Name of invention: Device and method for checking whether a contactor provided in ESS is fused
Technical field
[One]
The present invention relates to an apparatus and method for checking whether a contactor provided in an ESS is fused.
[2]
Specifically, it relates to an apparatus and method for checking whether a contactor is fused without blocking the flow of current.
[3]
Background
[4]
Recently, due to the depletion of fossil energy and environmental pollution due to the use of fossil energy, interest in electric products that can be driven using secondary battery batteries is increasing. Accordingly, technology development for mobile devices, electric vehicles (EV), hybrid vehicles (HV), energy storage systems (ESS), and uninterruptible power supplies (UPS), etc. As the demand and demand increase, the demand for secondary batteries as an energy source is rapidly increasing.
[5]
Such a secondary battery is attracting attention as a new energy source for environmentally friendly and energy efficiency enhancement in that it does not generate by-products from the use of energy as well as the primary advantage that it can dramatically reduce the use of fossil energy.
[6]
Meanwhile, a plurality of secondary batteries may be connected to form a module, and the modules may be connected to form one energy storage system.
[7]
In the energy storage system formed in this way, a contactor is used to electrically connect the external device and the energy storage system.
[8]
The contactor is artificially opened when a problem occurs in the use of the energy storage system. Therefore, the BSC of the energy storage system should periodically check whether the contactor provided in the energy storage system is fused.
[9]
In the prior art for checking whether the contactor is fused, the current flowing through the contactor is blocked, and then the fusion state of the contactor is checked.
[10]
However, since the energy storage system is always connected to the power grid, it was difficult to block the flow of current to check whether the contactor was fused.
[11]
Accordingly, the present invention proposes an apparatus and method for checking whether a contactor of an energy storage system is fused without blocking the flow of current.
[12]
[13]
(Prior technical literature) Korean Patent Publication KR 10-2017-0093040 A
[14]
Detailed description of the invention
Technical challenge
[15]
The present invention provides an apparatus and method for checking whether a contactor of an energy storage system is fused without blocking the flow of current.
[16]
Means of solving the task
[17]
The energy storage system connected to the power grid according to an embodiment of the present invention includes a BSC that determines whether to use an ESS based on current, voltage, and temperature of a battery, a plurality of battery racks connected in series or parallel with each other, the It may be configured to include a (+) output terminal for outputting power supplied from a plurality of battery racks to the outside, and an ESS power cut-off unit that blocks the use of the ESS by receiving a command from the BSC.
[18]
The ESS power cut-off unit has one end connected to the battery rack of the ESS and the other end connected to the (+) output terminal of the ESS, a contactor forming an electrical path between the battery rack and the (+) output terminal of the ESS, the It may be configured to include a current measuring unit located on the electrical path between the battery rack and the contactor to measure the current of the path and transmit it to the BSC.
[19]
The contactor has one end connected to the output of the current measuring unit, the other end connected to the (+) output terminal of the ESS to form a first current path, one end connected to the output of the current measuring unit, and the other end of the ESS. A second relay connected to the (+) output terminal to form a second current path, a first sensing unit that detects whether the first relay is fused and transmits the detection result to the BSC, and detects whether the second relay is fused. And a second detector configured to transmit a detection result to the BSC, and the first relay and the second relay may be connected in parallel.
[20]
The first detection unit, one end is connected to the output terminal of the current measuring unit, the other end is connected to the (+) output terminal of the ESS, to form a parallel circuit with the first relay, when the first relay is open, on a parallel path It is a current measuring device that measures current, and the second sensing unit has one end connected to the output terminal of the current measuring unit and the other end connected to the (+) output terminal of the ESS to form a parallel circuit with the second relay to form a second relay. When is open, it may be a current meter that measures the current on the parallel path.
[21]
The first sensing unit is configured to include a first photo coupler, and the first photo coupler is connected in parallel with the first relay so that current flows through the first photo coupler to emit light when the first relay is open. , The first photo coupler includes a first light-emitting unit and a first light-receiving unit that are insulated from each other, and the first light-emitting unit emits light when there is no fusion to the first relay, If present, it does not emit light, and the first light receiving unit may transmit an electrical signal to the BSC when an optical signal is input from the first light emitting unit.
[22]
And a second photo coupler, wherein the second photo coupler is connected in parallel with the second relay so that current flows through the second photo coupler to emit light when the second relay is opened, and the second photo coupler The coupler includes a second light-emitting unit and a second light-receiving unit that are insulated from each other, and the second light-emitting unit emits light when there is no fusion bonding to the second relay, and does not emit light when there is fusion bonding on the second relay. When an optical signal is input from the second light emitting unit, the second light receiving unit may transmit an electrical signal to the fraudulent BSC.
[23]
A method of detecting whether a contactor of an ESS connected to the power grid is fused at all times according to an embodiment of the present invention is a current measurement step of measuring an output current of a current ESS in a current measuring unit, and the measured output current of the ESS A current checking step of checking whether the configured first relay and the second relay are less than the allowable current, and when the output current of the ESS is less than the allowable current of the first and second relays, the first relay constituting the contactor A first relay fusion check step of checking whether the first relay is fused using a first detection unit and closing the opened first relay and opening the second relay After that, it may be configured to include a step of confirming whether the second relay is fused by using the second detection unit.
[24]
In the step of confirming whether the first relay is fused, the first relay is opened, the first current path is blocked, and current flows only through the second current path. And, in the step of confirming whether the second relay is fused, the first relay is closed and the second relay is open to block the second current path, and the second current flows only through the first current path. It is possible to check whether or not the second relay is fused by using the sensing unit.
[25]
The step of confirming whether the second relay is fused is performed only when fusion of the first relay is not detected, and when fusion of the first relay is detected in the step of confirming whether the first relay is fused, the first relay fusion detection signal May be transmitted to the BSC, and the step of confirming whether the second relay is fused may not be performed.
[26]
Effects of the Invention
[27]
The present invention can check whether the contactor of the energy storage system is fused without blocking the flow of current.
[28]
Brief description of the drawing
[29]
1 is a flow chart showing a method of checking whether an ESS contactor is fused according to an embodiment of the present invention.
[30]
2 is a diagram showing an ESS according to another embodiment of the present invention.
[31]
Best mode for carrying out the invention
[32]
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those of ordinary skill in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and similar reference numerals are attached to similar parts throughout the specification.
[33]
Terms including ordinal numbers, such as first and second, may be used to describe various elements, but the elements are not limited by the terms. These terms are only used for the purpose of distinguishing one component from other components. For example, without departing from the scope of the present invention, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element. The terms used in the present application are used only to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise.
[34]
Throughout the specification, when a part is said to be “connected” to another part, this includes not only the case that it is “directly connected”, but also the case that it is “electrically connected” with another element in between. . In addition, when a part "includes" a certain component, it means that other components may be further included rather than excluding other components unless otherwise stated. As used throughout the specification of the present application, the term "step (to)" or "step of" does not mean "step for".
[35]
The terms used in the present invention have been selected from general terms that are currently widely used while considering functions in the present invention, but this may vary according to the intention or precedent of a technician working in the field, the emergence of new technologies, and the like. In addition, in certain cases, there are terms arbitrarily selected by the applicant, and in this case, the meaning of the terms will be described in detail in the description of the corresponding invention. Therefore, the terms used in the present invention should be defined based on the meaning of the term and the overall contents of the present invention, not a simple name of the term.
[36]
1. A method of checking whether an ESS contactor is fused according to an embodiment of the present invention.
[37]
1 is a flow chart showing a method of checking whether an ESS contactor is fused according to an embodiment of the present invention.
[38]
Hereinafter, a method of checking whether an ESS contactor is fused according to an embodiment of the present invention will be described with reference to FIG. 1.
[39]
A method of checking whether an ESS contactor is fused according to an embodiment of the present invention includes a current measurement step (S100) of measuring the current output current of the ESS in a current measurement unit, and the measured output current of the ESS forms a contactor. Current check step (S200) of checking whether the current is less than the allowable current of the 1 relay and the second relay (S200), when the measured output current of the ESS is less than the allowable current of the first relay and the second relay, open the first relay And, the first relay fusion check step (S300) of checking whether the first relay is fused using the first detection unit, after closing the opened first relay and opening the second relay It may be configured to include a second relay fusion check step (S400) of checking whether the second relay is fused using the second detection unit.
[40]
On the other hand, the method of checking whether the ESS contactor of the present invention is fused or not is when detecting whether or not fusion of the two relays constituting the contactor is fused, the connection of one relay for measuring fusion is disconnected, and only through the other relay. Since current flows, you must check whether the current value is within the current range that one relay can tolerate.
[41]
In other words, since both relays are normally closed, current flows through both the first current path through which current flows through the first relay and the second current path through which current flows through the second relay.
[42]
However, the method of checking whether the contactor is fused is difficult to completely cut off the flow of current since the ESS is always connected to the power supply. Therefore, in the step (S300) of confirming whether the first relay is fused, the first relay is opened (S310), and the second relay is kept closed so that current flows only through the second current path. And check whether the first relay is fused (S320).
[43]
As described above, if the current flowing in both the first and second current paths flows through the second current path in the step (S300) of checking whether the first relay is fused, damage to the second relay may occur, and thus, the current checking step (S200) ), you must check whether the current measured by the current measuring unit is within the allowable range of one second relay.
[44]
In other words, as a result of checking in the current checking step S200, it is possible to check whether the contactor is fused only when the current is within a range that can be handled by one relay.
[45]
On the other hand, in the step (S300) of checking whether the first relay is fused, it may be checked (S320) whether the first relay is fused using the first detection unit. For example, the first sensing unit may be configured to include a first photo coupler. Specifically, the first photo coupler has a first light-emitting part and a first light-receiving part at the same time, the first light-emitting part and the first light-receiving part are electrically insulated, and a signal may be transmitted by an optical signal. The principle of operation is that the first light-emitting unit of the first photo coupler emits light, and when this light is incident on the first light-receiving unit, the conduction state is established. The photo coupler is unidirectional.
[46]
Therefore, since the first relay is opened (S310) in the step (S300) of determining whether the first relay is fused, it is normal for the light emitting unit to emit light by flowing current through the first photo coupler.
[47]
Conversely, even though the command to open the first relay is executed, if fusion occurs in the first relay and the first relay is not turned off and remains closed, the first relay path is routed instead of the first photo coupler. Since most of the current flows and no current flows through the first photo coupler, the first light emitting portion does not emit light.
[48]
In other words, since the first relay is opened (S310) in the step (S300) of checking whether the first relay is fused, the first photo coupler emits light, and the first relay is in a normal state, and the first photo coupler does not emit light. It means that fusion has occurred in the first relay.
[49]
On the other hand, the above-described first relay fusion check step (S300) is only an example of detecting whether the first relay is fused using a photo coupler, but is not limited thereto, and various methods for checking whether the relay is fused. Can be used.
[50]
On the other hand, in the first relay fusion check step (S300), if the fusion of the first relay is not detected as a result of the fusion check of the first relay by the first detection unit, the second relay fusion check step (S400) is performed. I can.
[51]
However, when fusion of the first relay is detected in the first relay fusion check step (S300), the first detection unit transmits a first relay fusion detection signal to the BSC (S500), and the second relay fusion check step ( S400) may not be performed.
[52]
Specifically, that the fusion of the first relay is detected means that it is difficult for the first relay to perform its normal function. That is, since the first relay has failed, it cannot be checked whether the second relay is fused.
[53]
That is, in the step (S400) of checking whether the second relay is fused or not, only the first relay is closed, and the second relay is in an open state. Since fusion occurs in the first relay, the first relay performs a normal function. can not do. Therefore, it is not desirable to open the second current path to check whether the second relay is fused, and to pass current only through the abnormal first current path.
[54]
Therefore, it is preferable not to perform the step of confirming whether the second relay is fused.
[55]
Meanwhile, in the step S400 of checking whether the second relay is fused, it may be checked whether the second relay is fused or not using the second detection unit (S430). At this time, since the first relay is closed (S410) and the second relay is open (S420), current flows only through the first path.
[56]
The second sensing unit may include, for example, a photo coupler. Specifically, the second photo coupler has a second light-emitting part and a second light-receiving part at the same time, the second light-emitting part and the second light-receiving part are electrically insulated, and a signal may be transmitted by an optical signal. The principle of operation is that when a signal is input to the light emitting diode in the second photo coupler, the first light emitting unit emits light, and the second light receiving unit receives this light to generate an electric signal.
[57]
Therefore, since the second relay is opened (S420) in the step (S400) of confirming whether the second relay is fused, it is normal for the light emitting unit to emit light through the photo coupler.
[58]
On the contrary, even though the command to open the second relay is executed, if fusion occurs in the second relay and the second relay is kept closed, most of the current flows through the second relay path, not the photo coupler. Since no current flows through the photo coupler, the light emitting portion does not emit light.
[59]
In other words, since the second relay is opened in the step of confirming whether the second relay is fused, the fact that the photo coupler emits light is in a normal state, and that the photo coupler does not emit light indicates that fusion has occurred in the second relay. it means.
[60]
On the other hand, the above-described second relay fusion check step (S400) is only an example of detecting whether the first relay is fused using a photo coupler, but is not limited thereto, and various methods for checking whether the relay is fused. Can be used.
[61]
On the other hand, if fusion of the second relay is not detected in the second relay fusion check step (S400), the open second relay may be closed (S440), and the above-described ESS contactor fusion check procedure may be terminated. .
[62]
On the other hand, in the second relay fusion confirmation step, when fusion of the second relay is detected, the second detection unit transmits a second relay fusion detection signal to the BSC (S500), and then the above-described ESS contactor fusion check procedure Can be terminated.
[63]
[64]
2. ESS according to another embodiment of the present invention
[65]
2 is a diagram showing an ESS according to another embodiment of the present invention.
[66]
Hereinafter, an ESS according to another embodiment of the present invention will be described with reference to FIG. 2.
[67]
The ESS 10 according to another embodiment of the present invention is always connected to the power grid.
[68]
Therefore, it is impossible to completely cut off the current flowing through the ESS 10.
[69]
Meanwhile, the ESS 10 is supplied from the BSC 200 that determines whether to use the ESS based on the current, voltage, and temperature of the battery, a plurality of battery racks connected in series or in parallel with each other, and the plurality of battery racks. It may be configured to include a (+) output terminal that outputs received power to the outside and an ESS power cut-off unit 100 that blocks the use of the ESS by receiving a command from the BSC.
[70]
The ESS power cut-off unit 100 has one end connected to the battery rack of the ESS and the other end connected to the (+) output terminal of the ESS 10, and an electrical path between the battery rack and the (+) output terminal of the ESS. And a current measuring unit 110 located on an electrical path between the battery rack and the contactor and measuring a current of the path and transmitting the measured current to the BSC 200.
[71]
On the other hand, in the ESS of the present invention, when checking whether fused among the two relays constituting a contactor, the connection of one relay for checking fusion is disconnected, and since current flows only through the other relay, the current value is It should be checked whether a relay is in the allowable current range.
[72]
In other words, since both relays are normally closed, current flows through both the first current path through which current flows through the first relay and the second current path through which current flows through the second relay.
[73]
However, when checking whether the contactor is fused, for example, when checking whether the first relay is fused, the first relay is opened (S310), and the second relay is kept closed so that current flows only through the second current path. And check whether the first relay is fused.
[74]
That is, when checking the fusion of the first relay, since current flows only to the second relay, the output current of the ESS must be within the range allowed by the second relay.
[75]
Meanwhile, the BSC 200 may periodically check whether the contactor 120 is fused.
[76]
Specifically, the contactor 120 is a first relay ( 121), a second relay 122 having one end connected to the output terminal of the current measuring unit 110 and the other end connected to the (+) output terminal of the ESS to form a second current path 12, the first relay ( 121) detects the fusion of the first detection unit 123 and transmits the detection result to the BSC 200, detects whether the second relay 122 is fused, and transmits the detection result to the BSC 200 It may be configured to include a second detection unit 124.
[77]
On the other hand, the reason why the connection relationship between the input and output terminals of the first and second sensing units is not clearly implemented in FIG. 2 is because the connection relationship with the first and second relays is determined according to the components used as the first and second sensing units. to be.
[78]
For example, when the first and second sensing units are configured as photo couples, the first and second sensing units may be connected in parallel with the first and second relays, respectively.
[79]
On the other hand, when the first detection unit 123 detects whether or not the first relay 121 is fused, the first current path 11 is blocked, and current flows only through the second current path 12, and the When the second sensing unit 124 detects whether the second relay 122 is fused, the second current path 12 is blocked, and current may flow only through the first current path 11.
[80]
By connecting the first and second relays in parallel as described above, it is possible to sequentially check whether the first and second relays are fused without interrupting the flow of current.
[81]
In other words, when the first sensing unit has one end connected to the output terminal of the current measuring unit and the other end connected to the (+) output terminal of the ESS, forming a parallel circuit with the first relay to open the first relay, It may be a current meter that measures the current on the parallel path.
[82]
For example, the first sensing unit 123 may be configured to include a first photo coupler. Specifically, the first photo coupler has a first light-emitting part and a first light-receiving part at the same time, and the first light-emitting part and the first light-receiving part are electrically insulated, and a signal may be transmitted by an optical signal. The principle of operation is that when a current flows through the first photo coupler, the first light emitting unit emits light, and when the light is received by the first light receiving unit, an electric signal can be generated. In other words, when the first relay is open, the first photo coupler is connected in parallel with the first relay so that current flows through the first photo coupler to emit light.
[83]
Therefore, since the first detection unit 123 of the present invention detects whether the first relay is fused while the first relay 121 is open, it is normal for the first light emitting unit to emit light by flowing current through the first photo coupler. to be.
[84]
Meanwhile, the first light receiving unit of the first sensing unit 123 may receive an optical signal from the first light-emitting unit, convert the received optical signal into an electrical signal, and transmit it to the BSC 200. On the other hand, when fusion occurs in the first relay 121, it is preferable not to detect whether the second relay 122 is fused.
[85]
Specifically, that the fusion of the first relay 121 is detected means that the first relay 121 is difficult to perform a normal function. That is, when checking whether the second relay is fused in the present invention, only the first relay is in a closed state and the second relay is in an open state. Since fusion has occurred in the first relay, the first relay cannot perform a normal function. . Therefore, it is not desirable to open the second current path 12 to check whether the second relay is fused, and to pass current only through the abnormal first current path 11.
[86]
Therefore, it is preferable not to detect whether the second relay 122 is fused.
[87]
On the other hand, if fusion has not occurred in the first relay 121, it is possible to check whether the second relay 122 is fused.
[88]
Specifically, when checking whether the first relay 121 is fused, the opened first relay 121 is closed to form a first current path 11, and the second relay 122 is open ( open) so that the second current path 12 can be disconnected.
[89]
On the other hand, the specific details of checking whether the second relay 122 is fused by the second detection unit 124 is the procedure for detecting whether the first relay 121 is fused by the first detection unit 123 described above. Can be the same as
[90]
Specifically, when the second sensing unit has one end connected to the output terminal of the current measuring unit and the other end connected to the (+) output terminal of the ESS, forming a parallel circuit with the first relay to open the second relay, It may be a current meter that measures the current on the parallel path.
[91]
For example, the second sensing unit 123 may include a second photo coupler. Specifically, the second photo coupler has a second light-emitting part and a second light-receiving part at the same time, the light-emitting part and the light-receiving part are electrically insulated, and a signal may be transmitted by an optical signal. The principle of operation is that when a current flows through the second photo coupler, the second light-emitting unit emits light, and when the second light-receiving unit receives the light, an electric signal can be generated. In other words, when the second relay is open, the second photo coupler is connected in parallel with the second relay so that current flows through the second photo coupler to emit light.
[92]
Therefore, since the second detection unit 123 of the present invention detects whether the second relay is fused while the second relay 122 is open, it is normal for the second light emitting unit to emit light by flowing current through the second photo coupler. to be.
[93]
Meanwhile, when the second light receiving unit of the second sensing unit 124 receives an optical signal from the second light-emitting unit, the received optical signal is converted into an electrical signal and transmitted to the BSC 200.
[94]
On the other hand, when the second detection unit 124 determines that there is no fusion of the second relay 122, the second relay may be closed to allow current to flow in both the first and second current paths.
[95]
On the other hand, although the technical idea of ​​the present invention has been described in detail according to the above embodiment, it should be noted that the above embodiment is for the purpose of explanation and not for the limitation thereof. In addition, those skilled in the art in the technical field of the present invention will be able to understand that various embodiments are possible within the scope of the technical idea of ​​the present invention.
[96]
[97]
Claims
[Claim 1]
In an energy storage system (ESS) that is always connected to a power grid, the ESS includes: a BSC that determines whether to use the ESS based on current, voltage, and temperature of a battery; A plurality of battery racks connected in series or parallel to each other; A (+) output terminal for outputting the power supplied from the plurality of battery racks to the outside; An ESS power cut-off unit that blocks the use of the ESS by receiving a command from the BSC; And the ESS power cut-off unit, one end is connected to the battery rack of the ESS and the other end is connected to the (+) output terminal of the ESS, and an electrical path between the battery rack and the (+) output terminal of the ESS A contactor to form; A current measuring unit positioned on an electrical path between the battery rack and the contactor to measure a current in the path and transmit it to the BSC; ESS, characterized in that configured to include
[Claim 2]
The method as set forth in claim 1, wherein the contactor comprises: a first relay having one end connected to the output of the current measuring unit and the other end connected to the (+) output terminal of the ESS to form a first current path; A second relay having one end connected to the output of the current measuring unit and the other end connected to the (+) output terminal of the ESS to form a second current path; A first detection unit detecting whether the first relay is fused and transmitting a detection result to the BSC; A second sensing unit detecting whether the second relay is fused and transmitting a detection result to the BSC; It is configured to include, the first relay and the second relay ESS, characterized in that connected in parallel.
[Claim 3]
The method according to claim 2, wherein the first detection unit, one end is connected to the output terminal of the current measuring unit, the other end is connected to the (+) output terminal of the ESS, to form a parallel circuit with the first relay to open the first relay. In this case, it is a current measuring device that measures a current on a parallel path, and the second sensing unit has one end connected to the output terminal of the current measuring unit, and the other end connected to the (+) output terminal of the ESS, so that the second relay and the parallel circuit are connected. ESS, characterized in that it is a current measuring device that measures the current on a parallel path when the second relay is opened.
[Claim 4]
The method according to claim 3, wherein the first sensing unit is configured to include a first photo coupler, and the first photo coupler is the first relay to emit light by flowing a current through the first photo coupler when the first relay is open. Is connected in parallel with, the second sensing unit includes a second photo coupler, and the second photo coupler includes the second photo coupler so that current flows through the second photo coupler to emit light when the second relay is open. ESS characterized in that it is connected in parallel with a relay
[Claim 5]
The apparatus of claim 4, wherein the first photo coupler comprises: a first light-emitting part and a first light-receiving part that are insulated from each other; And the first light emitting unit emits light when there is no fusion bonding to the first relay, does not emit light when there is fusion bonding to the first relay, and the first light receiving unit receives an optical signal from the first light emitting unit. When input, ESS, characterized in that transmitting an electrical signal to the BSC.
[Claim 6]
The method according to claim 4, wherein the second sensing unit is configured to include a second photo coupler, and the second photo coupler is the second relay so that, when the second relay is open, current flows through the second photo coupler to emit light. And a second light-emitting unit and a second light-receiving unit, which are connected in parallel with and are insulated from each other; The second light emitting unit emits light when there is no fusion bonding to the second relay, does not emit light when there is fusion bonding to the second relay, and the second light receiving unit receives an optical signal from the second emission unit. When input, ESS, characterized in that transmitting an electrical signal to the BSC.
[Claim 7]
A method of detecting whether a contactor of an ESS connected to a regular power grid is fused, the method comprising: measuring a current output current of a current ESS in a current measuring unit; A current checking step of checking whether the measured output current of the ESS is less than the allowable currents of the first and second relays constituting the contactor; When the output current of the ESS is less than the allowable current of the first and second relays, the first relay constituting the contactor is opened, and the first detection unit is used to check whether the first relay is fused. Checking whether the first relay is fused; A second relay fusion check step of closing the opened first relay and opening a second relay, and then using a second detector to check whether the second relay is fused; Method for checking whether or not the ESS contactor is fused, characterized in that it comprises a.
[Claim 8]
The method of claim 7, wherein in the step of confirming whether the first relay is fused, the first relay is opened to block the first current path, and the first relay is used in a state in which current flows only through the second current path. In the step of checking whether or not the second relay is fused, the first relay is closed and the second relay is open to block the second current path, and current flows only through the first current path. In the state, using the second detection unit to check whether the second relay is fused or not.
[Claim 9]
The method of claim 7, wherein the step of confirming whether the second relay is fused is performed only when fusion of the first relay is not detected.
[Claim 10]
The method according to claim 7, wherein when the first relay is detected in the step of confirming whether the first relay is fused, the first relay fusion detection signal is transmitted to the BSC, and the second relay fusion is not confirmed. How to check whether the ESS contactor is fused or not.