Method for electric vehicle battery charging and discharging

Abstract

The present invention relates to a method for leveling the load by controlling the charging and discharging of an electric vehicle battery based on a load pattern and a solar power output pattern. A method for charging and discharging an electric vehicle battery according to the present embodiment includes the steps of: calculating a system pattern based on a load pattern and a solar power output pattern; setting a charging setting value and a discharging setting value based on an initial charge amount of the electric vehicle battery and the system pattern; setting the discharging setting value as a discharge reference value and continuously increasing the discharging setting value by a reference amount from the discharge reference value until the discharge energy determined according to the discharging setting value is less than the maximum charge amount of the electric vehicle battery; and charging or discharging the electric vehicle battery according to the charging setting value and the discharging setting value. This project (result) is the result of the Local Government-University Cooperation-based Regional Innovation Project conducted in 2022 with funding from the Ministry of Education and support from the National Research Foundation of Korea. (2021RIS-002)This results were supported by "Regional Innovation Strategy (RIS)" through the National Research Foundation of Korea(NRF) funded by the Ministry of Education(MOE)(2021RIS-002)

Description

Technology Field

[0001] The present invention relates to a method for leveling the load by controlling the charging and discharging of an electric vehicle battery based on a load pattern and a solar power output pattern. Background Technology

[0003] Generally, electric vehicles use unidirectional chargers to receive electrical energy from the power grid to charge the battery, and then use the stored energy to operate the vehicle. However, with various recent attempts to utilize electric vehicles in the smart grid domain, the application of bidirectional chargers and bidirectional charging systems is being considered.

[0004] The application of power charging and discharging modes to bidirectional chargers, such as V2G (Vehicle to Grid), which allows drivers to store electricity at low prices and sell it back to the power grid at high prices by retransmitting electrical energy stored in electric vehicle batteries to the grid, or V2H (Vehicle to Home), which supplies electrical energy accumulated in batteries to homes in the event of a power outage, is emerging as a core solution for smart grids.

[0005] However, there is a problem in that power system instability occurs if load fluctuations between electric vehicle batteries and the power grid are inconsistent. Therefore, there is a need for a system capable of supplying power to the grid consistently by controlling charging and discharging power within the capacity range of the electric vehicle battery. The problem to be solved

[0007] The present invention aims to flatten the load by controlling the charging and discharging of an electric vehicle battery based on a load pattern and a solar power output pattern.

[0008] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof set forth in the claims. means of solving the problem

[0010] A method for charging and discharging an electric vehicle battery according to an embodiment of the present invention for achieving the aforementioned purpose comprises the steps of: calculating a system pattern based on a load pattern and a solar power output pattern; setting a charging setting value and a discharging setting value based on an initial charging amount of the electric vehicle battery and the system pattern; setting the discharging setting value as a discharge reference value and continuously increasing the discharging setting value by a reference amount from the discharge reference value until the discharge energy determined according to the discharging setting value is less than the maximum charging amount of the electric vehicle battery; and charging or discharging the electric vehicle battery according to the charging setting value and the discharging setting value.

[0011] The step of calculating the above system pattern is characterized by including the step of subtracting the solar power output pattern from the above load pattern.

[0012] The step of charging or discharging the electric vehicle battery is characterized by including the step of charging the electric vehicle battery when the system pattern is less than or equal to the charging setting value, and discharging the electric vehicle battery when the system pattern is greater than or equal to the discharging setting value.

[0013] The step of setting the charging setting value is characterized by including the step of setting the charging setting value to the minimum value of the system pattern if the discharge energy is less than the initial charge amount of the electric vehicle battery.

[0014] delete

[0015] The step of setting the charging setting value includes the step of setting the charging setting value as a charging reference value if the discharge energy is greater than the initial charge amount of the electric vehicle battery, and

[0016] The method is characterized by including a step of continuously increasing the charging setting value by a reference amount from the charging reference value until the sum of the charging energy determined according to the charging setting value and the initial charging amount of the electric vehicle battery is greater than the discharge energy.

[0017] The step of setting the above-mentioned charging setting value as the charging reference value is characterized by including the step of identifying the minimum load power in the above-mentioned system pattern and the step of setting the above-mentioned minimum load power as the charging reference value.

[0018] The method is characterized by comprising the steps of: calculating a system pattern based on a load pattern and a solar power output pattern; receiving a target SOC; setting a charging setting value and a discharging setting value based on the initial charging amount of the electric vehicle battery, the system pattern, and the target SOC; setting the discharging setting value as a discharge reference value and continuously increasing the discharging setting value by a reference amount from the discharge reference value until the discharge energy determined according to the discharging setting value is less than the maximum charging amount of the electric vehicle battery; and charging or discharging the electric vehicle battery according to the charging setting value and the discharging setting value.

[0019] The step of calculating the above system pattern is characterized by including the step of subtracting the solar power output pattern from the above load pattern.

[0020] The step of charging or discharging the electric vehicle battery is characterized by including the step of charging the electric vehicle battery when the system pattern is less than or equal to the charging setting value, and discharging the electric vehicle battery when the system pattern is greater than or equal to the discharging setting value.

[0021] The step of setting the charging setting value is characterized by including the step of setting the charging setting value to the minimum value of the system pattern if the discharge energy is less than the initial charge amount of the electric vehicle battery.

[0022] delete

[0023] The step of setting the charging setting value is characterized by including the step of setting the charging setting value as a charging reference value when the discharge energy is greater than the initial charge amount of the electric vehicle battery, and the step of continuously increasing the charging setting value by a reference amount from the charging reference value until the value obtained by subtracting the discharge energy from the sum of the charging energy determined according to the charging setting value and the initial charge amount of the electric vehicle battery is greater than the target SOC.

[0024] The step of setting the above-mentioned charging setting value as the charging reference value is characterized by including the step of identifying the minimum load power in the above-mentioned system pattern and the step of setting the above-mentioned minimum load power as the charging reference value. Effects of the invention

[0026] The present invention can mitigate load peaks by flattening the load, thereby improving system stability.

[0027] The present invention can reduce the power consumed by a load by supplementing the power consumed by the load with power produced by a photovoltaic power generation system.

[0028] In addition to the effects described above, the specific effects of the present invention are described together with the specific details for implementing the invention below. Brief explanation of the drawing

[0030] FIG. 1 is a flowchart illustrating a method for charging and discharging an electric vehicle battery according to one embodiment of the present invention. Figure 2 is a diagram illustrating load leveling. Figure 3 is a graph illustrating the energy charged or discharged according to the charge / discharge setting value. FIG. 4 is a flowchart illustrating a method for setting charge / discharge setting values ​​according to an embodiment of the present invention. FIG. 5 is a flowchart illustrating a method for charging and discharging an electric vehicle battery according to another embodiment of the present invention. FIG. 6 is a flowchart illustrating a method for setting charge / discharge setting values ​​according to another embodiment of the present invention. Specific details for implementing the invention

[0031] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, thereby enabling those skilled in the art to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions would unnecessarily obscure the essence of the invention. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the attached drawings. In the drawings, the same reference numerals are used to indicate the same or similar components.

[0032] In this specification, terms such as "first," "second," etc. are used to describe various components, but these components are not limited by these terms. These terms are used merely to distinguish one component from another, and unless specifically stated otherwise, the first component may be the second component.

[0033] Furthermore, where it is stated in this specification that one component is "connected," "coupled," or "connected" to another component, it should be understood that while the components may be directly connected or connected to each other, another component may be "interposed" between each component, or each component may be "connected," "coupled," or "connected" through another component.

[0034] Additionally, singular expressions used in this specification include plural expressions unless the context clearly indicates otherwise. In this application, terms such as "composed of" or "comprising" should not be interpreted as necessarily including all of the various components or steps described in the specification, and should be interpreted as meaning that some of the components or steps may not be included, or that additional components or steps may be included.

[0035] Additionally, in this specification, "A and / or B" means A, B, or A and B unless specifically stated otherwise, and "C to D" means C or more and D or less, unless specifically stated otherwise.

[0036] The present invention relates to a method for charging and discharging an electric vehicle battery that can flatten the load by controlling the charging and discharging of the electric vehicle battery based on a load pattern and a solar power output pattern. Hereinafter, with reference to FIGS. 1 to 6, a method for charging and discharging an electric vehicle battery according to each embodiment of the present invention will be described in detail.

[0037] FIG. 1 is a flowchart illustrating a method for charging and discharging an electric vehicle battery according to one embodiment of the present invention.

[0038] Figure 2 is a diagram illustrating load leveling.

[0039] Figure 3 is a graph illustrating the energy charged or discharged according to the charge / discharge setting value.

[0040] FIG. 4 is a flowchart illustrating a method for setting charge / discharge setting values ​​according to an embodiment of the present invention.

[0041] FIG. 5 is a flowchart illustrating a method for charging and discharging an electric vehicle battery according to another embodiment of the present invention.

[0042] FIG. 6 is a flowchart illustrating a method for setting charge / discharge setting values ​​according to another embodiment of the present invention.

[0043] FIGS. 1 to 4 illustrate a method for charging and discharging an electric vehicle battery according to a first embodiment of the present invention.

[0044] Referring to FIG. 1, a method for charging and discharging an electric vehicle battery may include a step of calculating a system pattern based on a load pattern and a solar power output pattern (S100), a step of setting a charging setting value and a discharging setting value based on an initial charging amount of the electric vehicle battery and the system pattern (S200), and a step of charging or discharging the electric vehicle battery according to the charging setting value and the discharging setting value (S300). However, the method for charging and discharging an electric vehicle battery illustrated in FIG. 1 is according to one embodiment, and the steps constituting the invention are not limited to the embodiment illustrated in FIG. 1, and some steps may be added, changed, or deleted as necessary.

[0045] The method of charging and discharging an electric vehicle battery illustrated in FIG. 1 can be performed by a charging and discharging module connected to the electric vehicle, and the charging and discharging module may include at least one physical element among ASICs (application specific integrated circuits), DSPs (digital signal processors), DSPDs (digital signal processing devices), PLDs (programmable logic devices), FPGAs (field programmable gate arrays), controllers, processors, microprocessors, and microcontrollers to perform the operation described below.

[0046] Below, each step illustrated in FIG. 1 will be explained.

[0047] The charge / discharge module can calculate a system pattern based on the load pattern and the solar power output pattern (S100).

[0048] To be more specific, the charge / discharge module (10) receives a load pattern (100) and a solar power output pattern (200), respectively, and can calculate a system pattern (400) by subtracting the solar power output pattern (200) from the load pattern (100).

[0049] Here, the load pattern (100) may be a waveform representing a change in power consumed by the load, and in the present invention, the load may be any load having a constant power consumption pattern, such as a household load or an industrial load.

[0050] For example, the charge / discharge module (10) may be connected to a power meter in a home or factory to receive a load pattern (100) from the home or factory, or may receive a load pattern (100) from a home or industrial power management system (PMS). In addition, the charge / discharge module (10) may receive a load pattern (100) from various devices and / or servers.

[0051] The solar power output pattern (200) may be a waveform representing a change in power output from a solar power generation system, and in the present invention, the solar power generation system may have a constant power output pattern.

[0052] Meanwhile, the charging / discharging module (10) receives the power output pattern from the solar power generation system, but it may also receive the power output pattern from various other renewable energy generation systems (e.g., wind, hydroelectric, thermal power, etc.).

[0053] The system pattern (400) may be a waveform produced by subtracting the solar power output pattern (200) from the load pattern (100). That is, the power consumed by the load can be reduced by supplementing the power consumed by the load with power produced by the solar power generation system.

[0054] Referring to FIG. 2, the operation of the present invention can be schematically described. By controlling the charge / discharge power according to the system pattern (400) received as above and the current charge amount of the electric vehicle battery (300), the present invention can flatten the power supplied to the grid (Grid Power).

[0055] To this end, first, the charging / discharging module (10) has a system pattern (400) and an initial charge amount (E) of the electric vehicle battery (300). BAT i Based on ), the charging setting value (P c ) and discharge setting value (P d You can set ) (S200), and the charging setting value (P c) and discharge setting value (P d The electric vehicle battery (300) can be charged or discharged according to (S300).

[0056] Referring to FIG. 3, the charging setting value (P c ) is a reference value for starting and ending charging of the electric vehicle considering the system pattern (400) and the capacity of the electric vehicle battery (300), and the discharge setting value (P d ) is a reference value for starting and ending the discharge of an electric vehicle by taking into account the system pattern (400) and the capacity of the electric vehicle battery (300).

[0057] Below, the charging / discharging module (10) has a charging setting value (P c ) and discharge setting value (P d Each embodiment that sets ) and performs charging and discharging operations accordingly will be described.

[0058] Referring to FIG. 4, in one embodiment, the charge / discharge module (10) has a discharge setting value (P d ) discharge reference value (P di It can be initially set to ) (S210). Subsequently, the charge / discharge module (10) can set the discharge setting value (P d Discharge setting value (P) until the discharge energy (DE) determined according to ) is less than the maximum charge amount (max) of the electric vehicle battery (300). d ) discharge reference value (P di It can be continuously increased by a reference value from ) (S220, S230).

[0059] The maximum amount of energy that can be discharged from the electric vehicle battery (300) cannot exceed the maximum charge amount (max) of the electric vehicle battery (300). Accordingly, the charge / discharge module (10) has a discharge setting value (P) even when considering the system pattern (400). d Discharge setting value (P) until the discharge energy (DE) determined by ) is less than the maximum charge amount (max) of the electric vehicle battery (300). d ) can be gradually increased.

[0060] In other words, if the discharge energy (DE) of the charging / discharging module (10) is greater than the maximum charge amount (max) of the electric vehicle battery (300), the discharge setting value (P d Discharge setting value (P) until the discharge energy (DE) determined according to ) is less than the maximum charge amount (max) of the electric vehicle battery (300). d ) discharge reference value (P di It can be continuously increased by the reference value from ).

[0061] Meanwhile, the discharge reference value (P di ) can be set to an arbitrary value, for example, average load power (P avg ) can be set to. To this end, the charge / discharge module (10) can be set to the average load power (P) in the system pattern (400). avg ) can be produced.

[0062] The charging / discharging module (10) has a previously determined discharge energy (DE) and an initial charge amount (E) of the electric vehicle battery (300). BAT i ) can be compared, and the discharge energy (DE) is the initial charge amount (E BAT i If smaller than ), charging setting value (P c ) can be set as the minimum value (min) of the system pattern (400) (240, 250).

[0063] Charging setting value (P c When this is set to the minimum value (min) of the system pattern (400), the charging energy (CE) can be 0, as can be expected from the graph in FIG. 3. That is, in this embodiment, the charging / discharging module (10) can flatten the load by only discharging the electric vehicle battery (300).

[0064] In contrast, the previously determined discharge energy (DE) is the initial charge amount (E BAT i If it is greater than ), the charge / discharge module (10) is the charge setting value (P c ) charging reference value (P ci ) can be set to (260). Next, the charge / discharge module (10) can set the charge setting value (P cThe charging energy (CE) determined according to ) and the initial charging amount (E) of the electric vehicle battery (300) BAT i Charge setting value (P) until the sum of ) is greater than the discharge energy (DE). c ) charging reference value (P ci It can be continuously increased by a reference value from ) (S270, S280).

[0065] The maximum amount of energy to be discharged from the electric vehicle battery (300) is the amount of energy to be charged to the electric vehicle battery (300) prior to discharge and the initial charge amount (E) of the electric vehicle battery (300). BAT i The sum of ) cannot be exceeded. Accordingly, the charging / discharging module (10) has a charging setting value (P) even when considering the system pattern (400). c Charge energy (CE) and initial charge amount (E) determined by ) BAT i Charge setting value (P) until the sum of ) becomes greater than the discharge energy (DE). c ) can be gradually increased.

[0066] Meanwhile, the charging reference value (P ci ) can be set to an arbitrary value, but in order to gradually increase the charging energy (CE) from the minimum value (min), the charging reference value (P) ci ) can be set to the minimum load power of the system pattern (400). To this end, the charge / discharge module (10) can identify the minimum load power based on the system pattern (400).

[0067] In this embodiment, as can be expected from the graph in FIG. 3, the predetermined discharge energy (DE) and the initial charge amount (E) of the electric vehicle battery (300) BAT i Depending on the charging energy (CE), the charging energy (CE) can gradually increase. Accordingly, in this embodiment, the charging / discharging module (10) can level the load by charging and then discharging the electric vehicle battery (300).

[0068] FIGS. 5 and FIGS. 6 illustrate a charging and discharging method for an electric vehicle battery (300) according to a second embodiment of the present invention.

[0069] Referring to FIG. 5, a method for charging and discharging an electric vehicle battery may include the steps of calculating a system pattern based on a load pattern and a solar power output pattern (S400), receiving a target SOC (S500), setting a charging setting value and a discharging setting value based on the initial charge amount of the electric vehicle battery, the system pattern, and the target SOC (S600), and charging or discharging the electric vehicle battery according to the charging setting value and the discharging setting value (S700).

[0070] However, the method of charging and discharging an electric vehicle battery illustrated in FIG. 5 is according to one embodiment, and the steps constituting the invention are not limited to the embodiment illustrated in FIG. 5, and some steps may be added, changed, or deleted as necessary.

[0071] Elements having the same function as those in the drawings described above are indicated by the same reference numerals, and the operation of components not described below should be understood as being the same as the operation described above in the first embodiment.

[0072] Below, each step illustrated in FIG. 5 will be explained.

[0073] The present invention can flatten the grid power supplied to the grid by controlling the charge / discharge power according to the system pattern (400), the current charge amount of the electric vehicle battery (300), and the target SOC.

[0074] To perform this, the charge / discharge module (10) can calculate a system pattern (400) based on a load pattern (100) and a solar power output pattern (200) (S400).

[0075] Next, the charging / discharging module (10) can receive a target SOC (S500). The target SOC (State Of Charge) is the target charge amount of the electric vehicle battery (300), and the target SOC can be entered directly by the user into the charging / discharging module (10) or the charging / discharging module (10) can receive from the user terminal.

[0076] The charging / discharging module (10) is the initial charge amount (E) of the electric vehicle battery (300). BAT i Based on ), system pattern (400) and target SOC, charging setting value (P c ) and discharge setting value (P d You can set ) (S600), and charging setting value (P c ) and discharge setting value (P d The electric vehicle battery (300) can be charged or discharged according to ) (S700).

[0077] Below, the charging / discharging module (10) has a charging setting value (P c ) and discharge setting value (P d An example of setting ) and performing charge / discharge operations accordingly will be described.

[0078] Referring to FIG. 6, the discharge setting value (P) in the second embodiment d The operation (610) of setting ) is, in the first embodiment, the discharge setting value (P d It may be the same as the operation (S200) for setting )

[0079] The previously determined discharge energy (DE) is the initial charge amount (E BAT i If it is greater than ), the charge / discharge module (10) is the charge setting value (P c ) charging reference value (P ci It can be set to ). Subsequently, the charge / discharge module (10) can be set to a charge setting value (P c The charging energy (CE) determined according to ) and the initial charging amount (E) of the electric vehicle battery (300) BAT i Charge setting value (P) until the value obtained by subtracting discharge energy (DE) from the sum of ) is greater than the target SOC c ) charging reference value (Pci It can be continuously increased by a reference value from ) (S620, S630).

[0080] Meanwhile, the charging reference value (P ci ) can be set to an arbitrary value, but in order to gradually increase the charging energy (CE) from the minimum value (min), the charging reference value (P) ci ) can be set to the minimum load power of the system pattern (400). To this end, the charge / discharge module (10) can identify the minimum load power based on the system pattern (400).

[0081] In this embodiment, the predetermined discharge energy (DE) and the initial charge amount (E) of the electric vehicle battery (300) BAT i The charging energy (CE) can be gradually increased according to the method, until the SOC of the electric vehicle battery (300) being finally charged reaches a target SOC or higher. That is, in this embodiment, the charging / discharging module (10) can perform load leveling by charging and discharging the electric vehicle battery (300), and at the same time, enable the SOC of the electric vehicle battery (300) to reach a target SOC set by the user.

[0082] Although the present invention has been described above with reference to the illustrated drawings, the present invention is not limited by the embodiments and drawings disclosed in this specification, and it is obvious that various modifications can be made by a person skilled in the art within the scope of the technical concept of the present invention. Furthermore, even if the effects of the configuration of the present invention were not explicitly described while explaining the embodiments of the present invention above, it is natural to acknowledge that the effects predictable by said configuration should also be recognized.

Claims

Claim 1 A method for charging and discharging an electric vehicle battery that controls the charging and discharging of the electric vehicle battery according to a current charge amount, comprising: a step of calculating a system pattern based on a load pattern and a solar power output pattern; a step of setting a charge setting value and a discharge setting value based on an initial charge amount of the electric vehicle battery and the system pattern; a step of setting the discharge setting value as a discharge reference value and continuously increasing the discharge setting value by a reference amount from the discharge reference value until the discharge energy determined according to the discharge setting value is less than the maximum charge amount of the electric vehicle battery; and a step of charging or discharging the electric vehicle battery according to the charge setting value and the discharge setting value. Claim 2 A method for charging and discharging an electric vehicle battery according to claim 1, wherein the step of calculating the system pattern includes the step of subtracting the solar power output pattern from the load pattern. Claim 3 A method for charging and discharging an electric vehicle battery according to claim 1, wherein the step of charging or discharging the electric vehicle battery includes the step of charging the electric vehicle battery when the system pattern is less than or equal to the charging setting value, and discharging the electric vehicle battery when the system pattern is greater than or equal to the discharging setting value. Claim 4 delete Claim 5 A method for charging and discharging an electric vehicle battery according to claim 1, wherein the step of setting the charging setting value includes the step of setting the charging setting value to the minimum value of the system pattern if the discharge energy is less than the initial charge amount of the electric vehicle battery. Claim 6 A method for charging and discharging an electric vehicle battery according to claim 1, wherein the step of setting the charging setting value comprises: a step of setting the charging setting value as a charging reference value if the discharge energy is greater than the initial charge amount of the electric vehicle battery; and a step of continuously increasing the charging setting value by a reference amount from the charging reference value until the sum of the charging energy determined according to the charging setting value and the initial charge amount of the electric vehicle battery is greater than the discharge energy. Claim 7 A method for charging and discharging an electric vehicle battery according to claim 6, wherein the step of setting the charging setting value as a charging reference value includes the step of identifying a minimum load power in the system pattern and the step of setting the minimum load power as the charging reference value. Claim 8 A method for charging and discharging an electric vehicle battery that controls the charging and discharging of the electric vehicle battery according to a current charge amount, comprising: a step of calculating a system pattern based on a load pattern and a solar power output pattern; a step of receiving a target State of Charge (SOC); a step of setting a charge setting value and a discharge setting value based on the initial charge amount of the electric vehicle battery, the system pattern, and the target SOC; a step of setting the discharge setting value as a discharge reference value and continuously increasing the discharge setting value by a reference amount from the discharge reference value until the discharge energy determined according to the discharge setting value is less than the maximum charge amount of the electric vehicle battery; and a step of charging or discharging the electric vehicle battery according to the charge setting value and the discharge setting value. Claim 9 A method for charging and discharging an electric vehicle battery according to claim 8, wherein the step of calculating the system pattern comprises the step of subtracting the solar power output pattern from the load pattern. Claim 10 A method for charging and discharging an electric vehicle battery according to claim 8, wherein the step of charging or discharging the electric vehicle battery includes the step of charging the electric vehicle battery when the system pattern is less than or equal to the charging setting value, and discharging the electric vehicle battery when the system pattern is greater than or equal to the discharging setting value. Claim 11 delete Claim 12 A method for charging and discharging an electric vehicle battery according to claim 8, wherein the step of setting the charging setting value includes the step of setting the charging setting value to the minimum value of the system pattern if the discharge energy is less than the initial charge amount of the electric vehicle battery. Claim 13 A method for charging and discharging an electric vehicle battery according to claim 8, wherein the step of setting the charging setting value comprises: a step of setting the charging setting value as a charging reference value if the discharge energy is greater than the initial charge amount of the electric vehicle battery; and a step of continuously increasing the charging setting value by a reference amount from the charging reference value until the value obtained by subtracting the discharge energy from the sum of the charging energy determined according to the charging setting value and the initial charge amount of the electric vehicle battery is greater than the target SOC. Claim 14 A method for charging and discharging an electric vehicle battery according to claim 13, wherein the step of setting the charging setting value as a charging reference value includes the step of identifying a minimum load power in the system pattern and the step of setting the minimum load power as the charging reference value.

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