery 110 can be rapidly charged by a predetermined margin.

If Yes in step S1, the ECU 160 determines whether or not the accumulated damage amount QCd is less than the threshold value R (step S2). The threshold value R is a value that is lower than the maximum value of the accumulated damage amount QCd by a predetermined margin so as not to affect deterioration of the performance of the battery 110 due to rapid charging. The threshold R is, for example, 3600, but is not limited to this. In the case of Yes in step S2, the ECU 160 permits rapid charging (step S3) and terminates this control. In a state in which rapid charging is permitted, charging current value In can be controlled to be equal to or less than allowable current value β to quickly charge battery 110 . By maintaining the charging current value In at a high value within the range of the allowable current value β or less, the charging of the battery 110 can be completed in a short time.

If No in either one of steps S1 and S2, the ECU 160 limits rapid charging (step S4) and ends this control. In the present embodiment, when rapid charging is restricted, the charging current value In is limited to the infinite rated current value α or less so that rapid charging can be performed. Since the charging current value In is limited to the infinite rated current value α or less, it takes more time to complete charging than when there is no such limitation. can be charged. For example, when the damage accumulation amount QCd increases to the threshold value R or more during rapid charging and rapid charging is restricted, the ECU 160 controls the charging device 180 to limit the charging current value In to an infinite rated current value α or less. Continue charging. The processing of steps S3 and S4 is an example of processing executed by the charging control unit.

Next, calculation control of the accumulated damage amount QCd executed by the ECU 160 will be described. FIG. 4B is a flowchart showing an example of calculation control of the accumulated damage amount QCd. The ECU 160 determines whether or not the battery 110 is being rapidly charged (step S11). For example, when the current value indicated by the current sensor 113 is equal to or greater than a predetermined value, it can be determined that the battery 110 is being rapidly charged. If Yes in step S11, the ECU 160 acquires the current charging current value In (step S12), and determines whether or not the charging current value In is greater than the infinite rated current value α (step S13).

In the case of Yes in step S13, the ECU 160 increases the accumulated damage amount QCd according to the above-described equations (1) and (2) (step S14), and ends this control. If No in either step S11 or S13, the accumulated damage amount QCd is decreased by the above-described equations (1) and (3) (step S15), and this control ends. Since the control shown in FIGS. 4A and 4B is repeatedly executed at predetermined time intervals, the accumulated damage amount QCd is calculated at any time, and whether or not to permit rapid charging is determined at any time according to the amount of accumulated damage QCd. be. The processing of steps S14 and S15 is an example of processing executed by the calculation unit.

As described above, the accumulated damage amount QCd for determining whether or not to permit rapid charging is calculated based on the magnitude of the charging current value In. In the case of charging, rapid charging is less likely to be restricted, and it is possible to avoid excessively restricting opportunities for rapid charging. In addition, since the accumulated damage amount QCd is calculated in consideration of the SOC and the temperature of the battery 110 in addition to the magnitude of the charging current value In, the accumulated damage amount QCd can be calculated more accurately. Opportunities can be avoided from being overly limited. Furthermore, the accumulated damage amount QCd decreases when the charging current value In is less than the infinite rated current value α or when rapid charging is not performed. It is also possible to avoid excessively restricting opportunities for quick charging.

Next, transitions of the charging current value In and the amount of accumulated damage QCd will be specifically described. FIG. 5 is a timing chart showing changes in the amount of accumulated damage QCd when rapid charging is performed while maintaining the charging current value In at the allowable current value β, and then the rapid charging is suspended. FIG. 5 shows changes in the charging current value In, the infinite rated current value α, the allowable current value β, and the accumulated damage amount QCd. As shown in FIG. 3B, the infinite rated current value α and allowable current value β change according to the SOC. When charging starts at time t0, the charge current value In is maintained at the allowable current value β, so the accumulated damage amount QCd rapidly increases. When charging is completed at time t1, the damage accumulation amount QCd gradually decreases, and at time t2, the damage accumulation amount QCd decreases to zero.

FIG. 6 is a timing chart showing changes in the amount of accumulated damage QCd when charging is started at a charging current value In equal to or lower than the infinite rated current value α and then rapid charging is suspended. When charging is started at time t0, the charge current value In is maintained at a predetermined value equal to or lower than the infinite rated current value α, so the accumulated damage amount QCd remains zero. When the infinite rated current value α decreases and the charging current value In becomes equal to or greater than the infinite rated current value α at time t1, the accumulated damage amount QCd starts to increase. After that, when the allowable current value β decreases and the charging current value In is maintained at the allowable current value β, and the rapid charging is completed at time t2, the damage accumulation amount QCd gradually decreases, and at time t3, the damage accumulation amount QCd. drops to zero.

As shown in FIGS. 5 and 6, when the charging current value In is maintained at the allowable current value β, rapid charging can be completed in a short time. It takes time for the accumulated damage amount QCd to return to zero.

[Modification]
In the above embodiment, the case where the charging current value In is limited to the infinite rated current value α or less as the limitation of the rapid charging is explained as an example. In this modified example, a case where charging is stopped until the accumulated damage amount QCd becomes zero will be described as an example of limiting rapid charging.

First, a case where rapid charging and discharging are repeated in a short time when the charging current value In is limited to an infinite rated current value α or less as a limitation of rapid charging will be described. FIG. 7 is a timing chart showing changes in the amount of accumulated damage QCd when rapid charging and discharging are repeated while maintaining the charging current value In at the allowable current value β. Rapid charging is performed from time t0 to time t1, and battery 110 is discharged from time t1 to time t2. The accumulated damage amount QCd gradually decreases during discharging, but at time t2, rapid charging is started again, and as a result, the accumulated damage amount QCd starts increasing before it sufficiently decreases. By repeating this, at time t3, the accumulated damage amount QCd becomes equal to or greater than the threshold value R during rapid charging, and the rapid charging is limited, and the charging current value In is maintained at the infinite rated current value α. In this state, when the damage accumulation amount QCd decreases and becomes less than the threshold value R, the restriction on rapid charging is lifted, and the charging current value In is maintained at the allowable current value β again. When the charging current value In is maintained at the allowable current value β, the accumulated damage amount QCd becomes equal to or greater than the threshold value R again, and rapid charging is restricted again. In this way, the charging current value In may hunt during charging, which may affect the deterioration of the performance of the battery 110 .

FIG. 8 is a timing chart showing changes in the amount of accumulated damage QCd when rapid charging and discharging are repeated while the charging current value In is maintained at the infinite rated current value α. Rapid charging is performed from time t0 to time t1, and battery 110 is discharged from time t1 to time t2. When rapid charging and discharging are repeated in this manner, the accumulated damage amount QCd becomes equal to or greater than the threshold value R at time t3, and rapid charging is restricted. During subsequent discharge, the accumulated damage amount QCd becomes less than the threshold value R, and the restriction on rapid charging is lifted. As a result, the accumulated damage amount QCd is always maintained at a high value, which may affect the deterioration of the performance of the battery 110 .

In this modification, an example will be described in which charging is stopped until the accumulated damage amount QCd becomes zero as a restriction on rapid charging. FIG. 9 is a timing chart showing changes in the amount of accumulated damage QCd when charging is stopped after repeating rapid charging and discharging while maintaining the charging current value In at the allowable current value β. FIG. 10 is a timing chart showing changes in the amount of accumulated damage QCd when charging is stopped after repeating rapid charging and discharging while maintaining the charging current value In at the infinite rated current value α. In either case, rapid charging and discharging are repeated from time t0, and when the accumulated damage amount QCd reaches the threshold value R at time t1, charging is stopped until the accumulated damage amount QCd becomes zero. Specifically, the ECU 160 keeps the charging relay RY OFF until the accumulated damage amount QCd becomes zero. As a result, the aforementioned hunting of the charging current value In during charging and the maintenance of the accumulated damage amount QCd at a high value can be avoided, and deterioration of the performance of the battery 110 can be suppressed.

[others]
As an example of rapid charging limitation, the case where charging is allowed while limiting the charging current value In to the infinite rated current value α or less, and the case where charging is stopped until the accumulated damage amount QCd becomes zero have been described. It is not limited to this. For example, charging may be performed while maintaining the charging current value In at a value lower by a predetermined value than when rapid charging is not limited.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations can be made within the scope of the gist of the present invention described in the scope of claims. Change is possible.

100 vehicle 110 battery 120 PCU
130MG
140 drive wheel 150 inlet 160 ECU (charging control device)
162 CPUs
164 memory 170 HMI device 180 charging device SMR system main relay RY charging relay

Claims (1)

a calculation unit that calculates a damage accumulation amount indicating an accumulation amount of damage to the battery due to rapid charging of the battery;
rapid charging of the battery is permitted when the accumulated damage amount is less than a threshold; and a charging control unit that limits rapid charging,
The calculation unit calculates that the longer the period in which the charging current value, which is the current value of the battery during rapid charging, is greater than a predetermined value, the greater the amount of accumulated damage, and the longer the period in which the charging current value is equal to or less than the predetermined value. A charging control device that calculates the amount of accumulated damage so that the amount of accumulated damage decreases as the non-charging period of the battery increases.

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