Vehicle-to-Grid (V2G) Operation Devices and Methods for Electric Vehicles

Abstract

A vehicle-to-grid (V2G) operation apparatus and method for an electric vehicle are disclosed. The V2G operation apparatus includes a communication unit configured to receive information about hourly electrical load from a server. The apparatus also includes a SOC measurement unit configured to measure the state of charge (SOC) of the battery pack. Furthermore, the apparatus includes a V2G operation unit configured to operate the vehicle-to-grid (V2G) based on the hourly electrical load information and the battery pack's SOC information.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit and priority of Korean Patent Application No. 10-2024-0173762, filed with the Korean Intellectual Property Office on November 28, 2024, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] This disclosure relates to apparatus and methods for vehicle-to-grid (V2G) communication for operating electric vehicles, as well as electric vehicle V2G methods. Background Technology

[0004] As the distribution of electric vehicles equipped with high-capacity batteries increases, the demand for electricity for charging is also rising rapidly. This places a heavy burden on the power infrastructure and continuously requires the expansion of charging infrastructure. However, electric vehicles are actually used for only about 4% of the day on average, leaving the electricity available for charging idle most of the time. This inefficient operation of electricity wastes the resources of the power supply network and hinders the full utilization of the potential economic value of electric vehicles.

[0005] Therefore, vehicle-to-grid (V2G) technology has been introduced to connect electric vehicle batteries to the power grid for sending and receiving energy in both directions. Under V2G technology, electric vehicle batteries are used as energy storage devices to return unused energy to the grid to supply power during periods of high electricity demand or to store renewable energy. This approach has attracted attention as a way to improve electric vehicle efficiency, enhance grid stability, and further achieve economic benefits.

[0006] However, according to related V2G technology, when the state of charge (SOC) of the electric vehicle battery cannot be properly controlled, the V2G function may terminate at high SOC or fully discharged states. In such cases, prolonged exposure to undesirable conditions accelerates battery degradation, leading to a decrease in the economic value of the electric vehicle. Specifically, when the battery remains fully discharged for an extended period, it not only causes inconvenience when the user attempts to use the vehicle but also severely impacts battery lifespan.

[0007] Therefore, in order to operate V2G technology in electric vehicles more efficiently and extend battery life, techniques for appropriately controlling the scope of SOC usage are needed. The subjects described in this Background section are intended to facilitate an understanding of the background techniques of this disclosure and may therefore include subjects not well known to those skilled in the art. Summary of the Invention

[0008] This disclosure provides a vehicle-to-grid (V2G) operation device and method for electric vehicles. Compared with not using V2G, the device and method can suppress excessive battery degradation caused by V2G use.

[0009] This disclosure provides an electric vehicle V2G operating device and a V2G method for electric vehicles, which can appropriately control the battery's SOC range and depth of discharge (DOD) by limiting the V2G usage range to be different in each SOC range during V2G operation, thereby delaying battery degradation.

[0010] This disclosure also provides an electric vehicle V2G operating device and an electric vehicle V2G method, which can use information about hourly power load to operate V2G during peak load periods and can charge the battery during extremely low load periods to improve economic efficiency.

[0011] This disclosure is not limited to the objectives described above. Other objectives and advantages not mentioned in this disclosure should be understood from the following description and should become apparent from the implementation of this disclosure. It should also be understood that the objectives and advantages of this disclosure can be achieved by the means and combinations thereof set forth in this disclosure.

[0012] To achieve the above objectives, according to one aspect of this disclosure, a vehicle-to-grid (V2G) operation device for an electric vehicle includes a communication unit configured to receive information about hourly power load from a server. The V2G operation device also includes a SOC measurement unit configured to measure the state of charge (SOC) of a battery pack. The V2G operation device further includes a V2G operation unit configured to operate the V2G based on the power load information and the battery pack's SOC information. The V2G calculation unit is further configured to determine whether the start time of V2G operation falls within the peak load period of the power load information. The V2G operation unit is also configured to control the battery pack to charge during off-peak load periods after the V2G operation ends.

[0013] When the start time of V2G operation falls within the peak load period specified in the power load information, the V2G operation unit can operate V2G. The SOC measurement unit can measure the current flowing through the battery pack to determine whether the battery pack is in a charging or discharging state. The SOC measurement unit can also measure the voltage change of each of the multiple battery cells in the battery pack to predict the SOC change of the battery pack.

[0014] When V2G is running, the V2G operating unit can change the V2G operating method based on the SOC range defined by the SOC control strategy to which the battery pack's SOC value belongs at the start of V2G operation.

[0015] The SOC range may include a first reference value and a second reference value, and based on the first reference value and the second reference value, the SOC range is divided into a high SOC range, a medium SOC range, and a low SOC range.

[0016] When the SOC value of the battery pack falls into the high SOC range at the start of V2G operation, the V2G operating unit can use the predetermined value as the maximum DoD value to operate V2G.

[0017] When the SOC value of the battery pack falls within the medium SOC range at the start of V2G operation, the V2G operating unit can use the difference between the SOC value of the battery pack and the second reference value at the start of V2G operation as the maximum DoD value to operate V2G.

[0018] When the battery pack's SOC value falls into the low SOC range at the start of V2G operation, the V2G operation unit can terminate V2G operation and check whether charging is required.

[0019] Meanwhile, according to another aspect of this disclosure, a V2G operation method for an electric vehicle includes receiving information about hourly electrical load from a server. The method also includes measuring the state of charge (SOC) of the battery pack. The method further includes the step of operating the V2G based on the electrical load information and the battery pack's SOC information. The method also includes determining whether the start time of V2G operation falls within a peak load period in the electrical load information. The method further includes controlling the battery pack to charge during off-peak load periods after the V2G operation ends.

[0020] Operating V2G includes: activating V2G when the start time of V2G operation falls within the peak load period specified in the power load information. The V2G operation method may also include measuring the current flowing through the battery pack to determine whether the battery pack is in a charging or discharging state. The V2G operation method may also include measuring the voltage change of each of the multiple battery cells in the battery pack to predict the state of charge (SOC) change of the battery pack.

[0021] Running V2G includes: changing the V2G operation method based on the SOC range defined by the SOC control strategy to which the battery pack's SOC value belongs at the start of V2G operation.

[0022] According to this disclosure, excessive battery degradation caused by using V2G can be prevented compared to not using V2G.

[0023] Furthermore, according to this disclosure, by limiting the V2G usage range to be different in each SOC range during V2G operation, the battery usage SOC range and depth of discharge (DOD) can be appropriately controlled, thereby delaying battery degradation.

[0024] Furthermore, according to this disclosure, V2G is operated during peak load periods using information about hourly power load and the battery is charged during extremely low load periods to improve economic efficiency. Attached Figure Description

[0025] The above and other aspects, features, and advantages of this disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 This is a diagram of a vehicle-to-grid (V2G) operating device for an electric vehicle according to an embodiment of the present disclosure;

[0027] Figure 2 This is a flowchart before dividing the operating mode in the V2G operation method of an electric vehicle according to an embodiment of the present disclosure;

[0028] Figure 3 This is a view showing the state of charge (SOC) range of a SOC control strategy according to an embodiment of the present disclosure;

[0029] Figure 4 This is a flowchart of V2G operation in an electric vehicle V2G operation method according to an embodiment of the present disclosure when the initial SOC value of the battery pack is in the high SOC range;

[0030] Figure 5 This is a flowchart illustrating the V2G operation method for electric vehicles according to embodiments of the present disclosure, where the initial SOC value of the battery pack is within the medium SOC range.

[0031] Figure 6 This is a flowchart illustrating the V2G operation method for electric vehicles according to embodiments of the present disclosure, where the initial SOC value of the battery pack is in a low SOC range; and

[0032] Figure 7 This is a flowchart illustrating the process after V2G operation is terminated in an electric vehicle V2G operation method according to an embodiment of this disclosure. Detailed Implementation

[0033] In the following description, reference is made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings and described below. Even though the same or similar elements are described in different drawings, these elements are indicated by the same reference numerals, and therefore redundant descriptions are omitted. In the following description of embodiments, terms such as “module” and “component” are provided or used interchangeably for convenience. These terms do not have a distinguishing meaning or function from each other. In the following description of embodiments of the present disclosure, detailed descriptions of known functions and configurations incorporated herein have been omitted where detailed descriptions might make the subject matter of the disclosure considerably unclear. Furthermore, the accompanying drawings are used to describe embodiments of the present disclosure and should not be construed as limiting oneself to the embodiments set forth herein. It should be understood that embodiments of the present disclosure are intended only to disclose the present disclosure and cover modifications, equivalents, or alternatives that should fall within the scope and technical field of the present disclosure.

[0034] In the following description of the embodiments, terms such as “first” and “second” are used only to describe various elements, and these elements should not be construed as being limited by these terms. These terms are only used to distinguish one element from another.

[0035] When a component or layer is referred to as being "connected to" or "coupled to" another component or layer, the component or layer may be directly connected to or coupled to the other component or layer, or there may be intermediate components or layers between them. Conversely, when a component or layer is referred to as being "directly connected to" or "directly coupled to" another component or layer, there may be no intermediate components or layers between them. When the controllers, units, modules, components, devices, elements, etc. of this disclosure are described as having a purpose or performing operation, function, etc., the controllers, units, modules, components, devices, elements, etc., should be regarded herein as being "configured to" satisfy that purpose or perform that operation or function. Each controller, unit, module, component, device, element, etc., may be embodied individually or included as part of a device together with a processor and memory (such as a non-transitory computer-readable medium).

[0036] In the following text, see references Figures 1 to 7 The present disclosure provides a detailed description of the vehicle-to-grid (V2G) operation device and V2G operation method for electric vehicles.

[0037] Figure 1 This is a diagram illustrating an electric vehicle V2G operating device according to an embodiment of the present disclosure. (See reference) Figure 1 According to an embodiment of the present disclosure, the electric vehicle V2G operating device 100 includes a communication unit 110 (e.g., a communicator, transceiver), a state of charge (SOC) measurement unit 120, and an operating unit 130 (e.g., a processor).

[0038] Communication unit 110 receives information about hourly power load from the server.

[0039] For example, the server could be an open portal server for electricity data operated by Korea Electric Power Corporation (KEPCO). Communication unit 110 can receive real-time information from the server, such as hourly electricity demand, supply, and electricity market prices. Specifically, through the electricity supply company's OpenAPI (e.g., KEPCO OpenAPI), communication unit 110 can be provided with electricity load data every 15 minutes or every hour, hourly electricity charges, or peak electricity hours information.

[0040] For reference, Table 1 below provides an example of hourly power load.

[0041] [Table 1]

[0042]

[0043] At this time, on Saturdays, the electricity consumed during peak load periods is measured as the electricity consumed during off-peak load periods, and the maximum required and consumed electricity during holidays is measured as the electricity consumed during ultra-low-peak load periods.

[0044] The SOC measurement unit 120 measures the SOC value of the battery pack.

[0045] For example, the SOC measurement unit 120 includes multiple current sensors, voltage sensors, and temperature sensors, and collects accurate state information from multiple battery cells in the battery pack. The current sensors measure the current flowing through the battery pack to determine whether the battery pack is in a charging or discharging state, and the voltage sensors measure the voltage change of each battery cell to predict changes in the battery pack's SOC. Furthermore, the temperature sensors sense temperature rises or overheating in the battery cells and module to provide control data for ensuring thermal stability.

[0046] In addition, the SOC measurement unit 120 measures the SOC value based on information generated by measuring the physical variables of the battery pack in real time, such as current, voltage and temperature.

[0047] The V2G operation unit 130 operates the vehicle-to-grid (V2G) based on information about the hourly power load and the battery pack's SOC.

[0048] Specifically, if the start time of V2G operation falls within the peak load period of the hourly power load information, then the V2G operation unit 130 operates V2G. If the start time of V2G operation does not fall within the peak load period, then the V2G operation unit 130 charges without operating V2G.

[0049] Figure 2 This is a flowchart before dividing the operating mode in the V2G operation method for electric vehicles according to the embodiments of this disclosure.

[0050] refer to Figure 2 When the V2G charger is plugged in ( Figure 2 In step S210), the V2G operation unit 130 checks the time period during which peak load occurs in the power load every hour and determines whether the time when V2G operation starts ("V2G operation start time") belongs to the peak load period. Figure 2 Step S220).

[0051] This is to maximize the economic benefits of V2G operation. To improve the economic efficiency of V2G operation, the degradation of the battery pack and the associated costs need to be carefully considered, and it is desirable to operate V2G during peak load periods to reduce cost burdens. V2G operation unit 130 maximizes profits and minimizes economic losses due to battery pack degradation by operating V2G during peak load periods and selling electricity when the unit price of electricity supplied to the grid is highest.

[0052] If the start time of V2G operation does not fall within the peak load period ( Figure 2 If the step S220 is not successful, then the V2G operation unit 130 restricts V2G operation. Figure 2 Step S230), and instead, priority is given to charging the battery pack so that the user can use the vehicle without any inconvenience. Figure 2 Step S240).

[0053] If the V2G operation starts during peak load periods ( Figure 2 In step S220, if the V2G operation unit 130 operates V2G to transfer power from the battery to the external power grid, then the V2G operation unit 130 will operate V2G to transfer power from the battery to the external power grid. Figure 2 (Step S250). Supplying power during peak load periods improves grid stability and efficiency, and ensures economic benefits.

[0054] Furthermore, when V2G is running, the V2G operation method varies depending on the SOC range of the SOC control strategy to which the SOC value of the battery pack ("starting SOC value") belongs at the start of V2G operation, causing the V2G operation unit 130 to check which SOC range of the SOC control strategy the SOC at the start of V2G operation belongs to. Figure 2 Step S260).

[0055] For example, a greater depth of discharge (DoD) leads to more battery pack degradation. This means that if V2G is used with a reduced DoD, the time spent in a high state of charge (SOC) state will increase, negatively impacting degradation. Therefore, the V2G operation unit 130 can set different DoD limit values ​​based on the SOC range of the SOC control strategy to which the battery pack's SOC value belongs at the start of V2G operation.

[0056] In the implementation, the SOC range of the SOC control strategy includes a first reference value and a second reference value, and based on the first and second reference values, the SOC range is divided into a high SOC range, a medium SOC range, and a low SOC range (see...). Figure 3 ).

[0057] Specifically, the first reference value is the SOC value set by subtracting a predetermined value from the maximum SOC value of the battery pack. Here, the predetermined value is the DoD value. The DoD value is set to enable V2G operation in high SOC regions, and is determined by deriving the DoD value that maximizes electricity sales revenue compared to the economic loss due to battery pack degradation. This maximizes the economic efficiency of V2G operation while minimizing battery pack degradation by testing various average SOC values ​​based on an initial SOC value of 100.

[0058] Furthermore, by considering that degradation occurs differently depending on the midpoint position when the DoD is the same, through experiments, when the battery pack is repeatedly charged and discharged at a constant DoD below the first reference value, the point at which the battery pack deteriorates and discharges faster is set as the second reference value.

[0059] Next, if the SOC value of the battery pack is in the high SOC range at the start of V2G operation, the V2G operation unit 130 will run V2G by setting a predetermined value to the maximum DoD value.

[0060] Figure 4 This is a flowchart illustrating the V2G operation method for electric vehicles according to embodiments of the present disclosure, where the initial SOC value of the battery pack is in the high SOC range.

[0061] refer to Figure 4 If V2G is running in a high SOC range ( Figure 4 In step S410), the V2G operation unit 130 runs V2G ( Figure 4 Step S420), and prevents the value obtained by subtracting the SOC value of the battery pack at the end of V2G operation ("end SOC value") from the start SOC value of the battery pack from the end SOC value of the battery pack ("end SOC value") from the start SOC value of the battery pack from the end SOC value of the V2G operation, from exceeding the predetermined DoD value ( Figure 4 Step S430). Furthermore, when this value reaches or exceeds a predetermined DoD value ( Figure 4(In S430) V2G operation unit 130 terminates V2G operation and enters standby mode (see S430). Figure 4 Step S440).

[0062] Furthermore, if the SOC value of the battery pack is in the medium SOC range at the start of V2G operation, the V2G operation unit 130 will use the difference between the SOC value of the battery pack and the second reference value at the start of V2G operation as the maximum DoD value to operate V2G.

[0063] Figure 5 This is a flowchart illustrating the V2G operation method for electric vehicles according to embodiments of the present disclosure, where the initial SOC value of the battery pack is within the medium SOC range.

[0064] refer to Figure 5 When running V2G within the SOC range ( Figure 5 In step S510), the V2G operating unit 130 determines whether the ending SOC value is lower than the second reference SOC value. Figure 5 Step S530), run V2G ( Figure 5 (Step S520) reaches the limit of the second reference SOC value, causing the final SOC value to be higher than the second reference SOC value. Furthermore, when the SOC value of the battery pack reaches or falls below the second reference SOC value ( Figure 5 In step S530, the V2G operation unit 130 terminates V2G operation and enters standby mode. Figure 5 Step S540).

[0065] In addition, if the SOC value of the battery pack is in the low SOC range at the start of V2G operation, the V2G operation unit 130 terminates V2G operation and checks whether charging is required.

[0066] Figure 6 This is a flowchart illustrating the V2G operation method for electric vehicles according to embodiments of the present disclosure, where the initial SOC value of the battery pack is in a low SOC range.

[0067] refer to Figure 6 When the V2G operating unit 130 operates V2G in the low SOC range ( Figure 6 In step S610), the V2G operation unit 130 receives information from the user regarding not running V2G ( Figure 6 In step S620, is charging performed? Figure 6 Confirmation of step S630). If the user does not want to charge ( Figure 6 In step S630 (no), the V2G operating unit 130 is in standby mode, and V2G operation has stopped. Figure 6Step S640). If the user wants to charge ( Figure 6 In step S630, the V2G operating unit 130 is charged. Figure 6 Step S650).

[0068] Furthermore, after V2G operation ends, if the V2G operation ends during an off-peak load period as indicated by the hourly power load data, the V2G operation unit 130 will charge. If the V2G operation ends outside of an off-peak load period, the V2G operation unit 130 will enter standby mode.

[0069] Figure 7 This is a flowchart illustrating the process after V2G operation is terminated in an electric vehicle V2G operation method according to an embodiment of this disclosure.

[0070] refer to Figure 7 After ending V2G operation ( Figure 7 In the standby state following step S710, the V2G operation unit 130 checks whether the current time belongs to the ultra-low load period in the hourly power load information. Figure 7 Step S720). If the current time does not belong to the ultra-low load period ( Figure 7 If the step S720 is not successful, then the V2G operating unit 130 is in standby mode. Figure 7 Step S730). If the current time is during a period of extremely low load ( Figure 7 In step S720, the V2G operating unit is charged to ensure economic efficiency. Figure 7 Step S740).

[0071] The V2G operation unit 130 determines whether the SOC value of the battery pack exceeds a first reference value. Figure 7 Step S750) limits the charging range of the battery pack. If the SOC value of the battery pack exceeds the first reference value ( Figure 7 In step S750, the V2G operating unit finishes charging. Figure 7 Step S760) is used to reduce battery pack degradation, prevent overheating, and enhance stability.

[0072] In this disclosure, elements may be in a singular or plural form. Furthermore, when a scope is stated in this disclosure, the statement includes the implementation to which the individual value within that scope applies (unless otherwise stated) and is identical to the statement constituting the individual value within that scope in a specific embodiment of this disclosure.

[0073] Unless there is a stated order or a statement contrary to the steps constituting the method according to this disclosure, the steps may be performed in any suitable order. This disclosure is not necessarily limited to the described order of steps. The use of any illustrative or explanatory terminology in this disclosure is only for the purpose of describing the disclosure in detail, and the scope of this disclosure is not limited by illustrative or explanatory terminology unless limited by the claims. Furthermore, those skilled in the art will understand that various modifications, combinations, and changes can be made according to design conditions and factors within the scope of the appended claims or their equivalents.

[0074] Therefore, the spirit of this disclosure should not be limited to the above-described embodiments, and the scope of the appended claims and all scopes equivalent to or modified from the claims are within the scope of this disclosure.

Claims

1. A vehicle-to-grid (V2G) operating device for an electric vehicle, the V2G operating device comprising: The communication unit is configured to receive information about the hourly power load from the server; The state of charge measurement unit is configured to measure the state of charge of the battery pack. as well as The vehicle is configured to operate from the power grid unit as follows: Based on the power load information and the state of charge information of the battery pack, the vehicle is connected to the power grid; Determine whether the start time of the vehicle's operation to the power grid falls within the peak load period of the power load information; and After the vehicle's connection to the grid is terminated, the battery pack is controlled to charge during periods of extremely low load.

2. The vehicle-to-grid operation device according to claim 1, wherein, When the start time of the vehicle-to-grid operation falls within the peak load period specified in the power load information, the vehicle-to-grid operation unit is configured to operate the vehicle-to-grid operation. The state of charge measurement unit is further configured as follows: The current flowing through the battery pack is measured to determine whether the battery pack is in a charging or discharging state; and The voltage change of each of the multiple battery cells in the battery pack is measured to predict the state of charge change of the battery pack.

3. The vehicle-to-grid operation device according to claim 2, wherein, When the vehicle-to-grid operation is performed, the vehicle-to-grid operation unit is configured to change the vehicle-to-grid operation method based on the state of charge range defined by the state of charge control strategy to which the state of charge value of the battery pack belongs at the start time of the vehicle-to-grid operation.

4. The vehicle-to-grid operation device according to claim 3, wherein, The state of charge range includes a first reference value and a second reference value, and Based on the first reference value and the second reference value, the state of charge range is divided into a high state of charge range, a medium state of charge range, and a low state of charge range.

5. The vehicle-to-grid operation device according to claim 4, wherein, The first reference value is a state of charge value set by subtracting a predetermined value from the maximum state of charge value of the battery pack, and The predetermined value is a depth of discharge value configured to minimize the degradation of the battery pack while maximizing the economic efficiency of the vehicle's grid connection when discharging at the maximum state of charge value of the battery pack.

6. The vehicle-to-grid operation device according to claim 4, wherein, The second reference value is the state of charge value of the battery pack during accelerated discharge, and the second reference value is set to be lower than the first reference value.

7. The vehicle-to-grid operation device according to claim 5, wherein, When the state of charge (SOC) value of the battery pack falls within the high SOC range at the start of the vehicle-to-grid operation, the vehicle-to-grid operation unit is configured to operate the vehicle-to-grid system using the predetermined value as the maximum depth of discharge value.

8. The vehicle-to-grid operation device according to claim 4, wherein, When the state of charge (SOC) value of the battery pack falls within the medium SOC range at the start of the vehicle-to-grid operation, the vehicle-to-grid operation unit is configured to operate the vehicle-to-grid system using the difference between the SOC value of the battery pack and the second reference value at the start of the vehicle-to-grid operation as the maximum depth of discharge value.

9. The vehicle-to-grid operation device according to claim 4, wherein, When the state of charge (SOC) value of the battery pack falls within the low SOC range at the start of the vehicle-to-grid operation, the vehicle-to-grid operation unit is configured to terminate the vehicle-to-grid operation and check whether charging is required.

10. The vehicle-to-grid operation device according to claim 4, wherein, The vehicle-to-grid operating unit is configured to limit the charging range, and The charging range is defined using the first reference value as the maximum state of charge value.

11. A method for vehicle-to-grid operation of an electric vehicle, the method comprising: Receive information about hourly power load from the server; Measure the state of charge of the battery pack; Based on the power load information and the state of charge information of the battery pack, the vehicle is connected to the power grid; Determine whether the start time of the vehicle's operation to the power grid falls within the peak load period in the power load information; and After the vehicle's connection to the grid is terminated, the battery pack is controlled to charge during periods of extremely low load.

12. The vehicle-to-grid operation method according to claim 11, wherein, Operating the vehicle to the power grid includes: When the start time of the vehicle's operation to the power grid falls within the peak load period in the power load information; The vehicle-to-grid operation method further includes: The current flowing through the battery pack is measured to determine whether the battery pack is in a charging or discharging state; and The voltage change of each of the multiple battery cells in the battery pack is measured to predict the state of charge change of the battery pack.

13. The vehicle-to-grid operation method according to claim 12, wherein, Operating the vehicle to the power grid includes: The vehicle-to-grid operation method is changed based on the state of charge range defined by the state of charge control strategy to which the state of charge value of the battery pack belongs at the start time of the vehicle-to-grid operation.

14. The vehicle-to-grid operation method according to claim 13, wherein, The state of charge range includes a first reference value and a second reference value, and Based on the first reference value and the second reference value, the state of charge range is divided into a high state of charge range, a medium state of charge range, and a low state of charge range.

15. The vehicle-to-grid operation method according to claim 14, further comprising: The state of charge (SOC) value obtained by subtracting a predetermined value from the maximum SOC value of the battery pack is set as the first reference value, and The predetermined value is the depth of discharge value that minimizes the degradation of the battery pack while maximizing the economic efficiency of the vehicle's grid connection when discharging at the maximum state of charge value of the battery pack.

16. The vehicle-to-grid operation method according to claim 14, wherein, The second reference value is the state of charge value of the battery pack during accelerated discharge, and the second reference value is set to be lower than the first reference value.

17. The vehicle-to-grid operation method according to claim 15, wherein, Operating the vehicle to the power grid includes: Based on the determination that the state of charge value of the battery pack falls within the high state of charge range at the start time of the vehicle-to-grid operation, the predetermined value is used as the maximum depth of discharge value to operate the vehicle-to-grid system.

18. The vehicle-to-grid operation method according to claim 14, wherein, Operating the vehicle to the power grid includes: Based on the determination that the state of charge (SOC) value of the battery pack falls within the medium SOC range at the start of the vehicle-to-grid operation, the difference between the SOC value of the battery pack and the second reference value at the start of the vehicle-to-grid operation is used as the maximum depth of discharge value to operate the vehicle-to-grid system.

19. The vehicle-to-grid operation method according to claim 14, wherein, Operating the vehicle to the power grid includes: Based on the determination that the state of charge (SOC) value of the battery pack falls within the low SOC range at the start of the vehicle-to-grid operation, the vehicle-to-grid operation is terminated and a check is performed to determine whether charging should commence.

20. The vehicle-to-grid operation method according to claim 14, wherein, Operating the vehicle to the power grid includes: Limited charging range, and The charging range is defined using the first reference value as the maximum state of charge value.

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