Charging system

Abstract

To appropriately estimate an amount of damage of a battery at the time of charging.SOLUTION: A control unit performs processing including: a step (S102) of calculating a damage integrated amount during quick charging when it is determined that quick charging is being performed (YES in S100); a step (S104) of determining whether or not the damage integrated amount is equal to or larger than a threshold value; a step (S106) of restricting quick charging when it is determined that the damage integrated amount is equal to or greater than the threshold value (YES in S104); and a step (S108) of determining whether or not charging has ended.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a charging system. [Background technology]

[0002] For example, Patent Document 1 (JP 2022-147323 A) discloses that the accumulated damage amount is calculated so that the accumulated damage amount increases as the period during which the charging current value of an in-vehicle battery during rapid charging is greater than a predetermined value becomes longer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-147323 Summary of the Invention [Problem to be solved by the invention]

[0004] However, for example, in a high SOC (State of Charge) region, the charging current value is set low, so if the calculation of the cumulative damage amount depends only on the charging time, the amount of damage may be overestimated. As a result, if the charging time becomes long, unnecessary charging restrictions may be imposed.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a charging system that appropriately estimates the amount of damage to a battery during charging. [Means for solving the problem]

[0006] A charging system according to an aspect of the present disclosure includes a battery and a control device that limits charging operation when an accumulated damage amount indicating a battery degradation evaluation value becomes equal to or exceeds a threshold value during charging of the battery. The control device calculates, as a section damage amount, an amount of damage in a section corresponding to a current value of the SOC among multiple sections set using the battery's SOC during charging. The control device calculates, as the accumulated damage amount, an accumulated value of the section damage amount since the start of charging. The control device calculates the section damage amount using a ratio between the battery's allowable current value in the section and the battery's charging current value.

[0007] In this way, the amount of damage to the section is calculated based on the ratio between the battery's allowable current value and the charging current value, so that the amount of damage can be appropriately estimated when the SOC is high and the charging current value is small, and unnecessary charging restrictions can be prevented.

[0008] In this embodiment, the control device calculates the section damage amount by multiplying the ratio of the allowable current value to the charging current value by the charging time.

[0009] In this way, the amount of damage to the section is calculated by multiplying the charging time by the ratio of the charging current to the allowable current value. Therefore, for example, if the charging current value is small compared to the allowable current value, the amount of damage to the section is prevented from being overestimated, thereby preventing unnecessary charging restrictions from being implemented.

[0010] Furthermore, in this embodiment, the control device calculates the section damage amount using the ratio between the accumulated damage amount when charging the battery from the lower limit value of the SOC to the upper limit value of the SOC and the charging time when charging the battery from the lower limit value to the upper limit value.

[0011] In this way, the amount of damage can be appropriately estimated in each of the multiple sections of the SOC. [Effects of the Invention]

[0012] According to the present disclosure, it is possible to provide a charging system that appropriately estimates the amount of damage to a battery during charging. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a diagram illustrating an example of the configuration of a charging system. [Figure 2] 10 is a flowchart illustrating an example of processing executed by a control unit. [Figure 3] FIG. 10 is a diagram showing the relationship between charging time, current value, and damage amount. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0015] An example of the configuration of a charging system 1 according to this embodiment will be described below. Fig. 1 is a diagram showing an example of the configuration of the charging system 1. As shown in Fig. 1, the charging system 1 includes a charging station 10 and a vehicle 200. Vehicle 200 may be any vehicle equipped with a power storage device that can be externally charged, and may be, for example, an electric vehicle or a plug-in hybrid vehicle.

[0016] The vehicle 200 includes an ECU (Electronic Control Unit) 100 , a battery 214 , an inverter 216 , an MG (Motor Generator) 218 ​​, and an inlet 220 .

[0017] Battery 214 may be any rechargeable power storage device, including, for example, a secondary battery such as a lithium ion battery or a nickel-metal hydride battery.

[0018] The inverter 216 is configured to be able to convert DC power from the battery 214 and AC power from the MG 218 in both directions in response to a control signal from the ECU 100 .

[0019] The MG 218 is a drive source that drives the drive wheels of the vehicle 200, and is configured by, for example, a three-phase AC rotating electric machine or the like.

[0020] The inlet 220 has a shape that allows the connector 17 to be attached. The inlet 220 is electrically connected to the battery 214.

[0021] Sensors 102, 104, and 106 for acquiring the voltage, current, and temperature of battery 214 are connected to ECU 300. ECU 300 includes a CPU (Central Processing Unit) and a memory (neither of which are shown). ECU 300 controls each device based on signals received from each sensor and information such as maps and programs stored in the memory, so that vehicle 200 is in a desired state.

[0022] The ECU 300 has a function of sequentially calculating the SOC (State Of Charge) of the battery 214 based on the detection values ​​of the sensors 102, 104, and 106. As a method for calculating the SOC, various known methods can be used, such as a method based on current value integration (coulomb counting) or a method based on open circuit voltage (OCV) estimation. The ECU 300 is configured to be able to communicate with a control unit 14 of the charging stand 10, which will be described later.

[0023] Charging stand 10 includes a control unit 14, a charging unit 15, a cable 16, and a connector 17. Charging stand 10 includes, for example, a rapid charger that completes charging in a shorter time than normal charging by supplying higher charging power than normal charging. Normal charging includes, for example, charging using a household AC power source such as 100V or 200V.

[0024] Control unit 14 controls the operation of charging unit 15 (for example, charging voltage and charging current). Control unit 14 includes, for example, a CPU and a memory (neither of which are shown). Control unit 14 controls charging unit 15 based on information received from vehicle 200 and information such as maps and programs stored in the memory. When connector 17 is attached to inlet 220, control unit 14 is configured to be able to acquire information about battery 214 (for example, information about SOC, charging voltage, and allowable current value) using various communication methods such as power line communication.

[0025] Charging unit 15 converts AC power from system power supply 400 into DC power in response to a control signal from control unit 14. One end of cable 16 is connected to charging unit 15. The other end of cable 16 is connected to connector 17.

[0026] Connector 17 has a shape that allows it to be attached to inlet 220. When connector 17 is attached to inlet 220, DC power can be supplied from charging unit 15 to battery 214 in response to a control signal from control unit 14.

[0027] For example, when connector 17 is connected to inlet 220 of vehicle 200 in a stopped state, charging stand 10 operates charging unit 15 to convert AC power from system power supply 400 into DC power and supplies the converted DC power to battery 214. While battery 214 is being charged, ECU 300 transmits information about the SOC and the allowable current value calculated using the detection values ​​of sensors 102, 104, and 106 to control unit 14. For example, when ECU 300 calculates the SOC, it obtains the allowable current value corresponding to the calculated SOC and transmits the information about the SOC and the allowable current value to control unit 14.

[0028] Rapid charging of the battery 214 using the charging stand 10 places a load on the battery 214 compared to normal charging, which accelerates deterioration. By calculating an evaluation value (deterioration evaluation value) for determining this deterioration as the amount of damage, it becomes possible to determine whether or not charging restrictions are necessary when charging is performed repeatedly.

[0029] As an example of such a deterioration evaluation value, for example, the time (number of seconds) during charging may be calculated as the amount of damage. For example, the control unit 14 accumulates the elapsed time during charging. If the accumulated value (accumulated amount of damage) exceeds a threshold, the control unit 14 implements a charging restriction, thereby making it possible to suppress the progression of deterioration.

[0030] However, when the SOC of battery 214 is in the high SOC range, the charging current value is set low, and so the damage amount may be overestimated if the calculation of the damage amount depends only on the charging time. As a result, if the charging time becomes long, unnecessary charging restrictions may be imposed.

[0031] Therefore, in this embodiment, the control unit 14 operates as follows. That is, the control unit 14 calculates, as the section damage amount, the amount of damage in a section corresponding to the current value of SOC among multiple sections set using the SOC of the battery 214 during charging. The control unit 14 calculates, as the integrated damage amount, the integrated value of the section damage amounts since the start of charging. The control unit 14 calculates the section damage amount using the ratio between the allowable current value of the battery 214 in the section and the charging current value of the battery 214, and the charging time.

[0032] In this way, by calculating the section damage amount based on the ratio between the allowable current value and the charging current value of battery 214, the damage amount can be appropriately estimated even when the SOC is high and the charging current value is low, and unnecessary charging restrictions can be prevented.

[0033] An example of the processing executed by the control unit 14 will be described below with reference to Fig. 2. Fig. 2 is a flowchart showing an example of the processing executed by the control unit 14. A series of processing steps shown in this flowchart is repeatedly executed at predetermined intervals.

[0034] In step (hereinafter, step will be abbreviated as S) 100, control unit 14 determines whether quick charging is in progress. For example, control unit 14 receives information about the SOC and allowable current value from vehicle 200 when connector 17 is attached to inlet 220, starts operation of charging unit 15, and sets an operation flag to the ON state. Therefore, control unit 14 determines that quick charging is in progress when the operation flag is in the ON state. If it is determined that quick charging is in progress (YES in S100), the process proceeds to S102.

[0035] In S102, control unit 14 executes a process for calculating the amount of damage during rapid charging. Control unit 14 identifies a section corresponding to the current SOC value from among a plurality of sections set using the SOC. The plurality of sections includes, for example, a first section of 15%-20% SOC, a second section of 20%-25% SOC, a third section of 25%-30% SOC, a fourth section of 30%-35% SOC, a fifth section of 35%-40% SOC, a sixth section of 40%-45% SOC, a seventh section of 45%-50% SOC, an eighth section of 50%-55% SOC, a ninth section of 55%-60% SOC, a tenth section of 60%-65% SOC, an eleventh section of 65%-70% SOC, a twelfth section of 70%-75% SOC, and a thirteenth section of 75%-80% SOC.

[0036] The control unit 14 calculates the amount of damage in each section from the SOC section at the time charging started to the current SOC section, and the integrated value of the amount of damage from the section at the time charging started to the current section (hereinafter referred to as the integrated damage amount).

[0037] When calculating the amount of damage in a section of the current SOC, the control unit 14 acquires a charging current value corresponding to the section of the current SOC and an allowable current value of the battery 214 corresponding to the section of the current SOC. The control unit 14 acquires the charging time (number of seconds) in the current section. Furthermore, the control unit 14 calculates the section damage amount by multiplying a value obtained by dividing the allowable current value by the charging current value (the ratio of the allowable current value to the charging current value) by the charging time. The allowable current value is a value set in advance for each section of the SOC of the battery 214. The charging current value is a current flowing from the charging station 10 to the vehicle 200, and may be detected by the charging unit 15, or a value detected in the vehicle 200 may be acquired by the control unit 14. For example, if the charging time in the current SCO section is 135 seconds, the allowable current value is 280 A, and the charging current value is 140 A, the section damage amount is calculated as 270 using the formula 280 / 140×135.

[0038] Furthermore, the control unit 14 multiplies the calculated section damage amount by a conversion factor to calculate a converted value of the section damage amount. The conversion factor is a value for converting the calculated section damage amount into a value comparable to the section damage amount calculated from only the charging time. For example, the conversion factor is calculated by the ratio of the charging time from SOC 15% in the first section to SOC 80% in the thirteenth section (the accumulated damage amount calculated from only the charging time) to the accumulated damage amount from SOC 15% in the first section to SOC 80% in the thirteenth section. The conversion factor may be a predetermined value calculated, for example, by a prior experiment or the like. Alternatively, the conversion factor may be set to a predetermined value until charging from SOC 15% to SOC 80% is performed for the first time, and updated using an actual measurement value when charging from SOC 15% to SOC 80%, and the converted value of the accumulated damage amount may then be calculated using the updated conversion factor. Furthermore, the conversion factor may be a value that changes depending on the temperature of the battery 214. For example, if the charging time required to increase the SOC from 15% to 80% is 2500 seconds and the cumulative damage during that time is 4500, then 0.56 is set as the conversion factor using the formula 2500 / 4500. Therefore, if the section damage amount is calculated as 270, the conversion value is calculated as 151.2 (= 270 × 0.56). This value is 1.12 times the value when the section damage amount is set as the charging time. Note that the allowable current value and charging current value are reduced in high SOC sections. For example, if the charging time is 300 seconds, the allowable current value is 120 A, and the charging current value is 85 A, the section damage amount is calculated as 423.5 using the formula 120 / 85 × 300, and the conversion value is calculated as 237.2 (= 423.5 × 0.56). This value is 0.79 times the value when the section damage amount is set as the charging time.

[0039] The control unit 14 calculates the cumulative amount of damage by accumulating the converted values ​​since the start of charging. Then, the process proceeds to S104.

[0040] In S104, control unit 14 determines whether the calculated cumulative damage amount is equal to or greater than a threshold value. The threshold value may be, for example, a predetermined value that is adapted and set through experiments or the like, or may be a value that is set according to the temperature of battery 214. Thereafter, the process proceeds to S106.

[0041] In S106, control unit 14 executes a process to limit rapid charging. Specifically, control unit 14 limits rapid charging by reducing the charging current during rapid charging by a predetermined value, by a predetermined rate, or to a predetermined value or less. Thereafter, the process proceeds to S108.

[0042] In S108, control unit 14 determines whether charging has been completed. Control unit 14 terminates charging when the SOC of battery 214 has reached a predetermined value (for example, 80%). Therefore, control unit 14 may determine that charging has been completed when the SOC of battery 214 has reached a predetermined value, for example. If it is determined that charging has been completed (YES in S108), this process is terminated. If it is determined that charging has not been completed (NO in S108), the process returns to S102. If it is determined that quick charging is not being performed (NO in S100), this process is terminated.

[0043] An example of the operation of the control unit 14 based on the above-described structure and flowchart will now be described.

[0044] For example, assume that connector 17 is attached to inlet 220, rapid charging begins, and charging occurs from SOC 15% to SOC 80%. Figure 3 shows the relationship between charging time, current value, and damage amount. LN1 (solid line) in Figure 3 shows the change in the accumulated damage amount when the accumulated value of the converted value is used as the accumulated damage amount. LN2 (dashed line) in Figure 3 shows the change in the accumulated damage amount calculated from charging time alone. LN3 (dashed line) in Figure 3 shows the change in charging current during rapid charging.

[0045] For example, the cumulative damage calculated from only the charging time increases in proportion to the increase in charging time, as shown by LN2 in Figure 3. In other words, the cumulative damage increases at the same rate (slope) even in the SOC 15%-80% range.

[0046] On the other hand, when the section damage amount is calculated by multiplying the ratio of the charging current value to the allowable current value during rapid charging by the charging time, the charging current value remains constant in the low SOC section until the SOC reaches SOC(0), so the accumulated damage amount increases as the charging time increases, for example, as shown in LN3 of Figure 3. At this time, the charging current value is higher in the period until the SOC reaches SOC(0) than in other periods, so the accumulated damage amount increases at a slope greater than the slope of LN2 of Figure 3, as shown in LN1 of Figure 3.

[0047] When the SOC reaches a high SOC range above SOC(0), the charging current value decreases in proportion to the increase in SOC. Therefore, as shown by LN1 in Figure 3, the accumulated damage increases on a curve that is gentler than the slope of LN2 in Figure 3. And because LN1 in Figure 3 is the accumulated value of the converted value, the accumulated damage when the SOC reaches 80% is the same as the accumulated damage calculated from only the charging time.

[0048] In the damage accumulation amount shown in LN1 of Figure 3, which changes in this way, the range of change in the section where SOC increases from 65% to 80% is smaller than the range of change in the damage accumulation amount shown in LN2 of Figure 2, which changes in the section where SOC increases from 65% to 80%.

[0049] That is, when a situation in which charging is performed in a high SOC section is repeated multiple times, the increase in the accumulated damage amount is smaller than in the case shown in LN2 of Figure 2. In other words, the accumulated damage amount is prevented from being unnecessarily overestimated. As a result, unnecessary charging restrictions are prevented from being implemented during fast charging, and excessive charging time is prevented.

[0050] As described above, according to the charging system 1 of this embodiment, by calculating the section damage amount by multiplying the ratio of the allowable current value to the charging current value of the battery 214 by the charging time, the damage amount can be appropriately estimated when the SOC is high and the charging current value is low, and unnecessary charging restrictions can be prevented. In particular, when the charging current value is small relative to the allowable current value in the high SOC region, the section damage amount is prevented from being overestimated compared to when the charging current value is large in the low SOC region. As a result, unnecessary charging restrictions are prevented from being implemented when charging in the high SOC region is repeated, for example. Therefore, a charging system can be provided that appropriately estimates the amount of damage to a battery during charging.

[0051] Furthermore, by calculating the damage amount for each section using a conversion multiplier to convert the accumulated damage amount from the first section corresponding to the lower limit value of the SOC to the second section corresponding to the upper limit value of the SOC into an accumulated damage amount calculated only from the charging time from the first section to the second section, the damage amount can be appropriately estimated for each of the multiple sections of the SOC.

[0052] Modifications will be described below. In the above embodiment, it has been explained that the accumulated damage amount is calculated in the control unit 14 and charging restrictions are implemented in accordance with the calculated accumulated damage amount. However, for example, if the operation of the charging unit 15 can be controlled by the ECU 100, or if a charging device that converts charging power is installed in the vehicle 200 and the charging device can be controlled by the ECU 100, the accumulated damage amount may be calculated in the ECU 100 and charging restrictions may be implemented in accordance with the calculated accumulated damage amount.

[0053] Furthermore, in the above-described embodiment, it has been explained that the accumulated damage amount is calculated in the control unit 14 and charging restrictions are implemented in accordance with the calculated accumulated damage amount, but the configuration may also be such that the calculation of the accumulated damage amount and charging restrictions in accordance with the accumulated damage amount are implemented by a server (not shown) that can communicate with the charging stand 10.

[0054] Furthermore, in the above-described embodiment, the case where the accumulated damage amount increases during charging has been described, but for example, the accumulated damage amount may be reduced when charging is not in progress, or when the load on battery 214 is low even during charging and the deterioration state is resolved.

[0055] The above-described modifications may be implemented in whole or in part in appropriate combination. The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims, not by the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0056] 1 Charging system, 10 charging stand, 14 control unit, 15 charging unit, 16 cable, 17 connector, 100 ECU, 102, 104, 106 sensor, 200 vehicle, 214 battery, 216 inverter, 218 MG, 220 inlet, 400 grid power supply.

Claims

1. A battery, a control device that limits a charging operation when an accumulated amount of damage indicating a deterioration evaluation value of the battery becomes equal to or greater than a threshold value during charging of the battery, The control device calculating, as a section damage amount, an amount of damage in a section corresponding to a current value of the SOC among a plurality of sections set using the SOC (State Of Charge) of the battery during the charging; calculating an integrated value of the section damage amount from the start of charging as the integrated damage amount; calculating the section damage amount using a ratio between an allowable current value of the battery in the section and a charging current value of the battery; The control device calculates the section damage amount by multiplying a ratio of the allowable current value to the charging current value by a charging time.

2. 2. The charging system according to claim 1, wherein the control device calculates the section damage amount using a ratio between the accumulated damage amount when charging the battery from the lower limit value of the SOC to the upper limit value of the SOC and a charging time when charging the battery from the lower limit value to the upper limit value.

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