Relay diagnosis device, relay diagnosis method, battery system, and electric vehicle

Abstract

A relay diagnosis device according to the present application includes a first voltage detection circuit for generating a first diagnosis voltage at a voltage between a chassis and a positive terminal of a battery assembly, a second voltage detection circuit for generating a second diagnosis voltage at a voltage between the chassis and a negative terminal of the battery assembly, and a controller for determining a first insulation resistance between the positive terminal and the chassis and a second insulation resistance between the negative terminal and the chassis on the basis of the first diagnosis voltage at a first time point and the second diagnosis voltage at a second time point when first and second relays are controlled to be in an open state. The controller determines a third insulation resistance between the positive terminal and the chassis and a fourth insulation resistance between the negative terminal and the chassis on the basis of the first diagnosis voltage at a third time point and the second diagnosis voltage at a fourth time point when the first and second relays are controlled to be in a closed state. The controller detects a failure of at least one of the first and second relays on the basis of the first to fourth insulation resistances.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a technology of diagnosing a relay installed on a power line connecting a battery to a load.

[0002] This application claims the benefit of Korean Patent Application No. 10-2020-0133688, filed October 15, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. BACKGROUND

[0003] Recently, there is a sharp increase in demand for portable electronic products such as laptop computers, video cameras, mobile phones, and as electric vehicles, energy storage batteries, robots, satellites are widely developed, many studies are being conducted on high-performance batteries that can be repeatedly recharged.

[0004] Currently marketed batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, lithium batteries, etc., among which lithium batteries have almost no or no memory effect, and thus are more concerned than nickel-based batteries because lithium batteries have the advantages of recharging anywhere, anytime, very low self-discharge rate, and high energy density.

[0005] In general, various types of electrical devices (e.g., electric vehicles) requiring electrical energy include a battery assembly, an electrical load, and two relays, each of which is installed on each of the positive and negative sides of the battery. In order for stable power supply between the battery assembly and the electrical load, each relay needs to be able to normally switch between an on state and an off state in response to an external command.

[0006] There are two typical relay failure types: a short-circuit failure (referred to as a "closed stuck fault") and an open-circuit failure (referred to as an "open stuck fault"). The short-circuit failure refers to a relay stuck in an on state and unable to switch from the on state to an off state. In contrast, the open-circuit failure refers to a relay stuck in an off state and unable to switch from the off state to the on state.

[0007] In relation thereto, a relay failure diagnosis method based on a voltage difference between both ends of the relay is widely used.

[0008] However, when the relay remains in the on state for a predetermined time or longer, a smoothing capacitor (also referred to as an "X-cap") provided in the electrical load is charged at a voltage level equal to that of the battery assembly. Therefore, the relay normally switches from the on state to the off state, but a sufficient voltage difference is not generated across both ends of the relay, and thus there is a high probability of false diagnosis that the relay is in a short-circuit failure.

[0009] To solve the above problem, there is a method of forcibly discharging a smoothing capacitor by connecting a discharge circuit (a series circuit of a discharge switch and a discharge resistor) in parallel to the smoothing capacitor before relay diagnosis. However, when a failure occurs in the discharge circuit, it is not possible to discharge the smoothing capacitor, and even if the discharge circuit is normal, the process of forcibly discharging a high-capacity smoothing capacitor takes a considerable amount of time. SUMMARY

[0010] TECHNICAL PROBLEM

[0011] The present disclosure is designed to solve the above problem, and thus relates to providing an apparatus and method for performing failure detection of each relay by controlling a switch between an on state and an off state of two relays based on a change in an insulation resistance between a battery assembly of an electric vehicle and a chassis, and an electric vehicle including the apparatus, each relay being installed on each of a pair of power lines connecting the battery assembly to an electric load.

[0012] These and other objects and advantages of the present disclosure can be understood from the following description, and will be apparent to those skilled in the art from the embodiments of the present disclosure. Also, it will be readily understood that the objects and advantages of the present disclosure can be realized by the means set forth in the claims and combinations thereof. The above and other objects, features and advantages of the present disclosure will become more apparent from the following description when taken in conjunction with the accompanying drawings, in which:

[0013] TECHNICAL SOLUTION

[0014] A relay diagnosis apparatus according to an aspect of the present disclosure is for a first relay and a second relay, each relay being installed on each of a pair of power lines connecting an electric load of an electric vehicle to a battery assembly. The relay diagnosis apparatus includes a first voltage detection circuit configured to generate a first diagnosis voltage at a voltage between a positive terminal of the battery assembly and a chassis of the electric vehicle, a second voltage detection circuit configured to generate a second diagnosis voltage at a voltage between a negative terminal of the battery assembly and the chassis, and a controller configured to determine a first insulation resistance between the positive terminal and the chassis and a second insulation resistance between the negative terminal and the chassis based on the first diagnosis voltage at a first time point and the second diagnosis voltage at a second time point when the first relay and the second relay are controlled to enter an off state. The controller is configured to determine a third insulation resistance between the positive terminal and the chassis and a fourth insulation resistance between the negative terminal and the chassis based on the first diagnosis voltage at a third time point and the second diagnosis voltage at a fourth time point when the first relay and the second relay are controlled to enter an on state. The controller is configured to detect a failure of at least one of the first relay or the second relay based on the first insulation resistance to the fourth insulation resistance.

[0015] The first voltage detection circuit can be a series circuit of a first voltage divider connected between the positive terminal and the chassis and a first switch. The second voltage detection circuit can be a series circuit of a second voltage divider connected between the negative terminal and the chassis and a second switch. Each voltage divider can be a series circuit of two resistors.

[0016] The first time point can be a time point at which the first switch and the second switch are controlled by the controller to enter the on state and the off state, respectively. The second time point can be a time point at which the first switch and the second switch are controlled by the controller to enter the off state and the on state, respectively.

[0017] The third time point can be a time point at which the first switch and the second switch are controlled by the controller to enter the on state and the off state, respectively. The fourth time point can be a time point at which the first switch and the second switch are controlled by the controller to enter the off state and the on state, respectively.

[0018] The controller can be configured to determine that the first relay is faulty when a resistance difference between the first insulation resistance and the third insulation resistance is equal to or less than a threshold resistance, or when a ratio of the resistance difference to the first insulation resistance is equal to or less than a threshold ratio.

[0019] The controller can be configured to determine that the first relay is in an open-circuit fault when the third insulation resistance is equal to or greater than a first reference resistance.

[0020] The controller can be configured to determine that the second relay is faulty when a resistance difference between the second insulation resistance and the fourth insulation resistance is equal to or less than a threshold resistance, or when a ratio of the resistance difference to the second insulation resistance is equal to or less than a threshold ratio.

[0021] The controller can be configured to determine that the second relay is in an open-circuit fault when the fourth insulation resistance is equal to or greater than a second reference resistance.

[0022] An electric vehicle according to another aspect of the present disclosure includes the relay diagnosis apparatus.

[0023] A relay diagnosis method according to still another aspect of the present disclosure can be performed by the relay diagnosis apparatus. The relay diagnosis method includes the steps of determining a first insulation resistance between a positive terminal and a chassis and a second insulation resistance between a negative terminal and the chassis based on a first diagnosis voltage at a first time point and a second diagnosis voltage at a second time point when the first relay and the second relay are controlled into an off state, determining a third insulation resistance between the positive terminal and the chassis and a fourth insulation resistance between the negative terminal and the chassis based on the first diagnosis voltage at a third time point and the second diagnosis voltage at a fourth time point when the first relay and the second relay are controlled into an on state, and detecting a failure of at least one of the first relay or the second relay based on the first insulation resistance to the fourth insulation resistance.

[0024] Advantageous Effects

[0025] According to at least one embodiment of the present disclosure, a defect of each relay can be detected by controlling a switch between an on state and an off state of two relays based on a change in insulation resistance between a battery assembly of an electric vehicle and a chassis, each relay being installed on each of a pair of power lines connecting the battery assembly to an electrical load.

[0026] In addition, according to at least one embodiment of the present disclosure, a failure of each relay can be detected without an element (e.g., a discharge circuit) and a control process required to forcibly discharge a smoothing capacitor.

[0027] In addition, according to at least one embodiment of the present disclosure, a failure of each relay can be detected without an element (e.g., a voltage sensor) and a process required to measure a voltage on an electrical load side, i.e., a voltage across the smoothing capacitor.

[0028] Effects of the present disclosure are not limited to what has been described expressly above and the skilled person will understand these and other effects from the appended claims. BRIEF DESCRIPTION OF DRAWINGS

[0029] The accompanying drawings, which are included to provide a further understanding of the technical features of the present disclosure and are incorporated herein, illustrate embodiments of the present disclosure and, together with the foregoing disclosure, serve to provide further understanding of the technical features of the present disclosure, and thus the present disclosure should not be construed as being limited to the drawings.

[0030] Figure 1 FIG. 1 is a diagram exemplarily illustrating a configuration of an electric vehicle according to the present disclosure.

[0031] Figure 2 FIG. 2 is a flowchart exemplarily illustrating a relay diagnosis method according to the first embodiment, which can be performed by the relay diagnosis apparatus shown in FIG. 1. Figure 1 FIG. 2 is a flowchart exemplarily illustrating a relay diagnosis method according to the first embodiment, which can be performed by the relay diagnosis apparatus shown in FIG. 1.

[0032] FIG. 2 is a flowchart exemplarily illustrating a relay diagnosis method according to the first embodiment, which can be performed by the relay diagnosis apparatus shown in FIG. 1.Figure 3 and Figure 4 is an exemplary diagram illustrating a relay diagnosis method according to a second embodiment that can be executed by Figure 1 is a flowchart of a relay diagnosis method according to a second embodiment that can be executed by the relay diagnosis apparatus shown in DETAILED DESCRIPTION

[0033] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms or words used in the specification and the appended claims should not be interpreted as being limited to general and dictionary meanings and should be interpreted based on the meanings and concepts corresponding to the technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to define terms appropriately for the best explanation of the invention.

[0034] Accordingly, the embodiments described herein and the examples illustrated in the drawings are merely the most preferred embodiments of the present disclosure, and are not intended to describe only the technical aspects of the present disclosure, and it should be understood that various other equivalents and modifications can be made thereto at the time of filing the application.

[0035] The terms including ordinal numbers such as "first," "second," or the like are used to distinguish one element from another element in various elements, but are not intended to limit the elements by the terms.

[0036] Unless the context clearly indicates otherwise, it will be understood that the term "comprise" used in the present specification designates the presence of the stated element but does not exclude the presence or addition of one or more other elements. In addition, the term "unit" means a processing unit of at least one function or operation, and this can be implemented by hardware and software alone or in combination.

[0037] In addition, throughout the specification, it will be further understood that when one element is referred to as being "connected to" another element, the one element can be directly connected to the other element or an intermediate element can be present.

[0038] Figure 1 is an exemplary diagram illustrating a configuration of an electric vehicle 1 according to the present disclosure.

[0039] Referring to Figure 1 , the electric vehicle 1 includes a chassis 2, a battery assembly 10, an electric load 20, a first relay 31, a second relay 32, and a relay diagnosis apparatus.

[0040] The battery assembly 10 includes a plurality of battery cells 11 connected in series. The battery cells 11 can be, for example, lithium-ion battery cells 11. The battery cells 11 are not limited to a specific type and can include any type of battery cells that can be repeatedly recharged.

[0041] The electric load 20 includes a smoothing capacitor 21, an inverter 22, and an electric motor 23.

[0042] The smoothing capacitor 21 is connected in parallel to the series circuit of the battery assembly 10, the first relay 31, and the second relay 32 to prevent a sharp change in direct current between the battery assembly 10 and the inverter 22.

[0043] When both the first relay 31 and the second relay 32 are in the on state, the inverter 22 converts the direct current supplied from the battery assembly 10 through the smoothing capacitor 21 into alternating current and supplies the alternating current to the electric motor 23.

[0044] The first relay 31 is installed on the power line L1 connecting the positive terminal B P of the battery assembly 10 to the positive terminal E P of the electric load 20. That is, the first end and the second end of the first relay 31 are connected to the positive terminal B P of the battery assembly 10 and one end of the smoothing capacitor 21, respectively.

[0045] The second relay 32 is installed on the power line L2 connecting the negative terminal B N of the battery assembly 10 to the negative terminal E N of the electric load 20. That is, the first end and the second end of the second relay 32 are connected to the negative terminal B N of the battery assembly 10 and the other end of the smoothing capacitor 21, respectively.

[0046] Furthermore, Figure 1 each of R A1 , R A2 , R B1 , and R B2 indicates four insulation resistances present in the electric vehicle 1. Each insulation resistance is not a resistance of a physical resistor, but a virtual resistance component indicating an insulation condition between a specific position of the electric vehicle 1 and the chassis 2.

[0047] The insulation resistance R A1 indicates a first insulation condition between the positive terminal B P of the battery assembly 10 and the chassis 2, the insulation resistance R A2 indicates a second insulation condition between the negative terminal B N of the battery assembly 10 and the chassis 2, the insulation resistance R B1 indicates a third insulation condition between the positive terminal E P of the electric load 20 and the chassis 2, and the insulation resistance R B2 indicates a fourth insulation condition between the negative terminal E N of the electric load 20 and the chassis 2.

[0048] When the insulation condition is normal, each insulation resistance has a very large value of, for example, 10 [MΩ] or more. When the insulation condition is abnormal due to flood damage of the electric vehicle 1, i.e., dielectric breakdown, each insulation resistance decreases to a very small value of, for example, 10 [Ω] or less.

[0049] When the first relay 31 is in the off state, the insulation resistance R B1 is electrically separated from the insulation resistance R A1 is electrically separated, and thus only the insulation resistance R A1 affects the first diagnostic voltage V1. In contrast, when the first relay 31 is in the on state, the insulation resistance R B1 is connected in parallel with the insulation resistance R A1 , and thus the combined resistance of the insulation resistance R A1 and the insulation resistance R B1 affects the first diagnostic voltage V1.

[0050] When the second relay 32 is in the off state, the insulation resistance R B2 is electrically separated from the insulation resistance R A2 , and thus only the insulation resistance R A2 affects the second diagnostic voltage V2. In contrast, when the second relay 32 is in the on state, the insulation resistance R B2 is connected in parallel with the insulation resistance R A2 , and thus the combined resistance of the insulation resistance R A2 and the insulation resistance R B2 affects the second diagnostic voltage V2.

[0051] That is, the first diagnostic voltage V1 and the second diagnostic voltage V2 can be changed between the off state and the on state by the switching of each of the first relay 31 and the second relay 32.

[0052] The relay diagnosis device 100 includes a first voltage detection circuit 110, a second voltage detection circuit 120, and a controller 130.

[0053] The first voltage detection circuit 110 is disposed such that it is connectable between the positive terminal B P and the chassis 2. The first voltage detection circuit 110 can selectively provide a first current path between the positive terminal B P and the chassis 2. When the first current path is provided, the first voltage detection circuit 110 can divide a voltage between the positive terminal B P and the chassis 2 at a predetermined ratio to generate the first diagnostic voltage V1.

[0054] The first voltage detection circuit 110 can be a series circuit of a first voltage divider 111 and a first switch SW1. The first voltage divider 111 can include a first protection resistor 113 and a first detection resistor 115 connected in series. When the first switch SW1 is in an on state, a first current path is provided. The first diagnostic voltage V1 can be a voltage across the first detection resistor 115.

[0055] The second voltage detection circuit 120 is arranged such that it can be connected between the negative terminal B N and the chassis 2. The second voltage detection circuit 120 can selectively provide a second current path between the negative terminal B N and the chassis 2. When the second current path is provided, the second voltage detection circuit 120 can divide a voltage between the negative terminal B N and the chassis 2 at a predetermined ratio to generate a second diagnostic voltage V2.

[0056] The second voltage detection circuit 120 can be a series circuit of a second voltage divider 121 and a second switch SW2 or a constant voltage source 127, a series circuit of the second voltage divider 121 and the second switch SW2. The second voltage divider 121 can include a second protection resistor 123 and a second detection resistor 125 connected in series. When the second switch SW2 is in an on state, a second current path is provided. The second diagnostic voltage V2 can be a sum of a voltage across the second detection resistor 125 and an output voltage of the constant voltage source 127.

[0057] The resistance of the first protection resistor 113 can be equal to the resistance of the second protection resistor 123. The resistance of the first detection resistor 115 can be equal to the resistance of the second detection resistor 125.

[0058] By the output voltage of the constant voltage source 127, a voltage greater than 0 [V] can be input to the controller 130 as the second diagnostic voltage V2. The magnitude of the output voltage can be preset in consideration of the rated voltage of the battery assembly 10 and the resistance ratio between the second protection resistor 123 and the second detection resistor 125.

[0059] The first switch SW1 and the second switch SW2 can include a well-known switching device such as a MOSFET.

[0060] The controller 130 is operatively coupled to the first voltage detection circuit 110 and the second voltage detection circuit 120. The controller 130 can be additionally operatively coupled to the first relay 31 and the second relay 32. The operative coupling refers to a direct / indirect connection to transmit and receive signals in one or both directions.

[0061] The controller 130 can include a data processing unit. The data processing unit can be implemented in hardware, including at least one of an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a microprocessor, or an electrical unit for performing other functions. The data processing unit is responsible for various calculation processes for relay diagnosis and output of various signals for relay control.

[0062] The controller 130 can include a switch driver. The switch driver can output a switching signal for on / off control of each of the first relay 31, the second relay 32, the first switch SW1, and the second switch SW2 in response to a command from the data processing unit.

[0063] The controller 130 can include an analog-to-digital converter. The analog-to-digital converter can convert analog signals of the first diagnosis voltage V1 and the second diagnosis voltage V2 into digital values.

[0064] The controller 130 can include a memory. The memory can store programs and data required to perform the following methods. The memory can include at least one type of storage medium such as a flash memory type, a hard disk type, a solid state drive (SSD) type, a silicon disk drive (SDD) type, a multimedia card micro type, a random access memory (RAM), a static random access memory (SRAM), a read-only memory (ROM), an electrically erasable programmable read-only memory (EEPROM), or a programmable read-only memory (PROM).

[0065] The controller 130 can individually control the on / off of the first relay 31, the second relay 32, the first switch SW1, and the second switch SW2.

[0066] The controller 130 controls the first switch SW1 to enter an on state and the second switch SW2 to enter an off state at a first time point, while controlling the first relay 31 and the second relay 32 to enter an off state. The controller 130 can record a first measured value of the first diagnosis voltage V1 generated by the first voltage detection circuit 110 at the first time point in the memory. The controller 130 controls the first switch SW1 to enter an off state and the second switch SW2 to enter an on state at a second time point, while controlling the first relay 31 and the second relay 32 to enter an off state. The controller 130 can record a second measured value of the second diagnosis voltage V2 generated by the second voltage detection circuit 120 at the second time point in the memory.

[0067] The controller 130 controls the first switch SW1 to enter the on state and controls the second switch SW2 to enter the off state at the third point in time while controlling the first relay 31 and the second relay 32 to enter the on state. The controller 130 can record in the memory a third measured value of the first diagnostic voltage V1 generated by the first voltage detection circuit 110 at the third point in time. The controller 130 controls the first switch SW1 to enter the off state and controls the second switch SW2 to enter the on state at the fourth point in time while controlling the first relay 31 and the second relay 32 to enter the on state. The controller 130 can record in the memory a fourth measured value of the second diagnostic voltage V2 generated by the second voltage detection circuit 120 at the fourth point in time.

[0068] The controller 130 can monitor (predict) the first to fourth insulation resistances described below while controlling the on / off of the first relay 31 and the second relay 32. The following equations can be examples of functions that can be used by the controller 130 to calculate each of the first to fourth insulation resistances.

[0069]

[0070]

[0071] ∴

[0072] ∴

[0073] ∴

[0074] ∴

[0075] In the above equations, R Leak(+) represents the insulation resistance between the positive terminal B P and the chassis 2, R Leak(-) represents the insulation resistance between the negative terminal B N and the chassis 2, V Bat represents the voltage across the battery assembly 10, V1 represents the first diagnostic voltage, V2 represents the second diagnostic voltage, R1 represents the resistance of the first protection resistor 113, R2 represents the resistance of the first detection resistor 115, and VDC represents the output voltage of the constant voltage source 127.

[0076] The controller 130 can determine V Bat by multiplying the sum of the first diagnostic voltage V1 and the second diagnostic voltage V2 by the above ratio when controlling the first switch SW1 and the second switch SW2 to enter the on state. Alternatively, V Bat can be measured by an additional voltage detection circuit (not shown) connected in parallel to the battery assembly 10.

[0077] The controller 130 can record in the memory R Leak(+) and R Leak(-) when the first diagnostic voltage V1 at the first time point and the second diagnostic voltage V2 at the second time point are input to V1 and V2 of the above equation as the first insulation resistance and the second insulation resistance. P N The first insulation resistance and the second insulation resistance indicate the insulation resistance between the positive terminal B P and the chassis 2 and the insulation resistance between the negative terminal B N and the chassis 2 when the first relay 31 and the second relay 32 are controlled to enter the open state, respectively.

[0078] When the first relay 31 is in the open state at the first time point without a short circuit failure, the first insulation resistance can be equal to the insulation resistance R A1 . In contrast, when the first relay 31 remains in the closed state at the first time point due to a short circuit failure, the first insulation resistance can be equal to the combined resistance of the insulation resistance R A1 and the insulation resistance R B1 . The combined resistance of the insulation resistance R A1 and the insulation resistance R B1 is (R A1 × R B1 ) / (R A1 + R B1 ).

[0079] When the second relay 32 is in the open state at the second time point without a short circuit failure, the second insulation resistance can be equal to the insulation resistance R A2 . In contrast, when the second relay 32 remains in the closed state at the second time point due to a short circuit failure, the second insulation resistance can be equal to the combined resistance of the insulation resistance R A2 and the insulation resistance R B2 . The combined resistance of the insulation resistance R A2 and the insulation resistance R B2 is (R A2 × R B2 ) / (R A2 + R B2 ).

[0080] The controller 130 can record in the memory R Leak(+) and R Leak(-) when the first diagnostic voltage V1 at the third time point and the second diagnostic voltage V2 at the fourth time point are input to V1 and V2 of the above equation as the third insulation resistance and the fourth insulation resistance. Pthe insulation resistance between the first relay 31 and the chassis 2 N the insulation resistance between the first relay 31 and the chassis 2

[0081] The above equation is an example of a function for determining the first insulation resistance to the fourth insulation resistance, and instead of the above equation, at least one other known function can be used.

[0082] When the first relay 31 is in the on state at the third time point without an open circuit failure, the third insulation resistance can be equal to the combination resistance of the insulation resistance R A1 and the insulation resistance R B1 . In contrast, when the first relay 31 remains in the off state at the third time point due to an open circuit failure, the third insulation resistance can be equal to the insulation resistance R A1 .

[0083] When the second relay 32 is in the on state at the fourth time point without an open circuit failure, the fourth insulation resistance can be equal to the combination resistance of the insulation resistance R A2 and the insulation resistance R B2 . In contrast, when the second relay 32 remains in the off state at the fourth time point due to an open circuit failure, the second insulation resistance can be equal to the insulation resistance R A2 .

[0084] Figure 2 is an exemplary flowchart of the relay diagnosis method according to the first embodiment that can be executed by the relay diagnosis apparatus 100 shown in Figure 1 .

[0085] With reference to Figure 1 and Figure 2 , in step S210, the controller 130 controls the first relay 31 and the second relay 32 to enter the off state.

[0086] In step S220, the controller 130 records in the memory the first detection value indicating the first diagnosis voltage V1 when the first switch SW1 and the second switch SW2 are controlled to enter the on state and the off state, respectively.

[0087] In step S230, the controller 130 records in the memory the second detection value indicating the second diagnosis voltage V2 when the first switch SW1 and the second switch SW2 are controlled to enter the off state and the on state, respectively.

[0088] In step S240, the controller 130 determines the first insulation resistance and the second insulation resistance based on the first detection value and the second detection value.

[0089] In step S250, the controller 130 controls the first relay 31 and the second relay 32 to enter the on state.

[0090] In step S260, the controller 130 records in its memory the third detection value indicating the first diagnostic voltage V1 when the first switch SW1 and the second switch SW2 are controlled to enter the on state and the off state, respectively.

[0091] In step S270, the controller 130 records in its memory the fourth detection value indicating the second diagnostic voltage V2 when the first switch SW1 and the second switch SW2 are controlled to enter the off state and the on state, respectively.

[0092] In step S280, the controller 130 determines the third insulation resistance and the fourth insulation resistance based on the third detection value and the fourth detection value.

[0093] In step S292, the controller 130 determines whether the first relay 31 is faulty by comparing the first insulation resistance with the third insulation resistance. (i) When the resistance difference between the first insulation resistance and the third insulation resistance is equal to or less than the threshold resistance, or (ii) when the ratio of the resistance difference to the first insulation resistance is equal to or less than the threshold ratio, the controller 130 can determine that the first relay 31 is faulty. When the value of step S292 is "yes", step S294 can be executed.

[0094] In step S294, the controller 130 outputs a first diagnostic signal indicating that the first relay 31 is faulty. The first diagnostic signal can be transmitted to an external device via wired / wireless communication.

[0095] In step S296, the controller 130 determines whether the second relay 32 is faulty by comparing the second insulation resistance with the fourth insulation resistance. (i) When the resistance difference between the second insulation resistance and the fourth insulation resistance is equal to or less than the threshold resistance, or (ii) when the ratio of the resistance difference to the second insulation resistance is equal to or less than the threshold ratio, the controller 130 can determine that the second relay 32 is faulty. When the value of step S296 is "yes", step S298 can be executed.

[0096] In step S298, the controller 130 outputs a second diagnostic signal indicating that the second relay 32 is faulty. The second diagnostic signal can be transmitted to an external device via wired / wireless communication.

[0097] Figure 3 and Figure 4 This is an illustrative example of what can be achieved by... Figure 1 The flowchart shows the relay diagnostic method performed by the relay diagnostic device 100 according to the second embodiment.

[0098] When in Figure 2 If it is determined in step S292 that the first relay 31 is faulty, another step can be performed.Figure 3 The method. Refer to Figure 1 and Figure 3 In step S310, the controller 130 determines whether the third insulation resistance is equal to or greater than the first reference resistance. When both the first and third insulation conditions are normal, the first reference resistance can be the indicative insulation resistance R. A1 and insulation resistance R B1 The predetermined value of the combined resistance. The third insulation resistance being equal to or greater than the first reference resistance indicates that: (i) at least the first insulation condition is normal, and (ii) the first relay 31 is in an open-circuit fault.

[0099] In step S320, the controller 130 outputs a third diagnostic signal indicating that the first insulation condition is normal and the first relay 31 is in an open-circuit fault state. The third diagnostic signal can be transmitted to an external device via wired / wireless communication.

[0100] When in Figure 2 If it is determined in step S292 that the first relay 31 is faulty, another step can be performed. Figure 4 The method. Refer to Figure 1 and Figure 4 In step S410, the controller 130 determines whether the fourth insulation resistance is equal to or greater than the second reference resistance. When both the second and fourth insulation conditions are normal, the second reference resistance can be the indicative insulation resistance R. A2 and insulation resistance R B2 The predetermined value of the combined resistance. The second reference resistance may be equal to the first reference resistance. The fourth insulation resistance being equal to or greater than the second reference resistance indicates that: (i) at least the second insulation condition is normal, and (ii) the second relay 32 is in an open-circuit fault.

[0101] In step S420, the controller 130 outputs a fourth diagnostic signal indicating that the second insulation condition is normal and the second relay 32 is in an open-circuit fault state. The fourth diagnostic signal can be transmitted to an external device via wired / wireless communication.

[0102] The embodiments of the present disclosure described above are not limited to devices and methods, but can also be implemented by a program that performs functions corresponding to the configuration of the embodiments of the present disclosure or by a recording medium on which the program is recorded. Such implementation can be easily implemented by those skilled in the art from the disclosure of the embodiments described above.

[0103] Although the present disclosure has been described above with respect to a limited number of embodiments and drawings, the present disclosure is not limited thereto and it will be apparent to those skilled in the art that various modifications and changes can be made thereto in the technical aspects of the present disclosure and the equivalent scope of the appended claims.

[0104] Furthermore, since those skilled in the art can make many substitutions, modifications and changes to the above-described present disclosure without departing from the technical aspects of the present disclosure, the present disclosure is not limited to the above-described embodiments and accompanying drawings, and some or all of the embodiments can be selectively combined to allow various modifications.

Claims

1. A relay diagnosis device for a first relay and a second relay, the first relay being installed on a first power line connecting an electrical load of an electric vehicle to a battery assembly and the second relay being installed on a second power line connecting the electrical load of the electric vehicle to the battery assembly, the relay diagnosis device comprising: a first voltage detection circuit configured to generate a first diagnosis voltage at a first location between a positive terminal of the battery assembly and a chassis of the electric vehicle, wherein the first voltage detection circuit is a series circuit of a first voltage divider connected between the positive terminal and the chassis and a first switch; a second voltage detection circuit configured to generate a second diagnosis voltage at a second location between a negative terminal of the battery assembly and the chassis, wherein the second voltage detection circuit is a series circuit of a second voltage divider connected between the negative terminal and the chassis and a second switch, and each of the first voltage divider and the second voltage divider is a series circuit of two resistors; and a controller configured to: determine a first insulation resistance between the positive terminal and the chassis and a second insulation resistance between the negative terminal and the chassis based on the first diagnosis voltage at a first time point when the first switch is controlled into an on state and the second switch is controlled into an off state and the second diagnosis voltage at a second time point when the first switch is controlled into an off state and the second switch is controlled into an on state, while the first relay and the second relay are controlled into an off state; determine a third insulation resistance between the positive terminal and the chassis and a fourth insulation resistance between the negative terminal and the chassis based on the first diagnosis voltage at a third time point when the first switch is controlled into an on state and the second switch is controlled into an off state and the second diagnosis voltage at a fourth time point when the first switch is controlled into an off state and the second switch is controlled into an on state, while the first relay and the second relay are controlled into an on state; detect a failure of the first relay based on the first insulation resistance and the third insulation resistance; and detect a failure of the second relay based on the second insulation resistance and the fourth insulation resistance.

2. The relay diagnosis apparatus according to claim 1, wherein The first voltage detection circuit provides a first current path between the positive terminal and the chassis when the first switch is in an on state, and divides a voltage between the positive terminal and the chassis at a predetermined ratio to generate the first diagnosis voltage when the first current path is provided.

3. The relay diagnosis apparatus according to claim 1, wherein The second voltage detection circuit provides a second current path between the negative terminal and the chassis when the second switch is in an on state, and divides a voltage between the negative terminal and the chassis at a predetermined ratio to generate the second diagnostic voltage when the second current path is provided.

4. The relay diagnosis apparatus according to claim 1, wherein The controller is configured to determine that the first relay is faulty when a resistance difference between the first insulation resistance and the third insulation resistance is equal to or smaller than a threshold resistance or when a ratio of the resistance difference to the first insulation resistance is equal to or smaller than a threshold ratio.

5. The relay diagnosis apparatus according to claim 4, wherein The controller is configured to determine that the first relay is in an open-circuit failure when the third insulation resistance is equal to or larger than a first reference resistance.

6. The relay diagnosis apparatus according to claim 1, wherein The controller is configured to determine that the second relay is faulty when a resistance difference between the second insulation resistance and the fourth insulation resistance is equal to or smaller than a threshold resistance or when a ratio of the resistance difference to the second insulation resistance is equal to or smaller than a threshold ratio.

7. The relay diagnosis apparatus according to claim 6, wherein The controller is configured to determine that the second relay is in an open-circuit failure when the fourth insulation resistance is equal to or larger than a second reference resistance.

8. An electric vehicle including the relay diagnosis apparatus according to any one of claims 1 to 7.

9. A relay diagnosis method executable by the relay diagnosis apparatus according to any one of claims 1 to 7, the relay diagnosis method including: determining a first insulation resistance between the positive terminal and the chassis and a second insulation resistance between the negative terminal and the chassis based on the first diagnostic voltage at a first time point and the second diagnostic voltage at a second time point when the first relay and the second relay are controlled into an off state; determining a third insulation resistance between the positive terminal and the chassis and a fourth insulation resistance between the negative terminal and the chassis based on the first diagnostic voltage at a third time point and the second diagnostic voltage at a fourth time point when the first relay and the second relay are controlled into an on state; and detecting a failure of the first relay based on the first insulation resistance and the third insulation resistance, and detecting a failure of the second relay based on the second insulation resistance and the fourth insulation resistance.

8. An electric vehicle including the relay diagnosis apparatus according to any one of claims 1 to 7.

9. A relay diagnosis method executable by the relay diagnosis apparatus according to any one of claims 1 to 7, the relay diagnosis method including: determining a first insulation resistance between the positive terminal and the chassis and a second insulation resistance between the negative terminal and the chassis based on the first diagnostic voltage at a first time point and the second diagnostic voltage at a second time point when the first relay and the second relay are controlled into an off state; determining a third insulation resistance between the positive terminal and the chassis and a fourth insulation resistance between the negative terminal and the chassis based on the first diagnostic voltage at a third time point and the second diagnostic voltage at a fourth time point when the first relay and the second relay are controlled into an on state; and detecting a failure of the first relay based on the first insulation resistance and the third insulation resistance, and detecting a failure of the second relay based on the second insulation resistance and the fourth insulation resistance.

Images