High voltage relay system of vehicle and diagnosis method thereof

Abstract

The present invention relates to a high-voltage relay system of a vehicle and a diagnostic method thereof. The system includes: a relay, a first contact component located between a battery and a power converter, a voltage applying unit, and a second contact component located between the voltage applying unit and the ground. A first resistor is connected in series with a second end of the second contact component at its first end, and is connected to the ground at the second end of the first resistor. A controller operates the relay in response to an on / off control signal to short-circuit or open-circuit contacts at both ends of the first contact component or contacts at both ends of the second contact component, and determines whether the relay is faulty based on the type of the on / off control signal and the voltage value at both ends of the first resistor.

Description

Technical Field

[0001] The present invention relates to a high-voltage relay system of a vehicle and a diagnostic method thereof, and more particularly to a high-voltage relay system of a vehicle and a diagnostic method thereof, which can diagnose relay faults in a system with a simplified structure when the relay is in an on or off state. Background Art

[0002] An electric vehicle or a hybrid vehicle is equipped with a high-voltage battery as a main power source for supplying power to a motor as a driving source, and includes a charging device configured to charge the battery, a power converter configured to operate the motor, etc. The power converter drives the motor by phase-converting the power supplied from the high-voltage battery in response to a control signal of a motor control unit (MCU).

[0003] Figure 1 The figure schematically shows the configuration and connection of a high voltage circuit suitable for a conventional electric vehicle or a hybrid vehicle according to the prior art. Figure 1 The first main relay 21 is installed on the circuit between the positive terminal of the battery 10 and the positive terminal of the direct current (DC) link, the second main relay 22 is installed on the circuit between the negative terminal of the battery 10 and the negative terminal of the DC link, and the pre-charge relay 23 and the pre-charge resistor 24 are installed on the bypass circuit bypassing the first main relay 21. The relay of the power relay assembly 20 is turned on / off in response to the relay control signal output by the battery management system (BMS) controller 50 or the motor control unit (MCU) 30.

[0004] The problem with these relays is that they may fail (including welding, etc.). When the relay is welded, high voltage electricity continues to be exposed even during the period when the ignition device (IG) is turned off (for example, when the vehicle is parked), which may cause safety accidents such as electric shock. Therefore, in order to avoid safety accidents, it is necessary to develop a technology that can determine whether a failure (including relay welding, etc.) exists.

[0005] The above is only intended to help understand the background of the present invention, and is not intended to indicate that the present invention falls within the scope of the prior art known to those skilled in the art. Summary of the invention

[0006] Accordingly, the present invention provides a high-voltage relay system for a vehicle and a diagnostic method thereof, which can operate the relay in response to an on / off control signal to short-circuit or open-circuit the contacts at both ends of the first contact component or the contacts at both ends of the second contact component through the corresponding relay, and can determine whether the corresponding relay is faulty based on the type of the on / off control signal and the voltage across the first resistor.

[0007] According to one aspect of the present invention, a high-voltage relay system of a vehicle may include: a first contact component, a second contact component, a relay, a first resistor and a controller, wherein the first contact component is located between a battery and a power converter of the vehicle; the second contact component is located between a voltage application unit configured to apply a constant voltage and ground; the relay is arranged between the first contact component and the second contact component and is short-circuited or open-circuited; the first resistor is arranged between the second contact component and ground; and the controller connects the relay to the first contact component and the second contact component in response to an on / off control signal.

[0008] Specifically, the controller can be configured to determine whether the relay is faulty based on the on / off control signal and the voltage value across the first resistor. The high-voltage relay system can further include a voltage sensor configured to measure the voltage across the first resistor. When the voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and an on signal is applied to the relay is "0", the controller can be configured to determine that the relay is normal.

[0009] When the voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and a switch-on signal is applied to the relay exceeds "0" and is a predetermined voltage value (which is less than or equal to the voltage applied by the voltage applying unit), the controller can be configured to determine that the relay is open. In addition, when the voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and a switch-off signal is applied to the relay exceeds "0" and is a predetermined voltage value (which is less than or equal to the voltage applied by the voltage applying unit), the controller can be configured to determine that the relay is normal.

[0010] When a voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and a disconnection signal is applied to the relay is "0", the controller may be configured to determine that the relay is short-circuited and welded to the first contact part. The relay may be connected to at least one of the positive terminal and the negative terminal of the battery.

[0011] The high-voltage relay system may further include: a pre-charge relay and a pre-charge resistor, the pre-charge relay and the pre-charge resistor are connected in parallel to both ends of the relay, and the pre-charge relay and the pre-charge resistor are connected in series with each other. The high-voltage relay system may further include: a first switch and a second switch, the first switch and the second switch are connected in parallel to both ends of the relay, and the first switch and the second switch are connected in series with each other. The relay may only conduct one of the first contact part and the second contact part. The voltage application unit may be configured to apply a constant voltage to the second contact part for fault diagnosis of the relay.

[0012] According to another aspect of the present invention, a method for diagnosing a relay fault in a vehicle may include: applying a constant voltage to a second contact member through a voltage applying unit; applying an on or off signal to the relay through a controller; measuring the voltage across a first resistor through a voltage sensor; and determining whether the relay is faulty based on the type of signal applied to the relay by the controller and the measured voltage value across the first resistor.

[0013] When determining whether the relay is faulty, when the voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and a switch-on signal is applied to the relay is "0", the controller can be configured to determine that the relay is normal. In addition, when the voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and a switch-on signal is applied to the relay exceeds "0" and is a predetermined voltage value (which is less than or equal to the voltage applied by the voltage applying unit), the controller can be configured to determine that the relay is open.

[0014] When the voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and a disconnect signal is applied to the relay exceeds "0" and is a predetermined voltage value (which is less than or equal to the voltage applied by the voltage applying unit), the controller can be configured to determine that the relay is normal. When determining whether the relay is faulty, when the voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and a disconnect signal is applied to the relay is "0", the controller can be configured to determine that the relay is short-circuited and welded to the first contact part.

[0015] It is obvious from the above description that according to the present invention, it is possible to control the relay in response to the on / off control signal, so that the contacts at both ends of the first contact part or the contacts at both ends of the second contact part are short-circuited or open-circuited through the corresponding relay, and it is easier to determine whether the corresponding relay is faulty based on the type of the on / off control signal and the voltage across the first resistor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other objects, features and advantages of the present invention will be more clearly understood from the following detailed description presented in conjunction with the accompanying drawings, in which:

[0017] Figure 1 A schematic diagram showing a high voltage circuit suitable for a conventional electric vehicle or a hybrid vehicle according to the prior art;

[0018] Figure 2 A schematic diagram schematically showing an overall configuration of a high voltage relay system of a vehicle according to an exemplary embodiment of the present invention;

[0019] Figure 3A schematic diagram showing that, in a high voltage relay system for a vehicle according to an exemplary embodiment of the present invention, a relay is normal in a state where a voltage applying unit applies a constant voltage and applies an on signal to the relay;

[0020] Figure 4 A schematic diagram showing that a relay is disconnected in a state where a voltage applying unit applies a constant voltage and applies an on signal to a relay in a high voltage relay system of a vehicle according to an exemplary embodiment of the present invention;

[0021] Figure 5 A schematic diagram showing that, in a high voltage relay system for a vehicle according to an exemplary embodiment of the present invention, a relay is normal in a state where a voltage applying unit applies a constant voltage and applies a disconnection signal to the relay;

[0022] Figure 6 A schematic diagram showing that, in a high voltage relay system for a vehicle according to an exemplary embodiment of the present invention, a relay is short-circuited and fused to a first contact member in a state where a voltage applying unit applies a constant voltage and applies an opening signal to the relay; and

[0023] Figure 7 A flowchart illustrating a method of diagnosing a relay failure of a vehicle according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0024] It should be understood that the term "vehicle" or "vehicle-based" or other similar terms used herein generally include motor vehicles, such as passenger cars including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, ships including various boats, vessels, aircraft, etc., and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from non-petroleum energy sources). As referred to herein, a hybrid vehicle is a vehicle having two or more power sources, such as both gasoline-powered and electric-powered vehicles.

[0025] Although the exemplary embodiments are described as using multiple units to perform the exemplary processes, it is understood that the exemplary processes can also be performed by one or more modules. In addition, it is understood that the term controller / control unit refers to a hardware device including a memory and a processor. The memory is configured to store the modules, and the processor is specifically configured to run the modules to perform one or more processes described further below.

[0026] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the present invention. As used herein, the singular forms "one", "an" and "the" are intended to also include plural forms, unless the context clearly indicates otherwise. It will also be understood that when the terms "comprising" and / or "including" are used in this specification, it is indicated that the features, integral bodies, steps, operations, elements and / or components exist, but the presence or addition of one or more other features, integral bodies, steps, operations, elements, components and / or their groups are not excluded. As used herein, the term "and / or" includes any and all combinations of one or more related enumerated items.

[0027] Unless otherwise stated or apparent from the context, the term "approximately" as used herein is understood to be within the normal tolerance range in the art, such as within 2 standard deviations of the average. "Approximately" may be understood to be within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of a specified value. Unless the context clearly indicates otherwise, all numerical values ​​provided herein are modified by the term "approximately".

[0028] Hereinafter, a high voltage relay system of a vehicle and a diagnosis method thereof according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

[0029] Figure 2 is a diagram schematically showing an overall configuration of a high voltage relay system for a vehicle according to an exemplary embodiment of the present invention. Figure 3 It is a schematic diagram showing that the relay is normal in a state where the voltage applying unit applies a constant voltage and applies an on signal to the relay. Figure 4 It is a schematic diagram showing that the relay is disconnected in a state where a voltage applying unit applies a constant voltage and applies an on signal to the relay. Figure 5 It is a schematic diagram showing that the relay is normal in a state where the voltage applying unit applies a constant voltage and applies an opening signal to the relay. Figure 6 It is a schematic diagram showing that the relay is short-circuited and fused to the first contact part in a state where the voltage applying unit applies a constant voltage and applies an opening signal to the relay.

[0030] like Figure 2As shown, a high-voltage relay system of a vehicle according to an exemplary embodiment of the present invention (which is indicated by reference numeral 1) may include: a first contact component 400, a second contact component 600, a relay 100, a first resistor R1 and a controller 700; the first contact component 400 is arranged between a battery 200 and a power converter 300 of the vehicle; the second contact component 600 is arranged between a voltage applying unit 500 configured to apply a constant voltage and the ground; the relay 100 is arranged between the first contact component 400 and the second contact component 600 and is short-circuited or open-circuited; the first resistor R1 is arranged between the second contact component 600 and the ground G; the controller 700 connects the relay to the first contact component 400 and the second contact component 600 in response to an on / off control signal, and the controller 700 may be configured to determine whether the relay 100 is faulty based on the on / off control signal and the voltage value across the first resistor R1.

[0031] The relay 100 may be a main relay of the vehicle and may be a relay connected to at least one of the positive terminal and the negative terminal of the battery 200. In other words, the relay 100 may include: a first main relay connected to the positive terminal of the battery 200 and a second main relay connected to the negative terminal of the battery 200. Specifically, as Figure 2 As shown in the exemplary embodiment of the present invention, the first relay 100 and the second relay 100 may be connected to the positive terminal and the negative terminal of the battery 200 of the vehicle. In the present invention, it is possible to diagnose whether the corresponding first relay 100 and the second relay 100 connected to the positive terminal and the negative terminal of the battery 200 are faulty or malfunctioning. A detailed description thereof will be given when explaining the controller.

[0032] The relay 100 may be arranged on a line that connects the first contact part 400 located between the battery 200 and the power converter 300 to the second contact part 600 located between the voltage applying unit 500 and the ground G. In addition, the relay 100 may only conduct one of the first contact part 400 and the second contact part 600. Specifically, the relay 100 may be turned on or off in response to an on / off control signal received from the controller 700 to short-circuit or disconnect the contacts at both ends of the first contact part 400 or the contacts at both ends of the second contact part 600. In the following, for ease of description, it is assumed that in a normal state of the relay 100, the contacts at both ends of the first contact part 400 are short-circuited when receiving a connection signal from the controller 700, and the contacts at both ends of the second contact part 600 are short-circuited when receiving a disconnection signal from the controller 700.

[0033] In addition, the battery 200 of the vehicle may be a high-voltage battery configured to supply power to drive a motor of an electric vehicle or a hybrid vehicle. The power converter 300 may include a plurality of switching elements and may be configured to drive a motor installed in an electric vehicle or a hybrid vehicle by performing phase conversion on the power supplied by the battery 200 in response to a control signal of a motor control unit (MCU) (not shown). Since driving a motor by performing phase conversion on the power supplied by the high-voltage battery of the vehicle in a power converter is well known in the prior art, a detailed description thereof will be omitted.

[0034] In an exemplary embodiment, the voltage applying unit 500 can be configured to apply a constant voltage to one end of the second contact member 600 for fault diagnosis of the relay 100, and can be configured to apply a voltage of approximately 5V to the second contact member 600. In an exemplary embodiment, the controller 700 can be a battery management system (BMS) controller or a motor control unit (MCU). In addition, the controller 700 can be configured to operate the relay 100, the pre-charging relay 900, the first switch 920, and the second switch 930 (to be described later) to apply an on / off control signal to the relay 100 and turn the relay 100 on or off. The controller 700 can be configured to determine whether the relay 100 is faulty based on the type of control signal applied to the relay 100 and the measured value of the voltage sensor 800 (which is configured to measure the voltage across the first resistor R1). Reference will be made later Figures 3 to 6 Determination of whether the relay 100 is faulty in the controller 700 is described in more detail.

[0035] Meanwhile, the high-voltage relay system 1 of the vehicle according to the exemplary embodiment of the present invention may further include: a second resistor R2 and a voltage sensor 800; the second resistor R2 is arranged between the second contact part 600 and the first resistor R1; the voltage sensor 800 is configured to measure the voltage across the first resistor R1. In addition, the high-voltage relay system 1 of the vehicle according to the exemplary embodiment of the present invention may further include a pre-charge relay 900 and a pre-charge resistor 910, which are connected in parallel with both ends of the relay 100 and the pre-charge relay 900 and the pre-charge resistor 910 are connected in series with each other. The pre-charge relay 900 can be selectively turned on or off in response to a control signal received from the controller 700.

[0036] In addition, the high-voltage relay system 1 of the vehicle according to the exemplary embodiment of the present invention may further include: a first switch 920 and a second switch 930, the first switch 920 and the second switch 930 are connected in parallel with both ends of the relay 100 and the first switch 920 and the second switch 930 are connected in series with each other. The first switch 920 and the second switch 930 can be selectively turned on or off in response to a control signal received from the controller 700. In addition, the first switch 920 and the second switch 930 can be semiconductor switching elements, and prevent the relay 100 from surges, arcs, etc. when the relay 100 is turned on / off.

[0037] At the same time, the state of the relay 100 can be divided into three types. In other words, the state of the relay 100 can be divided into three types: a steady state, a short-circuit welding state, and an open circuit state. Specifically, the steady state means that the relay 100 is in a normal state and operates in response to a control signal applied from the controller 700. The short-circuit welding state means that the relay 100 is fixed in a short-circuit state. Accordingly, when the relay 100 is short-circuited and welded, the relay 100 can remain in a short-circuit state (on state) regardless of the control signal applied from the controller 700. The open circuit state means that the relay 100 is fixed in an open circuit state. Accordingly, when the relay 100 is open circuited, the relay 100 can remain in an open circuit state (disconnected state) regardless of the control signal applied from the controller 700.

[0038] In the following, reference will be made to Figures 3 to 6 Determination of whether the relay 100 is faulty in the controller 700 is described in more detail. Figure 3 Schematic diagram showing that the relay is normal in a state where the voltage applying unit applies a constant voltage and applies a connection signal to the relay. Specifically, in a state where a constant voltage is applied to the second contact member 600 by the voltage applying unit 500 and a connection signal is applied to the relay 100 by the controller 700, when the voltage value across the first resistor R1 measured by the voltage sensor 800 is "0", the controller 700 can be configured to determine that the relay 100 is normal. Specifically, when a connection signal is applied to the relay 100 by the controller 700 in a state where the relay 100 is normal, the relay 100 can be operated to short-circuit the contacts across the first contact member 400 and disconnect the contacts across the second contact member 600, so the voltage across the first resistor R1 measured by the voltage sensor 800 can be "0".

[0039] Figure 4A schematic diagram showing a relay being open circuited in a state where a voltage applying unit applies a constant voltage and applies an on signal to the relay. Specifically, in a state where a constant voltage is applied to the second contact member 600 by the voltage applying unit 500 and an on signal is applied to the relay 100 by the controller 700, when the voltage value across the first resistor R1 measured by the voltage sensor 800 exceeds "0" and is a predetermined voltage value (which is less than or equal to the voltage applied by the voltage applying unit), the controller 700 can be configured to determine that the relay 100 is in an open circuit state. In addition, when an on signal is applied to the relay 100 by the controller 700 in a normal state of the relay 100, the relay 100 can short-circuit the contacts across the first contact member 400. However, as Figure 4 As shown, when the relay 100 is in the off state, although the on signal is applied from the controller 700, the relay 100 can also short-circuit the contacts at both ends of the second contact member 600, so the voltage across the first resistor R1 measured by the voltage sensor 800 can exceed "0" and be the voltage applied by the voltage applying unit. Due to the voltage drop caused by the resistor, the above voltage is less than or equal to the voltage applied by the voltage applying unit.

[0040] Figure 5 Schematic diagram showing that the relay is normal in a state where the voltage applying unit applies a constant voltage and applies a disconnection signal to the relay. Specifically, in a state where a constant voltage is applied to the second contact member 600 by the voltage applying unit 500 and a disconnection signal is applied to the relay 100 by the controller 700, when the voltage value across the first resistor R1 measured by the voltage sensor 800 exceeds 0 and is a predetermined voltage value (which is less than or equal to the voltage applied by the voltage applying unit), the controller 700 can be configured to determine that the relay 100 is normal. It is worth noting that the predetermined voltage value can be approximately 4V. In addition, as Figure 5 As shown, when a constant voltage is applied to the second contact part 600 by the voltage applying unit 500 and a disconnection signal is applied to the relay 100 by the controller 700 in a normal state of the relay 100, the relay 100 can short-circuit the contacts at both ends of the second contact part 600, so that the voltage across the first resistor R1 measured by the voltage sensor 800 can be equal to or greater than a specific voltage.

[0041] Figure 6Schematic diagram showing that the relay is fused to the first contact part in a state where a voltage applying unit applies a constant voltage and a disconnection signal is applied to the relay. Specifically, in a state where a constant voltage is applied to the second contact part 600 by the voltage applying unit 500 and a disconnection signal is applied to the relay 100 by the controller 700, when the voltage value across the first resistor R1 measured by the voltage sensor 800 is "0", the controller 700 can be configured to determine that the relay 100 is fused to the first contact part 400. When a disconnection signal is applied to the relay 100 by the controller 700 in a normal state of the relay 100, the relay 100 can short-circuit the contacts across the second contact part 600. However, as Figure 6 As shown, when the relay 100 is welded to the first contact part 400, although a disconnection signal is applied from the controller 700, the relay 100 can also short-circuit the contacts at both ends of the first contact part 400, so the voltage across the first resistor R1 measured by the voltage sensor 800 can be "0".

[0042] Figure 7 1 is a flowchart showing a method for diagnosing a relay fault of a vehicle according to an exemplary embodiment of the present invention. The method described below may generally be executed by a controller configured to operate various components of the system. Figure 7 , a method for diagnosing a relay fault of a vehicle according to an exemplary embodiment of the present invention may include: applying a constant voltage to a second contact member through a voltage applying unit; applying an on or off signal to the relay through a controller; measuring the voltage across a first resistor through a voltage sensor; determining whether the relay is faulty through a controller based on the type of signal applied to the relay and the voltage value across the measured first resistor. For example, a relay fault may include a relay short circuit, resulting in the vehicle engine possibly being unable to stop. Accordingly, an alarm regarding such a fault may be output. As another example, a relay fault may include a relay open circuit fault, resulting in the engine possibly being unable to start.

[0043] Specifically, when determining whether the relay is faulty, when the voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and a switch-on signal is applied to the relay is "0", the controller can be configured to determine that the relay is normal. In addition, when the voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and a switch-on signal is applied to the relay exceeds "0" and is a predetermined voltage value (which is less than or equal to the voltage applied by the voltage applying unit), the controller can be configured to determine that the relay is open.

[0044] When the voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and a disconnect signal is applied to the relay exceeds "0" and is a predetermined voltage value (which is less than or equal to the voltage applied by the voltage applying unit), the controller can be configured to determine that the relay is normal. In addition, when the voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and a disconnect signal is applied to the relay is "0", the controller can be configured to determine that the relay is short-circuited and welded to the first contact part.

[0045] Although exemplary embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A high voltage relay system for a vehicle, comprising: A first contact component is arranged between a battery of the vehicle and a power converter of the vehicle, and both ends of the first contact component have contacts; a second contact member disposed between a voltage applying unit other than a battery of the vehicle and ground, the second contact member having contacts at both ends thereof, wherein the voltage applying unit is configured to apply a constant voltage; a relay arranged between the first contact member and the second contact member, wherein the relay is short-circuited or open-circuited; a first resistor disposed between the second contact member and ground; A controller connects the relay to the first contact member or the second contact member in response to an on / off control signal so that contacts at both ends of the first contact member and the second contact member are short-circuited or open-circuited.

2. The high voltage relay system for a vehicle according to claim 1, wherein: The controller is configured to determine whether the relay is faulty based on an on / off control signal and a voltage value across the first resistor.

3. The high voltage relay system for a vehicle according to claim 1, further comprising: A voltage sensor is configured to measure a voltage across the first resistor.

4. The high voltage relay system for a vehicle according to claim 1, wherein: The controller determines that the relay is normal when a voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and an on signal is applied to the relay is 0.

5. The high voltage relay system for a vehicle according to claim 1, wherein: The controller determines that the relay is disconnected when a voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and an on signal is applied to the relay exceeds 0 and is a predetermined voltage value less than or equal to the voltage applied by the voltage applying unit.

6. The high voltage relay system for a vehicle according to claim 1, wherein: The controller determines that the relay is normal when a voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and an opening signal is applied to the relay exceeds 0 and is a predetermined voltage value less than or equal to the voltage applied by the voltage applying unit.

7. The high voltage relay system for a vehicle according to claim 1, wherein: The controller determines that the relay is short-circuited and welded to the first contact part when a voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and an opening signal is applied to the relay is 0.

8. The high voltage relay system for a vehicle according to claim 1, wherein: The relay is connected to at least one of a positive terminal and a negative terminal of the battery.

9. The high voltage relay system for a vehicle according to claim 1, further comprising: A pre-charging relay and a pre-charging resistor are connected in parallel to both ends of the relay, and the pre-charging relay and the pre-charging resistor are connected in series with each other.

10. The high voltage relay system for a vehicle according to claim 1, further comprising: A first switch and a second switch are connected in parallel to both ends of the relay, and the first switch and the second switch are connected in series to each other.

11. The high voltage relay system for a vehicle according to claim 1, wherein: The relay conducts only one of the first contact part and the second contact part.

12. The high voltage relay system for a vehicle according to claim 1, wherein: The voltage applying unit is configured to apply a constant voltage to the second contact member for fault diagnosis of the relay.

13. A method for diagnosing a fault in a high voltage relay system of a vehicle according to claim 1, comprising: Applying a constant voltage to the second contact member by a controller; Applying an on signal or an off signal to the relay through the controller; Measuring the voltage across the first resistor by using a voltage sensor through the controller; Whether the relay is faulty is determined by the controller based on the type of signal applied to the relay and the voltage value measured across the first resistor.

14. The method according to claim 13, wherein: In determining whether the relay is faulty, the controller determines that the relay is normal when a voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and an on signal is applied to the relay is 0.

15. The method according to claim 13, wherein: When determining whether the relay is faulty, the controller determines that the relay is open when the voltage value across the first resistor measured when a constant voltage is applied by a voltage applying unit and a connection signal is applied to the relay exceeds 0 and is a predetermined voltage value less than or equal to the voltage applied by the voltage applying unit.

16. The method according to claim 13, wherein: When determining whether the relay is faulty, the controller determines that the relay is normal when the voltage value across the first resistor measured when a constant voltage is applied by a voltage applying unit and a disconnect signal is applied to the relay exceeds 0 and is a predetermined voltage value less than or equal to the voltage applied by the voltage applying unit.

17. The method according to claim 13, wherein: In determining whether the relay fails, the controller determines that the relay is short-circuited and welded to the first contact part when a voltage value across the first resistor measured in a state where a constant voltage is applied by the voltage applying unit and an opening signal is applied to the relay is 0.

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