KR101241333B1 - An apparatus of monitering a leakage of an electric source and an apparatus of charging an electric vehicle - Google Patents

Abstract

Disclosed herein is a ground fault detector and a ground fault detection method according to an exemplary embodiment of the present invention. In particular, one example of the ground fault detector according to the present invention includes a link stage for supplying power to a load; A relay for connecting each resistor connected to ground with the link terminal; And a control unit controlling the connection of the relay according to a short circuit detecting request and detecting whether a short circuit is present in the link terminal. Here, when the short circuit is detected, the controller may control to cut off power supply from the link terminal to the load. When the short circuit detection is completed, the controller may open the relay to control the connection between each resistor connected to the ground and the link terminal.

Description

Leakage Detector and Electric Vehicle Charger {An apparatus of monitering a leakage of an electric source and an apparatus of charging an electric vehicle}

The present invention relates to a ground fault detection, and more particularly, to a ground fault detector and an electric vehicle charger for detecting a ground fault.

Although electric cars were manufactured earlier than gasoline or diesel cars, they were not put to practical use due to the heavy weight of batteries and the time required for charging. However, due to the recent depletion of fossil energy and environmental pollution, electric vehicles do not use fossil energy. As interest in electric vehicles increases, studies on this are being actively conducted.

An electric vehicle (EV) refers to a vehicle that does not use petroleum fuel and an engine but uses an electric battery and an electric motor, that is, an electric vehicle. Such electric vehicles require a charger to charge the battery because the electric motor is driven by rotating the motor with electricity accumulated in the battery.

A common problem in using electricity, including electric vehicles, is a leakage problem. In particular, in the case of automobiles, the chassis of the body corresponds to ground, so there is a high risk of electric shock when the ground fault occurs. Therefore, short circuit detection is also an important issue for preventing the burnout of human life and automobiles with respect to electricity use. In addition, the power supply for supplying electricity to the vehicle should be well grounded and insulated except when detecting a short circuit.

One object of the present invention is to provide a ground fault detector for detecting a ground fault of a power supply device.

Another object of the present invention is to implement perfect insulation after a short circuit detection in a power supply of an ungrounded system.

Still another object of the present invention is to provide an electric vehicle charger including the ground fault detector.

Disclosed herein is a ground fault detector and an electric vehicle charger according to the present invention.

An example of the ground fault detector according to the present invention includes a link stage for supplying power to a load; A relay for connecting each resistor connected to ground with the link terminal; And a control unit controlling the connection of the relay according to a short circuit detecting request and detecting whether a short circuit is present in the link terminal.

Here, when the short circuit is detected, the controller may control to cut off power supply from the link terminal to the load.

When the short circuit detection is completed, the controller may open the relay to control the connection between each resistor connected to the ground and the link terminal.

In addition, the controller may control the relay connection with the link terminal, and then request test power supply to detect a short circuit.

Another example of the earth leakage detector according to the present invention includes: a pressure reducing unit configured to connect each resistor connected to the ground, the respective resistors and a link terminal for supplying power to the load, and to reduce the input high voltage; An adder for obtaining a gain between the link end and ground; And a controller configured to determine whether a short circuit occurs from the gain of the adder.

Here, when the short circuit is detected, the controller may control to cut off power supply from the link terminal to the load.

The decompression unit may include a relay for connecting the resistor and the link terminal.

The control unit may control to short-circuit the relay according to a short circuit detection request, and control to open the relay when the short circuit detection is completed according to the short circuit detection request.

The controller may control the relay connection with the link terminal and request supply of test power to detect a short circuit.

The earth leakage detector may further include a buffer unit configured to prevent a change in an output voltage of the decompression unit; And an output unit configured to output a digital value according to the determination of whether the controller detects a ground fault.

The adder may output a specific value by multiplying a gain by adding a first decompression value of the voltage between the link terminal and the ground and a second decompression value of the voltage between the link terminal and the ground.

An example of an electric vehicle charger according to the present invention, the power supply for supplying power; And a charging unit which charges the electric vehicle using the supplied electric power and includes an electric leakage detector for detecting an electric leakage in the charging process, wherein the electric leakage detector includes a link for supplying power to each resistor and load connected to ground. And a connection control means positioned between the stages and controlling the connection of each of the resistors and the link stage to detect whether the link stage is shorted.

Here, the connection control means may include a relay, and after detecting the leakage of the link terminal, the connection between each resistor and the link terminal may be released.

And the charging unit, a charger for supplying power to the electric vehicle; And a local server controlling the charger.

The charger may further include a converter for converting input AC power into DC power; An inverter for converting the converted DC power into AC power; A transformer for transforming the inverted AC power; And a rectifier for rectifying the transformed AC power to generate DC electricity.

The earth leakage detector may include: a pressure reducing unit configured to reduce a high voltage input through a link terminal for supplying power to a load including the connection control means; An adder for obtaining a gain between the link end and ground; And a controller configured to determine whether a short circuit occurs from the gain of the adder. A buffer unit for preventing a change in an output voltage of the decompression unit; And an output unit configured to output a digital value according to whether the controller detects a ground fault.

According to the present invention,

First, there is an effect of providing a ground fault detector for detecting a ground fault of a power supply.

Second, there is an effect that can achieve perfect insulation after the earth leakage detection in the power supply of the non-grounded system.

Third, there is an effect that can provide an electric vehicle charger including the earth leakage detector.

1 is a view illustrating an example of an electric vehicle charging system according to the present invention;
2 is a view illustrating an example of a charger including a ground fault detector according to the present invention;
3 is a flowchart illustrating an example of a charging process according to the present invention;
4 and 5 are views for explaining an example of the ground fault detector circuit according to the present invention;
FIG. 6 is a view illustrating a detailed configuration of a DC ground fault detector including the ground fault detector circuit of FIG. 5; and
7 is a flowchart illustrating a detailed operation of the DC ground fault detector circuit according to the present invention.

Hereinafter, various embodiments of the present invention will be described in detail with reference to the accompanying drawings.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

The present invention relates to a leak detecting (leakage detecting or monitering), and more particularly to an electric leak detecting device for detecting the electric leak in a variety of electrical devices that produce or / and supply electricity and an electric vehicle charging system including the electric leak detector. will be.

In the present specification, for the convenience of description and convenience of description, an EV charger (hereinafter referred to as an EV charger) for supplying (charging) DC (direct current) power for charging an electric vehicle (EV) (hereinafter, referred to as an electric vehicle) may be used. An electrical leak detector and a leakage detection method for detecting a short circuit in the charger will be described as an example.

However, the electric vehicle is only one embodiment for describing the technical idea of the present invention, and the scope of the present invention is not limited thereto. Accordingly, the scope of the present invention will be extended to all electrical devices of the same or different technical fields that can be applied (applied) or applied the same or similar principles as the claims and the technical idea of the present invention described herein.

Hereinafter, as described above, a ground fault detector for detecting a ground fault of a charger for charging an electric vehicle and a ground fault detection method thereof will be described in detail with reference to the accompanying drawings.

1 is a view illustrating an example of an electric vehicle charging system according to the present invention.

An example of the electric vehicle charging system 100 according to the present invention is configured to include a power supply unit and a charger 130, the electric vehicle 140 operates by the power supplied through the charger 130.

Hereinafter, in the present specification, the term “power supply unit” generally includes a grid, such as a power corporation that produces and supplies electricity, and means for producing or / and supplying electricity in addition to the grid. It is used to include all power sources capable of supplying electricity to the charger 130.

For example, the charger 130 receives electricity generated from the grid, the grid, and supplies electricity to railroads or urban railways, and small hydropower, photovoltaic (PV), and solar thermal. Renewable energy processing that supplies electricity from renewable energy such as wind power, waste energy, waste energy, bio energy, geothermal and ocean energy. At least one of the systems may be supplied with electricity from a power supply.

In addition, the charger 130 and the power supply unit, a smart-grid (intelligent power grid) means a next-generation power system and its management system implemented through the convergence and complex of the modernized power technology and information and communication technology that is emerging recently ) Is also possible.

However, in the present specification, for the sake of understanding and convenience of the present invention, as shown in FIG. 1, the primary power service provider 110 and the secondary power service provider meaning urban railway works are shown as a power supply unit. Although the case of using 120 is illustrated and described as an example, only one of the primary power provider 110 and the secondary power provider 120 may be used.

The central management server system 125 manages the primary and / or secondary power providers 110 and 120 and the charger 130 to be connected with each other. In particular, the central management server system 125 receives the power supply request from the charger 130, the power is supplied from the primary or / and secondary power providers (110, 120) to the charger 130 in response to the received power supply request To be supplied. In this process, the central management server system 125 may support and provide all necessary infrastructure such as a communication protocol for supplying / receiving power between the primary and / or secondary power providers 110 and 120 and the charger 130.

The charger 130 includes a rapid charger 133 for supplying power to the electric vehicle 140 connected to the local server 132 communicating with the central management server system 125. In this case, the charger 130 may further include a smart meter 131 to control power supply / supply according to a situation. In particular, the smart meter 131 can more precisely control the power supply / supply based on the supply / demand of the power, charging related information, etc. in the above-described smart-grid environment.

The local server 132 collects, transmits, and provides various infrastructures based on the information required between the power supply unit and the electric vehicle 140. For example, when the rapid charger 133 is connected to the electric vehicle 140, the local server 132 receives additional information from the electric vehicle 140. The local server 132 requests the power supply unit to supply necessary power based on the received additional information. The additional information includes information for charging, and the local server 132 calculates and displays the charge for the amount of power supply based on the information of the smart meter 131 for the charging information received from the electric vehicle 140. Etc. may be directly processed, and if necessary, the information may be processed after transmission to an external server (not shown). In addition, the local server 132 may transmit the above information to the central management server system 125 to receive and display the charging information.

The rapid charger 133 is provided with a coupler as a connector that is directly connected to the innet provided to the electric vehicle 140 to supply power, and the electric vehicle is connected through the connection of the innet and the coupler. The information of the 140 is transmitted to the local server 132, and the electric power supplied through the power supply unit is supplied to the electric vehicle 140 through the coupler based on the transmitted information to the battery of the electric vehicle 140. To charge. In connection with the present invention, a more detailed description of the charging process between the charger 133 and the electric vehicle 140 will be described later.

Hereinafter, a detailed configuration of the charger 130 including the ground fault detector according to the present invention.

2 is a view illustrating an example of a charger including a ground fault detector according to the present invention.

The charger 130 according to the present invention receives electric power from the AC power source 210, converts it into DC electricity, and charges the electric vehicle 140. In the above, the AC power source 210 refers to a power supply unit including at least one or more of the first and second power providers 110 and 120 of FIG. 1.

Referring to FIG. 2, an example of a charger according to the present invention includes a converter 226, an inverter 228, a transformer 230, a rectifier 232, and a short circuit. And detectors 224 and 236.

The AC leakage breaker 224 detects whether a short circuit occurs while the AC power supply 210 is input to the charger 130, and cuts off the supply of the charger 9130 of the AC power supply 210 when a short circuit occurs.

The converter 226 converts AC power supplied from the power supply to DC power.

The inverter 228 inverts the DC power converted in the converter 226 back to the AC power.

The transformer 230 is to electrically insulate the electric vehicle of the power supply unit and the charger 130, and converts the inverted AC power input to a desired voltage.

The above-described converter 226, inverter 228 and transformer 230 is to adjust this due to the difference in the power supply / supply method between the power supply and the charger 130, some components are omitted or added as necessary May be

The rectifier 232 rectifies the transformed AC power to generate desired DC electricity.

The DC leakage breaker 236 detects whether a short circuit occurs in the process of supplying the DC electricity rectified by the rectifier 232 to the electric vehicle 140, and electrically disconnects the charger 130 and the electric vehicle 140 when a short circuit occurs. do. A more detailed description thereof will be described in more detail below, and will be omitted here.

Hereinafter, a process of charging the battery of the electric vehicle by supplying power received from the power supply unit from the charger 130 to the electric vehicle 140 will be described. Among such a charging process, a short-circuit detection process according to the present invention is also included, and the present invention will be described together with the charging process.

3 is a flowchart illustrating an example of a charging process according to the present invention.

An example of a process of charging the electric vehicle 140 from the charger 130 according to the present invention will be described below. However, hereinafter, the detailed description of the power supply process from the power supply unit to the charger 130 uses the above description, and will be omitted here.

The charging process between the charger 130 and the electric vehicle 140 is started by the combination of the charger 130 and the electric vehicle 140. That is, the coupler of the charger 130 is coupled to the internet of the electric vehicle 140 and starts with the two devices connected (S310).

Here, the coupler of the charger 130 and the internet of the electric vehicle 140 may be provided with a plurality of terminals as determined by the relevant standards. For example, the coupler of the charger 130, the electric supply terminal for supplying electricity to the electric vehicle 140 should be basically provided, and an additional terminal for receiving and supplying signals necessary for the charging process may be further provided. . Such additional terminals include, for example, a ground terminal, a charge start / stop terminal, a connection check terminal, and a CAN area controller. Can be. CAN communication is a kind of communication protocol for transmitting and receiving data through parallel connection between devices.

As described in step S310, when the coupler of the charger 130 is connected to the internet of the electric vehicle 140, the charger 130 and the electric vehicle 140 recognize each other (S320, S330). That is, the coupler of the charger 130 and the internet of the electric vehicle 140 may recognize each other's connection by using identifier information included in signals transmitted and received through signal terminals.

When the charger 130 and the electric vehicle 140 are recognized through the steps S320 to S330, prior to the start of the actual charging process, the state of the charger 130, for example, an abnormality in the charger 130 according to the present invention. That is, it is determined whether there is a risk of leakage (S340). If a short circuit is not properly checked, and a high voltage of electricity is supplied from the power supply unit to the electric vehicle 140 through the charger 130, the risk of human or electric vehicle burnout may occur due to the short circuit. Therefore, in order to prevent such a problem in advance, it is necessary to first check whether or not a short circuit occurs before supplying power to the electric vehicle 140.

In this regard, the charger 130 may detect whether a short circuit occurs by using a test voltage generated by itself.

Referring to the leak detector for determining the risk of leakage at step S340 described above in detail with reference to the accompanying drawings, as follows.

4 and 5 are diagrams for explaining an example of the ground fault detector circuit according to the present invention.

Generally, leakage or leakage refers to a phenomenon in which electricity flows to a place that should not flow with insulation broken in a system designed to be insulated.

4 (a) and 4 (b) illustrate the ground fault detector in an ungrounded system, and FIG. 4 (a) shows an insulated case and FIG. 4 (b) shows a non-insulated case.

The electric vehicle 140 and the charger 130 should be insulated from a power system (DC link terminal, Vout, dc) that supplies power and ground. In this case, the grounding of the electric vehicle corresponds to the chassis of the chassis, and therefore, there is a high risk of electric shock when a short circuit occurs in the ground.

For a short circuit, connect the same resistors between the isolated DC links, connect each resistor to ground, and then compare the voltages applied between the positive and ground terminals and the negative and ground terminals of the DC link terminals. Can be detected. That is, compare the voltage applied to the resistor. Here, when the two resistance values are the same, the same voltage (Vout, dc / 2) is formed.

However, if the insulation is broken as shown in FIG. / R3), the difference between the two voltages (Vout, dc * R2 / {R2 + (R1 // R3)}, Vout, dc * (R1 // R3) / {R2 + (R1 // R3)}) Will occur.

As described above, in the case of FIGS. 4A and 4B, the insulation may be intentionally broken because the resistor is connected to the ground in order to detect a short circuit. In addition, since a high voltage is applied, the resistance value of the resistor installed in the DC link terminal should be large, but its precision may be relatively low, and thus it may be difficult to accurately measure the voltage difference.

Therefore, an error may occur when detecting a short circuit. This means that even if a short circuit occurs, a short circuit may not be detected or a short circuit may be detected as a short circuit, thereby reducing reliability, and thus a loss may occur. In addition, except when detecting a short circuit, the DC link terminal must be insulated, which may be problematic.

Accordingly, in the present invention, as shown in Fig. 5, by configuring the ground fault detector, it is possible to prevent the occurrence of an error in connection with the ground fault detection, and to prevent the damage of the insulation in the DC link stage other than the ground fault detection.

That is, in the ground fault detection circuit configured as shown in FIG. 4 (a), it is intended to include relays 610 and 620 between each high resistance connected to the ground and the DC link terminal.

If after entering the above step S320 to 230 and enters step S340, prior to performing the actual charging process, if a short circuit check request is received, the relay (610, 620) is closed in accordance with the control signal. That is, by shorting the relays 610 and 620 and configuring a circuit as shown in FIG. 4A, a short circuit is detected and a short circuit of the charger is checked (S340).

In step S340, as a result of a short circuit check, if there is no short circuit in the charger, the charger 130 is safe, thus informing the start of the actual charging process for supplying power to the electric vehicle 14, that is, the charger allowing the charging process. Make a safety declaration (S350).

In step S350, when the charger safety declaration is made, the charger 130 now allows power supplied from the power supply unit to the electric vehicle 140 (S360), and orders a charging (S370). These charge commands can be replaced by passing voltage and current command values.

The charger 130 generates a voltage and current command value delivered to the electric vehicle 140 to supply DC electricity to charge the battery of the electric vehicle 140 (S380).

Here, since the ground fault detector circuit does not always operate like the DC power distribution network, the charger 130 reopens the relays 510 and 520, which have been short-circuited at any of steps S350 to S360.

In addition, when a short circuit is detected after the start of charging, charging should be stopped immediately.

Therefore, according to the present invention, if the relays 510 and 520 are opened after the earth leakage detection, perfect insulation of the non-grounded system can be realized, and thus there is no damage to the insulation by the earth leakage detector.

FIG. 6 is a diagram illustrating a detailed configuration of a DC ground fault detector including the ground fault detector circuit of FIG. 5.

Referring to FIG. 6, an example of the DC ground fault detector according to the present invention includes a decompression unit 610, an adder 630, and a controller. The DC ground fault detector may further include a buffer unit 620, an absolute value converter 640, and an output unit 650. In addition, in FIG. 5, the load 430 may be, for example, a configuration under the pressure reducing unit 610 of FIG. 6, that is, the buffer unit 620 to the output unit 650, and the battery of the electric vehicle 140. It can also be

Since the pressure reduction unit 610 is difficult to directly process the high voltage of the DC link terminal for supplying power to the load, the pressure reduction unit 610 reduces the voltage to a degree necessary for detecting a short circuit. Here, the voltage required to detect the short circuit in the above is, for example, as shown in Figure 6, considering the ratio of R2 / R1 and R3 / R4, the ratio of each resistance can be formed to an appropriate degree. Can be configured to determine. In the present specification, for example, R1 and R4 are 10 megohms (10 MΩ), and R2 and R3 are 100 kiloohms (KkHz), and the ratio thereof is described as an example. Therefore, when the ratio of the resistance is 0.01 as described above, the high voltage (for example, 100 V) before the pressure reducing unit 610 is reduced to the low voltage (1 V). In addition, according to the present invention, the decompression unit 610 is located between the resistors R1 and R4 connected between the link terminal and the ground and the link terminals Vdd and Vee to connect / disconnect the resistor and the link terminal. (612,614).

The buffer unit 620 may change the sensed voltage when the input circuit of the controller that reads the voltage of the decompression unit 610 has a low impedance. In order to prevent this, the output of each link stage may be implemented. To the buffer.

The adder 630 obtains a gain between the decompressed link terminal and ground. That is, the gain is multiplied by adding the first reduced pressure value of the voltage between the DC high voltage portion Vdd and the ground and the second reduced pressure value of the voltage between the DC high voltage portion Vee and the ground. In general, when a short circuit does not occur, the multiplied gain value should be 0. However, when a short circuit occurs, the multiplied gain value, that is, the adder 630 due to the voltage difference between the first decompression value and the second decompression value. ) Will have a non-zero specific value.

The absolute value conversion unit 640 converts the output value of the adder of the (+) value and the (-) value into an absolute value.

The output unit 650 converts the analog value of the absolute value converting unit 640 into a specific digital value, that is, 0 and 1. If a short circuit is detected based on the output value of the adder 630, a short circuit is detected. If not, output 0.

The controller controls the decompression unit 610 such that the relays 612 and 614 are connected between the DC high voltage unit Vdd and R1 and between the DC high voltage unit Vee and R4, that is, a short circuit, when the short circuit detection request is made.

The control unit determines whether a short circuit occurs from the output of the adder 630. In this case, when the short circuit is detected according to the result of the short circuit determined from the output of the adder 630, the controller outputs 1 at the output unit 650 to control the charging process to stop without further progress. . However, the controller is configured to output 0 at the output unit 650 when a short circuit is not detected according to the result of the short circuit determined from the output of the adder 630, and is connected to detect the short circuit at the pressure reducing unit 610. The relays 612 and 614 are controlled to be disconnected.

7 is a flowchart illustrating a detailed operation of the DC ground fault detector circuit according to the present invention.

FIG. 7 is a flowchart illustrating a more detailed process of steps S340 to S350 in the above-described process of FIG. 3. Steps S340 and S350 of FIG. 3 correspond to steps S710 and S770 in FIG. 7, respectively.

That is, first, when an electric leakage checking request of the charger 130 is received (S710), the DC electric leakage detecting circuit is connected to the DC system (S720). As described above, in order to connect the DC ground fault detector circuit to the DC system, the control unit controls the relays 612 and 614 of the decompression unit 610 so that the DC ground fault detector is connected to the DC system.

Afterwards, the DC ground fault detector circuit connected to the DC system forms a voltage by test-operating the charger to check a ground fault (S730). The voltage formed as described above is decompressed to the extent necessary to detect the DC short circuit via the decompression unit 610 and is input to the adder 630 via the buffer unit 620.

The control unit adds the DC leakage detection and the safety of the charger from the gain value calculated based on the difference between the voltage values of the DC system in step S630 (S740).

Thereafter, the control unit requests to stop the test operation of the charger (S750), and if the short circuit is not detected as a result of the determination, releases the connection by opening a relay shorted for connection with the DC system for detecting the short circuit (S760).

After that, the control unit declares safety as no short circuit is detected in the charger (S770), and controls to supply power from the charger to the electric vehicle.

Therefore, according to the present invention, by simply controlling the relay without a separate component such as deliberately destroying the insulation for detecting a short circuit, it is not only possible to prevent the stability problem of the circuit due to intentional insulation, etc. It also increases the efficiency of the circuit.

As described above, the DC ground fault detector according to the present invention is included in a charger for charging an electric vehicle. However, as an embodiment, as described above, the earth leakage detection circuit according to the present invention may be used or applied as a resource to all fields in which a power supply charging system is provided and the earth leakage detection is required.

The above embodiment is an example for explaining the technical idea of the present invention in detail, and the present invention is not limited to the above embodiment, various modifications are possible, and various embodiments of the technical idea are all protected by the present invention. It belongs to the scope.

130: charger 131: smart meter
132: local server 133: fast charger
610: pressure reduction unit 612, 614: relay
620: buffer unit 630: the adder
640: absolute value conversion unit 650: output unit

Claims (17)

A link stage for supplying power to the load;
A relay for connecting each resistor connected to ground with the link terminal;
A decompression unit for depressurizing a high voltage input through a link terminal for supplying power to a load;
An adder for obtaining a gain between the link end and ground;
A buffer unit for preventing a change in an output voltage of the decompression unit;
A control unit which controls the connection of the relay according to a short circuit detecting request and detects whether a short circuit exists in a link terminal from the gain of the adding unit; And
And an output unit configured to output a digital value according to a result of determining whether the control unit detects a short circuit. The method of claim 1,
The control unit,
And a short circuit detector controlling to cut off power supply from the link terminal to a load when a short circuit is detected. The method of claim 1,
The control unit,
And a ground fault detector, when the ground fault detection is completed, controlling the connection of each resistor and the link terminal connected to the ground to be disconnected by opening the relay. The method of claim 3,
The control unit,
A ground fault detector requesting a test power supply to detect a ground fault after controlling the relay with the link terminal. delete delete delete delete delete delete delete A power supply for supplying power; And
And a charging unit including an electric leakage detector for charging an electric vehicle using the supplied electric power and detecting an electric leakage during the charging process.
The earth leakage detector,
Connection control means located between each resistor connected to ground and a link terminal for supplying power to the load, and controlling the connection between each resistor and the link terminal;
Decompression unit for reducing the high voltage input through the link stage for supplying power to the load including the connection control means;
An adder for obtaining a gain between the link end and ground;
A control unit for determining whether a short circuit occurs from the gain of the adding unit;
A buffer unit for preventing a change in an output voltage of the decompression unit; And
And an output unit for outputting a digital value according to a result of determining whether the control unit detects a short circuit. The method of claim 12,
The connection control means,
And an electric vehicle charger for disconnecting the respective resistors and the link terminals after detecting the leakage of the link terminals. The method of claim 13,
The connection control means, an electric vehicle charger comprising a relay. The method of claim 12,
The charging unit includes:
A charger for supplying power to an electric vehicle; And
And a local server controlling the charger. 16. The method of claim 15,
The charger,
A converter for converting input AC power into DC power;
An inverter for converting the converted DC power into AC power;
A transformer for transforming the inverted AC power; And
And a rectifier for rectifying the transformed AC power to generate DC electricity. delete

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