KR20170105214A - Electric vehicle charger system - Google Patents

Abstract

The present invention relates to an electric vehicle charging system for controlling an electric vehicle charger which comprises: a sensing unit for sensing voltage applied to the electric vehicle charger as charging voltage, and sensing a voltage size of the charging voltage; and a control unit for controlling to turn on and off the electric vehicle charger when the voltage size is less than or equal to first reference voltage which is a reference of a risk state. The control unit controls the electric vehicle charger to have voltage size lower than or equal to the first reference voltage to be higher than or equal to second reference voltage which is a reference of a safe state.

Description

[0001] ELECTRIC VEHICLE CHARGER SYSTEM [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric vehicle charging system, and more particularly to an electric vehicle charging system.

An electric vehicle can be an electric vehicle. Such an electric vehicle can be broadly divided into a battery-powered electric vehicle and a hybrid electric vehicle.

A pure electric vehicle is a vehicle that uses electricity only and can be generally named as an electric car.

Hybrid electric vehicles are meant to run on electricity and fossil fuels.

The pure electric vehicle and the hybrid electric vehicle may be provided with a battery that supplies electricity for running.

Particularly, in the case of a plug-in type hybrid electric vehicle of a pure electric vehicle and a hybrid electric vehicle, the battery can be charged by a current supplied from an external power source and can be driven by an electric motor.

The electric vehicle may have a cord set type charger of a charger for charging, and in the case of a cord set type charger, a commercial power supply may be used to charge the electric car.

The cord set type charger can be connected to an outlet and an electric vehicle provided in a home or an office, and can supply electric power to the electric car.

The cord set may be a device that provides an electrical interface between an AC or DC power network and an onboard charger (OBC), which is an in-car device for charging an electric vehicle battery, to enable electric vehicle charging using a power grid.

The cord set type electric vehicle has a CCID (Charging Circuit Interruption Device) type code set incorporating a CCID (Charging Circuit Interruption Device) that can control the charging current to enable more secure charging and a code There can be three forms.

Particularly, a cord set type electric vehicle incorporating a CCID (Charging Circuit Interruption Device) can communicate with an onboard charger (OBC), which is an internal device of a car, The charging current can be controlled so as to be safely charged by sensing the voltage, current, and temperature applied to the battery.

The cord set type electric vehicle incorporating such a CCID (Charging Circuit Interruption Device) can continuously stop the charging by generating a low voltage fault when the voltage drops below the predetermined size while continuously sensing the input voltage.

However, when such a low voltage fault is continuously generated, the main relay of the cord set type electric vehicle having a built-in charging circuit interrupting device (CCID) can be repeatedly turned on and off, A chattering phenomenon that is an on or turn-off operation occurs.

An object of the present invention is to provide an electric vehicle charging system capable of preventing a chattering phenomenon in advance by applying a margin to a voltage section when a low voltage fault is continuously generated in charging an electric car.

In the electric vehicle charging system for controlling an electric car charger according to an embodiment of the present invention, a sensing unit senses a voltage applied to the electric car charger as a charging voltage and senses a voltage magnitude of the charging voltage; And a control unit for controlling the electric car charger to be turned off when the voltage level of the charging voltage decreases and becomes less than the voltage at the time of application and becomes equal to or less than a first reference voltage that becomes a reference of a dangerous state,

The controller may control the electric charger so that the voltage magnitude below the first reference voltage is greater than the charging voltage and equal to or greater than a second reference voltage that is a reference for a safe state.

The controller may control the electric charger so that the voltage magnitude below the first reference voltage is greater than the charging voltage and equal to or greater than a second reference voltage that is a reference for a safe state.

The controller may control the electric vehicle charger to be turned on when the voltage level equal to or lower than the first reference voltage is equal to or higher than the second reference voltage.

The controller may maintain the electric charger in a turned-off state such that the voltage magnitude that is equal to or less than the first reference voltage becomes the second reference voltage.

The sensing unit senses that the electric car charger is connected to the power grid and the electric vehicle, and senses the charging voltage applied to the electric car in the electric power grid.

The electric vehicle charging system may further include an observing unit for observing an internal state of the electric car charger and a change in the voltage magnitude.

The sensing unit may sense at least one of voltage, current, and temperature of the electric vehicle charger through an internal state of the electric vehicle charger observed by the observing unit.

The electric vehicle charging system may further include an output unit for outputting at least one of a result of the observing unit and a result of sensing the sensing unit.

The output unit may output at least one of voltage, current, and temperature of the electric charger sensed by the sensing unit.

Wherein the output unit includes a first output unit and a second output unit different from the first output unit, the first output unit outputs, as a danger notification, that the voltage level is in the dangerous state, It is possible to output the safety notification that the size has reached the safety state.

Wherein the electric car charger includes a relay and the control unit controls the relay to be turned off when the charging voltage becomes equal to or less than the first reference voltage, It can be controlled to be turned on.

The controller may maintain the relay to be in the turned-off state such that the voltage magnitude that is equal to or less than the first reference voltage becomes the second reference voltage.

The electric vehicle charging system may further include a determination unit for determining a voltage level of the charging voltage, and the controller may check the determination result of the determination unit.

According to the present invention, the electric car charger can be kept turned off until the voltage level below the first reference voltage becomes equal to or higher than the second reference voltage, thereby reducing repetitive performance of turning on and off of the electric car charger, The phenomenon can be prevented and the durability of the electric car charger can be improved.

In addition, the dangerous state and the safety state can be informed through the output unit, and it is possible to check the electric car charger in advance, and at least one of voltage, current and temperature of the electric car charger can be measured through the sensing unit, There is a good advantage.

1 is a block diagram illustrating a connection of a charging process of an electric vehicle to which an embodiment of the present invention is applied.
2 is a block diagram illustrating an electric vehicle charger to which an embodiment of the present invention is applied.
3 is a block diagram of an electric vehicle charging system according to an embodiment of the present invention.
FIG. 4 is a diagram for explaining the variation of the charging voltage, which is one embodiment of the present invention.
5 is a flowchart illustrating an electric vehicle charging system according to an embodiment of the present invention.

Hereinafter, embodiments related to the present invention will be described in detail with reference to the drawings. The suffix "module" and " part "for the components used in the following description are given or mixed in consideration of ease of specification, and do not have their own meaning or role.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions in the embodiments of the present invention, which may vary depending on the intention of the user, the intention or the custom of the operator. Therefore, the definition should be based on the contents throughout this specification.

Combinations of the steps of each block and flowchart in the accompanying drawings may be performed by computer program instructions. These computer program instructions may be embedded in a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus so that the instructions, which may be executed by a processor of a computer or other programmable data processing apparatus, Thereby creating means for performing the functions described in the step. These computer program instructions may also be stored in a computer usable or computer readable memory capable of directing a computer or other programmable data processing apparatus to implement the functionality in a particular manner so that the computer usable or computer readable memory It is also possible to produce manufacturing items that contain instruction means that perform the functions described in each block or flowchart illustration in each step of the drawings. Computer program instructions may also be stored on a computer or other programmable data processing equipment so that a series of operating steps may be performed on a computer or other programmable data processing equipment to create a computer- It is also possible for the instructions to perform the processing equipment to provide steps for executing the functions described in each block and flowchart of the drawings.

Also, each block or each step may represent a module, segment, or portion of code that includes one or more executable instructions for executing the specified logical function (s). It should also be noted that in some alternative embodiments, the functions mentioned in the blocks or steps may occur out of order. For example, two blocks or steps shown in succession may in fact be performed substantially concurrently, or the blocks or steps may sometimes be performed in reverse order according to the corresponding function.

Hereinafter, a portable electric vehicle charging system according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram illustrating a charging process of an electric vehicle to which an embodiment of the present invention is applied.

1, the electric vehicle charger 200 may be connected to the electric power network 100 and the electric vehicle 300, respectively.

The power grid 100 receives power from a power plant, an electric power distribution station, and the like, and can supply power to the electric vehicle 300 through the electric car charger 200.

The power grid 100 may be a power source for use in a home, an office or the like after receiving power from a power plant, an electric power station, etc., and the power grid 100 may include a socket outlet (not shown).

The electric vehicle charger 200 may be connected to the electric power network 100 to supply the electric power to the electric vehicle 300. That is, the electric car charger 200 can be connected to the socket outlet.

The electric vehicle charger 200 may be provided in the electric vehicle 300 or may be a portable electric vehicle charger 200 that can be carried.

The electric vehicle 300 can receive power supplied from the electric power network 100 through the electric car charger 200.

The electric vehicle 300 may include an on board charger (OBC) 320 and a battery 340.

The On Board Charger (OBC) 320 may be a charger mounted on a vehicle. In other words, the battery 340 can be charged with the charging power supplied from the electric car charger 200.

The battery 340 may receive power from an onboard charger (OBC) 320 and store the charging power.

The battery 340 can supply power to the electric vehicle 300 using the stored charging power, and can also supply electric power to electric components used in the electric vehicle 300.

The battery 340 may be a secondary cell battery, a secondary battery, a battery that is semi-permanently charged, an eco-friendly part, and a nickel-cadmium battery, lithium Ion batteries, nickel-hydrogen batteries, and lithium-polymer batteries.

2 is a block diagram illustrating an electric vehicle charger to which an embodiment of the present invention is applied.

1 and 2, the electric vehicle charger 200 may include a plug 210, an electric vehicle charging system 230, a connector 250, a communication control device 290 and a relay 270.

The plug 210 may be connected to the power grid 100 and in particular to the socket outlet of the power grid 100 and the preferred embodiment of the plug 210 may be a grid plug 210 .

The connector 250 may be connected to the electric vehicle 300 and may supply charging power to the onboard charger 320 of the electric vehicle 300 through the connector 250.

The communication control device 290 can receive a control signal input from an external higher control system (not shown), and can convert the state of the electric car charger 200 into a signal and transmit the signal to the higher control system.

The communication control unit 290 can communicate with the onboard charger 320 of the electric vehicle 300 and can recognize the state of the electric vehicle 300 and control the battery of the electric vehicle 300 The battery 340 of the electric vehicle can be safely charged by detecting an overvoltage, an undervoltage, an overcurrent, an abnormal temperature, a current leakage,

The relay 270 may be turned on or off and may be a power switch, for example.

The electric vehicle charging system 230 controls the electric car charger 200 and detects the charging power applied to the electric car charger 200, the control of the relay 270, the notification output when the electric charger 200 is abnormally generated, 200, and the communication control device 290 can be controlled.

The electric vehicle charging system 230 may be a programmable data processing equipment or system or firmware.

Also, the electric vehicle charging system 230 may be, for example, a Charging Circuit Interruption Device (CCID).

The CCID (Charging Circuit Interruption Device) may be a device for controlling the charging current and the charging voltage so as to perform the charging more safely.

3 is a block diagram of an electric vehicle charging system according to an embodiment of the present invention.

1 to 3, the electric vehicle charging system 230 may include a sensing unit 231, a control unit 233, an output unit 237, and an observation unit 239, and the determination unit 235 .

The sensing unit 231 can sense that the electric vehicle 300 and the electric car charger 200 are connected to each other and also can detect that the electric power car charger 200 is connected to the electric power network 100. That is, the sensing unit 231 can detect that the electric car charger 200 is connected to the power grid 100 and the electric vehicle 300, respectively.

The observation unit 239 can observe a change in the internal state of the electric car charger 200 and the voltage magnitude of the charging voltage.

That is, when the electric car charger 200 is connected to the electric grid 300 and the electric grid 300 to supply the charging voltage to the electric vehicle 300, the observation unit 239 changes the voltage magnitude of the supplied charging voltage Can be observed. For example, it is possible to observe when the charging power supply is suddenly disconnected due to an accident or the like of the power grid 100, and it is also possible to observe that the voltage magnitude of the charging voltage is reduced due to the voltage drop, Can be observed.

The sensing unit 231 can sense at least one of voltage, current, and temperature of the electric car charger 200 through the internal state of the electric car charger 200 observed by the observation unit 239.

The determination unit 235 can determine the variation of the voltage magnitude of the charging voltage sensed by the sensing unit 231 and the control unit 233 can confirm the determination result of the determination unit 235. [

The output unit 237 may output at least one of a result observed by the observing unit 239 and a result detected by the sensing unit 231.

The output unit 237 may output at least one of voltage, current, and temperature of the electric car charger 200 sensed by the sensing unit 231. [ For example, the output unit 237 may output at least one of voltage, current, and temperature to a light signal or a monitor capable of monitoring at least one of voltage, current, and temperature.

The output unit 237 can output the result observed by the observing unit 239 and the output unit 237 can output the output results of the first output unit 237 and the second output unit 237 ).

The electric vehicle charger 200 may include a relay 270 and the control unit 233 may control the electric car charger 200 and the relay 270. [

The control unit 233 can control the electric car charger 200 to be turned off when the voltage level of the charge voltage is smaller than the voltage at the point of time when the voltage level of the charge voltage is applied and becomes less than the first reference voltage,

That is, the sensing unit 231 senses the voltage applied to the electric car charger 200 as a charging voltage, and can also sense the voltage magnitude of the sensed charging voltage.

The controller 233 can control the voltage magnitude that is equal to or less than the first reference voltage to be greater than the charging voltage and equal to or greater than the second reference voltage that is the reference of the safety state.

That is, the controller 233 can control the electric car charger 200 to turn off and maintain the turn-off state so that the voltage level that is equal to or lower than the first reference voltage becomes the second reference voltage.

The control unit 233 controls the electric car charger 200 to be turned on so that the electric vehicle 300 can be recharged when the voltage of the voltage level equal to or lower than the first reference voltage is equal to or higher than the second reference voltage.

That is, when the voltage level of the charging voltage sensed by the sensing unit 231 is lower than the applied charging voltage to the electric car charger 200 through the power grid 100 due to a voltage drop or the like, When the voltage becomes lower than the reference voltage, the electric car charger 200 can be controlled to be turned off.

When the electric car charger 200 is turned off, the voltage magnitude reduced due to the voltage drop or the like may increase. At this time, the controller 233 can control the electric car charger 200 to be maintained in the turn-off state until the magnitude of the increased voltage becomes equal to or greater than the second reference voltage.

The first reference voltage may be a reference voltage at which the applied charge voltage continuously decreases and becomes a fault state.

The second reference voltage may be, for example, a hysteresis period. The hysteresis period may be a period for adding a margin to the M (%) of the minimum operating voltage at which the electric car charger 200 can operate.

That is, the hysteresis period may be from a first reference voltage to a second reference voltage to prevent a chattering phenomenon, and may increase the voltage magnitude from a first reference voltage smaller than the charge voltage to a second reference voltage larger than the charge voltage, The margin of the voltage drop of the voltage magnitude of the voltage to the first reference voltage can be increased.

That is, for example, if the minimum operating voltage is 100 (V) and M (&) is 10 (%), the second reference voltage may be 110 (V).

The control unit 233 can turn on the electric car charger 200 and charge the electric vehicle 300 again when the voltage level of the charging voltage exceeds the second reference voltage.

That is, the second reference voltage can be set to be higher than the charging voltage, so that a margin can be provided in a period in which the voltage magnitude is lowered due to the voltage drop, so that the electric car charger 200 can be prevented from repeatedly performing the turn- So that the durability of the electric vehicle charger 200 can be improved.

The turn-on and turn-off operations of the electric car charger 200 may be the turn-on and turn-off operations of the relay 270 included in the electric vehicle charger 200.

When the relay 270 of the electric vehicle charger 200 continuously performs the turn-on or turn-off operation, the chattering phenomenon occurs and the life of the relay 270 may be shortened due to a physical impact. The present embodiment has an operation effect that can prevent the occurrence of the chattering phenomenon through the second reference voltage in advance.

In another embodiment, the electric vehicle charger 200 may include a power switch (not shown), and the control unit 233 may control the relay 270 (for example, due to a break in the electric car charger 200, Or the electric vehicle charger 200 or may control the relay 270 and the power switch simultaneously so that the voltage magnitude of the charging voltage becomes the first reference voltage or the second reference voltage.

That is, the control unit 233 can control the power switch to be open-contacted when the charging voltage is lower than the first reference voltage.

In addition, the controller 233 can control the power switch to be turned on when the charging voltage becomes equal to or higher than the second reference voltage.

That is, when an error such as failure or disconnection of the relay 270 occurs, the control unit 233 determines whether the voltage of the charging voltage sensed by the sensing unit 231 is higher than the charging And when the voltage drops below the first reference voltage, the power switch can be controlled to be open-contacted.

When the power switch is opened, the magnitude of the reduced voltage may increase due to a voltage drop or the like. At this time, the control unit 233 can control the power switch to be maintained in the turn-on state until the magnitude of the increased voltage becomes equal to or greater than the second reference voltage.

The control unit 233 can control the power switch to be turned on when the voltage level of the charging voltage becomes equal to or higher than the second reference voltage.

FIG. 4 is a diagram for explaining the variation of the charging voltage, which is one embodiment of the present invention.

4A, when the voltage level Va of the charge voltage applied to the electric car charger 200 through the power grid 100 is greater than the first reference voltage Vd The electric vehicle charger 200 can be turned off at a first point of time t1 when the electric vehicle charger 200 is turned off.

The control unit 233 maintains the turn-off state of the electric car charger 200 and turns on the electric car charger 200 at the second time point t2 at which the voltage magnitude of the charge voltage becomes the second reference voltage Vc have.

That is, the control unit 233 can maintain the relay 270 of the electric car charger 200 in the turn-off state until the voltage level Va, which is lower than the first reference voltage Vb, becomes the second reference voltage Vc have.

That is, the first voltage Vb to the second voltage interval Vc may be a margin period of the voltage magnitude that is a hysteresis voltage interval.

Accordingly, the voltage at the time when the voltage Va of the charging voltage measured by the sensing unit 231 is applied can be higher than the voltage at the time of application of the voltage, so that the chattering phenomenon can be prevented.

Referring to FIGS. 1 to 4, referring to FIG. 4B, the second reference voltage Vc may be equal to or greater than the first reference voltage Vb and the maximum voltage Vd.

The maximum voltage Vd may be a maximum value of the voltage tolerance that can be applied to the electric car charger 200. The interval between the first reference voltage Vb and the maximum voltage Vd is equal to or less than the maximum voltage Vd, Voltage range.

In addition, the first reference voltage Vb and the second reference voltage Vc may be a margin period of the voltage magnitude that is a hysteresis voltage section.

5 is a flowchart illustrating an electric vehicle charging system according to an embodiment of the present invention.

1 to 5, the sensing unit 231 may sense that the electric car charger 200 is connected to the power grid 100 and the electric vehicle 300, respectively.

The sensing unit 231 senses the charging voltage applied to the charger 200 and senses the voltage level of the charging voltage (S1).

The determination unit 235 may determine whether the voltage magnitude is greater than or equal to the first reference voltage (S3), and may start charging if the voltage magnitude is greater than the first reference voltage (S4).

When the voltage applied to the electric car charger 200 during charging is less than the first reference voltage, the electric car charger 200 can be turned off (S5).

That is, the controller 233 can control the electric car charger 200 to be turned off when the voltage level is smaller than the charging voltage and becomes equal to or lower than the first reference voltage, which is a criterion for the dangerous state.

The control unit 233 can control the voltage level of the charging voltage to be greater than the charging voltage and equal to or higher than the second reference voltage that is the reference of the safety state.

That is, the controller 233 can maintain the electric car charger 200 in the turned-off state so that the voltage magnitude that is equal to or less than the first reference voltage becomes the second reference voltage (S7).

The control unit 233 can control the electric vehicle charger 200 to be turned on when the voltage of the voltage equal to or less than the first reference voltage is equal to or greater than the second reference voltage (S9) (S11).

The sensing unit 231 of the electric vehicle charging system 230 together with the electric power network 100 and the electric vehicle 300 can sense that the electric car charger 200 is connected to the electric power network 100 and the electric power vehicle 300 . At this time, the electric vehicle charging system 230 can receive at least one of voltage, current, and temperature of the battery through the communication control device 290.

The sensing unit 231 of the electric vehicle charging system 230 senses the charging voltage applied to the electric car charger 200 and can sense the voltage level of the charging voltage and can sense the voltage of the battery 300 of the electric vehicle 300 340), thereby determining the amount of charge voltage.

The determination unit 235 of the electric vehicle charging system 230 may determine whether the voltage level is equal to or less than the first reference voltage and the controller 233 determines whether the voltage level is equal to or less than the first reference voltage The relay 270 can be turned off.

The controller 233 can control the relay 270 to be turned off when the voltage level is smaller than the charging voltage and becomes equal to or lower than the first reference voltage that is a reference of the dangerous state.

The control unit 233 can control the voltage level of the charging voltage to be greater than the charging voltage and to be equal to or higher than the second reference voltage that is the reference of the safety state, The relay 270 can be kept in the turn-off state

The controller 233 may control the relay 270 to be turned on when the voltage level of the voltage equal to or lower than the first reference voltage is equal to or higher than the second reference voltage.

According to an embodiment of the present invention, the above-described method can be implemented as a code that can be read by a processor on a medium on which the program is recorded. Examples of the medium that can be read by the processor include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, etc., and may be implemented in the form of a carrier wave (e.g., transmission over the Internet) .

The embodiments described above are not limited to the configurations and methods described above, but the embodiments may be configured by selectively combining all or a part of the embodiments so that various modifications can be made.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention.

100; Power grid, 200; Electric car charger,
210; Plug, 230; Electric vehicle charging system,
231; Sensing unit, 233; The control unit,
235; Determination unit 237; Output section,
239; Observation section, 250; connector,
270; Relay, 290; Communication control device,
300; Electric vehicle, 320; Onboard Chargers,

Claims (10)

An electric vehicle charging system for controlling an electric car charger,
A sensing unit sensing a voltage applied to the electric car charger as a charging voltage and sensing a voltage magnitude of the charging voltage; And
And a controller for controlling the electric car charger to be turned off when the voltage level becomes equal to or less than a first reference voltage that is a criterion for a dangerous state,
The control unit
The electric vehicle charger is controlled such that the voltage magnitude that is equal to or less than the first reference voltage is equal to or greater than a second reference voltage that is a reference of the safety state
Electric vehicle charging system. The method according to claim 1,
The control unit
And controlling the electric car charger to be turned on when the voltage magnitude below the first reference voltage becomes equal to or greater than the second reference voltage
Electric vehicle charging system. The method according to claim 1,
The control unit
Maintaining the electric car charger in a turn-off state such that the voltage magnitude below the first reference voltage becomes the second reference voltage
Electric vehicle charging system. The method according to claim 1,
The sensing unit
The electric vehicle charger detects that the electric car charger is connected to the electric grid and the electric grid, respectively, and detects the charging voltage applied to the electric car in the electric grid
Electric vehicle charging system. The method according to claim 1,
Further comprising an observing unit for observing an internal state of the electric car charger and a change in the voltage magnitude,
The sensing unit
And the at least one of voltage, current, and temperature of the electric car charger is sensed through the internal state of the electric car charger observed by the observing unit
Electric vehicle charging system. 6. The method of claim 5,
And an output unit for outputting at least one of a result of the observing unit and a result of sensing the sensing unit,
The output
And outputs at least one of voltage, current, and temperature of the electric charger sensed by the sensing unit
Electric vehicle charging system. The method according to claim 6,
The output
And a second output portion different from the first output portion,
The first output
And outputting, as a danger notification, that the voltage magnitude becomes the danger state,
The second output
And outputting a safety notification that the voltage magnitude has reached the safety state
Electric vehicle charging system. 3. The method of claim 2,
The electric vehicle charger includes a relay,
The control unit
And controls the relay to be turned off when the charging voltage becomes lower than the first reference voltage,
And controls the relay to be turned on when the charging voltage becomes equal to or higher than the second reference voltage
Electric vehicle charging system. 9. The method of claim 8,
The control unit
Maintaining the relay to be in the turned-off state such that the voltage magnitude that is less than the first reference voltage becomes the second reference voltage
Electric vehicle charging system. The method according to claim 1,
And a determination unit for determining a voltage magnitude of the charging voltage,
The control unit
A determination result of the determination unit
Electric vehicle charging system.

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