Determination diagnosis device

Abstract

To diagnose a detection part while determining whether or not a leakage current is generated.SOLUTION: A determination diagnosis device that determines whether or not a leakage current has occurred based on a detection value from a detection unit that detects a current flowing between an electric circuit and a predetermined location, and diagnoses a state of the detection unit, the determination diagnosis device comprising: And a determination diagnosis unit configured to determine whether or not a leakage current has occurred based on the detection value and a first threshold value, and to diagnose a state of the detection unit based on the detection value, the first threshold value, and a second threshold value different from the first threshold value while performing diagnosis control for controlling the connection release unit such that the electric path and the predetermined point are connected to each other.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a determination and diagnosis device. [Background technology]

[0002] Conventionally, a device has been proposed for determining whether a leakage current is occurring, which includes a detection unit that detects the leakage current of a high-voltage DC power supply mounted on a vehicle as a detected voltage value (see, for example, Patent Document 1). In this device, a protective resistor, two detection resistors, and another protective resistor are connected in that order between the positive and negative lines from the high-voltage DC power supply, with the two detection resistors grounded and a switch connected in parallel to each protective resistor. This device then controls the opening and closing of the switch, waits for a certain period of time, discharges stray capacitance between the high-voltage DC power supply and the body, and then determines whether a leakage current is occurring based on the voltage across the detection resistor. This suppresses errors in the voltage across the detection resistor due to stray capacitance, allowing for a more accurate determination of whether a leakage current is occurring. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 9-274062 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned document does not disclose diagnosing the state of the detection unit. If an abnormality occurs in the detection unit, it is not possible to properly determine whether a leakage current is occurring. Therefore, diagnosing the state of the detection unit is recognized as an important issue. One possible method for diagnosing the state of the detection unit is to diagnose the detection unit during a standby period after controlling the opening and closing of the switch. However, with this method, it is not possible to determine whether a leakage current is occurring during the diagnosis of the detection unit, i.e., during a standby period after controlling the opening and closing of the switch.

[0005] The main purpose of the determination and diagnosis device of the present disclosure is to determine whether or not a leakage current is occurring while diagnosing the detection unit. [Means for solving the problem]

[0006] The determination and diagnosis device of the present disclosure employs the following means to achieve the above-mentioned main object.

[0007] A first determination and diagnosis device of the present disclosure includes: A determination and diagnosis device that determines whether or not a leakage current is occurring based on a detection value from a detection unit that detects a parameter that reflects a current flowing between an electric circuit and a predetermined location, and diagnoses a state of the detection unit, a disconnection unit that connects and disconnects the resistor connected to the electric path to the predetermined location; a determination and diagnosis unit that determines whether or not the leakage current is occurring based on the detection value and a first threshold value, and diagnoses the state of the detection unit based on the detection value, the first threshold value, and a second threshold value different from the first threshold value while executing diagnostic control that controls the connection disconnection unit so that the electric path and the predetermined location are connected via the resistor; The gist of the project is to provide the following:

[0008] In a first determination and diagnosis device disclosed herein, the presence or absence of leakage current is determined based on a detection value and a first threshold value, and the state of the detection unit is diagnosed based on the detection value, the first threshold value, and a second threshold value different from the first threshold value while executing diagnostic control that controls a disconnection unit to connect the electrical circuit to a predetermined location. When the diagnostic control is executed, the electrical circuit is connected to the predetermined location via a resistor, and a current caused by the discharge of stray capacitance in the electrical circuit flows between the electrical circuit and the predetermined location. When the detection unit is normal, the detection value changes with a time constant due to the stray capacitance and resistance and stabilizes at a predetermined value between the first threshold value and the second threshold value. When an abnormality occurs in the detection unit, the detection value does not fall between the first threshold value and the second threshold value. Therefore, the detection unit can be diagnosed by diagnosing the state of the detection unit based on the detection value, the first threshold value, and a second threshold value different from the first threshold value while executing diagnostic control. If a leakage current occurs between the electrical circuit and the predetermined location during diagnostic control, a current caused by the discharge of stray capacitance flows between the electrical circuit and the predetermined location without passing through the resistance of the disconnecting unit, causing the detection value to change with a time constant smaller than when no leakage current is occurring and exceed the first threshold. Therefore, whether or not a leakage current is occurring is determined based on the detection value and the first threshold, and diagnostic control is performed to control the disconnecting unit so that the electrical circuit and the predetermined location are connected. By diagnosing the state of the detection unit based on the detection value, the first threshold, and a second threshold different from the first threshold, it is possible to determine whether or not a leakage current is occurring while diagnosing the detection unit. Here, the "predetermined location" may be the ground, the housing of another device, or the like.

[0009] In the first determination and diagnosis device of the present disclosure, the detection unit may detect the current flowing between the electric circuit and the predetermined location as a voltage, the determination and diagnosis unit may set the second threshold lower than the first threshold, determine that the leakage current is occurring when the detected value exceeds the first threshold at a time change rate equal to or greater than a predetermined rate, and diagnose that an abnormality has occurred in the detection unit when the detected value exceeds the first threshold while the diagnostic control is being executed and when the detected value becomes less than the second threshold within a predetermined period while the diagnostic control is being executed. This makes it possible to more accurately determine the occurrence of a leakage current and diagnose the occurrence of an abnormality in the detection unit.

[0010] In the first determination and diagnosis device of the present disclosure, at least one of the first threshold value and the second threshold value may be time-varying depending on the time elapsed since the start of the diagnosis control, thereby enabling more accurate diagnosis of an abnormality in the detection unit.

[0011] Furthermore, in the first determination and diagnosis device of the present disclosure, the determination and diagnosis unit may set the first threshold smaller around a first period between a first timing and a second timing after the start of the diagnostic control than during the first period, and may set the second threshold smaller around a second period between a third timing and a fourth timing after the start of the predetermined period than during the second period. This makes it possible to more accurately diagnose the occurrence of an abnormality in the detection unit.

[0012] The second determination and diagnosis device of the present disclosure comprises: A determination and diagnosis device that determines whether or not a leakage current is occurring based on a detection value from a detection unit that detects a current flowing between an electric circuit and a predetermined location, and diagnoses the state of the detection unit, a breaker that can interrupt and release the interruption of a current that flows between the electric path and a predetermined location via a resistor; a determination and diagnosis unit that determines whether or not the leakage current is occurring based on the detection value and a first threshold value, and diagnoses the state of the detection unit based on the detection value and a time-varying second threshold value while executing diagnostic control that controls the interrupter unit so as to release the interruption of the current between the electric circuit and the predetermined location; The gist of the project is to provide the following:

[0013] In a second determination and diagnosis device disclosed herein, the presence or absence of leakage current is determined based on the detection value and a first threshold value, and the state of the detection unit is diagnosed based on the detection value and a time-varying second threshold value while executing diagnostic control that controls the disconnection unit so that the electrical circuit is connected to the predetermined location via a resistor. When the diagnostic control is executed, the electrical circuit is connected to the predetermined location via a resistor, and a current due to the discharge of stray capacitance in the electrical circuit flows between the electrical circuit and the predetermined location. When the detection unit is normal, the detection value changes with a time constant determined by the stray capacitance and the resistance. When an abnormality occurs in the detection unit, the time constant of the detection value differs from the time constant of the detection value when the detection unit is normal. Therefore, by diagnosing the state of the detection unit based on the detection value and the time-varying second threshold value, the detection unit can be more accurately diagnosed. When leakage current occurs between the electrical circuit and the predetermined location during diagnostic control, the current due to the discharge of stray capacitance flows between the electrical circuit and the predetermined location without passing through the resistance of the disconnection unit, and the detection value changes with a time constant smaller than when leakage current is not occurring, exceeding the first threshold value. Therefore, whether or not a leakage current is occurring can be determined based on the detection value and the first threshold value, and by diagnosing the state of the detection unit based on the detection value and the time-varying second threshold value while executing diagnostic control that controls the disconnection unit so that the electric path is connected to a predetermined location via a resistor, whether or not a leakage current is occurring can be determined while diagnosing the detection unit. Here, the "predetermined location" can be the ground, the housing of another device, etc. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing an outline of the configuration of a charging station 20 equipped with a determination and diagnosis device according to the present embodiment. [Figure 2] This is an explanatory diagram for explaining an example of the change over time in the detection voltage Vdet when diagnosing the state of the detection unit 26 when the detection unit 26 is normal, the execution status of the upper limit judgment which is a judgment using the first threshold value Vth1 in the control unit 30, the execution status of the lower limit judgment which is a judgment using the second threshold value Vth2 in the control unit 30, the state of the negative electrode relay Rln, and whether the state of the detection unit 26 can be diagnosed in the control unit 30. [Figure 3]FIG. 10 is an explanatory diagram illustrating an example of time changes in whether or not the detection voltage Vdet, the execution state of the upper limit determination which is a determination using the first threshold value Vth1 in the control device 30, the execution state of the lower limit determination which is a determination using the second threshold value Vth2 in the control device 30, the state of the negative electrode relay Rln, and the state of the detection unit 26 in the control device 30 can be diagnosed in another embodiment. [Figure 4] FIG. 10 is an explanatory diagram illustrating an example of time changes in whether or not the detection voltage Vdet, the execution state of the upper limit determination which is a determination using the first threshold value Vth1 in the control device 30, the execution state of the lower limit determination which is a determination using the second threshold value Vth2 in the control device 30, the state of the negative electrode relay Rln, and the state of the detection unit 26 in the control device 30 can be diagnosed in another embodiment. [Figure 5] 10 is an explanatory diagram for explaining the time change of a ground fault current occurring in a positive electrode line 24a. FIG. [Figure 6] FIG. 10 is a diagram showing an outline of the configuration of a connection release unit 128 according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0015] An embodiment of the present disclosure will be described with reference to the drawings. FIG. 1 is a schematic diagram illustrating the configuration of a charging stand 20 equipped with a determination and diagnosis device according to the present embodiment. The charging stand 20 is configured to supply power to a battery (not shown) mounted on a vehicle 10 by being connected via a cable C to a power line 12 connected to the battery (not shown) mounted on the vehicle 10, and includes a power output unit 22, a detection unit 26, resistors Rpx and Rnx, a connection / disconnection unit 28, and a control device 30. The power line 12 is basically insulated from the ground (predetermined location). The power line 24 has stray capacitances Cva and Cvb between it and the ground.

[0016] The power output unit 22 supplies DC power to a positive line 24a and a negative line 24b of a power line (electrical path) 24 connected to the cable C. The power line 24 is basically insulated from the ground (a predetermined location). The power line 24 has stray capacitances Ca and Cb between it and the ground.

[0017] The detection unit 26 includes resistors Rp, Rn, and Rx and an amplifier Amp. One end of the resistor Rp is connected to the positive line 24a of the power line 24. One end of the resistor Rn is connected to the negative line 24b of the power line 24. One end of the resistor Rx is connected to the end of the resistor Rp that is not connected to the positive line 24a and the end of the resistor Rn that is not connected to the negative line 24b, and the other end is grounded. The amplifier Amp amplifies the voltage Vrx across the resistor Rx and outputs it to the control device 30 as a detection voltage (detection value) Vdet. The voltage Vrx across the resistor Rx is a voltage obtained by dividing the voltage between the positive line 24a and the negative line 24b of the power line 24 by the resistors Rp and Rn. Here, the resistance value of the resistor Rx is sufficiently smaller than the resistance values ​​of the resistors Rp and Rn. For example, if the resistance values ​​of the resistors Rp and Rn are 500 kΩ, the resistance values ​​of the resistors Rpx and Rnx should be set to 20 kΩ.

[0018] One end of the resistor Rpx is connected to the positive line 24a of the power line 24. One end of the resistor Rnx is connected to the negative line 24b of the power line 24.

[0019] The disconnection unit 28 includes a positive relay Rlp and a negative relay Rln. The positive relay Rlp is connected to the positive line 24a via a resistor Rpx, and its end not connected to the resistor Rpx is grounded. The positive relay Rlp connects and disconnects the positive line 24a to and from ground via the resistor Rpx. The negative relay Rln is connected to the negative line 24b via a resistor Rnx, and its end not connected to the resistor Rnx is grounded. The negative relay Rln connects and disconnects the negative line 24b to and from ground via the resistor Rnx. The resistance values ​​of the resistors Rpx and Rnx should be approximately the same as the resistance values ​​of the resistors Rp and Rn. For example, if the resistance values ​​of the resistors Rp and Rn are 500 kΩ, the resistance values ​​of the resistors Rpx and Rnx should be approximately 500 kΩ.

[0020] The control device 30 is configured as a microprocessor centered around a CPU, and in addition to the CPU, includes a ROM for storing processing programs, a RAM for temporarily storing data, a flash memory, an input / output port, a communication port, etc. The control device 30 receives a detection voltage Vdet from the amplifier Amp. The control device 30 outputs control signals to the positive relay Rlp and the negative relay Rln.

[0021] In the charging stand 20 equipped with the determination and diagnosis device of this embodiment configured as described above, the control device 30 performs an upper limit determination to determine whether the detected voltage Vdet from the amplifier Amp exceeds a first threshold Vth1, thereby determining whether a ground fault current (leakage current) is occurring in the power line 24, particularly the negative line 24b. The first threshold Vth1 is a threshold for determining whether a ground fault current is occurring in the power line 24 and is set to an upper limit threshold Vthmax that is greater than the upper limit of the voltage range that the detected voltage Vdet can normally assume when no ground fault current is occurring. When the detected voltage Vdet from the amplifier Amp is equal to or less than the first threshold Vth1, the control device 30 determines that no ground fault current is occurring in the power line 24. When the detected voltage Vdet exceeds the first threshold Vth1 at a time rate equal to or greater than a predetermined rate, the control device 30 determines that a ground fault current is occurring in the power line 24. In this manner, whether a ground fault current is occurring in the power line 24 can be determined based on the detected voltage Vdet and the first threshold Vth1.

[0022] Next, the operation of the charging stand 20 equipped with the determination and diagnosis device of this embodiment configured as described above will be described, particularly the operation when diagnosing the state (normal or not) of the detection unit 26. Fig. 2 is an explanatory diagram illustrating an example of the detected voltage Vdet when diagnosing the state of the detection unit 26 when the detection unit 26 is normal, the execution state of the upper limit determination in the control device 30 using the first threshold value Vth1, the execution state of the lower limit determination in the control device 30 using the second threshold value Vth2, the state of the negative electrode relay Rln, and whether the control device 30 can diagnose the state of the detection unit 26 over time. Here, the first threshold value Vth1 and the second threshold value Vth2 are constant values ​​regardless of the passage of time.

[0023] When diagnosing the detection unit 26, the charging stand 20 starts executing diagnostic control (time t0) by turning on the negative relay Rln and connecting the negative line 24b to the ground via the resistor Rnx. By turning on the negative relay Rln, the charges of the stray capacitance Cvb of the negative line 12b of the power line 24 of the vehicle 10 and the stray capacitance Cb of the negative line 24b are discharged via the resistor Rnx, causing a current simulating a ground fault to occur in the negative line 24b, and the voltage of the negative line 24b to decrease. The voltage Vrx across the resistor Rx (corresponding to the detection voltage Vdet output from the amplifier Amp) is the divided voltage of the voltage between the positive line 24a and the negative line 24b. When the detector 26 is operating normally, the voltage Vrx, i.e., the detected voltage Vdet, rises with a relatively large time constant until the charge on the stray capacitances Cvb and Cb is completely discharged, as shown by the solid line L1 in the figure. Once the charge on the stray capacitances Cvb and Cb is completely discharged, the detected voltage Vdet reaches a saturated state where it does not fluctuate (between times t11 and t12). When the negative relay Rln is subsequently turned off (time t12), the stray capacitances Cvb and Cb are charged, the voltage on the negative line 24b rises, and the detected voltage Vdet drops. The time constant of the detected voltage Vdet and the voltage in the saturated state at this time vary depending on the variations in the circuits connected to the power line 24, as shown by the solid lines L1 and L2. When an abnormality occurs in the detection unit 26, the detection voltage Vdet does not behave as shown by the solid lines L1 and L2 described above, and the time constant and saturated voltage of the detection voltage Vdet when the negative electrode relay Rln is turned on are different from those in normal conditions.

[0024] The control device 30 sets the second threshold Vth2 to a lower limit threshold Vthmin that is lower by a margin than the voltage that the detection voltage Vdet is estimated to reach in the saturated state, taking into account fluctuations in the detection voltage Vdet due to circuit variations when the detection voltage Vdet is in the saturated state. After turning on the negative electrode relay Rln, the control device 30 considers fluctuations in the time constant of the detection voltage Vdet due to circuit variations and diagnoses the detection unit 26 as normal when the detection voltage Vdet is equal to or greater than the second threshold Vth2 and equal to or less than the first threshold Vth1 during a period P (the period between times t11 and t12 in the figure) when the detection voltage Vdet is estimated to be in the saturated state. When the detection voltage Vdet is less than the second threshold Vth2 or exceeds the first threshold Vth1 during the period P, the control device 30 diagnoses the detection unit 26 as abnormal. In this way, during diagnostic control in which the negative electrode relay Rln is turned on, the state of the detector 26 is diagnosed based on whether the detected voltage Vdet is equal to or greater than the second threshold Vth2 and equal to or less than the first threshold Vth1 during the period P (by performing an upper limit determination and a lower limit determination), thereby enabling proper diagnosis of the detector 26. Even during such diagnostic control, the above-described ground fault determination can be performed by performing an upper limit determination. This makes it possible to determine whether a ground fault current, indicated by the dashed line L3 in the figure, is occurring while diagnosing the detector 26.

[0025] According to the charging stand 20 equipped with the determination and diagnostic device of this embodiment described above, it is possible to determine whether or not a ground fault current is occurring based on the detected voltage Vdet and the first threshold value (first threshold value) Vth1, and to diagnose the state of the detection unit 26 based on the detected voltage Vdet, the first threshold value Vth1, and a second threshold value (second threshold value) Vth2 different from the first threshold value Vth1 while executing diagnostic control that controls the disconnection unit 28 so that the negative line 24b is connected to the ground, thereby determining whether or not a ground fault current is occurring while diagnosing the detection unit 26.

[0026] Furthermore, when the detected voltage Vdet exceeds the first threshold (first threshold) Vth1 at a time change rate equal to or greater than a predetermined rate, it is determined that a ground fault current is occurring, and when the detected voltage Vdet exceeds the first threshold Vth1 while diagnostic control is being executed, and when the detected voltage Vdet becomes less than the second threshold Vth2 during the period P while diagnostic control is being executed, it is diagnosed that an abnormality has occurred in the detection unit, thereby making it possible to more accurately determine the occurrence of leakage current and diagnose the occurrence of an abnormality in the detection unit 26.

[0027] In the above-described embodiment, the first threshold Vth1 and the second threshold Vth2 are constant (upper limit threshold Vthmax, lower limit threshold Vthmin) regardless of the passage of time. However, as illustrated in another embodiment of FIG. 3, the first threshold Vth1 and the second threshold Vth2 may be varied depending on the time elapsed since the start of execution of diagnostic control. In this case, the waveform of the detection voltage Vdet when the detector 26 is normal may be determined in advance through experimentation, analysis, or machine learning, and the first threshold Vth1 and the second threshold Vth2 may be set to avoid the waveform of the detection voltage Vdet. For example, as illustrated in FIG. 3, the first threshold Vth1 may be set smaller than the upper limit threshold Vthmax during a period (first period) Pp1 between time (first timing) t21 and time (second timing) t22 after the start of diagnostic control. Furthermore, the second threshold Vth2 may be set smaller than the lower limit threshold Vthmin during a period (second period) Pp2 between time (third timing) t23 and time (fourth timing) t24 from the start of the period (predetermined period) P. This allows for more accurate determination of the occurrence of a ground fault current and diagnosis of an abnormality in the detection unit 26. As illustrated in FIG. 4, when the detection voltage Vdet exceeds the lower limit threshold Vthmin (time t31), the first threshold Vth1 is set to the upper limit threshold Vthmax from a value lower than the upper limit threshold Vthmax. At time t32, a predetermined time after time t31, the second threshold Vth2 is set to a value lower than the lower limit threshold Vthmin, and diagnosis of the detection unit 26 using the first and second thresholds Vth1 and Vth2 is initiated. Then, at the timing (time t33) when the detection voltage Vdet stops changing, the first threshold Vth1 is set to the upper limit threshold Vhmax, and the second threshold Vth2 is set to the lower limit threshold Vthmin, and diagnosis of the detection unit 26 using the first and second thresholds Vth1 and Vth2 is continued. Furthermore, when the detection voltage Vdet does not change between the upper limit threshold Vthmax and the lower limit threshold Vthmin within a predetermined time tref1 from time t33 (time t34), it is determined that the detection voltage Vdet is saturated, and diagnosis of the detection unit 26 using the first and second thresholds Vth1 and Vth2 is continued. When a predetermined time tref2 has elapsed from time t34 (time t35), the second threshold Vth2 is set to a value lower than the lower limit threshold Vthmin, and the negative electrode relay Rln is turned off.Then, when a predetermined time tref3 has elapsed since time t35 (time t36), the diagnosis of detection unit 26 is terminated. Furthermore, when a predetermined time tref4 has elapsed since time t35 (time t37), first threshold value Vth1 is set to a value smaller than upper limit threshold value Vhmax. Because the voltage value and time constant of detection voltage Vdet vary depending on the stray capacitances Cva and Cvb of power line 24 of vehicle 10 connected to charging station 20, by changing first and second threshold values ​​Vth1 and Vth2 over time depending on the voltage value of detection voltage Vdet, it is possible to more accurately determine the occurrence of a ground fault current and diagnose the occurrence of an abnormality in detection unit 26.

[0028] In the above-described embodiment, the control device 30 determines whether a ground fault current is occurring in the power line 24, particularly the negative line 24b, by determining whether the detected voltage Vdet from the amplifier Amp exceeds the first threshold Vth1. However, the control device 30 may also determine whether a ground fault current is occurring in the power line 24, particularly the positive line 24a, by determining whether the detected voltage Vdet from the amplifier Amp is less than the third threshold Vth3. FIG. 5 is an explanatory diagram illustrating how the ground fault current occurring in the positive line 24a changes over time. The dashed line L4 indicates the time change of the ground fault current occurring in the positive line 24a. As shown in the figure, when a ground fault current occurs in the positive line 24a, the detected voltage Vdet decreases at a time change rate equal to or greater than a predetermined rate. Therefore, a third threshold Vth3 is set as a threshold for determining whether a ground fault current has occurred, and when the detected voltage Vdet from the amplifier Amp is equal to or greater than the third threshold Vth3, it is determined that a ground fault current has not occurred in the power line 24 (positive line 24a), and when the detected voltage Vdet from the amplifier Amp becomes less than the third threshold Vth3 at a time rate equal to or greater than a predetermined rate, it is determined that a ground fault current has occurred in the power line 24 (positive line 24a). In this way, it is possible to determine whether a ground fault current has occurred in the power line 24 based on the detected voltage Vdet and the third threshold Vth3.

[0029] In the above-described embodiment, the negative relay Rln is turned on during diagnostic control to connect the negative line 24b to ground via resistor Rnx. However, the positive relay Rlp may also be turned on during diagnostic control to connect the positive line 24a to ground via resistor Rpx. In this case, turning on the positive relay Rlp discharges the charges of the stray capacitances Cva and Ca via resistor Rpx, creating a pseudo-ground fault in the positive line 24a and causing the voltage of the positive line 24a to drop. When the detector 26 is normal, the detection voltage Vdet output from the amplifier Amp drops with a relatively large time constant until the charge of the stray capacitance Ca is completely discharged. Once the charge of the stray capacitance Ca is completely discharged, the detection voltage Vdet reaches a saturated state where it does not fluctuate. Then, when the positive relay Rlp is turned off, the stray capacitance Ca is charged, and the voltage of the positive line 24a increases, causing the detection voltage Vdet to rise. The time constant of the detection voltage Vdet and the voltage in the saturated state at this time vary due to variations in the circuits connected to the power line 24. Taking into account the fluctuations in the detection voltage Vdet when in the saturated state, the control device 30 sets the fourth threshold Vth4 to be larger by a margin than the voltage that the detection voltage Vdet is estimated to reach when in the saturated state and larger than the third threshold Vth3 illustrated in FIG. 5. During execution of diagnostic control, the control device 30 diagnoses the detection unit 26 as normal if the detection voltage Vdet is equal to or smaller than the fourth threshold Vth4 and equal to or larger than the third threshold Vth3 during a period P2 when the detection voltage Vdet is estimated to reach the saturated state in consideration of the fluctuations in the time constant of the detection voltage Vdet. However, the control device 30 diagnoses that an abnormality has occurred in the detection unit 26 when the detection voltage Vdet exceeds the fourth threshold Vth4 or is smaller than the third threshold Vth3 during the period P2. In this way, by diagnosing the state of the detection unit 26 based on the detection voltage Vdet and the third and fourth threshold values ​​Vth3 and Vth4 during the period P2 while the diagnostic control is being executed, it is possible to properly diagnose the detection unit 26. Even during such diagnostic control, it is possible to determine whether or not a ground fault current (leakage current) is occurring in the power line 24 based on the detection voltage Vdet and the third threshold value Vth3.

[0030] In the above-described embodiment, the disconnector 28 includes a positive relay Rlp and a negative relay Rln. However, since the disconnector 28 only needs to connect and disconnect the power line 24 to and from the ground, as illustrated in a disconnector 128 of another embodiment shown in FIG. 6 , transistors Tr1 and Tr2, such as MOSFETs, may be provided instead of the positive relay Rlp and the negative relay Rln, and the transistors Tr1 and Tr2 may be turned on and off to connect and disconnect the resistor connected to the power line 24 to and from the ground. Alternatively, the disconnector 28 may include a constant current circuit instead of the positive relay Rlp and the negative relay Rln, and the current value of the constant current circuit may be switched between a relatively large current I1 and a current value I2 that can be considered almost zero, thereby connecting and disconnecting the power line 24 to and from the ground.

[0031] In the above-described embodiment, the detector 26 determines whether a ground fault current (leakage current) is occurring in the negative line 24b based on the detected voltage Vdet from the amplifier Amp, which is based on the voltage Vrs of the resistor Rx, and the first threshold Vth1. However, the detector 26 only needs to be able to detect the current flowing between the power line 24 and the ground via the resistors Rn and Rp. For example, instead of the resistor Rx and the amplifier Amp, a current transformer or the like may be used to detect the current flowing between the power line 24 and the ground via the resistors Rn and Rp.

[0032] In the above-described embodiment, the second threshold Vth2 and the period P are adjusted in accordance with fluctuations in the voltage value and time constant of the detection voltage Vdet due to variations in the circuits connected to the power line 24. However, because the voltage value and time constant of the detection voltage Vdet fluctuate depending on the stray capacitances Cva and Cvb of the power line 24 of the vehicle 10 connected to the charging station 20, individual information about the vehicle 10 (manufacturer, vehicle model, vehicle name, vehicle model, vehicle identification number, etc.) may be received from the vehicle 10 via communication or the like, and the period P and the second threshold Vth2 may be adjusted in accordance with the individual information about the vehicle 10.

[0033] In the above-described embodiment, the detection unit 26 detects a ground fault in the power line 24 of the charging stand 20. However, the detection unit 26 is not limited to detecting a ground fault in the power line 24 of the charging stand 20, and may also detect leakage current to a nearby metal housing.

[0034] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be explained below. In the embodiment, the disconnection unit 28 corresponds to the "disconnection unit," and the control device 30 corresponds to the "determination and diagnosis unit."

[0035] The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the embodiments are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0036] Although the embodiments have been described above as modes for carrying out the present disclosure, the present disclosure is not limited to these embodiments and can, of course, be embodied in various forms without departing from the spirit and scope of the present disclosure. [Industrial Applicability]

[0037] The present disclosure is applicable to the manufacturing industry of diagnostic devices. [Explanation of symbols]

[0038] 10 vehicle, 12 power line, 12b negative line, 20 charging stand, 22 power output section, 24 power line, 24a positive line, 24b negative line, 26 detection section, 28 disconnection section, 30 control device, 128 disconnection section, Amp amplifier, C cable, Ca stray capacitance, Cb stray capacitance, Cva stray capacitance, Cvb stray capacitance, Rln negative relay, Rlp positive relay, Rn resistor, Rnx resistor, Rp resistor, Rpx resistor, Rx resistor, Tr1 transistor, Tr2 transistor.

Claims

1. A determination and diagnosis device that determines whether or not a leakage current is occurring based on a detection value from a detection unit that detects a current flowing between an electric circuit and a predetermined location, and diagnoses the state of the detection unit, a disconnection unit that connects and disconnects the resistor connected to the electric path to the predetermined location; a determination and diagnosis unit that determines whether or not the leakage current is occurring based on the detection value and a first threshold value, and diagnoses the state of the detection unit based on the detection value, the first threshold value, and a second threshold value different from the first threshold value while executing diagnostic control that controls the connection / disconnection unit so that the electric path and the predetermined location are connected; A determination and diagnosis device comprising:

2. 2. The determination and diagnosis device according to claim 1, the detection unit detects a current flowing between the electric path and the predetermined location as a voltage; The determination and diagnosis unit sets the second threshold lower than the first threshold, and determines that the leakage current is occurring when the detection value exceeds the first threshold at a time change rate equal to or greater than a predetermined rate, and diagnoses that an abnormality has occurred in the detection unit when the detection value becomes equal to or greater than the first threshold during execution of the diagnostic control, and when the detection value becomes less than the second threshold within a predetermined period during execution of the diagnostic control. Judgment diagnostic device.

3. 3. The determination and diagnosis device according to claim 1 or 2, At least one of the first threshold value and the second threshold value changes over time depending on the elapsed time since the start of the diagnostic control. Judgment diagnostic device.

4. 3. The determination and diagnosis device according to claim 2, The determination and diagnosis unit reduces the first threshold value before and after a first period between a first timing and a second timing from the start of the diagnostic control compared to the first period, and reduces the second threshold value before and after a second period between a third timing and a fourth timing from the start of the predetermined period compared to the second period. Judgment diagnostic device.

5. A determination and diagnosis device that determines whether or not a leakage current is occurring based on a detection value from a detection unit that detects a current flowing between an electric circuit and a predetermined location, and diagnoses the state of the detection unit, a disconnection unit that connects and disconnects the resistor connected to the electric path to the predetermined location; a determination and diagnosis unit that determines whether the leakage current is occurring based on the detection value and a first threshold value, and diagnoses the state of the detection unit based on the detection value and a time-varying second threshold value while executing diagnostic control that controls the connection / disconnection unit so that the electric path and the predetermined location are connected; A determination and diagnosis device comprising:

Images