Diagnosis system for secondary battery, diagnosis method for secondary battery, and vehicle

Abstract

A diagnosis system of a secondary battery of the present disclosure is provided with: a ripple current circuit configured to be able to apply a ripple current of a prescribed frequency to a secondary battery; a strain gauge configured to acquire a strain of the secondary battery accompanying application of the ripple current of the prescribed frequency; and an electronic control unit configured to diagnose whether the secondary battery is a regular component.

Description

Technical Field

[0001] This disclosure relates to a diagnostic system and method for secondary batteries, and particularly to a system and method for diagnosing whether a secondary battery is a legitimate component, as well as a vehicle equipped with the diagnostic system. Background Technology

[0002] In recent years, vehicles equipped with battery packs, such as hybrid vehicles and electric vehicles, have become increasingly popular. For onboard battery packs, there is a possibility that counterfeit products manufactured by companies other than authorized component manufacturers are circulating. Additionally, there is the possibility of modifications to authorized components. With these non-authorized components (counterfeit or third-party products), there is a possibility that inferior secondary batteries may be used, failing to meet the performance requirements of the vehicle. Therefore, a technology has been proposed to diagnose whether a battery pack (secondary battery) is an authorized or non-authorized component.

[0003] For example, Japanese Patent Application Publication No. 2012-174487 discloses a battery pack. If the difference between the weight of the battery measured in the initial state (first weight) and the current weight of the battery (second weight) within the battery pack is greater than a threshold, the control unit within the battery pack diagnoses the battery as not being a proper component. Summary of the Invention

[0004] In Japanese Patent Application Publication No. 2012-174487, the determination of whether a secondary battery is a legitimate component is based on its weight. Therefore, when considering secondary batteries with the same weight but different characteristics (including shape, structure, and materials), it may be impossible to make an appropriate diagnosis.

[0005] The content of this disclosure is: even when the weight of the regular parts and the non-regular parts are equal, it is possible to diagnose whether the secondary battery is a regular part.

[0006] The diagnostic system for a secondary battery according to a first aspect of this disclosure includes: a ripple current circuit configured to apply a ripple current of a predetermined frequency to the secondary battery; a strain gauge configured to acquire the strain of the secondary battery associated with the applied ripple current of the predetermined frequency; and an electronic control unit configured to diagnose whether the secondary battery is a normal component. The electronic control unit is configured to diagnose whether the secondary battery is a normal component based on the strain of the secondary battery acquired by the strain gauge.

[0007] In the first aspect of this disclosure, the electronic control unit may also be configured to diagnose that the secondary battery is not a normal component when the strain of the secondary battery obtained by the strain gauge deviates from a set range, wherein the set range includes the magnitude of the strain of a normal component when a ripple current of a specified frequency is applied.

[0008] In the first aspect of this disclosure, the ripple current circuit can also be configured to apply ripple currents of different frequencies to the secondary battery, and the electronic control unit can also be configured to calculate the slope of the strain of the secondary battery relative to the frequency of the ripple current based on the strain of the secondary battery obtained by the strain gauge, and diagnose the secondary battery as not being a normal component if the calculated slope of the strain of the secondary battery deviates from the set range of the slope of the strain of the normal component.

[0009] According to the first method described above, the strain of the secondary battery that occurs when a ripple current of a specified frequency is applied to the secondary battery is used to diagnose whether the secondary battery is a normal component. Therefore, even when the weight of normal components and non-normal components are equal, it is possible to diagnose whether the secondary battery is a normal component.

[0010] In the first aspect of this disclosure, the secondary battery can also be configured as follows: the secondary battery is a battery pack formed by stacking battery cells, the battery cell includes an electrode body and a housing that houses the electrode body, and the strain gauge is configured to detect the strain of the housing of the battery cell.

[0011] According to the first method, since the strain of the battery cell casing is detected, the strain of the secondary battery generated when a ripple current of a specified frequency is applied to the secondary battery can be detected with high precision.

[0012] The diagnostic method for a secondary battery according to the second aspect of this disclosure includes: applying a ripple current of a predetermined frequency to the secondary battery; acquiring the strain of the secondary battery associated with the applied ripple current of the predetermined frequency; and diagnosing whether the secondary battery is a normal component based on the acquired strain of the secondary battery.

[0013] In the second aspect of this disclosure, the diagnosis may also include: if the strain of the secondary battery obtained deviates from a set range, diagnosing the secondary battery as not being a normal component, wherein the set range includes the magnitude of the strain of the normal component when a ripple current of a specified frequency is applied.

[0014] In the second aspect of this disclosure, the application process may include applying ripple currents of different frequencies to the secondary battery, the acquisition process may include acquiring the strain of the secondary battery each time a different frequency of ripple current is applied, and the diagnosis process may include calculating the slope of the strain of the secondary battery relative to the frequency of the ripple current based on the acquired strain of the secondary battery, and diagnosing the secondary battery as not being a normal component if the calculated slope of the strain of the secondary battery deviates from the set range of the slope of the strain of a normal component.

[0015] According to the second method described above, the strain of the secondary battery that occurs when a ripple current of a specified frequency is applied to the secondary battery is used to diagnose whether the secondary battery is a normal component. Therefore, even when the weight of normal components and non-normal components are equal, it is possible to diagnose whether the secondary battery is a normal component.

[0016] The third-party vehicle disclosed herein includes a secondary battery and a diagnostic system for the secondary battery. The secondary battery is capable of external charging using power supplied from an external power source, and the electronic control unit of the diagnostic system is configured to diagnose whether the secondary battery is a legitimate component during external charging.

[0017] According to the third method, when the secondary battery installed in the vehicle is being externally charged, the electronic control unit diagnoses whether the secondary battery is a genuine component. Therefore, the diagnosis can be performed regularly, and the diagnosis of whether the secondary battery is a genuine component can be made more reliably.

[0018] The vehicle of the fourth aspect of this disclosure includes a secondary battery, a diagnostic system for the secondary battery, and a warning device configured to issue a warning when the electronic control unit of the diagnostic system diagnoses the secondary battery as not being a proper component.

[0019] According to the fourth method, the vehicle user can be notified of the situation where a secondary battery with non-standard components is installed.

[0020] According to the method disclosed herein, even when the weights of the standard and non-standard components are equal, it is possible to diagnose whether a secondary battery is a standard component. Attached Figure Description

[0021] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, in which the same reference numerals denote the same parts, wherein:

[0022] Figure 1 This is a diagram that schematically shows the overall configuration of a vehicle equipped with a diagnostic system for a secondary battery according to this embodiment.

[0023] Figure 2 This is a perspective view that schematically illustrates the structure of the battery pack in this embodiment.

[0024] Figure 3 This is a perspective view showing an example of the structure of a battery cell.

[0025] Figure 4 It is a diagram illustrating the strain that occurs in conjunction with the application of ripple current.

[0026] Figure 5A This is a diagram used to illustrate the diagnostic criteria for the regular components in this embodiment.

[0027] Figure 5B This is a diagram used to illustrate the diagnostic criteria for the regular components in this embodiment.

[0028] Figure 6 This is a flowchart illustrating the diagnostic process in this embodiment. Detailed Implementation

[0029] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, the same or equivalent parts in the drawings will be labeled with the same reference numerals, and their descriptions will not be repeated.

[0030] In the following embodiments, an example is described using a vehicle with the "secondary battery diagnostic system" disclosed herein mounted on it. However, the application of the "secondary battery diagnostic system" disclosed herein is not limited to vehicle use; for example, it can also be used for stationary applications.

[0031] System Composition

[0032] Figure 1 This diagram schematically illustrates the overall configuration of a vehicle equipped with a diagnostic system for the secondary battery according to this embodiment. In this embodiment, vehicle 1 is an electric vehicle (BEV). However, the type of vehicle 1 is not limited to any vehicle equipped with a battery pack. Vehicle 1 can be a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a fuel cell electric vehicle (FCEV).

[0033] Vehicle 1 includes a connector 10, an AC / DC converter 20, a charging relay (CHR) 30, a battery pack 40, a power control unit (PCU) 50, a motor generator (MG) 60, and an integrated electronic control unit (ECU) 70. The battery pack 40 includes a battery assembly 41, a monitoring unit 42, a ripple current circuit 43, and a battery ECU 44. The battery pack 40 is an example of the "diagnostic system for secondary batteries" disclosed herein.

[0034] The socket 10 is configured to allow a charging connector located at the front end of the charging cable 91 to be inserted. The vehicle 1 is electrically connected to an external power source (e.g., system power source) 92 located outside the vehicle 1 via the charging cable 91. The vehicle 1 is configured to perform "external charging," which involves charging the battery pack 41 using power supplied from the external power source 92.

[0035] AC / DC converter 20 is electrically connected between socket 10 and charging relay 30. AC / DC converter 20 converts AC power supplied from external power source 92 via socket 10 into DC power and outputs the DC power to charging relay 30. In addition, AC / DC converter 20 converts DC power supplied from battery pack 41 (or PCU 50) via charging relay 30 into AC power and outputs the AC power to socket 10.

[0036] The charging relay 30 is electrically connected to a power line that connects the AC / DC converter 20 to the battery pack 41. The charging relay 30 is switched on / off accordingly with control signals from the integrated ECU 70.

[0037] The battery pack 41 stores power for driving the electric generator 60 and supplies power to the electric generator 60 via the PCU 50. Additionally, the battery pack 41 is charged by power output from the AC / DC converter 20 during external charging. Furthermore, the battery pack 41 is also charged by receiving generated power via the PCU 50 when the electric generator 60 is generating electricity (e.g., during regenerative power generation).

[0038] The monitoring unit 42 includes a voltage sensor 421, a current sensor 422, a temperature sensor 423, and a strain gauge 424. The voltage sensor 421 detects the voltage V of the battery pack 41. The current sensor 422 detects the current I input to / output from the battery pack 41. The temperature sensor 423 detects the temperature TB of the battery pack 41. The strain gauge 424 measures the strain ε of the battery pack 41. Each sensor outputs a signal representing the detection or measurement result to the battery ECU 44.

[0039] The ripple current circuit 43 is configured to apply (superimpose) a ripple current to the charging and discharging current of the battery pack 41. The ripple current circuit 43 can generate the ripple current using the charging and discharging power from the AC / DC converter 20 to the battery pack 41, or it can generate the ripple current using power supplied from other power sources (e.g., power supplied from an auxiliary battery not shown). Alternatively, it can be configured to generate the ripple current using an electronic load connected to the battery pack 41. The AC signal generation unit of the ripple current circuit 43 can, for example, change its frequency between 100Hz and several kHz, allowing the ripple current circuit 43 to apply a ripple current between 100Hz and several kHz to the charging and discharging current of the battery pack 41.

[0040] The battery ECU 44 includes a processor 441 such as a CPU (Central Processing Unit), a memory 442 such as ROM (Read Only Memory) and RAM (Random Access Memory), and an input / output interface (not shown) for inputting and outputting various signals.

[0041] The battery ECU 44 manages the battery pack 41 in cooperation with the integrated ECU 70, based on signal inputs from various sensors in the monitoring unit 42 and graphs and programs stored in the memory 442. In this embodiment, as a major process performed by the battery ECU 44, a "diagnostic process" for diagnosing whether the battery pack 41 is a legitimate component is cited. The diagnostic process performed by the battery ECU 44 will be described later.

[0042] PCU 50 includes, for example, a converter and a transducer (neither shown). PCU 50 performs two-way power conversion between battery pack 41 and electric generator 60 according to control signals from integrated ECU 70.

[0043] The electric generator 60 is, for example, a three-phase AC rotating electrode with permanent magnets embedded in a rotor (not shown). The electric generator 60 uses power supplied from the battery pack 41 to rotate the drive shaft. Additionally, the electric generator 60 can generate electricity through regenerative braking. The AC power generated by the electric generator 60 is converted to DC power by the PCU 50 to charge the battery pack 41.

[0044] Like the battery ECU 44, the integrated ECU 70 includes a processor, memory, and input / output interfaces (none shown). Based on signal inputs from various sensors located in the vehicle 1, and graphs and programs stored in the memory, the integrated ECU 70 controls the various devices (AC / DC converter 20, charging relay 30, and PCU 50) to bring the vehicle 1 to a desired state. For example, the integrated ECU 70 controls the charging and discharging of the battery pack 41 by controlling the AC / DC converter 20 and / or the PCU 50. Furthermore, the ECUs mounted in the vehicle 1 can be appropriately integrated or configured separately for each function.

[0045] Battery pack construction

[0046] Figure 2 This is a perspective view schematically illustrating the structure of the battery pack 41 in this embodiment. The battery pack 41 comprises multiple battery stacks 410 (also called modules or blocks). The multiple battery stacks 410 can be connected in series or in parallel. Figure 2 In the image, one of the multiple battery stacks 410 is shown as a representative example.

[0047] The battery stack 410 includes multiple battery cells (cells) 81, multiple resin frames 82, a pair of end plates 83, and a pair of restraint straps 84. In the battery stack 410, the multiple battery cells 81 and the multiple resin frames 82 are stacked to form a laminate.

[0048] The multiple battery cells 81 are secondary batteries such as lithium-ion batteries or nickel-metal hydride batteries. The number of battery cells included in the battery stack 410 is not particularly limited. Each battery cell 81 has the same configuration, and the stacked battery cells 81 are electrically connected in series.

[0049] Multiple resin frames 82 are each disposed between two adjacent battery cells 81 in the stacking direction. A pair of end plates 83 are disposed at one end and the other end of the stack in the stacking direction. The end plates 83 are configured to sandwich the stack in the middle from both sides along the stacking direction.

[0050] A pair of constraint straps 84 are disposed on the upper and lower surfaces of the resin frame 82. The constraint straps 84 constrain a pair of end plates 83 that are in a state of sandwiching the laminate in the middle.

[0051] Figure 3 This is a perspective view showing an example of the configuration of battery cell 81. In this example, battery cell 81 is a lithium-ion battery.

[0052] The battery cell (battery unit) 81 is a square battery cell with a generally cubic shape. The battery cell 81 includes a housing 813 that houses the electrode body 812, and a cover 814 that seals the upper surface of the housing 813. A positive terminal 815 and a negative terminal 816 are disposed within the cover 814. One end of each of the positive and negative terminals 815 and 816 protrudes outward from the cover 814. The other end of each of the positive and negative terminals 815 and 816 is electrically connected inside the housing 813 to an internal positive terminal and an internal negative terminal (neither shown). Furthermore, although not shown, two adjacent battery cells 81 are electrically connected in series via a busbar.

[0053] An electrode body 812 is housed inside the housing 813. The electrode body 812 is formed, for example, as shown below: a positive electrode and a negative electrode are stacked with a separator in between, and then wound into a cylindrical shape. The electrolyte is held in the positive electrode, the negative electrode, and the separator. Alternatively, a stacked body may be used instead of a wound body as the electrode body 812.

[0054] A strain gauge 424 is attached to the housing 813 of the battery cell 81. The strain gauge 424 can be a metal strain gauge or a semiconductor strain gauge. In this embodiment, in order to detect the strain caused by the thickness change of the housing 813 near the positive terminal 815, the strain gauge 424 is attached to the side below the positive terminal 815 using an adhesive.

[0055] Application of ripple current

[0056] In the vehicle 1 configured as described above, the battery pack 41 within the battery pack 40 deteriorates with use or over time. When the deterioration of the battery pack 41 progresses to a certain extent, it may be considered to replace the battery pack 41 with a new battery pack (or a used battery pack whose deterioration has not progressed to a certain extent). At this time, there is a possibility of selecting non-standard battery packs such as counterfeit or third-party products.

[0057] As shown in Japanese Patent Application Publication No. 2012-174487, the determination of whether the battery pack 41 is a legitimate component is also considered based on its weight. However, if this determination is made in this way, it may not be possible to properly determine whether the battery pack 41 is a legitimate component if it is replaced with a battery pack 41 of equal weight but with different characteristics other than weight (such as the shape or structure of the battery cells or the battery material).

[0058] In this embodiment, the following configuration is employed: based on the strain when a ripple current of a predetermined frequency is applied to the battery pack 41, the system diagnoses whether the battery pack 41 is a regular or irregular component. The ripple current circuit 43 applies (superimposes) a ripple current to the charging and discharging current to the battery pack 41 according to instructions from the battery ECU 44. This causes a change in the thickness of the housing 813 of the battery cell 81, generating strain. A strain gauge 424 measures this strain. The battery ECU 44 (processor 441) diagnoses whether the battery pack 41 is a regular or irregular component based on the strain ε measured by the strain gauge 424.

[0059] Figure 4 This is a diagram illustrating the strain that occurs associated with the application of ripple current. Figure 4 In the figure, the horizontal axis represents the frequency (Hz) of the ripple current, and the vertical axis represents the magnitude of the strain generated at the casing of the battery cell (cell).

[0060] exist Figure 4 In the diagram, the solid line shows the relationship between the frequency of the ripple current and the magnitude of the strain in a regular component. For example... Figure 4 As shown, as a regular component, the strain increases relatively gradually in tandem with the increase in the frequency of the ripple current.

[0061] exist Figure 4 In the diagram, the dashed line shows the relationship between the frequency of the ripple current and the magnitude of the strain in the irregular component. As the frequency of the ripple current increases, the strain increases sharply compared to the regular component.

[0062] If a ripple current of frequency A is applied to both the normal and non-normal components, then in Figure 4 In the example shown, the strain value of the irregular component is larger than that of the regular component. There is a significant difference between the magnitudes of the two strains.

[0063] Furthermore, when a ripple current of frequency A is applied to both regular and irregular components, and then a ripple current of frequency B, which is higher than frequency A, is applied, the increase in strain accompanying the increase in the frequency of the ripple current (hereinafter also referred to as "the slope θ of strain relative to frequency," or simply "the slope θ of strain") becomes greater in the irregular component than in the regular component. Thus, there is a significant difference in the magnitude of the slope of strain relative to frequency.

[0064] The aforementioned phenomenon arises because the relationship between strain and ripple current frequency changes due to differences in the materials of the electrodes (positive and negative electrodes) and the casing structure of the battery cell (cell). Therefore, the relationship between standard and non-standard components is not limited to... Figure 4As shown in the example, depending on the composition of the battery cell (battery unit), there may be cases where the strain value of the regular component is larger than the strain value of the irregular component.

[0065] Diagnostic criteria

[0066] Figure 5A and Figure 5B This is a diagram used to illustrate the diagnostic criteria for the regular components in this embodiment. Figure 5A This illustrates the diagnostic criteria for determining whether the battery pack 41 is a normal component when using the strain ε measured by strain gauge 424. The strain εa of the normal component is measured beforehand when a ripple current of frequency A is applied to it, and a certain range including said strain εa is determined. Hereinafter, this range is also referred to as the "set range S". The upper limit of the set range S is denoted as Up, and the lower limit is denoted as Lo (Up < εa < Lo).

[0067] Then, for the battery pack being diagnosed (the target battery pack), the strain ε of the target battery pack is measured under conditions where a ripple current of frequency A is applied, and the measurement result is compared with a set range S. If the strain ε falls within the set range S, the target battery pack can be diagnosed as a normal component. On the other hand, if the strain ε falls outside the set range S, the target battery pack can be diagnosed as a non-normal component (a non-normal component).

[0068] Figure 5B This illustrates the diagnostic criteria for diagnosing whether battery pack 41 is a normal component using the slope θ of strain relative to frequency. A ripple current at frequency A is applied, and the strain εa at frequency A is measured. Then, a ripple current at frequency B, which is higher than frequency A, is applied to the normal component, and the strain εb at frequency B is measured. The slope θg of the strain is then calculated (=(εb-εa) / (BA)). In this way, the slope θg of the strain of the normal component is determined in advance, and a certain range including the slope θg of said strain is determined. Hereinafter, this range is also referred to as the "set range T". The upper limit of the set range T is denoted as UL, and the lower limit is denoted as LL (LL<θg<UL).

[0069] Then, a ripple current of frequency A is applied to the battery pack (target battery pack) being diagnosed, followed by a ripple current of frequency B. The slope θ of the strain of the target battery pack is calculated, and the calculation result is compared with a set range T. If the slope θ of the strain falls within the set range T, the target battery pack can be diagnosed as a normal component. On the other hand, if the slope θ of the strain falls outside the set range T, the target battery pack can be diagnosed as a non-normal component (an irregular component).

[0070] In this way, the battery ECU 44 can diagnose whether the battery pack 41 is a regular or irregular component based on the strain ε measured by the strain gauge 424.

[0071] Diagnosis and treatment

[0072] Figure 6 This is a flowchart illustrating the diagnostic process in this embodiment. The flowchart is executed when the battery pack 41 (battery stack 410) is replaced. For example, it can be executed simultaneously with the initialization process of the battery ECU 44 when the battery pack 41 is replaced. Each step is implemented through software processing performed by the battery ECU 44, but it can also be implemented through hardware (circuit) fabricated within the battery ECU 44. Hereinafter, each step will be abbreviated as "S".

[0073] In S1, the battery ECU 44 uses a weight sensor (not shown) to measure the weight W of the battery pack. The battery ECU 44's memory 442 non-volatilely stores the weight W0 of the battery pack 41 (a standard component) in its initial state (state at the time of shipment from the factory, etc.). Next, in S2, the battery ECU 44 calculates the weight difference ΔW (=W-W0) between the weight W measured in S1 and the initial weight W0. Then, the battery ECU 44 determines whether the weight difference ΔW is less than a predetermined threshold TH (S3). If the weight difference ΔW is above the threshold TH, a negative determination is made in S3, and the battery ECU 44 diagnoses the target battery pack as a non-standard component (S10). On the other hand, if the weight difference ΔW is less than the threshold TH, a positive determination is made in S3, and the battery ECU 44 proceeds the process to S4. For details of the processes in S1 to S3, please refer to Japanese Patent Application Laid-Open No. 2012-174487.

[0074] In S4, the battery ECU 44 controls the ripple current circuit 43 to apply a ripple current of frequency A to the charging and discharging current to the battery pack 41 (the target battery pack). Then, after a predetermined time (e.g., 5 minutes) has elapsed since the ripple current was first applied to the battery pack 41, the battery ECU 44 measures the strain ε based on the output signal (output voltage) of the strain gauge 424. For example, the strain ε is calculated and obtained based on the difference between the output voltage of the strain gauge 424 before the ripple current was applied and the output voltage of the strain gauge 424 after the predetermined time has elapsed since the ripple current was first applied.

[0075] Next, in S5, the battery ECU 44 determines whether the strain ε obtained in S4 is within the set range S (the range between the upper limit value Up and the lower limit value Lo). If the strain ε falls within the set range S, a positive determination is made, and the process proceeds to S6. If the strain ε falls outside the set range S, a negative determination is made, and the process proceeds to S10, diagnosing the target battery pack as a non-standard component. Furthermore, the processing in S4 and S5 is performed on all battery cells (cells) 81 equipped with strain gauge 424. If a positive determination is made for all battery cells 81 in S5, the process proceeds to S6. If a negative determination is made for any battery cell 81 in S5, the process proceeds to S10, diagnosing the target battery pack as a non-standard component.

[0076] In S6, the battery ECU 44 controls the ripple current circuit 43 to apply a ripple current of frequency B to the battery pack 41 (the target battery pack). Then, after a predetermined time (e.g., 5 minutes) has elapsed since the application of the ripple current of frequency B to the battery pack 41, the battery ECU 44 measures the strain ε based on the output signal (output voltage) of the strain gauge 424. For example, the strain ε is calculated and obtained based on the difference between the output voltage of the strain gauge 424 before the application of the ripple current of frequency A and the output voltage of the strain gauge 424 after the predetermined time has elapsed since the application of the ripple current of frequency B.

[0077] Next, in S7, the slope θ of the strain relative to the frequency is calculated. For example, if the strain ε obtained in S4 is εA and the strain ε obtained in S6 is εB, the slope θ of the strain is calculated as θ = (εB-εA) / (BA), and then proceeds to S8.

[0078] In S8, the battery ECU 44 determines whether the strain slope θ calculated in S7 is within the set range T (the range between the upper limit UL and the lower limit LL). If the strain slope θ falls within the set range T, a positive determination is made, and the process proceeds to S9. If the strain slope θ falls outside the set range T, a negative determination is made, and the process proceeds to S10, diagnosing the target battery pack as a non-standard component. Furthermore, the processes in S6 and S7 are performed on all battery cells (cells) 81 equipped with strain gauges 424. If the strain slope θ falls within the set range T for all battery cells 81, a positive determination is made in S8, and the process proceeds to S9. If a negative determination is made for any battery cell 81 in S8, the process proceeds to S10, diagnosing the target battery pack as a non-standard component.

[0079] In S9, if the target battery pack is diagnosed as a normal component, the process ends. In S10, if the target battery pack is diagnosed as an irregular component, the process proceeds to S11. The battery ECU 44 displays a warning message on an HMI (Human Machine Interface) such as an in-vehicle display to warn the user (driver) of vehicle 1, and then the process ends. Alternatively, the MIL (Malfunction Indication Lamp) can be illuminated, and a diagnosis code indicating that the battery pack 41 is an irregular component can be written to the memory of the integrated ECU 70.

[0080] In this embodiment, a strain gauge 424 is used to acquire the strain of the battery pack 41 generated when a ripple current of a specified frequency (frequency A, frequency B) is applied to the battery pack 41, and the strain is used to diagnose whether the battery pack 41 is a normal component. Therefore, even when the weights of normal and non-normal components are equal, it is possible to properly diagnose whether the battery pack 41 is a normal component.

[0081] In this embodiment, if the strain ε when a ripple current of frequency A is applied to the battery pack falls within a set range S, and the slope θ of the strain relative to the frequency falls within a set range T, the battery pack is diagnosed as a normal component. However, either the strain ε or the slope θ of the strain can be used to diagnose whether the battery pack is a normal component. For example, it can be omitted. Figure 6 S6 to S8, if a positive decision is made in S5, proceed to S9. Alternatively, S5 can be omitted.

[0082] In this embodiment, the slope θ of the strain is calculated based on the strain ε when ripple currents of frequency A and frequency B are applied. However, it is also possible to apply ripple currents of three or more different frequencies to the battery pack 41 and use the strain ε to calculate the slope θ of the strain.

[0083] In this embodiment, strain gauges 424 are installed on all battery cells (cells) 81 to measure the strain of all battery cells 81. However, it is also possible not to install strain gauges 424 on all battery cells 81 constituting the battery pack 41. In this case, it is also possible to properly diagnose whether the battery pack is a regular component or a non-regular component when replacing the battery pack on a unit basis of battery stack 410.

[0084] Variations

[0085] In the above embodiments, Figure 6 The diagnostic process is performed when battery pack 41 is replaced. In a variant, it is performed each time battery pack 41 is externally charged. Figure 6Diagnostic processing. For example, when the charging connector of the charging cable 91 is connected to the socket 10, the charging relay 30 is turned on, the AC / DC converter 20 starts to operate, and external charging begins, the battery ECU 44 executes... Figure 6 Diagnosis and treatment.

[0086] According to the modified example, since the battery pack 41 is diagnosed as a normal component or a non-normal component each time it is externally charged, the frequency of diagnosis can be increased and the diagnosis can be performed more reliably.

[0087] The embodiments disclosed herein should be considered illustrative in all respects and not limiting. The scope of this disclosure is not a description of the above embodiments, but rather indicated by the scope of protection of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of protection of the claims.

Claims

1. A diagnostic system for secondary batteries, characterized in that, have: A ripple current circuit configured to apply a ripple current of a specified frequency to the secondary battery; A strain gauge configured to acquire the strain of the secondary cell associated with the applied ripple current at the specified frequency; and An electronic control unit is configured to diagnose whether the secondary battery is a genuine component. The electronic control unit is configured to, based on the strain of the secondary battery obtained by the strain gauge when the same ripple current of the predetermined frequency is applied to the secondary battery, diagnose the secondary battery as a normal component if the strain of the secondary battery obtained by the strain gauge falls within a set range, and diagnose the secondary battery as a non-normal component if the strain of the secondary battery obtained by the strain gauge deviates from the set range, wherein the set range includes the magnitude of the strain of the normal component when the ripple current of the predetermined frequency is applied.

2. The diagnostic system for secondary batteries according to claim 1, characterized in that, The ripple current circuit is configured to apply ripple currents of different frequencies to the secondary battery. The electronic control unit is configured to calculate, based on the strain of the secondary battery obtained by the strain gauge, the slope of the strain of the secondary battery relative to the frequency of the ripple current, and to diagnose that the secondary battery is not a normal component if the calculated slope of the strain of the secondary battery deviates from a set range including the slope of the strain of the normal component.

3. The diagnostic system for secondary batteries according to claim 1 or 2, characterized in that, The secondary battery is a battery pack formed by stacking individual battery cells. The battery cell includes an electrode body and a housing that contains the electrode body. The strain gauge is configured to detect the strain of the casing of the battery cell.

4. A diagnostic method for a secondary battery, characterized in that, Include: A ripple current of a specified frequency is applied to the secondary battery; Obtain the strain of the secondary battery associated with the applied ripple current at the specified frequency; as well as Based on the strain of the secondary battery obtained by applying the same ripple current at the specified frequency to the secondary battery, if the obtained strain of the secondary battery falls within a set range, the secondary battery is diagnosed as a normal component; if the obtained strain of the secondary battery deviates from the set range, the secondary battery is diagnosed as a non-normal component, wherein the set range includes the magnitude of the strain of the normal component when the ripple current at the specified frequency is applied.

5. The diagnostic method for secondary batteries according to claim 4, characterized in that, During the application, ripple currents of different frequencies are applied to the secondary battery. The acquisition process includes: acquiring the strain of the secondary battery each time a different frequency of ripple current is applied. The diagnosis includes: calculating the slope of the strain of the secondary battery relative to the frequency of the ripple current based on the obtained strain of the secondary battery; and diagnosing the secondary battery as not being a normal component if the calculated slope of the strain of the secondary battery deviates from a set range including the slope of the strain of the normal component.

6. A vehicle, characterized in that, have: Secondary batteries; as well as A diagnostic system for a secondary battery according to any one of claims 1 to 3, The secondary battery can be externally charged using power supplied from an external power source. The electronic control unit of the diagnostic system is configured to diagnose whether the secondary battery is a legitimate component during the external charging process.

7. A vehicle, characterized in that, have: Secondary batteries; A diagnostic system for a secondary battery according to any one of claims 1 to 3; and A warning device is configured to issue a warning when the electronic control unit of the diagnostic system diagnoses that the secondary battery is not a proper component.

Images