Deterioration determination device

Abstract

The invention provides a deterioration determination device capable of determining deterioration of a component more appropriately. A deterioration determination device (1) determines whether or not each of a first switch (33A) and a fuse (F) provided on a power path (11) that transmits power from a power supply unit (10) to a load is in a deteriorated state. The power path (11) has a positive-electrode-side power line (17) and a negative-electrode-side power line (20). A first switch (33A) and a fuse (F) are provided on the negative electrode-side power line (20). A deterioration determination device (1) is provided with: a first potential detection unit (39A) that detects a first potential on one end side and a second potential on the other end side of a first shutter (33A); a second potential detection unit (39B) that detects a first potential on one end side of the fuse (F) and a second potential on the other end side of the fuse (F); and a control unit (15) that determines, on the basis of the potential differences (V1, V2) between the first potential and the second potential, whether or not each of the first switch (33A) and the fuse (F) is in a degraded state.

Description

Technical Field

[0001] The present disclosure relates to a degradation determination device. Background Art

[0002] Patent Document 1 discloses a technique for optimizing the degree of deterioration of a relay by adjusting the precharging time when a converter is precharged by a precharging circuit.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-78196 Summary of the invention

[0006] Problems to be solved by the invention

[0007] As a method for determining whether a component meets the required performance, the following method is known: an upper limit value of the number of times the component is energized is predetermined, and the number of times the component is energized is compared with the upper limit value to determine whether the component meets the required performance. However, in this method, the magnitude of the current flowing through the component and the potential difference between the two terminals of the component are not considered. Therefore, in this method, it may be impossible to properly determine whether the component meets the required performance in a form that conforms to the actual usage status of the component.

[0008] The present disclosure has been made based on the above-mentioned circumstances, and an object of the present disclosure is to provide a degradation determination device capable of more appropriately determining degradation of a component.

[0009] Means for solving problems

[0010] The degradation determination device disclosed in the present invention determines whether an element arranged on a power path is in a degraded state, wherein the power path is a path for transmitting power from a power supply unit to a load, and the degradation determination device is characterized in that the power path has: a positive pole side power line connected to a positive pole side terminal of the power supply unit; and a negative pole side power line connected to a negative pole side terminal of the power supply unit, and the element is arranged on the negative pole side power line, and the degradation determination device has: a potential detection unit for detecting a first potential on one end side of the element and a second potential on the other end side of the element; and a control unit for determining whether the element is in a degraded state based on a potential difference between the first potential and the second potential.

[0011] Effects of the Invention

[0012] According to the present disclosure, it is possible to more appropriately determine the degradation of a component. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1This is a circuit diagram illustrating a vehicle power supply system including the degradation determination device according to the first embodiment.

[0014] Figure 2 This is a flowchart showing an example of control performed by the control unit in the degradation determination device according to the first embodiment. DETAILED DESCRIPTION

[0015] [Description of Embodiments of the Present Disclosure]

[0016] First, embodiments of the present disclosure will be described below.

[0017] (1) A degradation determination device for determining whether an element disposed on a power path is in a degraded state, the power path being a path for transmitting power from a power supply unit to a load, wherein the power path has: a positive-side power line connected to a positive-side terminal of the power supply unit; and a negative-side power line connected to a negative-side terminal of the power supply unit, and the element is disposed on the negative-side power line, the degradation determination device comprising: a potential detection unit for detecting a first potential on one end side of the element and a second potential on the other end side of the element; and a control unit for determining whether the element is in a degraded state based on a potential difference between the first potential and the second potential.

[0018] In the degradation determination device of (1), since the element is provided on the negative-side power line, even if the voltage applied to the element changes at a predetermined rate of change, the amplitude of the change is smaller than that of the voltage changing at a predetermined rate of change in the positive-side power line. Therefore, it is easy to suppress the amplitude of the change of the calculated resistance value in the element provided on the negative-side power line to be smaller.

[0019] (2) According to the degradation determination device of (1), the element is a first element, and a second element different from the first element is provided on the positive electrode side power line. The degradation determination device also includes a temperature detection unit for detecting the respective temperatures of the first element and the second element, and the control unit determines whether the second element is in a degraded state based on the potential difference and the temperature value detected by the temperature detection unit.

[0020] The potential difference between the two terminals of the second element varies more widely than that of the first element, and the variation in resistance value may increase. Therefore, the degradation determination device of (2) can easily determine whether the second element is in a degraded state by the temperature detection unit.

[0021] (3) In the degradation determination device according to (2), the element is at least one of a relay and a fuse.

[0022] If the electrical characteristics of relays and fuses deteriorate due to degradation, the power path may not be cut off according to specifications. However, the degradation determination device (3) can easily take measures before such concerns arise by determining whether the relays and fuses are in a degraded state.

[0023] (4) The degradation determination device according to (3), wherein the element and the second element are the relays, and a precharge circuit is connected in parallel with the elements on the power path.

[0024] In the degradation determination device of (4), the relay connected in parallel with the pre-charging circuit is prone to inrush current, and thus degradation is prone to progress. Therefore, by measuring the resistance value of the relay connected in parallel with the pre-charging circuit, the degradation degree of the relay that is prone to progress can be grasped.

[0025] (5) In the degradation determination device according to any one of (1) to (4), the control unit performs abnormality handling processing when determining that the element is in a degraded state.

[0026] The degradation determination device of (5) can easily take measures corresponding to the degradation of the component by performing abnormality response processing.

[0027] [Details of Embodiments of the Present Disclosure]

[0028] Hereinafter, specific examples of the present disclosure will be described with reference to the drawings. It should be noted that the present invention is not limited to these examples, but is indicated by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0029] <Implementation Method 1>

[0030] [Structure of degradation determination device]

[0031] Figure 1 The vehicle power supply system 100 shown is a power supply system mounted on a vehicle, and includes a power supply unit 10, a power path 11, a system main relay 33, and a degradation determination device 1. The degradation determination device 1 includes a temperature detection unit 37, a current detection unit 38, a potential detection unit 39, and a control unit 15. The potential detection unit 39 includes a first potential detection unit 39A and a second potential detection unit 39B. The vehicle power supply system 100 is configured to be able to supply power from the power supply unit 10 to the load 35 via the power path 11, which is a path for transmitting power between the power supply unit 10 and the load 35.

[0032] The power supply unit 10 is a storage battery capable of supplying electric power to the load 35. For example, a lead storage battery or a battery pack formed by connecting a plurality of cells such as lithium ion batteries or nickel hydrogen batteries in series is used as the power supply unit 10.

[0033] The power path 11 includes a positive-side power line 17 and a negative-side power line 20. The positive-side power line 17 is electrically connected to the positive-side terminal of the power supply unit 10. The output voltage of the power supply unit 10 is applied to the positive-side power line 17. The negative-side power line 20 is electrically connected to the negative-side terminal of the power supply unit 10. The negative-side power line 20 has a lower potential than the positive-side power line 17. The negative-side terminal of the power supply unit 10 is electrically connected to, for example, a metal body of a vehicle and has the same potential as the metal body of the vehicle. The output voltage of the power supply unit 10 is equivalent to the potential difference between the positive-side terminal and the negative-side terminal. The power path 11 is a path for transmitting power from the power supply unit 10 to the load 35. A fuse F as a first element is provided on the negative-side power line 20. The fuse F cuts off the energization of the negative-side power line 20 when an excessive current flows in the negative-side power line 20. The fuse F is, for example, a thermal fuse.

[0034] In the present disclosure, "electrical connection" is preferably a structure in which the potentials of both connection objects are equal and the connection objects are connected in a mutually conductive state (a state in which current flows). However, it is not limited to this structure. For example, "electrical connection" may also be a structure in which an electrical element is sandwiched between two connection objects and the two connection objects are connected in a conductive state.

[0035] A load 35 is electrically connected to the positive-side power line 17 and the negative-side power line 20. The load 35 is an electronic component for vehicle use, and products such as electric components, ECUs, and ADAS target components are applied. In the first embodiment, the load 35 includes a converter 35A having a capacitor 35C and a motor 35B. The capacitor 35C smoothes the voltage based on the power supply unit 10 and supplies it to the converter 35A. The converter 35A is electrically connected to the power path 11. The converter 35A generates an AC voltage (for example, a three-phase AC) based on a DC voltage based on the voltage supplied from the power supply unit 10, and supplies it to the motor 35B. The motor 35B is, for example, a main engine motor. The motor 35B rotates based on the power supplied from the power supply unit 10, and applies a rotational force to the wheels of the vehicle. The current output from the positive-side terminal of the power supply unit 10 flows through the positive-side power line 17, the load 35, the negative-side power line 20, and the negative-side terminal of the power supply unit 10 in sequence.

[0036] The system main relay 33 is provided between the positive side power line 17 and the negative side power line 20 between the power supply unit 10 and the load 35. The system main relay 33 includes a first switch 33A which is a relay as a first element, a second switch 33B which is a relay as a second element, and a parallel switch path 33C. That is, the first element includes the first switch 33A and the fuse F. The second switch 33B is an element different from the first switch 33A. The first switch 33A and the second switch 33B are, for example, mechanical relay switches having contacts physically switched between a contact state and a separated state inside. The parallel switch path 33C is a so-called pre-charging circuit. The parallel switch path 33C includes a resistor 33D and a third switch 33E which is a relay connected in series with respect to the resistor 33D. The third switch 33E is a mechanical relay switch having the same structure as the first switch 33A and the second switch 33B. The third switch 33E is a so-called pre-charge relay.

[0037] The first switch 33A is provided on the negative-side power line 20 on the opposite side of the power supply unit 10 via the fuse F. The second switch 33B is provided on the positive-side power line 17. The resistor 33D and the third switch 33E of the parallel switch path 33C are electrically connected to the negative-side power line 20 in parallel with the first switch 33A. The first switch 33A, the second switch 33B, and the third switch 33E are controlled by a predetermined control device C (hereinafter, also referred to as the control device C) to switch between the on state and the off state. The first switch 33A, the second switch 33B, and the third switch 33E are switched between the on state and the off state, thereby switching the power path 11 between the on state and the off state.

[0038] The temperature detection unit 37 is provided separately for the first switch 33A and the second switch 33B, and detects the temperature of each contact in the first switch 33A and the second switch 33B when the corresponding first switch 33A and the second switch 33B are in the on state. The temperature detection unit 37 includes a first temperature detection unit 37A provided for the first switch 33A and a second temperature detection unit 37B provided for the second switch 33B. The first temperature detection unit 37A and the second temperature detection unit 37B output temperature values ​​indicating the detected temperatures. The control unit 15 determines the temperature of the contact when the first switch 33A and the second switch 33B are in the on state based on the temperature values ​​of the first temperature detection unit 37A and the second temperature detection unit 37B.

[0039] The current detection unit 38 is provided between the negative-side power line 20 on the power supply unit 10 side relative to the first switch 33A. The current detection unit 38 includes, for example, a resistor and a differential amplifier, and is configured to output a value indicating a current flowing through the negative-side power line 20 (specifically, an analog voltage corresponding to the value of the current flowing through the negative-side power line 20) as a current value A. That is, the current detection unit 38 detects the current state of the current flowing through the power path 11 as the current value A.

[0040] The first potential detection unit 39A is configured as a potential detection circuit, for example. The first potential detection unit 39A is configured to detect the first potential of the terminal on one end side of the first switch 33A, that is, the terminal on the power supply unit 10 side, and the second potential of the terminal on the other end side, that is, the terminal on the load 35 side, respectively, and can output the potential difference V1 between these first potential and second potential. In other words, the first potential detection unit 39A detects the potential difference V1 between the two terminals on the power supply unit 10 side and the load 35 side of the first switch 33A (the terminals on both sides of the side that supplies power to the first switch 33A and the side that outputs power).

[0041] The second potential detection unit 39B is configured as, for example, a potential detection circuit similar to the first potential detection unit 39A. The second potential detection unit 39B is configured to detect a first voltage of a terminal on one end side of the fuse F, i.e., a terminal on the power supply unit 10 side, and a second potential of a terminal on the other end side, i.e., a terminal on the load 35 side, respectively, and can output a potential difference V2 between these first potential and second potential. In other words, the second potential detection unit 39B detects a potential difference V2 between two terminals on the power supply unit 10 side and the load 35 side of the fuse F (terminals on both sides of the side supplying power to the fuse F and the side outputting power).

[0042] The potential differences V1 and V2 between the first potential and the second potential may be values ​​calculated by an analog circuit (eg, a differential amplifier circuit), or values ​​calculated by a digital circuit after AD conversion of the first potential and the second potential, respectively.

[0043] The control unit 15 is configured as a microcomputer, for example, and includes a storage unit 15D including a CPU, a ROM, a RAM, a nonvolatile memory, etc. The control unit 15 includes a resistance value calculation unit 15A, a degradation detection unit 15B, and a notification function unit 15C.

[0044] The resistance value calculation unit 15A is configured to input the current value A, the potential difference V1, and the potential difference V2 from the current detection unit 38, the first potential detection unit 39A, and the second potential detection unit 39B, respectively. The resistance value calculation unit 15A calculates the resistance value R1 of the first switch 33A and the resistance value R2 of the fuse F based on these values ​​(current value A, potential differences V1, V2). For example, the resistance value R1 of the first switch 33A is obtained by dividing the potential difference V1 by the current value A. Moreover, the resistance value R2 of the fuse F is obtained by dividing the potential difference V2 by the current value A. That is, the control unit 15 calculates the resistance values ​​R1 and R2 of the first switch 33A and the fuse F as the first element, respectively, based on the potential differences V1 and V2 between the first potential and the second potential. For example, the first switch 33A and the fuse F have the characteristic that the resistance values ​​R1 and R2 gradually increase if the power is repeatedly supplied and the power is stopped. That is, the control unit 15 comprehends the degree of degradation of each of the first switch 33A and the fuse F by calculating the resistance values ​​R1 and R2.

[0045] The degradation detection unit 15B is configured to execute degradation determination processing. The degradation determination processing is a process of comparing the resistance value R1 calculated by the resistance value calculation unit 15A with the resistance threshold value Th11 stored in the storage unit 15D of the control unit 15, and comparing the resistance value R2 calculated by the resistance value calculation unit 15A with the resistance threshold value Th12 stored in the storage unit 15D of the control unit 15.

[0046] For example, the degradation detection unit 15B is configured to output the degradation signal Sd if it is determined that the resistance value R1 exceeds the resistance threshold value Th11 or the resistance value R2 exceeds the resistance threshold value Th12. The degradation signal Sd is output when either the first switch 33A or the fuse F is in a degraded state. That is, the control unit 15 determines that the first switch 33A is in a degraded state when the resistance value R1 exceeds the resistance threshold value Th11, and determines that the fuse F is in a degraded state when the resistance value R2 exceeds the resistance threshold value Th12. The degradation detection unit 15B does not output the degradation signal Sd when it is determined in the degradation determination process that the magnitude of the resistance value R1 is less than the resistance threshold value Th11 and the magnitude of the resistance value R2 is less than the resistance threshold value Th12. In this case, the control unit 15 determines that the first switch 33A and the fuse F are not in a degraded state. In this way, the control unit 15 determines whether each of the first switch 33A and the fuse F is in a degraded state.

[0047] The notification function unit 15C is composed of, for example, a communication device, and is configured to perform abnormal response processing by sending information to an external device (not shown) such as a BMS (battery management system) based on the degradation signal Sd input from the degradation detection unit 15B. That is, the control unit 15 performs abnormal response processing when the resistance value R1 exceeds the resistance threshold Th11 and the first switch 33A is determined to be in a degraded state, and when the resistance value R2 exceeds the resistance threshold Th12 and the fuse F is determined to be in a degraded state.

[0048] [Regarding control in the control unit]

[0049] Next, refer to Figure 2 An example of control performed by the control unit 15 is described below. For example, in a vehicle equipped with the vehicle power supply system 100, when the start switch is turned off, the first switch 33A, the second switch 33B of the system main relay 33, and the third switch 33E of the parallel switch path 33C are maintained in the open state. At this time, the power path 11 is in the cut-off state in which the power supply from the power supply unit 10 to the load 35 is cut off.

[0050] From this state, first, step S1 is executed to switch the start switch from off to on. Then, when the process moves to step S2, the control device C outputs an on signal Son (see Figure 1 ), the first switch 33A, the second switch 33B, and the third switch 33E are switched from the off state to the on state based on the on signal Son. Specifically, the switching control is a control as follows: after the first switch 33A is set to the off state and the second switch 33B and the third switch 33E are set to the on state to start energizing the power path 11, the second switch 33B and the third switch 33E are maintained in the on state and the first switch 33A is switched to the on state. That is, the first switch 33A is switched from the off state to the on state after the second switch 33B.

[0051] When the second switch 33B and the third switch 33E are turned on, current starts to flow through the power path 11. Since the resistor 33D is connected in series with the third switch 33E, a current starts to flow slowly through the power path 11 so that the current gradually increases.

[0052] And, when the first switch 33A becomes the on state, the power path 11 becomes the on state that allows the power to be supplied from the power supply unit 10 to the load 35. If the first switch 33A is switched to the on state, the inrush current immediately flows through the first switch 33A. At this time, a current rise occurs in which the current value A flowing in the power path 11 rises sharply. In this way, the start of energization of the power path 11 or the current rise occurs by executing the switching control. After the first switch 33A is switched to the on state, the inrush current continues to flow for a predetermined short time, and after the predetermined short time has passed, the current flowing through the first switch 33A stabilizes to stay in a predetermined range smaller than the magnitude of the inrush current. In this way, the first switch 33A becomes the on state, and the current flows in the power path 11.

[0053] Then, the process moves to step S3. The control unit 15 has a timer function and starts measuring a predetermined short time when the current value A changes from 0 to a predetermined magnitude. The predetermined short time is the time when the current flowing through the first switch 33A stabilizes within a predetermined range smaller than the magnitude of the inrush current.

[0054] Then, when the process shifts to step S4, the control unit 15 determines whether a predetermined short time has passed since the current value A in the power path 11 changes from 0 to a predetermined value. In step S4, a process is performed to wait for the current flowing through the first switch 33A to stabilize within a predetermined range smaller than the magnitude of the inrush current by waiting for the predetermined short time to pass. For example, when the control unit 15 determines in step S4 that the predetermined short time has not passed since the current value A in the power path 11 changes from 0 to a predetermined value (No in step S4), the process shifts to step S3 again. When the process shifts to step S3 again, the count of the timer provided in the control unit 15 is advanced, and then the process of step S4 is repeated again.

[0055] Then, in step S4, when the control unit 15 determines that a predetermined short time has passed since the current value A in the power path 11 changed from 0 to a predetermined value (Yes in step S4), the process moves to step S5. When moving to step S5, the control unit 15 determines whether the magnitude of the current value A is maintained within a predetermined range. For example, the control unit 15 is configured to compare the current value A input from the current detection unit 38 with the current threshold Th13 and the upper limit current threshold Th14 greater than the current threshold Th13 stored in the storage unit 15D of the control unit 15. For example, the control unit 15 is configured to be able to use the timer function of the control unit 15 to determine whether the state in which the magnitude of the current value A is greater than the current threshold Th13 and less than the upper limit current threshold Th14 continues for a predetermined time (that is, the change of the current flowing in the power path 11 is stable). In step S5, if the control unit 15 determines that the state in which the magnitude of the current value A is greater than the current threshold Th13 and less than the upper limit current threshold Th14 does not continue for a predetermined time (No in step S5), the process of step S5 is repeated.

[0056] In step S5, if the control unit 15 determines that the current value A is greater than or equal to the current threshold value Th13 and less than the upper current threshold value Th14 for a predetermined time (Yes in step S5), the process moves to step S6. When the process moves to step S6, the control unit 15 calculates the resistance values ​​R1 and R2 in the resistance value calculation unit 15A based on the current value A and the potential differences V1 and V2 inputted from the current detection unit 38, the first potential detection unit 39A, and the second potential detection unit 39B, respectively. Then, the process moves to step S7.

[0057] When the process shifts to step S7, the control unit 15 performs a degradation determination process in which the resistance value R1 is compared with the resistance threshold value Th11 and the resistance value R2 is compared with the resistance threshold value Th12 in the degradation detection unit 15B. The control unit 15 performs a degradation determination process in which the resistance values ​​R1 and R2 are compared with the resistance threshold values ​​Th11 and Th12 when the switching control is performed by the control device C. For example, in the degradation determination process, if it is determined that the magnitude of the resistance value R1 is greater than the resistance threshold value Th11 or the magnitude of the resistance value R2 is greater than the resistance threshold value Th12 (yes in step S7), the process shifts to step S8, and the degradation signal Sd is output from the degradation detection unit 15B.

[0058] On the other hand, in the degradation determination process, if it is determined that the resistance value R1 is smaller than the resistance threshold value Th11 and the resistance value R2 is smaller than the resistance threshold value Th12 (No in step S7), the degradation signal Sd is not output and the process ends. Figure 2The control unit 15 calculates the resistance value R1 of the first switch 33A by using the potential difference V1 between the first potential on one end side of the first switch 33A and the second potential on the other end side of the first switch 33A. Then, the control unit 15 compares the resistance value R1 with the resistance threshold Th11 to determine whether the first switch 33A is in a degraded state. Then, the control unit 15 calculates the resistance value R2 of the fuse F by using the potential difference V2 between the first potential on one end side of the fuse F and the second potential on the other end side of the fuse F. Then, the control unit 15 compares the resistance value R2 with the resistance threshold Th12 to determine whether the fuse F is in a degraded state.

[0059] Next, when the degradation signal Sd is input to the notification function unit 15C, the notification function unit 15C transmits information to an external device (not shown). That is, the notification function unit 15C of the control unit 15 performs an abnormal response process to notify the outside that the resistance value R1 exceeds the resistance threshold Th11 and the first switch 33A is in a degraded state, and the resistance value R2 exceeds the resistance threshold Th12 and the fuse F is in a degraded state. In this way, Figure 2 The shown processing ends.

[0060] For example, the control unit 15 and Figure 2 The process shown in the figure is parallelly performed with the process of comparing the temperature value from the first temperature detection unit 37A with the temperature value from the second temperature detection unit 37B. Through this process, the control unit 15 compares the temperature of the first switch 33A with the temperature of the second switch 33B. For example, the control unit 15 may be configured so that, when it is determined that the temperature value from the second temperature detection unit 37B is greater than the temperature value from the first temperature detection unit 37A (that is, the temperature of the second switch 33B is greater than the temperature of the first switch 33A), it is estimated that the degree of deterioration of the second switch 33B is greater than the degree of deterioration of the first switch 33A.

[0061] In addition, the control unit 15 may be configured to calculate the temperature difference between the first switch 33A and the second switch 33B based on the temperature value from the second temperature detection unit 37B and the temperature value from the first temperature detection unit 37A. Furthermore, the control unit 15 may be configured to perform temperature correction on the calculated resistance value R1 of the first switch 33A using the temperature difference, and calculate the resistance value of the second switch 33B. That is, the control unit 15 determines whether the second switch 33B (second element) is in a degraded state based on the resistance value R1 calculated based on the potential difference V1 and the temperature value detected by the temperature detection unit 37.

[0062] Next, the effects of this structure are exemplified.

[0063] The degradation determination device 1 determines whether each of the first switch 33A and the fuse F (element) provided on the power path 11 is in a degraded state. The power path 11 is a path for transmitting power from the power supply unit 10 to the load 35. The power path 11 has a positive-side power line 17 connected to the positive-side terminal of the power supply unit 10 and a negative-side power line 20 connected to the negative-side terminal of the power supply unit 10. The first switch 33A and the fuse F (element) are provided on the negative-side power line 20. The degradation determination device 1 includes a first potential detection unit 39A, a second potential detection unit 39B, and a control unit 15. The first potential detection unit 39A detects a first potential on one end side of the first switch 33A and a second potential on the other end side of the first switch 33A. The second potential detection unit 39B detects a first potential on one end side of the fuse F and a second potential on the other end side of the fuse F. The control unit 15 determines whether each of the first switch 33A and the fuse F is in a degraded state based on the potential differences V1 and V2 between the first potential and the second potential.

[0064] In the degradation determination device 1, the first switch 33A and the fuse F are provided on the negative-side power line 20. Therefore, even if the voltage applied to each of the first switch 33A and the fuse F varies at a predetermined variation rate, the variation range is smaller than that of the voltage varying at a predetermined variation rate in the positive-side power line 17. Therefore, it is easy to suppress the variation range of the calculated resistance values ​​R1 and R2 in the first switch 33A and the fuse F provided on the negative-side power line 20 to be small.

[0065] The first switch 33A and the fuse F are first elements, and a second switch 33B (second element) different from the first switch 33A and the fuse F is provided on the positive-side power line 17. In addition, the degradation determination device 1 includes a temperature detection unit 37 for detecting the temperature of each of the first switch 33A and the second switch 33B. The control unit 15 determines whether the second switch 33B is in a degraded state based on the potential difference V1 and the temperature value detected by the temperature detection unit 37.

[0066] The potential difference between the two terminals of the second switch 33B varies more widely than that of the first switch 33A, and the resistance value of the second switch 33B may vary more. Therefore, the degradation determination device 1 can easily determine whether the second switch 33B is in a degraded state by the temperature detection unit 37 .

[0067] The components are the first switch 33A and the fuse F.

[0068] If the electrical characteristics of the first switch 33A and the fuse F deteriorate due to degradation, the power path 11 may not be cut off as specified. However, the degradation determination device 1 determines whether the first switch 33A and the fuse F are degraded, making it easy to deal with such concerns before they arise.

[0069] The first element is a first switch 33A as a relay, and the second element is a second switch 33B as a relay. A parallel switching path 33C (precharge circuit) is connected to the power path 11 in parallel with the first switch 33A (first element).

[0070] In the degradation determination device 1, the first switch 33A connected in parallel with the parallel switching path 33C easily flows with an inrush current, and thus degradation easily progresses. Therefore, by measuring the resistance value R1 of the first switch 33A connected in parallel with the parallel switching path 33C, the degradation degree of the first switch 33A, which is easy to progress in degradation, can be grasped.

[0071] The control unit 15 performs abnormality handling processing when the resistance value R1 of the first switch 33A exceeds the resistance threshold Th11 and the first switch 33A is determined to be in a degraded state, or when the resistance value R2 of the fuse F exceeds the resistance threshold Th12 and the fuse F is determined to be in a degraded state.

[0072] According to this configuration, by performing the abnormality handling process, it is easy to take a countermeasure corresponding to the deterioration of either the first switch 33A or the fuse F.

[0073] [Other embodiments of the present disclosure]

[0074] The embodiments disclosed this time should be considered in all respects as illustrative and non-restrictive.

[0075] Unlike the first embodiment, the position to which the voltage detection unit is connected may be any position as long as it is considered to be at the same potential as the terminals on both sides of the first switch.

[0076] Unlike the first embodiment, the notification function unit may be configured as a display unit such as a lamp or a display device to perform notification by display. The notification function unit may be configured as an audio device such as a speaker to perform notification by audio.

[0077] Unlike the first embodiment, the resistance value calculation unit, the degradation detection unit, and the notification function unit may be configured as separate information processing devices (separate microcomputers, etc.).

[0078] Different from the first embodiment, the control unit and the control device may be configured as one microcomputer.

[0079] Unlike the first embodiment, the degradation determination process may be performed after it is determined that the rate of increase of the current in the power path is below a certain value. For example, the change amount Ki of the current in the power path per unit time is calculated by the following formula 1. Ki = |A1-A2| / ΔT (Formula 1). Here, A1 is the current value A1 detected by the current detection unit this time, A2 is the current value A2 detected by the current detection unit last time, and ΔT is the period ΔT of the time when the current detection unit repeatedly detects the current value. The current value A2 is, for example, a structure that can be stored in the RAM of the control unit. The change amount Ki is the value obtained by dividing the absolute value of the difference between the current value A1 and the current value A2 by the period ΔT. For example, when the state in which the change amount Ki is smaller than the threshold value stored in the storage unit of the control unit continues for a predetermined time, it may be determined that the change of the current flowing in the power path is stable, and then the resistance value of the first switch is calculated.

[0080] Unlike Embodiment 1, the third switch may not be provided. In this case, a current rise in which the value of the current flowing in the power path rises sharply occurs by executing the switching control.

[0081] Unlike the first embodiment, table data defining resistance values ​​corresponding to current values ​​and voltage values ​​may be stored in advance in a storage unit, and the resistance values ​​corresponding to the current values ​​and voltage values ​​may be adopted from the table data.

[0082] Unlike the first embodiment, a configuration may be adopted in which the potential difference of only one of the first switch and the fuse is detected, and whether or not only one of the first switch and the fuse is in a degraded state is determined.

[0083] The degradation state may be the potential difference itself, the resistance value, or a value obtained by performing calculations using the potential difference or the resistance value as variables.

[0084] Description of Reference Numerals

[0085] 1…Degradation determination device

[0086] 10…Power supply

[0087] 11…Power Path

[0088] 15…Control Department

[0089] 15A…Resistance value calculation unit

[0090] 15B…Deterioration detection unit

[0091] 15C…Notification function department

[0092] 15D… Storage

[0093] 17…Positive side power line (power path)

[0094] 20…Negative side power line (power path)

[0095] 33…System main relay

[0096] 33A…First switch

[0097] 33B…Second switch

[0098] 33C…Parallel opening and closing path (pre-charge circuit)

[0099] 33D…Resistors

[0100] 33E…Third switch

[0101] 35…Load

[0102] 37…Temperature detection unit

[0103] 37A…First temperature detection unit (temperature detection unit)

[0104] 37B...Second temperature detection unit (temperature detection unit)

[0105] 38…Current detection unit

[0106] 39…Potential detection unit

[0107] 39A…first potential detection unit (potential detection unit)

[0108] 39B...Second potential detection unit (potential detection unit)

[0109] 100…Vehicle power supply system

[0110] A, A1, A2...current value

[0111] C…Control device

[0112] F…Fuse

[0113] Ki…Change

[0114] R1, R2...resistance value

[0115] Sd…degraded signal

[0116] Son...get the signal

[0117] Th11, Th12…Resistance threshold

[0118] Th13…Current threshold

[0119] Th14…Upper current threshold

[0120] V1, V2…potential difference

[0121] ΔT…period

Claims

1. A degradation determination device for determining whether a component provided on a power path is in a degraded state, the power path being a path for transmitting power from a power supply unit to a load, wherein: The power path includes: a positive-side power line connected to the positive-side terminal of the power source; and a negative-side power line connected to the negative-side terminal of the power source. The element is arranged on the negative electrode side power line, The degradation determination device comprises: a potential detection unit for detecting a first potential on one end side of the element and a second potential on the other end side of the element; and The control unit determines whether the element is in a degraded state based on a potential difference between the first potential and the second potential.

2. The degradation determination device according to claim 1, wherein: The element is a first element, A second element different from the first element is provided on the positive electrode side power line, The degradation determination device further includes a temperature detection unit for detecting the temperature of each of the first element and the second element. The control unit determines whether the second element is in a degraded state based on the potential difference and the temperature value detected by the temperature detection unit.

3. The degradation determination device according to claim 2, wherein: The element is at least one of a relay and a fuse.

4. The degradation determination device according to claim 3, wherein: The first element and the second element are the relays, A precharge circuit is connected to the power path in parallel with the first element.

5. The degradation determination device according to any one of claims 1 to 4, wherein: The control unit performs abnormality handling processing when determining that the element is in a degraded state.

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