Dual melt diagnostic method and apparatus in vehicle battery charging system

Abstract

A dual melt diagnostic device may include an inlet sharing a DC charging port and an AC charging port; a DC charging system electrically connected to the first current carrying path; the first relay group is arranged on the first current-carrying path; an AC charging system electrically connected to a second current carrying path branched from the inlet; a second relay group disposed on the second current-carrying path and selectively connecting the inlet and the AC charging system; and a controller configured to diagnose double melting of one of the first relay group and the second relay group, close the other relay group, generate a constant voltage in a charging system connected to the one relay group between the DC charging system and the AC charging system, and measuring a voltage detected at an input terminal of a charging system connected to another relay group.

Description

Technical Field

[0001] This disclosure relates to a method and apparatus for diagnosing dual relay fusion in a vehicle battery charging system. Background Technology

[0002] Typically, electric or hybrid vehicles include an energy storage device (e.g., a battery) that receives and stores AC grid power using charging facilities. To charge the energy storage device, the vehicle includes a charging unit that converts the AC grid power supplied from an external charging facility into DC power at a desired level.

[0003] Among the technologies used in charging systems installed in vehicles, the North American Charging Standard (NACS) is the widely used electric vehicle charging standard in North America. The NACS standard was developed by Tesla for its "Supercharger" electric vehicle chargers and supports both AC and DC power.

[0004] NACS is widely used in North America because of its high charging speed and high compatibility with various electric vehicle models, and many electric vehicle manufacturers have recently adopted NACS.

[0005] like Figure 1 As shown, in a typical NACS charging system that supports both slow and fast charging, a single NACS inlet 130 can be used for both slow charging using the slow charger 110 and fast charging using the fast charger 120. When a low voltage is input from an external source for slow charging of the vehicle, power is supplied to the slow charging circuit 150 via the slow charging relay 140, and when a high voltage is input for fast charging of the vehicle, power is supplied to the fast charging circuit 170 via the fast charging relay 160.

[0006] However, when a double melt occurs in the fast charging relay 160 under NACS, an inrush current may occur in the inverter or charger, which could damage the inverter or charger. And when a double melt occurs in the slow charging relay 140, excessive voltage may be input to the integrated charging control unit (ICCU), which could damage the ICCU.

[0007] Therefore, there is a need in this technical field for a double-melting technique that can diagnose relays in NACS-enabled vehicle battery charging systems. Summary of the Invention

[0008] This disclosure relates to environmentally friendly vehicle charging technology, and more specifically, to a dual-relay melt diagnostic method and apparatus in a vehicle battery charging system.

[0009] Therefore, this disclosure was made in view of the above-mentioned problems, and embodiments of this disclosure are capable of diagnosing double melting of relays in NACS-enabled vehicle battery charging systems.

[0010] Embodiments of this disclosure can diagnose relay double-melting without the need for a separate diagnostic control circuit for double-melting diagnostics, by utilizing an inverter and an on-board charger (OBC).

[0011] The technical advantages to be achieved by the embodiments of this disclosure are not necessarily limited to the technical advantages described above, and other technical advantages not mentioned can be understood by those skilled in the art to which this disclosure pertains from the following description.

[0012] According to embodiments of this disclosure, a dual-fuse diagnostic device may include: an inlet sharing a DC charging port and an AC charging port; a DC charging system electrically connected to a first current-carrying path branching from the inlet, and including a motor and an inverter; a first relay group disposed on the first current-carrying path and selectively connecting the inlet and the DC charging system; an AC charging system electrically connected to a second current-carrying path branching from the inlet; a second relay group disposed on the second current-carrying path and selectively connecting the inlet and the AC charging system; and a controller configured to diagnose the dual-fuse of one of the first and second relay groups, close the other relay group, generate a constant voltage in the charging system connected to one relay group between the DC and AC charging systems, and measure the voltage detected at the input terminal of the charging system connected to the other relay group.

[0013] The first current-carrying path may include a DC positive (+) line and a DC negative (-) line, and the first relay group may include a first relay on the DC positive (+) line and a second relay on the DC negative (-) line.

[0014] The second current-carrying path may include AC1 line and AC2 line, and the second relay group may include a third relay on AC1 line and a fourth relay on AC2 line.

[0015] The controller can maintain a constant voltage at the neutral point of the motor during the double-melting diagnostic process of the first relay group.

[0016] The controller can maintain a constant voltage in the AC charging system during the dual-melting diagnostic process of the second relay group.

[0017] The controller can determine whether a double melt has occurred in the first relay group based on the voltage measured at the input terminal of the AC charging system during the diagnosis of a double melt in the first relay group.

[0018] When the voltage measured at the input terminal of the AC charging system is higher than the threshold voltage, the controller can determine that double melting has occurred in the first relay group.

[0019] The controller can determine whether a double melt has occurred in the second relay group based on the voltage measured at the input terminal of the DC charging system during the diagnosis of a double melt in the second relay group.

[0020] When the voltage measured at the input terminal of the DC charging system is higher than the threshold voltage, the controller can determine that double melting has occurred in the second relay group.

[0021] According to embodiments of this disclosure, a double-melting diagnostic method may include: closing the other relay group in order to diagnose a double melt in one of a first relay group and a second relay group, wherein the first relay group is disposed on a first current-carrying path branching from the inlet and selectively connects the inlet to a DC charging system, and the second relay group is disposed on a second current-carrying path branching from the inlet and selectively connects the inlet to an AC charging system, the inlet sharing a DC charging port and an AC charging port; generating a constant voltage in the charging system connected to one relay group between the DC charging system and the AC charging system; and measuring the voltage detected at the input terminal of the charging system connected to the other relay group.

[0022] The method may further include determining whether double melting has occurred in a relay group based on the voltage detected at the input terminal of a charging system connected to another relay group.

[0023] Determining whether a double melt has occurred may include: during the diagnosis of a double melt in the first relay group, determining whether a double melt has occurred in the first relay group based on the voltage measured at the input terminal of the AC charging system.

[0024] Determining whether double melting has occurred may include: determining that double melting has occurred in the first relay group when the voltage measured at the input terminal of the AC charging system is higher than a threshold voltage.

[0025] Determining whether a double melt has occurred may include: during the diagnosis of a double melt in the second relay group, determining whether a double melt has occurred in the second relay group based on the voltage measured at the input terminal of the DC charging system.

[0026] Determining whether double melting has occurred may include determining that double melting has occurred in the second relay group when the voltage measured at the input terminal of the DC charging system is higher than a threshold voltage. Attached Figure Description

[0027] The above and other features and advantages of the exemplary embodiments of this disclosure will become clearer from the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0028] Figure 1 An example of a standard NACS charging system that supports both slow and fast charging is shown, and embodiments of this disclosure can be applied to such a standard NACS charging system;

[0029] Figure 2 An example of a dual-melting diagnostic device according to an embodiment of the present disclosure is shown;

[0030] Figure 3 Show Figure 2 An example of a dual-melting diagnostic device in the embodiment shown diagnosing the dual-melting of the first relay group based on the on / off state of each relay and the voltage measured by a voltage sensor;

[0031] Figure 4 Show Figure 2 An example of dual-melting diagnostic equipment in the embodiment shown diagnosing the second relay group based on the on / off state of each relay and the voltage measured by a voltage sensor;

[0032] Figure 5 This is a block diagram schematically illustrating an example of a dual-melt diagnostic device according to an embodiment of the present disclosure;

[0033] Figure 6 This is a flowchart illustrating a dual-melt diagnostic method for a vehicle battery charging system according to an embodiment of the present disclosure; and

[0034] Figure 7 This is a flowchart illustrating a dual-melt diagnostic method for a vehicle battery charging system according to an embodiment of the present disclosure. Detailed Implementation

[0035] In the following description, exemplary embodiments disclosed in this specification will be described in detail with reference to the accompanying drawings. Regardless of the symbols used, identical or similar components may be given the same reference numerals, and repeated descriptions thereof may be omitted. The suffixes “module” and “unit” used for elements in the following description may be used for convenience of description and are therefore interchangeable. When describing exemplary embodiments disclosed in this specification, detailed descriptions of related known art may be omitted if it is determined that a specific description of such art may obscure the spirit of the exemplary embodiments disclosed in this specification. The accompanying drawings are intended to facilitate understanding of the exemplary embodiments disclosed in this specification, and the technical ideas disclosed in this specification are not necessarily limited to the drawings and may be understood to include all modifications, equivalents, and alternatives within the spirit and scope of this disclosure.

[0036] Terms including ordinal numbers such as "first" and "second" can be used to describe various components, but these components are not necessarily limited by these terms. These terms may be used only for the purpose of distinguishing one component from another.

[0037] When a component is described as "connected" or "attached" to another component, it can be understood that the component can be directly connected to or attached to another component, but other components may exist between them. On the other hand, when a component is described as "directly connected" or "directly attached" to another component, it can be understood that no other components exist between them.

[0038] Unless the context explicitly indicates otherwise, a singular expression may include its plural expression.

[0039] In this specification, the terms “comprising” or “having” are intended to expressly indicate the presence of the features, quantities, steps, operations, components, parts or combinations thereof described in the specification, but should be understood to not exclude the presence or addition of one or more other features, quantities, steps, operations, components, parts or combinations thereof.

[0040] Figure 2 An example of a dual-melting diagnostic device according to an embodiment of the present disclosure is shown.

[0041] Reference Figure 2 A dual-melting diagnostic device according to embodiments of the present disclosure may include: an inlet 210 connected to an external power source to receive power; a first switch SW1 and a second switch SW2 for controlling the power supply within the inlet 210; a battery 220 charged by the external power source connected to the inlet 210 and using the charged energy to supply power when the vehicle is driven; a direct current (DC) charging system 230 electrically connected to a first current-carrying path branching from the inlet 210; a first relay group 240 disposed on the first current-carrying path; an alternating current (AC) charging system 250 electrically connected to a second current-carrying path branching from the inlet 210; a second relay group 260 disposed on the second current-carrying path; a first voltage sensor VS1 for measuring the voltage at the input terminal of the DC charging system 230; a second voltage sensor VS2 for measuring the voltage at the input terminal of the AC charging system 250; and a controller 270 for diagnosing dual-melting of one of the first and second relay groups by controlling the first relay group 240 and the second relay group 260, as well as the first voltage sensor VS1 and the second voltage sensor VS2.

[0042] although Figure 2 The diagram shows that the inlet 210 receives power from a DC power source, but the inlet 210 can receive power from a DC power source that supports fast charging or from an AC power source that supports slow charging via a shared DC charging port and AC charging port.

[0043] The current-carrying path from inlet 210 to battery 220 can be divided into a first current-carrying path and a second current-carrying path.

[0044] The first current-carrying path may include a DC positive (+) line and a DC negative (-) line, and the first relay group may include a first relay QcP on the DC positive (+) line and a second relay QcN on the DC negative (-) line.

[0045] The second current-carrying path may include AC1 line and AC2 line, and the second relay group may include the third relay ScA1 on AC1 line and the fourth relay ScA2 on AC2 line.

[0046] DC charging system 230 may include a motor and an inverter.

[0047] When the voltage of the DC charging power supplied from the outside is suitable for charging the battery 220, for example when the charging voltage is higher than the voltage of the battery 220, the DC charging system 230 can directly transfer the DC charging power to the battery 220 without boosting the voltage. When the charging voltage is lower than the voltage of the battery 220, the DC charging system 230 can charge the battery 220 by boosting the voltage of the charging power input through the motor neutral point through a boost converter topology, which is configured using the switching of the motor windings and the inverter.

[0048] The AC charging system 250 can be an on-board charger (OBC) for a vehicle or a corresponding component. For example, the AC charging system 250 can be implemented as an OBC or an integrated charging control unit (ICCU) that integrates an OBC and a DC-DC converter.

[0049] The first relay QcP and the second relay QcN can be set on the first current-carrying path branching from the inlet 210, so that the inlet 210 and the DC charging system 230 can be selectively connected.

[0050] The third relay ScA1 and the fourth relay ScA2 can be set on the second current-carrying path branching from the inlet 210, so that the inlet 210 and the AC charging system 250 can be selectively connected.

[0051] The controller 270 can control the first to fourth relays QcP, QcN, ScA1 and ScA2, and diagnose the double melting of the first relay QcP and the second relay QcN or the third relay ScA1 and the fourth relay ScA2 based on the voltage measurement values ​​of the first voltage sensor VS1 and the second voltage sensor VS2.

[0052] The controller 270 can determine whether double melting has occurred in the first relay QcP and the second relay QcN by short-circuiting the third relay ScA1 and the fourth relay ScA2 before receiving power from an external power source connected to the inlet 210, i.e., when the power supply from the external power source is cut off.

[0053] Double melting can refer to two switches closing simultaneously when they should be open. If double melting occurs in the first relay QcP and the second relay QcN, then when the third relay ScA1 and the fourth relay ScA2 are short-circuited, the voltage generated by the DC charging system 230 can be applied to the AC charging system 250. However, if the first relay QcP and the second relay QcN operate normally, then even after the third relay ScA1 and the fourth relay ScA2 are short-circuited, no voltage will be applied to the AC charging system 250.

[0054] On the other hand, in an embodiment, when the power supply from an external power source connected to inlet 210 is cut off, it can be determined whether double melting has occurred in the third relay ScA1 and the fourth relay ScA2 by short-circuiting the first relay QcP and the second relay QcN.

[0055] When a double melt occurs in the third relay ScA1 and the fourth relay ScA2, the voltage generated by the AC charging system 250 can be applied to the DC charging system 230 when the first relay QcP and the second relay QcN are short-circuited. However, if the third relay ScA1 and the fourth relay ScA2 are operating normally, no voltage will be applied to the DC charging system 230 even after the first relay QcP and the second relay QcN are short-circuited.

[0056] Figure 3 Show Figure 2 An example of a dual-melting diagnostic device in an embodiment diagnosing the dual-melting of a first relay group based on the on / off state of each relay and the voltage measured by a voltage sensor.

[0057] Reference Figure 2 and Figure 3 When the power supply from inlet 210 is cut off and the third relay ScA1 and the fourth relay ScA2, i.e. the second relay group 260, are short-circuited, a voltage is generated at the neutral point of the motor (not shown) constituting the DC charging system 230. Under normal circumstances, the second voltage sensor VS2 can measure a voltage of zero. However, when a double melt occurs in the first relay QcP and the second relay QcN, i.e. the first relay group 240, the second voltage sensor VS2 can measure a constant voltage.

[0058] The second voltage sensor VS2 can measure the same voltage as the voltage generated at the neutral point of the motor.

[0059] For example, if the voltage generated at the neutral point of the motor is 60V, the second voltage sensor VS2 can also measure a voltage of 60V.

[0060] Therefore, when a voltage is generated at the neutral point of the motor (not shown) constituting the DC charging system 230 in the case of a short circuit in the second relay group, the embodiment can determine whether double melting has occurred in the first relay group 240 based on the voltage value measured by the second voltage sensor VS2.

[0061] Figure 4 Show Figure 2 An example of a dual-melt diagnostic device in an embodiment diagnosing a second relay group based on the on / off state of each relay and the voltage measured by a voltage sensor.

[0062] Reference Figure 2 and Figure 4 When the power supply from inlet 210 is cut off and the first relay QcP and the second relay QcN, i.e. the first relay group 240, are short-circuited, a voltage is generated in the AC charging system 250. Under normal circumstances, the first voltage sensor VS1 can measure a voltage of zero. However, when a double melt occurs in the third relay ScA1 and the fourth relay ScA2, i.e. the second relay group 260, the first voltage sensor VS1 can measure a constant voltage.

[0063] The first voltage sensor VS1 can measure the same voltage as the voltage generated in the AC charging system 250.

[0064] For example, when the voltage generated in the AC charging system 250 is 60V, the first voltage sensor VS1 can also measure a voltage of 60V.

[0065] Therefore, in the example, when a voltage is generated in the AC charging system 250 in the case of a short circuit in the first relay group 240, it can be determined whether double melting has occurred in the second relay group 260 based on the voltage value measured by the first voltage sensor VS1.

[0066] Figure 5 This is a block diagram schematically illustrating an example of a dual-melt diagnostic device according to an embodiment of the present disclosure.

[0067] Reference Figure 5The dual-melting diagnostic device 500 according to embodiments of the present disclosure may include a power supply 510, a controller 520, a relay 530, a DC charging system 540, an AC charging system 550, a battery 560, and a sensor 570. Any one, any combination, or all of the power supply 510, controller 520, relay 530, DC charging system 540, AC charging system 550, battery 560, and sensor 570 may be multiple, or may include multiple components thereof.

[0068] The power supply 510 can provide power for charging the battery 560.

[0069] The power supply 510 may include a NACS inlet.

[0070] The input can share both a DC charging port and an AC charging port, and can receive either DC or AC voltage.

[0071] When DC voltage is input to power supply 510 from the outside, controller 520 can close the first relay group 531 to charge battery 560 through DC charging system 540, and when AC voltage is input, controller 520 can close the second relay group 535 to charge battery 560 through AC charging system 550.

[0072] In an embodiment, the controller 520 can operate in a dual-melt diagnostic mode for diagnosing the first relay group 531 or the second relay group 535.

[0073] In one embodiment, when an AC voltage is input to the power supply 510 from an external source, the controller 520 can operate in a dual-melting mode for diagnosing the first relay group 531.

[0074] In the dual-melt diagnostic mode for the first relay group 531, the controller 520 can short-circuit the second relay group 535 to generate a constant voltage in the DC charging system 540 and measure the voltage at the input terminal of the AC charging system 550.

[0075] The controller 520 can generate a constant voltage at the neutral point of the motor included in the DC charging system 540.

[0076] If no voltage is measured at the input terminal of the AC charging system 550, the controller 520 can determine that no double melting has occurred in the first relay group 531.

[0077] If a voltage higher than the threshold voltage is measured at the input terminal of the AC charging system 550, the controller 520 can determine that a double melt has occurred in the first relay group 531.

[0078] The threshold voltage can be any voltage selected by the user to determine the dual-melting voltage of the first relay group 531.

[0079] In this embodiment, if a DC voltage is input to the power supply 510 from an external source, the controller 520 can operate in a dual-melt mode for diagnosing the second relay group 535.

[0080] In the dual-melt diagnostic mode for the second relay group 535, the controller 520 can short-circuit the first relay group 531 to generate a constant voltage in the AC charging system 550 and measure the voltage at the input terminal of the DC charging system 540.

[0081] If no voltage is measured at the input terminal of the DC charging system 540, the controller 520 can determine that no double melting has occurred in the second relay group 535.

[0082] On the other hand, if a voltage higher than the threshold voltage is measured at the input terminal of the DC charging system 540, the controller 520 can determine that double melting has occurred in the second relay group 535.

[0083] The threshold voltage can be any voltage selected by the user to determine the dual-melting voltage of the second relay group 535.

[0084] The relay 530 can be selectively short-circuited or open-circuited under the control of the controller 520, and may include a first relay group 531 and a second relay group 535.

[0085] When DC voltage power is input to power supply 510, under the control of controller 520, DC charging system 540 can convert the DC high voltage power input to power supply 510 to charge battery 560.

[0086] When AC voltage power is input to power supply 510, under the control of controller 520, AC charging system 550 can convert the low-voltage AC power input to power supply 510 to charge battery 560.

[0087] Battery 560 can be charged using power supplied from power source 510, and the energy from the charge can be used to supply power while the vehicle is in operation.

[0088] Sensor 570 can measure the voltage of DC charging system 540 or AC charging system 550 to diagnose the double melting of the first relay group 531 or the second relay group 535.

[0089] Figure 6 This is a flowchart illustrating a dual-melt diagnostic method for a vehicle battery charging system according to an embodiment of the present disclosure.

[0090] The dual-melting diagnostic method according to embodiments of this disclosure can be derived from... Figure 2 The controller 270 of the embodiment shown is executed.

[0091] Reference Figure 6 The controller 270 can short-circuit the second relay group 260 (S610), generate a constant voltage in the DC charging system 230 (operation S620), and measure the voltage detected at the input terminal of the AC charging system 250 (operation S630).

[0092] In operation S620, the controller 270 can control the DC charging system 230 so that a constant voltage can be generated at the neutral point of the motor included in the DC charging system 230.

[0093] The controller 270 can determine whether the voltage detected at the input terminal of the AC charging system 250 is higher than the threshold voltage (operation S640), and if the detected voltage is higher than the threshold voltage, the controller 270 can determine that a double melt has occurred in the first relay group 240 (operation S650), output a warning that there is a problem with the vehicle (operation S660), and release the neutral point voltage of the motor (operation S680).

[0094] Warnings about vehicle problems can be issued by displaying a warning message on a screen inside the vehicle and / or by emitting a warning sound through speakers located in the vehicle.

[0095] If, as a result of operation S640, the detected voltage is lower than the threshold voltage, the controller 270 can determine that no double melting has occurred in the first relay group 240 (operation S670) and release the voltage of the DC charging system 230 (operation S680). The controller 270 can then open the first relay group 240 and the second relay group 260 (operation S690) and terminate the process.

[0096] Figure 7 This is a flowchart illustrating a dual-melt diagnostic method for a vehicle battery charging system according to an embodiment of the present disclosure.

[0097] The dual-melting diagnostic method according to embodiments of this disclosure can be derived from... Figure 2 The controller 270 of the embodiment shown is executed.

[0098] Reference Figure 7 The controller 270 can short-circuit the first relay group 240 (operation S710), generate a constant voltage in the AC charging system 250 (operation S720), and measure the voltage detected at the input terminal of the DC charging system 230 (operation S730).

[0099] The controller 270 can determine whether the voltage detected at the input terminal of the DC charging system 230 is higher than the threshold voltage (operation S740), and if the detected voltage is higher than the threshold voltage, the controller 270 can determine that a double melt has occurred in the second relay group 260 (operation S750), output a warning about a problem with the vehicle (operation S760), and release the voltage of the AC charging system (operation S780).

[0100] Warnings about vehicle problems can be issued by displaying a warning message on a screen inside the vehicle and / or by audible warnings from speakers located in the vehicle.

[0101] If, as a result of operation S740, the detected voltage is lower than the threshold voltage, the controller 270 can determine that no double melting has occurred in the second relay group 260 (operation S770) and release the voltage of the AC charging system 250 (operation S780). The controller 270 can then open the first relay group 240 and the second relay group 260 (operation S790) and terminate the process.

[0102] Based on the example embodiments of this disclosure described above, double melting of relays in an environmentally friendly vehicle charging system containing both slow-charging and fast-charging relays can be diagnosed.

[0103] According to embodiments of this disclosure, a relay double melt can be diagnosed using an inverter and an OBC without the need for a separate diagnostic control circuit for double melt diagnostics.

[0104] The exemplary embodiments described above can be implemented as computer-readable code on a medium in which a program is recorded. Computer-readable media can include all types of recording devices storing data that can be read by a computer system. Examples of computer-readable media include hard disk drives (HDDs), solid-state drives (SSDs), silicon disk drives (SDDs), ROM, RAM, CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, etc. Therefore, the detailed description above should not be construed as limiting, but rather as an illustrative description using exemplary embodiments. The scope of this disclosure can be determined by a reasonable interpretation of the appended claims, and variations within the equivalent scope of this disclosure can be included within its scope.

[0105] According to various embodiments of the present disclosure as described above, double melting of relays in a NACS-enabled vehicle battery charging system can be diagnosed.

[0106] According to various embodiments of the present disclosure as described above, a relay double melt can be diagnosed by utilizing an inverter and an OBC without the need for a separate diagnostic control circuit for double melt diagnostics.

[0107] Although exemplary embodiments of this disclosure have been disclosed for illustrative purposes, those skilled in the art will understand that various modifications, additions, and substitutions may be made without departing from the scope and spirit of this disclosure as disclosed in the appended claims.

Claims

1. A dual-relay fusion diagnostic device, comprising: The entrance features both a shared DC charging port and an AC charging port. The DC charging system is electrically connected to a first current-carrying path branching from the inlet and includes a motor and an inverter; A first relay group is disposed on the first current-carrying path and selectively connects the inlet and the DC charging system; The AC charging system is electrically connected to a second current-carrying path branching off from the inlet. A second relay group is disposed on the second current-carrying path and selectively connects the inlet and the AC charging system; as well as The controller diagnoses a double melt of a target group selected from the first relay group and the second relay group by: This causes the corresponding unselected groups in the first and second relay groups to close. A constant voltage is generated in a corresponding first charging system among the DC charging system and the AC charging system, the first charging system being connected to a selected target group, and The detection voltage detected at the input terminal of the corresponding second charging system is measured, and the second charging system is connected to the corresponding unselected group.

2. The device according to claim 1, wherein, The first current-carrying path includes a DC positive (+) line and a DC negative (-) line, and the first relay group includes a first relay on the DC positive (+) line and a second relay on the DC negative (-) line.

3. The device according to claim 1, wherein, The second current-carrying path includes AC1 line and AC2 line, and the second relay group includes a third relay on AC1 line and a fourth relay on AC2 line.

4. The device according to claim 1, wherein, The controller further controls the generation of a constant voltage at the neutral point of the motor during the double-melting diagnostic process of the first relay group.

5. The device according to claim 1, wherein, The controller further controls the generation of a constant voltage in the AC charging system during the double-melting diagnostics of the second relay group.

6. The device according to claim 1, wherein, The controller further determines whether a double melt has occurred in the first relay group during the diagnosis of a double melt in the first relay group, based on the detection voltage measured at the input terminal of the AC charging system.

7. The device according to claim 6, wherein, The controller further determines that a double melt has occurred in the first relay group in response to the detection voltage measured at the input terminal of the AC charging system being higher than a threshold voltage.

8. The device according to claim 1, wherein, The controller further determines whether a double melt has occurred in the second relay group during the diagnosis of a double melt in the second relay group, based on the detection voltage measured at the input terminal of the DC charging system.

9. The device according to claim 8, wherein, The controller further determines that a double melt has occurred in the second relay group in response to the detection voltage measured at the input terminal of the DC charging system being higher than a threshold voltage.

10. A dual-relay fusion diagnostic method, comprising: Diagnostic diagnosis of a dual-melt system, selecting one target group from a first relay group and a second relay group, wherein the first relay group is disposed on a first current-carrying path branching from the inlet, the inlet sharing a DC charging port and an AC charging port, the first relay group selectively connecting the inlet and the DC charging system; the second relay group is disposed on a second current-carrying path branching from the inlet, the second relay group selectively connecting the inlet and the AC charging system; and the diagnosis includes: This causes the corresponding unselected groups in the first and second relay groups to close; A constant voltage is generated in a respective first charging system of the DC charging system and the AC charging system, the first charging system being connected to a selected target group; and The detection voltage is measured at the input terminal of the corresponding second charging system connected to the corresponding unselected group.

11. The method of claim 10, further comprising: Based on the detection voltage detected at the input terminal of the corresponding second charging system connected to the corresponding unselected group, it is determined whether double melting has occurred in the target group.

12. The method according to claim 11, wherein, Determining whether double melting has occurred includes: During the diagnosis of double melting in the first relay group, it is determined whether double melting has occurred in the first relay group based on the detection voltage measured at the input terminal of the AC charging system.

13. The method according to claim 12, wherein, Determining whether double melting has occurred includes: In response to the detection voltage measured at the input terminal of the AC charging system being higher than the threshold voltage, it is determined that double melting has occurred in the first relay group.

14. The method according to claim 11, wherein, Determining whether double melting has occurred includes: During the diagnosis of double melting in the second relay group, it is determined whether double melting has occurred in the second relay group based on the detection voltage measured at the input terminal of the DC charging system.

15. The method according to claim 14, wherein, Determining whether double melting has occurred includes: In response to the detection voltage measured at the input terminal of the DC charging system being higher than the threshold voltage, it is determined that double melting has occurred in the second relay group.

16. A dual-relay melt detection method, the method comprising: A first control signal is sent to set a first relay group to an open circuit state and a second relay group to a closed circuit state. The vehicle battery charging system includes the first relay group and the second relay group, each of the first and second relay groups comprising two relays. The vehicle battery charging system further includes: The entrance shares the first and second charging ports; and A first charging system and a second charging system, wherein the second charging system is different from the first charging system, wherein the first relay group selectively connects the first charging system to the first charging port, and the second relay group selectively connects the second charging system to the second charging port. A first voltage is provided in the first charging system, and a first detection voltage is measured at the second input terminal of the second charging system; and In response to the first detection voltage being greater than the first threshold voltage level, it is determined that the first relay group has a first dual-relay melt state; or in response to the first detection voltage being less than the first threshold voltage level, it is determined that the first relay group does not have the first dual-relay melt state.

17. The method according to claim 16, wherein, The first charging port is a DC charging port, the first charging system is a DC charging system, the second charging port is an AC charging port, and the second charging system is an AC charging system.

18. The method according to claim 16, wherein, The first charging port is an AC charging port, the first charging system is an AC charging system, the second charging port is a DC charging port, and the second charging system is a DC charging system.

19. The method of claim 16, further comprising: Send a second control signal, which is used to set the first relay group to a closed state and the second relay group to an open state; A second voltage is provided in the second charging system, and a second detection voltage is measured at the first input terminal of the first charging system; as well as In response to the second detection voltage being greater than the second threshold voltage level, it is determined that the second relay group has a second dual relay melt state, or in response to the second detection voltage being less than the second threshold voltage level, it is determined that the second relay group does not have the second dual relay melt state.

20. The method according to claim 19, wherein, The first charging port is a DC charging port, the first charging system is a DC charging system, the second charging port is an AC charging port, and the second charging system is an AC charging system.

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