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

Abstract

The relay diagnostic device according to the present invention comprises: a diagnostic unit for a parallel battery pack assembly including a first battery pack having a first battery module and a first positive relay and a second battery pack having a second battery module and a second positive relay, and comprising a diagnostic switch and a diagnostic resistor connected between the first battery pack terminal and the second battery pack terminal; a first detector for detecting the current of the first battery module; a second detector for detecting the current of the second battery module; and a control unit for collecting a first detection value from the first detector and a second detection value from the second detector in a first diagnostic period when the first positive relay and the second positive relay are in an open working state and the diagnostic switch is in a closed working state. The control unit determines a normally closed fault of the first positive relay and a normally closed fault of the second positive relay based on the first detection value, the second detection value and the first threshold.

Description

Technical Field

[0001] The present disclosure relates to a fault diagnosis technology for a relay assembly provided in each of a plurality of battery packs connected in parallel.

[0002] This application claims the priority benefit of Korean Patent Application No. 10-2020-0069206 filed on June 8, 2020, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. Background Art

[0003] Recently, the demand for portable electronic products such as laptop computers, cameras, mobile phones has increased dramatically, and with the widespread development of electric vehicles, energy storage batteries, robots, satellites, many studies are being conducted on high-performance batteries that can be repeatedly charged and discharged.

[0004] Currently commercially available batteries include nickel-cadmium batteries, nickel-metal hydride batteries, nickel-zinc batteries, lithium batteries, etc. Among these batteries, lithium batteries have almost no memory effect or no memory effect, and therefore are more popular than nickel-based batteries because the advantages of lithium batteries are that they can be recharged anytime and anywhere, have a very low self-discharge rate, and have a high energy density.

[0005] A battery system installed in an electric vehicle may include a parallel battery pack assembly including a plurality of battery packs connected in parallel to meet high capacity requirements such as long-distance driving.

[0006] It is necessary to diagnose the fault of the relays responsible for connecting and disconnecting each battery pack and electrical load.

[0007] When the battery system includes only one battery pack, a failure of the relay may be detected based on a voltage at a load-side contact of the relay provided in the battery pack.

[0008] However, in a parallel battery pack assembly, the load-side contacts of the plurality of relays provided in each of the plurality of battery packs are connected to each other in common. Therefore, it is possible to identify that at least one of the plurality of relays has failed based on the voltage of the load-side contacts, but it is impossible to accurately identify which relay has failed. Summary of the invention

[0009] Technical issues

[0010] The present disclosure is designed to solve the above-mentioned problems, and thus the present disclosure aims to provide a relay diagnosis device, a relay diagnosis method, a battery system, and an electric vehicle for individually diagnosing faults of a plurality of relays provided in a plurality of battery packs of a parallel battery pack assembly.

[0011] These and other purposes and advantages of the present disclosure can be understood through the following description, and from the embodiments of the present disclosure, these and other purposes and advantages of the present disclosure will become apparent. In addition, it will be easily understood that the purposes and advantages of the present disclosure can be achieved by the means set forth in the appended claims and combinations thereof.

[0012] Technical Solution

[0013] A relay diagnostic device according to one aspect of the present disclosure is used for a parallel battery pack assembly, which includes a first battery pack having a first battery module and a first positive relay connected in series and a second battery pack having a second battery module and a second positive relay connected in series. The relay diagnostic device includes: a diagnostic unit, the diagnostic unit including a diagnostic switch and a diagnostic resistor connected in series between a first battery pack terminal and a second battery pack terminal of the parallel battery pack assembly; a first detector, the first detector is configured to detect a first module current as a current flowing through the first battery module; a second detector, the second detector is configured to detect a second module current as a current flowing through the second battery module; and a control unit, the control unit is operably connected to the first positive relay, the second positive relay, the diagnostic switch, the first detector, and the second detector. The control unit is configured to collect a first detection value from the first detector and a second detection value from the second detector in a first diagnostic period when the first positive relay and the second positive relay are in an open working state and the diagnostic switch is in a closed working state. The control unit is configured to determine whether the first positive relay has a normally closed fault (stuck-closed fault) based on the first detection value and the first threshold. The control unit is configured to determine whether the second positive relay has a normally closed type fault based on the second detection value and the first threshold value.

[0014] The control unit may be configured to determine that the first positive relay has a normally closed type fault in response to the first detection value being greater than a first threshold value.

[0015] The control unit may be configured to determine that the second positive relay has a normally closed type fault in response to the second detection value being greater than the first threshold value.

[0016] The relay diagnostic device may further include: a third detector configured to detect a first module voltage as a voltage across the first battery module; and a fourth detector configured to detect a second module voltage as a voltage across the second battery module.

[0017] The control unit may be configured to collect a third detection value from the third detector and a fourth detection value from the fourth detector in a first diagnostic period. The control unit may be configured to collect a fifth detection value from the third detector and a sixth detection value from the fourth detector in a second diagnostic period in which the first positive relay and the second positive relay are in an open working state and the diagnostic switch is in an open working state. The control unit may be configured to determine whether the first positive relay has a normally closed fault based on the first detection value, the third detection value, the fifth detection value, the first threshold value, and the second threshold value. The control unit may be configured to determine whether the second positive relay has a normally closed fault based on the second detection value, the fourth detection value, the sixth detection value, the first threshold value, and the second threshold value.

[0018] The control unit may be configured to determine that the first positive relay has a normally closed type fault in response to the first detection value being greater than a first threshold and a difference between the third detection value and the fifth detection value being greater than a second threshold.

[0019] The control unit may be configured to determine that the second positive relay has a normally closed type fault in response to the second detection value being greater than the first threshold and a difference between the fourth detection value and the sixth detection value being greater than the second threshold.

[0020] A battery system according to another aspect of the present disclosure includes a relay diagnostic device.

[0021] An electric vehicle according to yet another aspect of the present disclosure includes a battery system.

[0022] According to another aspect of the present disclosure, a relay diagnosis method is provided that can be performed by a relay diagnosis device. The relay diagnosis method includes: collecting, by a control unit, a first detection value from a first detector and a second detection value from a second detector in a first diagnosis period when a first positive relay and a second positive relay are in an open working state and a diagnostic switch is in a closed working state; determining, by the control unit, whether the first positive relay has a normally closed fault based on the first detection value and a first threshold value; and determining, by the control unit, whether the second positive relay has a normally closed fault based on the second detection value and the first threshold value.

[0023] Beneficial Effects

[0024] According to at least one of the embodiments of the present disclosure, faults of a plurality of relays provided in a plurality of battery packs of a parallel battery pack assembly may be individually diagnosed.

[0025] The effects of the present disclosure are not limited to the above-described effects, and those skilled in the art will clearly understand these and other effects from the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the detailed description of the foregoing disclosure, are used to provide a further understanding of the technical features of the present disclosure. Therefore, the present disclosure should not be construed as being limited to the accompanying drawings.

[0027] Figure 1 is a diagram exemplarily showing a configuration of a power system according to the present disclosure.

[0028] Figure 2 It is shown as an example Figure 1 FIG. 1 is a diagram of the configuration of the first detector and the second detector.

[0029] Figure 3 It is shown as an example Figure 1 FIG. 1 is a diagram of the configuration of the third detector and the fourth detector.

[0030] Figure 4 is a flowchart exemplarily showing the relay diagnosis method according to the first embodiment.

[0031] Figure 5 is a flowchart exemplarily showing a relay diagnosis method according to the second embodiment. DETAILED DESCRIPTION

[0032] Hereinafter, the 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 expressions used in the specification and the appended claims should not be interpreted as limited to the general meaning and dictionary meaning, but should be interpreted based on the meaning and concept corresponding to the technical aspects of the present disclosure on the basis of the principle that the inventor is allowed to appropriately define the terms for the best interpretation.

[0033] Therefore, the embodiments described herein and the illustrations shown in the drawings are merely the most preferred embodiments of the present invention and are not intended to fully describe the technical aspects of the present disclosure. Therefore, it should be understood that various other equivalents and modifications may be made thereto when an application is filed.

[0034] Terms including ordinal numbers such as “first,” “second,” etc. are used to distinguish one element from another among various elements, but are not intended to limit the elements by the terms.

[0035] Unless the context clearly indicates otherwise, it will be understood that the term "comprising" when used in this specification specifies the presence of the element, but does not exclude the presence or addition of one or more other elements. In addition, the term "control unit" used herein refers to a processing unit of at least one function or operation, and can be implemented by hardware or software alone or in combination.

[0036] Furthermore, throughout the specification, it will be further understood that when an element is referred to as being “connected to” another element, it can be directly connected to the other element or intervening elements may be present.

[0037] Figure 1 is a diagram schematically showing a configuration of a power system according to the present disclosure, Figure 2 It is shown as an example Figure 1 a diagram of a configuration of a first detector and a second detector, and Figure 3 It is shown as an example Figure 1 FIG. 1 is a diagram of the configuration of the third detector and the fourth detector.

[0038] Reference Figure 1 The power system 1 may be, for example, an energy storage system and an electric vehicle. The power system 1 includes a battery system 10, an inverter 2, and an electric load 3. The electric load 3 may be, for example, an electric motor.

[0039] The battery system 10 includes a parallel battery pack assembly 20 and a relay diagnostic device 100. The battery system 10 may further include a main relay assembly MR. In this specification, the parallel battery pack assembly 20 refers to a battery pack group including a parallel circuit of at least two battery packs (ie, a first battery pack 21 and a second battery pack 22) connected in parallel.

[0040] The main relay assembly MR can be connected between a pair of battery pack terminals P1 and P2 provided in the parallel battery pack assembly 20 and a pair of power terminals provided in the inverter 2. The main relay assembly MR includes a first main relay MR1. The two contacts of the first main relay MR1 are respectively connected to the first battery pack terminal P1 and one of the pair of power terminals. The main relay assembly MR may also include a second main relay MR2. The two contacts of the second main relay MR2 are respectively connected to the second battery pack terminal P2 and the other of the pair of power terminals.

[0041] The inverter 2 converts direct current (DC) power supplied from the parallel battery stack assembly 20 into alternating current (AC) power and supplies it to the electrical load 3 .

[0042] The first battery pack 21 includes a first battery module 31 and a first relay assembly 41. The first battery module 31 includes a plurality of battery cells electrically connected in series and / or in parallel.

[0043] The first relay assembly 41 is connected in series to the first battery module 31. The first relay assembly 41 includes a first positive relay 41A. Two contacts of the first positive relay 41A are respectively connected to the positive terminal of the first battery module 31 and the first battery pack terminal P1. The first relay assembly 41 may also include a first negative relay 41B. Two contacts of the first negative relay 41B are respectively connected to the negative terminal of the first battery module 31 and the second battery pack terminal P2.

[0044] The second battery pack 22 includes a second battery module 32 and a second relay assembly 42. The second battery module 32 includes a plurality of battery cells electrically connected in series and / or in parallel.

[0045] The second relay assembly 42 is connected in series to the second battery module 32. The second relay assembly 42 includes a second positive relay 42A. The two contacts of the second positive relay 42A are respectively connected to the positive terminal of the second battery module 32 and the first battery pack terminal P1. The second relay assembly 42 may also include a second negative relay 42B. The two contacts of the second negative relay 42B are respectively connected to the negative terminal of the second battery module 32 and the second battery pack terminal P2.

[0046] Each battery cell of the first battery module 31 and the second battery module 32 is not limited to a specific type, and includes any type of battery that can be repeatedly charged and discharged, such as a lithium-ion battery.

[0047] The relay diagnostic device 100 includes a first detector 110, a second detector 120, a diagnostic unit 150, and a control unit 160. The relay diagnostic device 100 may further include at least one of a third detector 130, a fourth detector 140, or an interface unit 170.

[0048] The diagnostic unit 150 is connected between the first battery terminal P1 and the second battery terminal P2. The diagnostic unit 150 includes a diagnostic switch SWD and a diagnostic resistor RD connected in series. The diagnostic switch SWD may include a well-known switching device, such as a field effect transistor (FET). When the main relay assembly MR is in the disconnected working state, the diagnostic unit 150 may be used to provide a current path between the first battery terminal P1 and the second battery terminal P2.

[0049] The first detector 110 is configured to detect a first module current I1, which is a current flowing through the first battery module 31. The first detector 110 may be installed on a negative-side line of the first battery module 31. The first detector 110 generates a detection signal S1 indicating the first module current I1.

[0050] The second detector 120 is configured to detect a second module current I2, which is a current flowing through the second battery module 32. The second detector 120 may be installed on a negative-side line of the second battery module 32. The second detector 120 generates a detection signal S1 indicating the second module current I2.

[0051] Reference Figure 2 , when the first relay assembly 41 includes the first negative relay 41B, the first detector 110 may be connected in parallel with the first negative relay 41B. The first detector 110 may include a first resistor R1 and a first switch SW1. A series circuit of the first resistor R1 and the first switch SW1 may be connected in parallel to the first negative relay 41B. When the first relay assembly 41 does not include the first negative relay 41B, the first switch SW1 may be removed from the first detector 110. In this case, the first resistor R1 may be connected in series between the negative terminal of the first battery module 31 and the second battery pack terminal P2.

[0052] When the second relay assembly 42 includes a second negative relay 42B, the second detector 120 may be connected in parallel to the second negative relay 42B. The second detector 120 may include a second resistor R2 and a second switch SW2. A series circuit of the second resistor R2 and the second switch SW2 may be connected in parallel to the second negative relay 42B. When the second relay assembly 42 does not include the second negative relay 42B, the second switch SW2 may be removed from the second detector 120. In this case, the second resistor R2 may be connected in series between the negative terminal of the second battery module 32 and the second battery pack terminal P2.

[0053] The third detector 130 is configured to detect a first module voltage V1, which is a voltage across the first battery module 31. The third detector 130 generates a detection signal S3 indicating the first module voltage V1. Figure 3 , the third detector 130 may include a third switch SW3, a third resistor R3, and a fourth resistor R4. A series circuit of the third switch SW3, the third resistor R3, and the fourth resistor R4 may be connected in parallel to the first battery module 31. The control unit 160 may control the third switch SW3 to enter a closed working state to generate a detection signal S3 indicating the first module voltage V1. When the third switch SW3 is controlled to enter a closed working state, the control unit 160 may determine the first module voltage V1 based on the voltage across the third resistor R3 or the fourth resistor R4. The closed working state refers to an open state that allows current to flow.

[0054] The fourth detector 140 is configured to detect a second module voltage V2, which is a voltage across the second battery module 32. The fourth detector 140 generates a detection signal S4 indicating the second module voltage V2. Figure 3 , the fourth detector 140 may include a fourth switch SW4, a fifth resistor R5, and a sixth resistor R6. A series circuit of the fourth switch SW4, the fifth resistor R5, and the sixth resistor R6 may be connected in parallel to the second battery module 32. The control unit 160 may control the fourth switch SW4 to enter a closed working state to generate a detection signal S4 indicating the second module voltage V2. When the fourth switch SW4 is controlled to enter a closed working state, the control unit 160 may determine the second module voltage V2 according to the voltage across the fifth resistor R5 or the sixth resistor R6.

[0055] The interface unit 170 is configured to support wired or wireless communication between the control unit 160 and the advanced controller 4 (e.g., an electronic control unit (ECU)). The advanced controller 4 is provided to manage the overall operation of the power system 1. The communication protocol is not limited to a specific type, and the wired communication may be, for example, a controller area network (CAN) communication, and the wireless communication may be, for example, Zigbee or Bluetooth communication. The interface unit 170 may include output devices such as a display and a speaker to provide information corresponding to a message from the control unit 160 in a recognizable format.

[0056] The control unit 160 is operably connected to the first positive relay 41A, the second positive relay 42A, the diagnostic switch SWD, the first detector 110 and the second detector 120. Operably connected refers to a direct / indirect connection that realizes the transmission and reception of signals in one or two directions. The control unit 160 can also be operably connected to the third detector 130, the fourth detector 140 and the interface unit 170. The control unit 160 can also be operably connected to the first main relay MR1, the second main relay MR2, the first negative relay 41B and the second negative relay 42B. That is, the control unit 160 can receive a detection signal from each detector included in the relay diagnostic device 100, and control the opening / closing of each relay and each switch.

[0057] The control unit 160 may be referred to as a "control circuit" and may be implemented in hardware using 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.

[0058] The control unit 160 may include a memory embedded therein. The memory may store programs and data required to perform the following methods. The memory may include, for example, at least one type of storage medium of 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).

[0059] The control unit 160 can control the main relay assembly MR to enter the disconnected working state in response to a command from the advanced controller 4 installed in the power system 1. The disconnected working state refers to a closed state in which the flow of current is interrupted. Of course, alternatively, the opening / closing of the main relay assembly MR can be controlled by the power system 1.

[0060] The control unit 160 may perform one of a first diagnostic process and a second diagnostic process described below for detecting a failure of at least one of the first positive relay 41A or the second positive relay 42A when the main relay assembly MR is controlled to be in the off-operation state.

[0061] <First Diagnosis Process>

[0062] The first diagnostic process is a process of diagnosing a normally closed fault of each of the first positive relay 41A and the second positive relay 42A using the first detector 110 and the second detector 120. A normally closed fault refers to a fault that cannot be switched from a closed working state to an open working state due to, for example, contact fusion, and when a signal directing an open working state is input to the corresponding relay, the closed working state is maintained. A normally closed fault may be referred to as a "short circuit fault".

[0063] When the relay diagnostic apparatus 100 does not include the third detector 130 and the fourth detector 140 , the first diagnostic process may be used.

[0064] In response to the relay diagnosis command from the high-level controller 4, the control unit 160 may control the first positive relay 41A and the second positive relay 42A to enter the open working state and control the diagnostic switch SWD to enter the closed working state during the first diagnostic period. The first diagnostic period may have a predetermined time length. The control unit 160 may control the first switch SW1 and the second switch SW2 to enter the closed working state during the first diagnostic period.

[0065] When the first relay assembly 41 includes the first negative relay 41B, the control unit 160 can control the first negative relay 41B to enter the disconnected working state during the first diagnostic period. When the second relay assembly 42 includes the second negative relay 42B, the control unit 160 can control the second negative relay 42B to enter the disconnected working state during the first diagnostic period.

[0066] When the first positive relay 41A has a normally closed fault, the first battery module 31, the first positive relay 41A, the diagnostic switch SWD, the diagnostic resistor RD and the first detector 110 form a closed circuit during the first diagnostic period. Therefore, a first module current I1 greater than 0A (ampere) flows through the first detector 110.

[0067] When the second positive relay 42A has a normally closed fault, the second battery module 32, the second positive relay 42A, the diagnostic switch SWD, the diagnostic resistor RD and the second detector 120 form a closed circuit during the first diagnostic period. Therefore, a second module current I2 greater than 0A flows through the second detector 120.

[0068] The control unit 160 collects (determines) a first detection value from the first detector 110 and a second detection value from the second detector 120 based on the detection signal S1 and the detection signal S2 during the first diagnostic period. The first detection value may be proportional to the magnitude of the first module current I1. The first detection value may indicate a voltage across the first resistor R1 during the first diagnostic period. The second detection value may be proportional to the magnitude of the second module current I2. The second detection value may indicate a voltage across the second resistor R2 during the first diagnostic period.

[0069] The control unit 160 is configured to determine whether the first positive relay 41A has a normally closed fault based on the first detection value and the first threshold. The control unit 160 may determine whether the second positive relay 42A has a normally closed fault based on the second detection value and the first threshold.

[0070] The first threshold value is a predetermined value for determining whether each of the first battery module 31 and the second battery module 32 is completely electrically disconnected from the diagnosis unit 150 during the first diagnosis period. That is, the first threshold value is used to detect whether the first module current I1 and the second module current I2 are interrupted by the first positive relay 41A and the second positive relay 42A, respectively.

[0071] When the first positive relay 41A is normally controlled to enter the disconnected working state, the first module current I1 is completely interrupted by the first positive relay 41A, and the voltage across the first resistor R1 will be 0V. In addition, when the second positive relay 42A is normally controlled to enter the disconnected working state, the second module current I2 is completely interrupted by the second positive relay 42A, and the voltage across the second resistor R2 will be 0V. Therefore, the first threshold value can be set to 0V. Alternatively, considering the voltage resolution and / or measurement noise of the control unit 160, the first threshold value can be set to a predetermined value greater than 0V (e.g., 0.01V).

[0072] The first detection value greater than the first threshold indicates that the first module current I1 flows when the first positive relay 41A is controlled to enter the open working state. Therefore, when the first detection value is greater than the first threshold, the control unit 160 determines that the first positive relay 41A has a normally closed type fault.

[0073] The second detection value greater than the first threshold indicates that the second module current I2 flows when the second positive relay 42A is controlled to enter the open working state. Therefore, when the second detection value is greater than the first threshold, the control unit 160 determines that the second positive relay 42A has a normally closed type fault.

[0074] <Second diagnostic process>

[0075] The second diagnostic process is a process of diagnosing a normally closed fault of each of the first positive relay 41A and the second positive relay 42A using the first detector 110, the second detector 120, the third detector 130, and the fourth detector 140. The second diagnostic process may be used when the relay diagnostic device 100 further includes the third detector 130 and the fourth detector 140. Of course, when the relay diagnostic device 100 includes the third detector 130 and the fourth detector 140, the first diagnostic process may be performed instead of the second diagnostic process.

[0076] In describing the second diagnosis process, repeated description of the same terms as the first diagnosis process is omitted here. The control unit 160 may control the first switch SW1, the second switch SW2, the third switch SW3 and the fourth switch SW4 to enter a closed working state during the first diagnosis period.

[0077] The control unit 160 determines a first detection value from the first detector 110, a second detection value from the second detector 120, a third detection value from the third detector 130, and a fourth detection value from the fourth detector 140 based on the detection signals S1, S2, S3, and S4 during the first diagnosis period. The third detection value may indicate a first module voltage V1 of the first battery module 31 during the first diagnosis period. The fourth detection value may indicate a second module voltage V2 of the second battery module 32 during the first diagnosis period.

[0078] The control unit 160 can control the first positive relay 41A and the second positive relay 42A to enter the disconnected working state during the second diagnostic period, and control the diagnostic switch SWD to enter the disconnected working state. The second diagnostic period can be a period with a predetermined time length before the start time of the first diagnostic period or after the end time of the first diagnostic period.

[0079] The control unit 160 may control the third switch SW3 and the fourth switch SW4 to enter a closed working state during the second diagnostic period. During the second diagnostic period, the diagnostic switch SWD remains in an open working state. Therefore, even if the first positive relay 41A has a normally closed fault, the first module current I1 is interrupted, and even if the second positive relay 42A has a normally closed fault, the second module current I2 is interrupted.

[0080] The control unit 160 determines a fifth detection value from the third detector 130 and a sixth detection value from the fourth detector 140 based on the detection signal S3 and the detection signal S4 during the second diagnosis period. The fifth detection value may indicate a first module voltage V1 of the first battery module 31 during the second diagnosis period. The sixth detection value may indicate a second module voltage V2 of the second battery module 32 during the second diagnosis period. The fifth detection value and the sixth detection value may indicate an open circuit voltage (OCV) of the first battery module 31 and an OCV of the second battery module 32, respectively.

[0081] When the first relay assembly 41 includes the first negative relay 41B, the control unit 160 may control the first negative relay 41B to enter an open operation state and control the first switch SW1 to enter a closed operation state during the second diagnosis period.

[0082] When the second relay assembly 42 includes the second negative relay 42B, the control unit 160 may control the second negative relay 42B to enter an open operation state and control the second switch SW2 to enter a closed operation state during the second diagnosis period.

[0083] The control unit 160 determines whether the first positive relay 41A has a normally closed type fault based on the first detection value, the first threshold value, the third detection value, the fifth detection value, and the second threshold value.

[0084] The second threshold value is a predetermined value for determining whether each of the first battery module 31 and the second battery module 32 is completely electrically disconnected from the diagnosis unit 150 during the first diagnosis period, further based on a voltage drop associated with the internal resistance of the battery. According to Ohm's law, a voltage drop is an instantaneous change in voltage across a battery, the magnitude of which corresponds to the product of the current of the battery and the internal resistance of the battery.

[0085] When the first positive relay 41A is normally controlled to enter the disconnected working state, the first module current I1 is interrupted (for example, maintained at 0 A) regardless of whether the diagnostic switch SWD is in the closed working state or the open working state. That is, when the first positive relay 41A is normally controlled to enter the disconnected working state, in the case where the working state of the diagnostic switch SWD changes, the voltage drop of the first battery module 31 due to the first module current I1 does not occur.

[0086] In contrast, when the first positive relay 41A has a normally closed fault, the first module current I1 is not interrupted. Therefore, the first module voltage V1 of the first battery module 31 changes instantaneously in response to the switching of the diagnostic switch SWD from the open working state to the closed working state or from the closed working state to the open working state.

[0087] When the second positive relay 42A is normally controlled to enter the disconnected working state, the second module current I2 is interrupted regardless of whether the diagnostic switch SWD is in the closed working state or the open working state. That is, when the second positive relay 42A is normally controlled to enter the disconnected working state, when the working state of the diagnostic switch SWD changes, the voltage drop of the second battery module 32 due to the second module current I1 does not occur.

[0088] In contrast, when the second positive relay 42A has a normally closed fault, the second module current I1 is not interrupted. Therefore, the second module voltage V2 of the second battery module 32 changes instantaneously in response to the switching of the diagnostic switch SWD from the open working state to the closed working state or from the closed working state to the open working state.

[0089] The difference between the third detection value and the fifth detection value is greater than the second threshold indicating that the first module current I1 cannot be interrupted by the first positive relay 41 A. Therefore, when the first detection value is greater than the first threshold and the difference between the third detection value and the fifth detection value is greater than the second threshold, the control unit 160 determines that the first positive relay 41A has a normally closed fault.

[0090] The difference between the fourth detection value and the sixth detection value is greater than the second threshold indicating that the second module current I2 cannot be interrupted by the second positive relay 42A. Therefore, when the second detection value is greater than the first threshold and the difference between the fourth detection value and the sixth detection value is greater than the second threshold, the control unit 160 determines that the second positive relay 42A has a normally closed fault.

[0091] After the first diagnostic process or the second diagnostic process is completed, the control unit 160 may send a diagnostic message indicating whether each of the first positive relay 41A and the second positive relay 42A has a normally closed type fault to the advanced controller 4 through the interface unit 170. When the diagnostic message indicates that at least one of the first positive relay 41A or the second positive relay 42A has a normally closed type fault, the advanced controller 4 may send a closing prohibition command of the main relay assembly MR to the control unit 160.

[0092] Figure 4 is a flowchart exemplarily showing the relay diagnosis method according to the first embodiment. Figure 4 The method corresponds to the first diagnostic process.

[0093] Reference Figure 1 , Figure 2 and Figure 4 In step S410, the control unit 160 controls the first positive relay 41A and the second positive relay 42A to enter the disconnected working state. When the first relay assembly 41 includes the first negative relay 41B, the control unit 160 can control the first negative relay 41B to enter the disconnected working state. When the second relay assembly 42 includes the second negative relay 42B, the control unit 160 can control the second negative relay 42B to enter the disconnected working state.

[0094] In step S420 , the control unit 160 controls the diagnosis switch SWD to enter a closed working state.

[0095] In step S430 , the control unit 160 collects the first detection value from the first detector 110 and the second detection value from the second detector 120 .

[0096] In step S440, the control unit 160 determines whether the first detection value is greater than the first threshold value. When the value of step S440 is "yes", step S452 is executed. When the value of step S440 is "no", step S454 is executed.

[0097] In step S452, the control unit 160 sets a first value indicating that the first positive relay 41A has a normally closed type fault as a first flag.

[0098] In step S454, the control unit 160 sets the second value indicating that the first positive relay 41A does not have a normally closed type fault as the first flag.

[0099] In step S460, the control unit 160 determines whether the second detection value is greater than the first threshold value. When the value of step S460 is "yes", step S472 is executed. When the value of step S460 is "no", step S474 is executed.

[0100] In step S472, the control unit 160 sets a third value indicating that the second positive relay 42A has a normally closed type fault as a second flag. The third value may be equal to the first value.

[0101] In step S474, the control unit 160 sets a fourth value indicating that the second positive relay 42A does not have a normally closed type fault as the second flag. The fourth value may be equal to the second value.

[0102] In step S480, the control unit 160 outputs a diagnostic message including the first flag and the second flag. The diagnostic message may be received by the interface unit 170. The interface unit 170 may output information corresponding to the diagnostic message to the user in response to the diagnostic message. The interface unit may send the diagnostic message to the high-level controller 4.

[0103] Figure 5 is a flowchart exemplarily showing a relay diagnosis method according to the second embodiment. Figure 5 The method corresponds to the second diagnostic process.

[0104] Reference Figure 1 , Figure 2 , Figure 3 and Figure 5 In step S510, the control unit 160 controls the first positive relay 41A and the second positive relay 42A to enter the disconnected working state. When the first relay assembly 41 includes the first negative relay 41B, the control unit 160 can control the first negative relay 41B to enter the disconnected working state. When the second relay assembly 42 includes the second negative relay 42B, the control unit 160 can control the second negative relay 42B to enter the disconnected working state.

[0105] In step S520 , the control unit 160 controls the diagnosis switch SWD to enter a closed working state.

[0106] In step S522 , the control unit 160 collects the first detection value from the first detector 110 , the second detection value from the second detector 120 , the third detection value from the third detector 130 , and the fourth detection value from the fourth detector.

[0107] In step S530 , the control unit 160 controls the diagnosis switch SWD to enter an off working state.

[0108] In step S532 , the control unit 160 collects the fifth detection value from the third detector 130 and the sixth detection value from the fourth detector 140 .

[0109] In step S540, the control unit 160 determines whether the first detection value is greater than the first threshold value and whether the difference between the third detection value and the fifth detection value is greater than the second threshold value. When the value of step S540 is "yes", step S552 is executed. When the value of step S540 is "no", step S554 is executed.

[0110] In step S552, the control unit 160 sets a first value indicating that the first positive relay 41A has a normally closed type fault as a first flag.

[0111] In step S554, the control unit 160 sets the second value indicating that the first positive relay 41A does not have a normally closed type fault as the first flag.

[0112] In step S560, the control unit 160 determines whether the second detection value is greater than the first threshold value and whether the difference between the fourth detection value and the sixth detection value is greater than the second threshold value. When the value of step S560 is "yes", step S572 is executed. When the value of step S560 is "no", step S574 is executed.

[0113] In step S572, the control unit 160 sets a third value indicating that the second positive relay 42A has a normally closed type fault as a second flag. The third value may be equal to the first value.

[0114] In step S574, the control unit 160 sets a fourth value indicating that the second positive relay 42A does not have a normally closed type fault as the second flag. The fourth value may be equal to the second value.

[0115] In step S580, the control unit 160 outputs a diagnostic message including the first flag and the second flag. The diagnostic message may be received by the interface unit 170. The interface unit 170 may output information corresponding to the diagnostic message to the user in response to the diagnostic message. The interface unit may send the diagnostic message to the high-level controller 4.

[0116] although Figure 4 and Figure 5 It is described that the first positive relay 41A is diagnosed earlier than the second positive relay 42A, but the present disclosure is not limited thereto. For example, the second positive relay 42A may be diagnosed earlier than the first positive relay 41A, or the first positive relay 41A and the second positive relay 42A may be diagnosed at the same time.

[0117] The embodiments of the present disclosure described above are not only implemented by devices and methods, but can also be implemented by programs that execute functions corresponding to the configurations of the embodiments of the present disclosure or by recording media on which the programs are recorded, and such an implementation method can be easily realized by those skilled in the art from the disclosure of the embodiments described above.

[0118] 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 may be made thereto within the technical aspects of the present disclosure and the equivalent scope of the appended claims.

[0119] In addition, since those skilled in the art can make many substitutions, modifications and changes to the present disclosure described above without departing from the technical aspects of the present disclosure, the present disclosure is not limited to the above-mentioned embodiments and the accompanying drawings, and some or all of the embodiments may be selectively combined to allow various modifications.

Claims

1. A relay diagnostic device for a parallel battery pack assembly, the parallel battery pack assembly comprising a first battery pack and a second battery pack, the first battery pack having a first battery module and a first positive relay connected in series, the second battery pack having a second battery module and a second positive relay connected in series, the relay diagnostic device comprising: a diagnostic unit including a diagnostic resistor and a diagnostic switch connected in series between a first battery terminal and a second battery terminal of the parallel battery assembly; a first detector configured to detect a first module current, the first module current being a current flowing through the first battery module; a second detector configured to detect a second module current, the second module current being a current flowing through the second battery module; as well as a control unit operably coupled to the first positive relay, the second positive relay, the diagnostic switch, the first detector, and the second detector, Wherein, the control unit is configured as: collecting a first detection value from the first detector and a second detection value from the second detector in a first diagnostic period, during which the first positive relay and the second positive relay are in an open working state and the diagnostic switch is in a closed working state, determining whether the first positive relay has a normally closed type fault based on the first detection value and a first threshold value, and Whether the second positive relay has the normally closed type fault is determined based on the second detection value and the first threshold value.

2. The relay diagnostic device according to claim 1, wherein: The control unit is configured to determine that the first positive relay has the normally closed type fault in response to the first detection value being greater than the first threshold value.

3. The relay diagnostic device according to claim 1, wherein: The control unit is configured to determine that the second positive relay has the normally closed type fault in response to the second detection value being greater than the first threshold.

4. The relay diagnostic device according to claim 1, in, The first detector includes only a first resistor or both a first resistor and a first switch, and the first detector is disposed between a negative terminal of the first battery module and the second battery pack terminal; The second detector includes only the second resistor or both the second resistor and the second switch, and the second detector is disposed between the negative terminal of the second battery module and the second battery pack terminal.

5. The relay diagnostic device according to claim 1, further comprising: a third detector configured to detect a first module voltage, the first module voltage being a voltage across the first battery module; as well as a fourth detector configured to detect a second module voltage, the second module voltage being a voltage across the second battery module, Wherein, the control unit is also operably connected to the third detector and the fourth detector.

6. The relay diagnostic device according to claim 5, wherein: The control unit is configured to: collecting a third detection value from the third detector and a fourth detection value from the fourth detector in the first diagnosis period, collecting a fifth detection value from the third detector and a sixth detection value from the fourth detector in a second diagnostic period, during which the first positive relay and the second positive relay are in an open working state and the diagnostic switch is in an open working state, determining whether the first positive relay has the normally closed fault based on the first detection value, the third detection value, the fifth detection value, the first threshold value, and the second threshold value, and Whether the second positive relay has the normally closed type fault is determined based on the second detection value, the fourth detection value, the sixth detection value, the first threshold value, and the second threshold value.

7. The relay diagnostic device according to claim 6, wherein: The control unit is configured to determine that the first positive relay has the normally closed fault in response to the first detection value being greater than the first threshold and a difference between the third detection value and the fifth detection value being greater than the second threshold.

8. The relay diagnostic device according to claim 6, wherein: The control unit is configured to determine that the second positive relay has the normally closed fault in response to the second detection value being greater than the first threshold and a difference between the fourth detection value and the sixth detection value being greater than the second threshold.

9. The relay diagnostic device according to claim 5, in, The third detector includes a third switch, a third resistor, and a fourth resistor, and a series circuit of the third switch, the third resistor, and the fourth resistor is connected in parallel to the first battery module; The fourth detector includes a fourth switch, a fifth resistor and a sixth resistor, and a series circuit of the fourth switch, the fifth resistor and the sixth resistor is connected in parallel to the second battery module. 10 . A battery system comprising the relay diagnosis device according to claim 1 .

11. An electric vehicle comprising the battery system according to claim 10.

12. A relay diagnosis method capable of being executed by the relay diagnosis device according to any one of claims 1 to 9, the relay diagnosis method comprising the following steps: collecting, by the control unit, a first detection value from the first detector and a second detection value from the second detector in a first diagnostic period, during which the first positive relay and the second positive relay are in an open working state and the diagnostic switch is in a closed working state; determining, by the control unit, whether the first positive relay has a normally closed fault based on the first detection value and the first threshold value; as well as Whether the second positive relay has the normally closed type fault is determined by the control unit based on the second detection value and the first threshold value.

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