Leakage detection device

Abstract

To provide an earth leakage detection device capable of highly accurately detecting earth leakage.SOLUTION: An earth leakage detection device 20 for detecting earth leakage, includes a first voltage divider circuit 30, a second voltage divider circuit 40 connected in parallel to the first voltage divider circuit 30, a second switch S2 configured to be able to switch between an energized state and an energized cutoff state of the second voltage divider circuit, and a control device 70 for executing switching control of the second switch S2 to input first voltage division values Vns1 and Vns2 from the first voltage divider circuit 30, and calculating insulation resistance from the input first voltage division values to detect the earth leakage. The first voltage divider circuit 30 includes a range change circuit 60 for changing a voltage division ratio of the first voltage divider circuit 30. When the input first voltage division values Vns01 and Vns02 are smaller than a threshold Vth, the control device 70 causes the range change circuit 60 to change the voltage division ratio of the first voltage divider circuit 30.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an earth leakage detection device. [Background technology]

[0002] Conventionally, vehicles such as hybrid vehicles and electric vehicles are equipped with a high-voltage battery and have a high-voltage circuit. In such vehicles, the high-voltage circuit is generally configured to be electrically isolated from the vehicle body (body ground, frame ground) to ensure safety. In such cases, a leakage current detector (insulation resistance detection circuit) is generally provided to detect the insulation state (ground fault) between the high-voltage circuit and the vehicle body (for example, Patent Document 1).

[0003] The insulation resistance detection circuit described in Patent Document 1 is configured to detect insulation resistance and also to detect a decrease in detection accuracy due to deterioration over time of the detection resistor that constitutes the voltage divider circuit or poor contact, etc. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-50964 Summary of the Invention [Problem to be solved by the invention]

[0005] In the insulation resistance detection circuit of Patent Document 1, the detected voltage decreases when the ground insulation resistance Rn (insulation resistance on the negative side) between the ground that determines the reference potential of the high-voltage electric circuit and the vehicle ground decreases. If the detected voltage becomes too small, the resolution of the insulation resistance detection circuit will result in a large detection error, and it may become impossible to correctly determine whether a leakage current is present.

[0006] The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an electric leakage detection device that can perform electric leakage detection with high accuracy. [Means for solving the problem]

[0007] The leakage detection device for solving the above problem comprises: 1. A leakage current detection device for detecting a leakage current between a power supply path connected to a battery terminal and ground, a first voltage divider circuit having one end connected to the power supply path side and the other end connected to the ground side; a resistor circuit having one end connected to the power supply path side and the other end connected to the ground side and connected in parallel to the first voltage dividing circuit; a switch unit configured to be able to switch between a conducting state and a non-conducting state of the resistor circuit; a control unit that controls switching of the switch unit to input a first divided voltage value of the first voltage divider circuit, calculates an insulation resistance from the input first divided voltage value, and detects a leakage current; the first voltage divider circuit has a range change circuit that changes the voltage division ratio of the first voltage divider circuit; When the input first voltage division value of the first voltage division circuit is smaller than a threshold value, the control unit changes the voltage division ratio of the first voltage division circuit by the range change circuit so that the first voltage division value becomes larger.

[0008] With this configuration, when the first divided voltage value is smaller than the threshold value, the control unit changes the voltage division ratio so that the first divided voltage value is increased, so that the resolution can be effectively reduced without changing the resolution of the control unit. Therefore, even if the insulation resistance decreases, the detection error can be reduced and leakage current detection can be performed accurately.

[0009] The leakage detection device for solving the above problem comprises: A leakage detection device for detecting a leakage current between a positive-side power supply path connected to a positive terminal of a battery and a ground, and a leakage current between a negative-side power supply path connected to a negative terminal of the battery and a ground, a first voltage divider circuit having one end connected to a first power supply path that is one of the positive power supply path and the negative power supply path, and the other end connected to the ground side; a resistor circuit having one end connected to the first power supply path side and the other end connected to the ground side and connected in parallel to the first voltage dividing circuit; a switch unit configured to be able to switch between a conducting state and a non-conducting state of the resistor circuit; a control unit that switches and controls the switch unit to input a first divided voltage value of the first voltage divider circuit, calculates an insulation resistance from the input first divided voltage value, and detects leakage current; and a resistor having one end connected to a second power supply path different from the first power supply path among the positive power supply path and the negative power supply path, and having the other end connected to the ground side.

[0010] This makes it possible to suppress the influence of an increase in insulation resistance. [Brief explanation of the drawings]

[0011] [Figure 1] Configuration diagram of an on-board power supply system. [Figure 2] 10 is a flowchart of a leakage detection process. [Figure 3] 10 is a flowchart of a switching process. [Figure 4] 10 is a flowchart of a calculation process. [Figure 5] 10 is a flowchart of a characteristic determination process. [Figure 6] 10 is a flowchart of an insulation resistance calculation process. [Figure 7] FIG. [Figure 8] 10 is a timing chart showing detection timing. [Figure 9] 10 is a timing chart showing detection timing. [Figure 10] FIG. 10 is a diagram showing detection accuracy in a comparative example. [Figure 11] FIG. 4 is a diagram showing detection accuracy in the present invention. [Figure 12]FIG. 10 is a configuration diagram of a modified in-vehicle power supply system. [Figure 13] 10A to 10C are diagrams showing calculation methods of various values ​​in a modified example. [Figure 14] FIG. 10 is a configuration diagram of a modified in-vehicle power supply system. [Figure 15] FIG. 10 is a configuration diagram of a modified in-vehicle power supply system. [Figure 16] FIG. 10 is a configuration diagram of a modified in-vehicle power supply system. [Figure 17] 10A to 10C are diagrams showing calculation methods of various values ​​in a modified example. [Figure 18] 10 is a flowchart of a leakage detection process according to a modified example. [Figure 19] 10A to 10C are diagrams showing calculation methods of various values ​​in a modified example. [Figure 20] FIG. 10 is a configuration diagram of an on-board power supply system according to a second embodiment. [Figure 21] FIG. 4 is a diagram showing a detection range and an on / off state of a switch. [Figure 22] 10 is a flowchart of a leakage detection process according to a second embodiment. [Figure 23] 10 is a flowchart of a range switching process. [Figure 24] 10 is a flowchart of a detection process. [Figure 25] 10 is a flowchart of an insulation resistance calculation process according to a second embodiment. [Figure 26] 10A to 10C are diagrams showing calculation methods of various values ​​in the second embodiment. [Figure 27] 10 is a timing chart showing switching of the detection range. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, a first embodiment in which the "earth leakage detection device" is applied to an on-board power supply system of a vehicle (for example, a hybrid vehicle or an electric vehicle) equipped with a rotating electric machine as an on-board main engine will be described with reference to the drawings. Note that in the following embodiments, identical or equivalent parts are assigned the same reference numerals in the drawings, and the explanations of the parts with the same reference numerals are incorporated herein.

[0013] (First embodiment) 1 includes a battery pack 10, which is a battery, and a leakage detection device 20. Although not shown or described, an electric load such as a rotating electric machine is connected to a positive power supply path L1 and a negative power supply path L2 connected to the battery pack 10.

[0014] The battery pack 10 is a storage battery having a terminal voltage V1 of, for example, 800 V. The battery pack 10 is configured by connecting a plurality of battery cells. For example, a lithium ion battery or a nickel-metal hydride battery can be used as the battery cells.

[0015] A positive power supply path L1 (corresponding to a power line) connected to a positive power supply terminal of the battery pack 10 is electrically insulated from a vehicle-side ground FG such as a vehicle body. The vehicle-side ground FG is the vehicle body or the like, and corresponds to a frame ground. The state of insulation (ground insulation resistance) between this positive power supply path L1 and the vehicle-side ground FG can be expressed as an insulation resistance Rp.

[0016] Similarly, the negative power supply path L2 connected to the negative power supply terminal of the battery pack 10 is electrically insulated from the vehicle ground FG. The state of insulation (ground insulation resistance) between this negative power supply path L2 and the vehicle ground FG can be expressed as insulation resistance Rn. The negative power supply path L2 corresponds to the ground (signal ground SG) that determines the reference potential of the high-voltage electrical circuit.

[0017] The leakage current detection device 20 is connected to the vehicle-side ground FG and the negative power supply path L2, and detects whether the positive power supply path L1 and the negative power supply path L2 are properly insulated from the vehicle-side ground FG, i.e., detects leakage current (ground fault).

[0018] A detailed description will be given of the leakage current detection device 20. The leakage current detection device 20 includes a first voltage dividing circuit 30, a second voltage dividing circuit 40 connected in parallel to the first voltage dividing circuit 30, a first switch S1, a second switch S2, and a control device 70 as a control unit that detects leakage current.

[0019] The first voltage dividing circuit 30 is connected between the vehicle side ground FG and the negative side power supply path L2, and divides the voltage between the negative side power supply path L2 and the vehicle side ground FG (the voltage across both ends of the first voltage dividing circuit 30) with a voltage dividing ratio α or a voltage dividing ratio α'.

[0020] To explain the configuration in detail, the first voltage dividing circuit 30 has a first-A detection resistor Rs1, a first-B detection resistor Rk1', and a first-C detection resistor Rk1. The first-C detection resistor Rk1 is connected in parallel to the first-B detection resistor Rk1'. The parallel connection of the first-C detection resistor Rk1 and the first-B detection resistor Rk1' is connected in series to the first-A detection resistor Rs1.

[0021] The first-A detection resistor Rs1 is connected to the vehicle-side ground FG, and a parallel connection consisting of the first-B detection resistor Rk1' and the first-C detection resistor Rk1 is connected to the negative-side power supply path L2. One end of a first output line L11 is connected to a first connection point P1 between the first-A detection resistor Rs1 and the parallel connection consisting of the first-B detection resistor Rk1' and the first-C detection resistor Rk1. A voltage signal (first divided voltage value) from the first voltage divider circuit 30 is output via the first output line L11.

[0022] Furthermore, a third switch S3 is connected in series to the first C detection resistor Rk1, and is configured so that the third switch S3 can switch between a conducting state and a non-conducting state. When the third switch S3 is turned on, the first C detection resistor Rk1 is in a conducting state, and the voltage division ratio of the first voltage divider circuit 30 becomes α. When the third switch S3 is turned off, the first C detection resistor Rk1 is in a non-conducting state, and the voltage division ratio of the first voltage divider circuit 30 becomes α'.

[0023] The third switch S3 is controlled to be turned on and off by the control device 70. The resistance value of the first-B detection resistor Rk1' is much larger than the resistance value of the first-C detection resistor Rk1, for example, approximately 10 times larger. Therefore, the voltage division ratio α' is larger than the voltage division ratio α, and the detection voltage increases when the third switch S3 is turned off. For example, if the resistance value of the first-B detection resistor Rk1' is 10 times larger than that of the first-C detection resistor Rk1, the voltage division value (voltage signal) will also be approximately 10 times larger. In other words, if the detection range is normally 0 to V1, switching the third switch S3 off will result in detection in the range of 0 to V1 / 10. In this embodiment, the first-B detection resistor Rk1' and the third switch S3 correspond to the range change circuit 60.

[0024] The second voltage-dividing circuit 40 is connected between the negative power supply path L2 and the vehicle ground FG, and divides the voltage between the negative power supply path L2 and the vehicle ground FG (the voltage across the second voltage-dividing circuit 40) by a voltage division ratio β. The second voltage-dividing circuit 40 corresponds to a resistor circuit. In the first embodiment, the negative power supply path L2 corresponds to the first power supply path, and the positive power supply path L1 corresponds to the second power supply path. The second voltage-dividing circuit 40 includes a second-A detection resistor Rs2 and a second-B detection resistor Rk2, which are connected in series. The second-A detection resistor Rs2 is connected to the vehicle ground FG, and the second-B detection resistor Rk2 is connected to the negative power supply path L2. One end of the second output line L12 is connected to a second connection point P2 between the second A detection resistor Rs2 and the second B detection resistor Rk2, and a voltage signal (second divided voltage value) from the second voltage divider circuit 40 is output via the second output line L12.

[0025] Next, the first switch S1 and the second switch S2 will be described. The first switch S1 and the second switch S2 are configured to be on / off controlled by the control device 70. The first switch S1 is configured to be able to switch between an energized state and an energized / deenergized state of the first voltage dividing circuit 30. The second switch S2 is configured to be able to switch between an energized state and an energized / deenergized state of the second voltage dividing circuit 40.

[0026] Specifically, the first switch S1 is connected between the first connection point P1 and the first A detection resistor Rs1 and is configured to be able to switch between a conducting state and a non-conducting state between the first connection point P1 and the first A detection resistor Rs1. The second switch S2 is connected between the second connection point P2 and the second A detection resistor Rs2 and is configured to be able to switch between a conducting state and a non-conducting state between the second connection point P2 and the second A detection resistor Rs2. The second switch S2 corresponds to a switch unit.

[0027] The control device 70 is primarily configured as a microcomputer equipped with a CPU, ROM, RAM, I / O, etc., and various functions are realized by the CPU executing programs stored in the ROM. Note that the various functions may be realized by electronic circuits, which are hardware, or at least a portion of the functions may be realized by software, i.e., by processing executed on a computer. The control device 70 has functions such as controlling the on / off states of the first switch S1 and the second switch S2, controlling the on / off state of the third switch S3, and detecting leakage current. Note that a switch control unit having functions such as controlling the on / off states of the various switches may be provided separately from the control device 70, and may cooperate with the control device 70 to detect leakage current.

[0028] The control device 70 estimates the values ​​of the insulation resistances Rp and Rn based on the voltage signal (first voltage division value) input from the first voltage division circuit 30, and detects leakage current. However, as the insulation resistance Rn decreases, the first voltage division value also decreases. If the first voltage division value becomes too small, the resolution of the control device 70 may result in a large detection error, making it impossible to correctly determine leakage current. Therefore, to prevent the first voltage division value from becoming too small, a range change circuit 60 is provided, which is configured to change the first voltage division ratio.

[0029] The leakage current detection process will be described in detail below with reference to Figures 2 to 6. Figure 7 shows the resistance values ​​R1 and R1' of the first voltage-dividing circuit 30, the resistance value R2 of the second voltage-dividing circuit 40, the voltage-dividing ratios α and α' of the first voltage-dividing circuit 30, the voltage-dividing ratio β of the second voltage-dividing circuit 40, the calculation formulas for the insulation resistances Rp, Rn, and Rp / / Rn, and the characteristic diagnostic formula.

[0030] 7, the left side shows how to calculate each value when the third switch S3 is on, and the right side shows how to calculate each value when the third switch S3 is off. That is, the resistance value R1 of the first voltage-dividing circuit 30 is the resistance value when the third switch S3 is on, and the resistance value R1' is the resistance value when the third switch S3 is off. Similarly, the voltage-dividing ratio α of the first voltage-dividing circuit 30 is the voltage-dividing ratio when the third switch S3 is on, and the voltage-dividing ratio α' is the voltage-dividing ratio when the third switch S3 is off.

[0031] The characteristic diagnostic formula is a formula used when performing characteristic determination to determine whether or not an abnormality has occurred in the characteristics of the first voltage divider circuit 30 and the second voltage divider circuit 40. Characteristic determination means, for example, determining whether or not the values ​​of the detection resistors Rs1, Rs2, Rk1, Rk1', and Rk2 have changed due to aging, poor contact, foreign matter contamination, disconnection, short circuit, etc.

[0032] The resistance value of the first-A detection resistor Rs1 is "Rs1," the resistance value of the first-B detection resistor Rk1' is "Rk1'," and the resistance value of the first-C detection resistor Rk1 is "Rk1." Similarly, the resistance value of the second-A detection resistor Rs2 is "Rs2," and the resistance value of the second-B detection resistor Rk2 is "Rk2." The inter-terminal voltage of the battery pack 10 is "V1."

[0033] The voltage across the insulation resistor Rn when the first switch S1 and the second switch S2 are turned on corresponds to "Vn1." The voltage across the insulation resistor Rn when the first switch S1 is turned on and the second switch S2 is turned off corresponds to "Vn2."

[0034] Furthermore, the first voltage division value from the first voltage dividing circuit 30 corresponds to "Vnsi", and the first voltage division value from the first voltage dividing circuit 30 when the first switch S1 and the second switch S2 are turned on corresponds to "Vns1". Furthermore, the first voltage division value from the first voltage dividing circuit 30 when the first switch S1 is turned on and the second switch S2 is turned off corresponds to "Vns2". Furthermore, the first voltage division value from the second voltage dividing circuit 40 when the first switch S1 and the second switch S2 are turned on corresponds to "Vrs1".

[0035] The leakage detection process shown in Fig. 2 is performed by the control device 70 at predetermined intervals (e.g., every several tens of milliseconds). When the leakage detection process is performed, the control device 70 first turns on all of the first switch S1 to the third switch S3 (step S101). As a result, the first voltage-dividing circuit 30 and the second voltage-dividing circuit 40 are both energized, and as a result, the first voltage-dividing circuit 30, the second voltage-dividing circuit 40, and the insulation resistor Rn are connected in parallel between the negative-side power supply path L2 and the vehicle-side ground FG. Furthermore, in the first voltage-dividing circuit 30, the first-B detection resistor Rk1' and the first-C detection resistor Rk1 are both energized, and the voltage division ratio of the first voltage-dividing circuit 30 becomes the voltage division ratio α.

[0036] Then, after a predetermined time has elapsed, the control device 70 performs a switching process of the third switch S3 (step S102). The switching process will now be described with reference to Fig. 3. Note that in the switching process of step S102, i is read as 1. For example, Vns0i in Fig. 3 is read as Vns01.

[0037] In the switching process, the control device 70 inputs (detects) the first voltage division value Vns0i from the first voltage division circuit 30 (step S201). When the third switch S3 is on, the first voltage division value Vns0i=α×Vni, and when it is off, the first voltage division value Vns0i=α′×Vni.

[0038] Next, the control device 70 determines whether the third switch S3 is on (step S202). If the determination result in step S202 is positive, the control device 70 determines whether the detected first divided voltage value Vns0i is smaller than a threshold value Vth (step S203). The threshold value Vth is an arbitrary value, and is set depending on the resolution of the control device 70, the required detection accuracy, etc.

[0039] If the determination result in step S203 is positive, the control device 70 switches the third switch S3 off (step S204). As a result, in the first voltage-dividing circuit 30, the first C detection resistor Rk1 is brought into a de-energized state, and the voltage division ratio of the first voltage-dividing circuit 30 becomes the voltage division ratio α'. If the determination result in step S203 is negative, the control device 70 ends the switching process and proceeds to the process of step S103.

[0040] On the other hand, if the determination result in step S202 is negative, the control device 70 determines whether the detected first divided voltage value Vns0i is equal to or greater than a limit value Vmax (step S205). The limit value Vmax is an arbitrary value, and is set depending on the resolution, withstand voltage, detection accuracy, etc. of the control device 70.

[0041] If the determination result in step S205 is positive, the control device 70 turns on the third switch S3 (step S206) and ends the switching process. As a result, in the first voltage dividing circuit 30, the first C detection resistor Rk1 is energized, and the voltage division ratio of the first voltage dividing circuit 30 becomes the voltage division ratio α. If the determination result in step S205 is negative, the control device 70 ends the switching process and proceeds to the process of step S103.

[0042] 2, after the switching process in step S102 is completed and a predetermined time has elapsed, the control device 70 inputs (detects) the first voltage division value Vns1 from the first voltage division circuit 30 and inputs (detects) the second voltage division value Vrs1 from the second voltage division circuit 40 (step S103). When the third switch S3 is on, the first voltage division value Vns1=α×Vn1, and when the third switch S3 is off, the first voltage division value Vns1=α′×Vn1. Also, the second voltage division value Vrs1=β×Vn1.

[0043] Next, the control device 70 performs a calculation process for Vn1 (step S104). Here, the calculation process will be described with reference to Fig. 4. Note that in the calculation process of step S104, i is replaced with 1. For example, Vni in Fig. 4 is replaced with Vn1, and Vnsi is replaced with Vns1.

[0044] In the calculation process, the control device 70 determines whether the third switch S3 is on (step S301). If the determination result in step S301 is positive, the control device 70 calculates Vnsi / α to calculate Vni (step S302) and ends the calculation process. On the other hand, if the determination result in step S301 is negative, the control device 70 calculates Vnsi / α' to calculate Vni (step S303) and ends the calculation process.

[0045] 2, after the calculation process in step S104 is completed, the control device 70 performs a characteristic determination process (step S105). Here, the characteristic determination process will be described with reference to FIG.

[0046] In the characteristic determination process of step S105, the control device 70 determines whether the third switch S3 is on (step S401). If the determination result of step S401 is positive, the control device 70 determines whether the result of equation (1) shown in FIG. 7 is approximately 1 (step S402). That is, as shown in FIG. 7, it determines whether the value (value of (Vns1 / α)×(β / Vrs1)) of the characteristic diagnosis equation (equation (1)) when the third switch S3 is on is within a predetermined range close to 1. The predetermined range is set in consideration of calculation accuracy. If this value is within the predetermined range close to 1, it is determined that there is no abnormality, and if it is not within the predetermined range, it is determined that there is an abnormality.

[0047] On the other hand, if the determination result in step S401 is negative, the control device 70 determines whether the result of equation (2) shown in FIG. 7 is approximately 1, as in step S402 (step S403). That is, as shown in FIG. 7, it determines whether the value (value of (Vns1 / α') × (β / Vrs1)) of the characteristic diagnostic equation (equation (2)) when the third switch S3 is off is within a predetermined range close to 1. The predetermined range is set in consideration of calculation accuracy. If this value is within the predetermined range close to 1, it is determined that there is no abnormality, and if it is not within the predetermined range, it is determined that there is an abnormality.

[0048] If the determination result in step S402 or step S403 is positive, it is determined that there is no characteristic abnormality, and the control device 70 ends the characteristic determination process and proceeds to the next step S106. On the other hand, if the determination result in step S402 or step S403 is negative, it is determined that there is a characteristic abnormality in the first voltage-divider circuit 30 or the second voltage-divider circuit 40, and the control device 70 interrupts the leakage detection process and performs a process to deal with the abnormality in the voltage-divider circuits 30, 40 (step S404). The process to deal with the abnormality in the voltage-divider circuits 30, 40 is, for example, a process to notify an external device of the abnormality and issue a warning that leakage detection is impossible.

[0049] As shown in Fig. 2, after the characteristic determination process has been completed successfully, the control device 70 switches the second switch S2 off when a predetermined time has elapsed (step S106). Thereafter, the control device 70 performs switching processing of the third switch S3 when a predetermined time has elapsed (step S107). Note that the switching processing of step S107 is the same as that described above if i=2 is used in the switching processing of step S102 and the description of Fig. 3. For example, if Vns0i is replaced with Vns02, the same is true. Therefore, a description thereof will be omitted here.

[0050] 2, after the switching process in step S107 is completed and a predetermined time has elapsed, the control device 70 inputs (detects) the first voltage division value Vns2 from the first voltage division circuit 30 (step S108). When the third switch S3 is on, the first voltage division value Vns2=α×Vn2, and when the third switch S3 is off, the first voltage division value Vns2=α′×Vn2.

[0051] Next, the control device 70 performs a calculation process for Vn2 (step S109). The calculation process in step S109 is the same as that described above if i=2 is used in the calculation process in step S104 and the description of FIG. 4. For example, if Vnsi is replaced with Vns2 and Vni is replaced with Vn2, the calculation process is the same as that described above. Therefore, a description thereof will be omitted here.

[0052] When the calculation process of step S109 is completed, the control device 70 performs an insulation resistance calculation process to calculate the insulation resistance (step S110), as shown in Fig. 2. The insulation resistance calculation process will be described with reference to Fig. 6.

[0053] In the insulation resistance calculation process of step S110, the control device 70 determines whether the third switch S3 is on (step S501). If the determination result of step S501 is positive, the control device 70 calculates the insulation resistance based on Vn1 and Vn2 calculated in steps S104 and S109 (step S502). In step S502, Rp / / Rn is calculated with reference to equation (3) shown in FIG. 7, that is, from the synthetic equation of the insulation resistances Rp and Rn when the third switch S3 is on. Note that the insulation resistances Rp and Rn may also be calculated from equations (5) and (7) shown in FIG. 7, respectively.

[0054] On the other hand, if the determination result in step S501 is negative, the control device 70 calculates the insulation resistance based on Vn1 and Vn2 calculated in steps S104 and S109 (step S503). In step S503, Rp / / Rn is calculated by referring to equation (4) shown in Fig. 7, that is, from the synthetic equation of the insulation resistances Rp and Rn when the third switch S3 is off. Note that the insulation resistances Rp and Rn may also be calculated from equations (6) and (7) shown in Fig. 7, respectively.

[0055] After calculating the insulation resistance, the insulation resistance calculation process ends, and the control device 70 determines whether or not there is a leak based on the calculated insulation resistance (step S111). In step S111, for example, the determination of whether or not there is a leak is based on whether or not the calculated Rp / / Rn is within a predetermined normal range. Alternatively, when the insulation resistances Rp and Rn are calculated, the determination of whether or not there is a leak may be based on whether or not they are equal to or less than the determination threshold values ​​Rp0 and Rn0, respectively.

[0056] If the determination result in step S111 is positive (if a leakage current is detected), the control device 70 performs processing to deal with the leakage current (step S112) and ends the leakage current detection processing. The processing to deal with the leakage current is, for example, processing to notify an external device of the leakage current and issue a warning. On the other hand, if the determination result in step S112 is negative (if a leakage current is not detected), the control device 70 determines that the device is normal and ends the leakage current detection processing.

[0057] Next, the detection timing of the voltage division value and the switching timing of the first switch S1 to the third switch S3 will be described with reference to FIGS.

[0058] 8 will be explained under the assumption that the insulation resistors Rp and Rn are all normal. When the first switch S1 to the third switch S3 are turned on (at time t1), the first voltage-dividing circuit 30 and the second voltage-dividing circuit 40 are both energized, and as a result, the first voltage-dividing circuit 30, the second voltage-dividing circuit 40, and the insulation resistor Rn are connected in parallel between the negative power supply path L2 and the vehicle-side ground FG. Furthermore, in the first voltage-dividing circuit 30, the first-B detection resistor Rk1' and the first-C detection resistor Rk1 are both energized, and the voltage division ratio of the first voltage-dividing circuit 30 becomes the voltage division ratio α.

[0059] To stabilize the voltage division value, the control device 70 performs a switching process on the third switch S3 after a predetermined time has elapsed (at time t2). That is, the control device 70 inputs the first voltage division value Vns01 from the first voltage division circuit 30 and determines whether the first voltage division value Vns01 is smaller than the threshold value Vth. As a result, the first voltage division value Vns01 is equal to or greater than the threshold value Vth, so the third switch S3 is not turned off (it remains on). After a predetermined time has elapsed (at time t3), the control device 70 inputs the first voltage division value Vns1 and performs a calculation process for Vn1. Here, because the third switch S3 is on, the control device 70 calculates Vns1 / α to calculate Vn1.

[0060] Also, although not shown, at this time t3, the control device 70 inputs the second voltage dividing value Vrs1 from the second voltage dividing circuit 40 and performs a characteristic determination by determining whether (Vns1 / α)×(β / Vrs1) is approximately 1.

[0061] After calculating Vn1 and the like, the control device 70 turns off the second switch S2 at a timing (time t4) when a predetermined time has elapsed. As a result, the first voltage-dividing circuit 30 is energized, while the second voltage-dividing circuit 40 is energized and cut off. As a result, the first voltage-dividing circuit 30 and the insulation resistor Rn are connected in parallel between the negative power supply path L2 and the vehicle-side ground FG. In addition, in the first voltage-dividing circuit 30, the first-B detection resistor Rk1' and the first-C detection resistor Rk1 are both energized, and the voltage division ratio of the first voltage-dividing circuit 30 becomes the voltage division ratio α.

[0062] To stabilize the voltage division value, the control device 70 switches the third switch S3 after a predetermined time has elapsed (at time t5). Specifically, the control device 70 inputs the first voltage division value Vns02 from the first voltage division circuit 30 and determines whether the first voltage division value Vns02 is smaller than the threshold value Vth. Since the first voltage division value Vns02 is equal to or greater than the threshold value Vth, the control device 70 does not turn off the third switch S3 (keeps it on). Then, after a predetermined time has elapsed (at time t6), the control device 70 inputs the first voltage division value Vns2 and performs calculation processing for Vn2. Here, since the third switch S3 is on, the control device 70 calculates Vns2 / α to calculate Vn2.

[0063] The control device 70 then calculates Rp / / Rn from the calculated Vn1 and Vn2 using equation (1) shown in Fig. 7. Then, it determines that no leakage has occurred based on whether Rp / / Rn is within the normal range.

[0064] Next, a description will be given based on Fig. 9. In Fig. 9, the description will be given on the assumption that a ground fault occurs in the insulation resistor Rn after the first switch S1 to the third switch S3 are all turned on (after time t1) and before the switching process of the third switch S3 is performed (before time t2).

[0065] When the first switch S1 to the third switch S3 are turned on (at time t1), the first voltage-dividing circuit 30 and the second voltage-dividing circuit 40 are both energized, and as a result, the first voltage-dividing circuit 30, the second voltage-dividing circuit 40, and the insulation resistor Rn are connected in parallel between the negative power supply path L2 and the vehicle-side ground FG. Also, in the first voltage-dividing circuit 30, the first-B detection resistor Rk1' and the first-C detection resistor Rk1 are both energized, and the voltage division ratio of the first voltage-dividing circuit 30 becomes the voltage division ratio α.

[0066] To stabilize the voltage division value, the control device 70 switches the third switch S3 after a predetermined time has elapsed (at time t2). Specifically, the control device 70 inputs the first voltage division value Vns01 from the first voltage division circuit 30 and determines whether the first voltage division value Vns01 is smaller than the threshold value Vth. Since the first voltage division value Vns01 is smaller than the threshold value Vth, the control device 70 turns off the third switch S3. This causes the first C detection resistor Rk1 in the first voltage division circuit 30 to enter a non-conductive state, and the voltage division ratio of the first voltage division circuit 30 becomes the voltage division ratio α'. As shown in FIG. 9, the detected first voltage division value (detected voltage value) increases (by approximately 10 times). Note that in FIG. 9, the detected voltage when the voltage division ratio α of the first voltage division circuit 30 remains unchanged is indicated by a dashed line.

[0067] After a predetermined time has elapsed (at time t3), the control device 70 receives the first voltage dividing value Vns1 and performs a process of calculating Vn1. Here, since the third switch S3 is off, the control device 70 calculates Vns1 / α' to calculate Vn1.

[0068] Also, although not shown, at this time t3, the control device 70 inputs the second voltage dividing value Vrs1 from the second voltage dividing circuit 40 and performs characteristic determination by determining whether (Vns1 / α')×(β / Vrs1) is approximately 1.

[0069] After calculating Vn1 and the like, the control device 70 turns off the second switch S2 when a predetermined time has elapsed (at time t4). As a result, the first voltage-dividing circuit 30 is energized, while the second voltage-dividing circuit 40 is deenergized. As a result, the first voltage-dividing circuit 30 and the insulation resistor Rn are connected in parallel between the negative power supply path L2 and the vehicle-side ground FG.

[0070] In order to stabilize the voltage division value, the control device 70 performs a switching process of the third switch S3 after a predetermined time has elapsed (at time t5). That is, the control device 70 inputs the first voltage division value Vns02 from the first voltage division circuit 30 and determines whether the first voltage division value Vns02 is equal to or greater than the limit value Vmax. As a result, since the first voltage division value Vns02 is not equal to or greater than the limit value Vmax, the third switch S3 is turned off (kept off). As a result, in the first voltage division circuit 30, the first C detection resistor Rk1 is maintained in an electrically deenergized state, and the voltage division ratio of the first voltage division circuit 30 becomes the voltage division ratio α'.

[0071] Then, after a predetermined time has elapsed (time t6), the control device 70 receives the first divided voltage value Vns2 and performs a process of calculating Vn2. Here, since the third switch S3 is off, the control device 70 calculates Vns2 / α' to calculate Vn2.

[0072] The control device 70 then calculates Rp / / Rn from the calculated Vn1 and Vn2 using equation (2) shown in Fig. 7. Then, it determines that a leak has occurred based on whether Rp / / Rn is within the normal range.

[0073] The effects of the above embodiment will be described below.

[0074] (1) In the past, when insulation resistances Rp and Rn decreased, the effect of circuit tolerances could temporarily increase. For example, as the actual insulation resistance Rn decreased, the voltage across the insulation resistance Rn decreased accordingly. As a result, the detected values ​​Vn1 and Vn2 also decreased and approached zero. As Vn1 and Vn2 approached zero, the effect of circuit tolerances relatively increased. This could result in Vn1 and Vn2 becoming equal, or Vn1 becoming larger than Vn2, resulting in a reversal of magnitude. Furthermore, as shown in Figure 10, when the actual insulation resistance (actual Rp / Rn) decreased, the calculated insulation resistance (detected Rp / Rn) based on the detected voltage value could diverge and become indeterminate. This could prevent the calculation of a correct insulation resistance and correct judgment. In Figures 10 and 11, the ideal insulation resistance (detected Rp / Rn) is shown by a solid line, the maximum value of the calculated insulation resistance (detected Rp / Rn) is shown by a dashed line, and the minimum value is shown by a dashed line.

[0075] Therefore, when the detected first voltage division values ​​Vns01, Vns02 of the first voltage division circuit 30 are smaller than the threshold value Vth, the control device 70 switches off the third switch S3 as shown in FIG. 9 to change the voltage division ratio α of the first voltage division circuit 30 from α to α', thereby increasing the detected first voltage division value. In this way, the first voltage division value can be increased, so the resolution of the control device 70 can be effectively reduced without changing it. Therefore, even after the insulation resistance Rn has decreased, that is, even when there is a high possibility that the insulation resistance Rn has shorted, the influence of circuit tolerances can be suppressed and the first voltage division value can be detected with high accuracy.

[0076] Specifically, as can be seen by comparing range E1 (see FIG. 10) with range E2 (see FIG. 11), by applying the above-described electric leakage detection device 20, the range in which the calculated insulation resistance (detected Rp / / Rn) begins to diverge can be narrowed. In other words, even if the actual insulation resistance (actual Rp / / Rn) drops significantly, the insulation resistance (detected Rp / / Rn) can be calculated with high accuracy without divergence. Furthermore, as can be seen by comparing FIG. 10 with FIG. 11, the maximum and minimum values ​​of the calculated insulation resistance (detected Rp / / Rn) can be brought closer to the ideal values. Therefore, the accuracy of electric leakage detection can be improved.

[0077] (2) The control device 70 performs the following steps when the second voltage-dividing circuit 40 is in a conducting state: a first input step (corresponding to step S103) of inputting the first voltage-dividing value Vns1 from the first voltage-dividing circuit 30; when the second voltage-dividing circuit 40 is in a non-conducting state, a second input step (corresponding to step S108) of inputting the first voltage-dividing value Vns2 from the first voltage-dividing circuit 30; and a leakage detection step (steps S104, S109, S110, S111) of calculating the insulation resistance from the first voltage-dividing value Vns1 and the first voltage-dividing value Vns2 and detecting a leakage current. Furthermore, before performing the first input step or the second input step, the control device 70 inputs the first voltage-dividing values ​​Vns01 and Vns02 of the first voltage-dividing circuit 30, and if the input first voltage-dividing value is smaller than the threshold value Vth, turns off the third switch S3 and changes the voltage division ratio of the first voltage-dividing circuit 30 to α'. In this way, since the switching is performed at a timing before detection, the first divided voltage values ​​Vns1 and Vns2 can be detected with high accuracy.

[0078] (3) In a first switching step (corresponding to step S101), the control device 70 switches both the first switch S1 and the second switch S2 on, and in a first input step (corresponding to step S103), inputs the first divided voltage value Vns1 and the second divided voltage value Vrs1. The control device 70 then performs a characteristic determination step using the first divided voltage value Vns1 and the second divided voltage value Vrs1 (corresponding to step S105). Thereafter, in a second switching step (corresponding to step S106), the control device 70 switches the second switch S2 off, and in a second input step (corresponding to step S108), inputs the first divided voltage value Vns2.

[0079] As a result, while the first and second input steps required for leakage detection are being performed, more specifically, while the first input step is being performed, the first and second voltage dividing values ​​Vns1 and Vrs1 required for characteristic determination can be input. This eliminates the need to switch the second switch S2 and set aside time for measurement just to obtain the first and second voltage dividing values ​​Vns1 and Vrs1 required for characteristic determination, allowing leakage detection and characteristic determination to be performed efficiently. Therefore, leakage detection and characteristic determination can be performed simultaneously, making it possible to constantly determine abnormalities in the voltage dividing circuits 30 and 40, such as while the vehicle is running.

[0080] (4) In the characteristic determination process, the control device 70 changes the characteristic diagnostic formula by turning on and off the third switch S3. As a result, even if the insulation resistance Rn decreases, the voltage division ratio is changed to increase the first voltage division value to be detected, thereby improving the detection accuracy. Therefore, a decrease in the accuracy of the characteristic determination can be suppressed.

[0081] (5) When detecting leakage current by calculating the value of Rp / / Rn using the arithmetic formula (3) or (4) in Figure 7, there is no need to measure the inter-terminal voltage V1 of the battery pack 10. This eliminates the need to consider measurement errors in the inter-terminal voltage V1, improving the accuracy of leakage current detection.

[0082] (Variation) The configuration of the above embodiment may be partially modified as follows. Modifications will be described below.

[0083] In the above embodiment, the processing order of steps S104 and S109 may be changed as desired, provided that they are performed before step S110.

[0084] In the above embodiment, the leakage detection device 20 is connected between the negative power supply path L2 and the vehicle ground FG, but as shown in Fig. 12, it may be connected between the positive power supply path L1 and the vehicle ground FG. More specifically, the first voltage dividing circuit 30 shown in the modified example of Fig. 12 is connected between the positive power supply path L1 and the vehicle ground FG, and divides the voltage between the positive power supply path L1 and the vehicle ground FG (the voltage across the first voltage dividing circuit 30) with a voltage division ratio α or a voltage division ratio α'. The first-A detection resistor Rs1 shown in Fig. 12 is connected to the positive power supply path L1 side, and the parallel connection of the first-B detection resistor Rk1' and the first-C detection resistor Rk1 is connected to the vehicle ground FG side.

[0085] 12 is connected between the positive power supply path L1 and the vehicle ground FG, and divides the voltage between the positive power supply path L1 and the vehicle ground FG (the voltage across the second voltage divider circuit 40) at a voltage division ratio β. The second-A detection resistor Rs2 shown in FIG. 12 is connected to the positive power supply path L1 side, and the second-B detection resistor Rk2 is connected to the vehicle ground FG side. The control device 70 receives signals from the first voltage divider circuit 30 and the second voltage divider circuit 40 using the vehicle ground FG as a reference potential.

[0086] 13, similarly to FIG. 7, shows the resistance values ​​R1, R1' of the first voltage-dividing circuit 30, the resistance value R2 of the second voltage-dividing circuit 40, the voltage-dividing ratios α, α' of the first voltage-dividing circuit 30, the voltage-dividing ratio β of the second voltage-dividing circuit 40, the calculation formulas for the insulation resistances Rp, Rn, Rp / / Rn, and the characteristic diagnostic formula.

[0087] In Fig. 13, the voltage across the insulation resistor Rp corresponds to "Vpi," and the voltage across the insulation resistor Rp when the first switch S1 and the second switch S2 are turned on corresponds to "Vp1." Furthermore, the voltage across the insulation resistor Rp when the first switch S1 is turned on and the second switch S2 is turned off corresponds to "Vp2." Furthermore, the first divided voltage value from the first voltage divider circuit 30 corresponds to "Vpsi," and the first divided voltage value from the first voltage divider circuit 30 when the first switch S1 and the second switch S2 are turned on corresponds to "Vps1." The rest is the same as in Fig. 7.

[0088] A portion of the first voltage divider circuit 30 in the above embodiment may be modified as shown in FIG. 14. Specifically, the first voltage divider circuit 30 includes a first-A detection resistor Rs1, a first-C detection resistor Rk1, and a first-B detection resistor Rk1', which are connected in series. A third switch S3 is connected in parallel to the first-B detection resistor Rk1'. In FIG. 14, the first-B detection resistor Rk1' and the third switch S3, which is connected in parallel to the first-B detection resistor Rk1' and serves as a voltage division ratio change switch that switches the first-B detection resistor Rk1' between a conductive state and a non-conductive state, correspond to the range change circuit 60.

[0089] A portion of the first voltage-dividing circuit 30 in the above embodiment may be modified as shown in FIG. 15. Specifically, the first voltage-dividing circuit 30 includes a first-A detection resistor Rs1, a first-B detection resistor Rk1' (corresponding to a range change circuit), and a first-C detection resistor Rk1, which are connected in series in this order from the vehicle-side ground FG side. Under normal conditions (when the insulation resistance is large), the control device 70 inputs the first divided voltage values ​​Vns0i and Vnsi (i = 1 or 2) from a connection point P101 between the first-B detection resistor Rk1' and the first-C detection resistor Rk1. That is, the control device 70 inputs the first divided voltage values ​​Vns0i and Vnsi (i = 1 or 2) from the channel CH1.

[0090] Then, when the first voltage division value Vns0i (i=1 or 2) input from channel CH1 is smaller than the threshold value Vth, the control device 70 inputs the first voltage division value Vnsi (i=1 or 2) from the connection point P102 between the firstA detection resistor Rs1 and the firstB detection resistor Rk1'. That is, the control device 70 inputs the first voltage division value Vnsi (i=1 or 2) from channel CH2. As a result, the first voltage division value is input at a voltage division ratio α', and the voltage division ratio of the first voltage divider circuit 30 can be changed.

[0091] In addition, when the first divided voltage value Vns0i (i = 1 or 2) input from channel CH2 is equal to or greater than the limit value Vmax, the control device 70 inputs the first divided voltage values ​​Vns0i, Vnsi (i = 1 or 2) from channel CH1.

[0092] In the above embodiment, a range change circuit may also be provided in the second voltage divider circuit 40. For example, as shown in Fig. 16, the second voltage divider circuit 40 has a secondA detection resistor Rs2, a secondB detection resistor Rk2, a secondC detection resistor Rk2', and a fourth switch S4 as a voltage division ratio changeover switch.

[0093] The fourth switch S4 is connected in series with the second-B detection resistor Rk2 and switches between a conductive state and a non-conductive state of the second-B detection resistor Rk2. The second-A detection resistor Rs2 is connected in series with the second-C detection resistor Rk2', and the series connection of the fourth switch S4 and the second-B detection resistor Rk2 is connected in parallel with the second-C detection resistor Rk2'. The second-C detection resistor Rk2' and the fourth switch S4 correspond to the range change circuit of the second voltage divider circuit 40.

[0094] The second voltage dividing circuit 40 shown in FIG. 16 can change the voltage dividing ratio β to a voltage dividing ratio β' by turning on and off the fourth switch S4.

[0095] 17, similar to FIG. 7, shows the resistance values ​​R1 and R1' of the first voltage-dividing circuit 30, the resistance values ​​R2 and R2' of the second voltage-dividing circuit 40, the voltage-dividing ratios α and α' of the first voltage-dividing circuit 30, the voltage-dividing ratios β and β' of the second voltage-dividing circuit 40, the calculation formulas for the insulation resistances Rp, Rn, and Rp / / Rn, and the characteristic diagnosis formula. In FIG. 17, the resistance value of the second C detection resistor Rk2' is "Rk2'." Furthermore, the resistance value of the second voltage-dividing circuit 40 when the fourth switch is turned on is "R2," and the resistance value of the second voltage-dividing circuit 40 when the fourth switch is turned off is "R2'." This can improve the accuracy of the characteristic determination.

[0096] In the leakage detection process in the above embodiment, if the detection voltages Vn1 and Vn2 calculated in steps S104 and S109 become sufficiently small, processing may be added to suppress the influence of circuit tolerances and the like.

[0097] The following description will be given based on Fig. 18. After the process of step S109, the control device 70 determines whether the calculated detected voltage Vn1 is greater than the first threshold value TL1 (step S601). The first threshold value TL1 is set to an arbitrary value that takes into account, for example, circuit tolerance. For example, as shown in Fig. 11, the voltage value when the maximum value of Rp / / Rn begins to diverge (the timing indicated by range E2) is set as the first threshold value TL1.

[0098] If the result of this determination is positive, that is, if the calculated detected voltage Vn2 is greater than the first threshold value TL1, the control device 70 determines whether the calculated detected voltage Vn2 is greater than a second threshold value TL2 (step S602). The second threshold value TL2 is set to an arbitrary value taking into consideration, for example, circuit tolerance. Note that the first threshold value TL1 and the second threshold value TL2 may be the same value or different values.

[0099] If the determination result in step S602 is positive, the control device 70 determines that accurate determination is possible using the value of Rp / / Rn calculated by the formula (3), and performs the processes from step S110 onwards, as in the first embodiment.

[0100] On the other hand, if the determination result in step S601 or step S602 is negative, the control device 70 sets a fixed value as the value of Rp / Rn (step S603). The fixed value indicates the presence of a leakage current and is determined according to the required specifications for the insulation resistances Rp and Rn. For example, 4 kΩ is set as the fixed value.

[0101] After step S603, the control device 70 performs step S110 to detect a leakage current. Note that if a fixed value is set in step S603, it is always determined that a leakage current exists.

[0102] As described above, when the insulation resistances Rp and Rn become small and the detection voltages Vn1 and Vn2 approach zero, the influence of circuit tolerances and other factors increases, and the value of the composite equation for the insulation resistances Rp and Rn may become unstable. Therefore, when the detection voltage Vn1 is equal to or less than the first threshold value TL1, or when the detection voltage Vn2 is equal to or less than the second threshold value TL2, a leakage current is detected without calculating the value of the composite equation for the insulation resistances Rp and Rn. This allows for accurate detection of leakage current without being affected by circuit tolerances.

[0103] A portion of the first voltage-dividing circuit 30 in the above embodiment may be modified as shown in FIG. 19 . That is, in the first voltage-dividing circuit 30, the first-A detection resistor Rs1 may be arranged on the negative-side power supply path L2 side, and the parallel connection of the first-B detection resistor Rk1′ and the first-C detection resistor Rk1 may be arranged on the vehicle-side ground FG side. Similarly, in the second voltage-dividing circuit 40, the second-A detection resistor Rs2 may be arranged on the negative-side power supply path L2 side, and the second-B detection resistor Rk2 may be arranged on the vehicle-side ground FG side. In this case, it is necessary to detect the voltage between the vehicle-side ground FG and the connection point via a differential amplifier circuit.

[0104] In the above embodiment, the control device 70 performs the process for detecting and dealing with electric leakage. However, this process may be performed by an external device. In this case, the control device 70 may calculate and transmit the values ​​of the insulation resistances Rp and Rn.

[0105] In the above embodiment, the third switch S3 may be a bipolar switch (semiconductor switch) such as a transistor, or a mechanical relay.

[0106] In the above embodiment, the range change circuit 60 is configured as one stage, and the voltage division ratio can be changed in one stage, but the range change circuit 60 may be configured as multiple stages, and the voltage division ratio can be changed in multiple stages.

[0107] In the above embodiment, if the characteristic determination is not performed, the second voltage dividing circuit 40 may be replaced with a simple resistor.

[0108] (Second embodiment) A second embodiment in which the configuration of the first embodiment is partially modified will be described below.

[0109] As described in the first embodiment, one of the reasons why the first voltage division value becomes small is a decrease in the insulation resistance Rn. However, there are other possible reasons why the first voltage division value becomes small. For example, one possible reason why the first voltage division value becomes small is when the insulation resistance on the side to which the first voltage division circuit 30 is not connected in parallel (in the first embodiment, the positive-side insulation resistance Rp) becomes too large. Because this insulation resistance is a resistance on the vehicle side, it is difficult to determine its maximum value based on specifications. In particular, when the relay switches of the power supply paths L1 and L2 are turned off and the current flow between the battery pack 10 and an electrical load such as a rotating electrical machine is interrupted, the insulation resistances Rn and Rp become almost infinite. Therefore, no matter how large the voltage division ratio is, the first voltage division value may become smaller than expected.

[0110] Therefore, in the second embodiment, a device is provided to keep the first voltage dividing value within an appropriate range even if the insulation resistance on the side to which the first voltage dividing circuit 30 is not connected in parallel (in the second embodiment, the positive side insulation resistance Rp) becomes large. In addition to this device, in the second embodiment, the range change circuit 60 is configured in multiple stages, so that the voltage dividing ratio can be changed in multiple stages. This will be explained in detail below.

[0111] First, the circuit configuration of the second embodiment will be described. Components similar to those of the first embodiment are assigned the same reference numerals and will not be described again. As shown in Fig. 20, the first voltage dividing circuit 130 of the second embodiment is connected between the vehicle ground FG and the negative power supply path L2, and divides the voltage between the negative power supply path L2 and the vehicle ground FG (the voltage across the first voltage dividing circuit 130) at a voltage division ratio α, a voltage division ratio α10, or a voltage division ratio α100. In the second embodiment, the negative power supply path L2 corresponds to the first power supply path, and the positive power supply path L1 corresponds to the second power supply path.

[0112] Describing the configuration of the first voltage divider circuit 130 in more detail, the first voltage divider circuit 130 includes a firstA detection resistor Rs1 and a range change circuit 160. The range change circuit 160 includes a firstB detection resistor Rk1, a firstC detection resistor Rk10, and a firstD detection resistor Rk100. The firstB detection resistor Rk1, the firstC detection resistor Rk10, and the firstD detection resistor Rk100 are connected in parallel.

[0113] More specifically, a third switch S3 is connected in series to the first-B detection resistor Rk1, and the third switch S3 can switch between a conductive state and a non-conductive state. A thirtieth switch S30 is connected in series to the first-C detection resistor Rk10, and the thirtieth switch S30 can switch between a conductive state and a non-conductive state. The first-D detection resistor Rk100 is connected in parallel to a series connection consisting of the first-B detection resistor Rk1 and the third switch S3, and a series connection consisting of the first-C detection resistor Rk10 and the thirtieth switch S30. This parallel connection corresponds to the range change circuit 160.

[0114] The range change circuit 160 is connected in series to the first A detection resistor Rs1. A Zener diode Da is connected in parallel to the range change circuit 160. The anode side of the Zener diode Da is connected to the negative power supply path L2.

[0115] The first A detection resistor Rs1 is connected to the vehicle-side ground FG, and the range change circuit 160 is connected to the negative power supply path L2. One end of a first output line L11 is connected to a first connection point P1 between the first A detection resistor Rs1 and the range change circuit 160. A voltage signal (first divided voltage value) from the first voltage divider circuit 130 is output via the first output line L11.

[0116] When the third switch S3 and the thirtieth switch S30 are turned on, the firstB detection resistor Rk1, the firstC detection resistor Rk10, and the firstD detection resistor Rk100 are brought into a conducting state, and the voltage division ratio of the first voltage dividing circuit 130 becomes α.

[0117] Furthermore, when the third switch S3 is turned off and the thirtieth switch S30 is turned on, the firstB detection resistor Rk1 is in a non-conductive state, the firstC detection resistor Rk10 and the firstD detection resistor Rk100 are in a conductive state, and the voltage division ratio of the first voltage divider circuit 130 becomes α10.

[0118] Furthermore, when the third switch S3 and the thirtieth switch S30 are turned off, the firstB detection resistor Rk1 and the firstC detection resistor Rk10 are in a non-conductive state, the firstD detection resistor Rk100 is in a conductive state, and the voltage division ratio of the first voltage divider circuit 130 becomes α100.

[0119] The third switch S3 and the thirtieth switch S30 are on / off controlled by the control device 70. The resistance value of the first-C detection resistor Rk10 is much larger than the resistance value of the first-B detection resistor Rk1, for example, about 10 times larger. Similarly, the resistance value of the first-D detection resistor Rk100 is much larger than the resistance value of the first-C detection resistor Rk10, for example, about 10 times larger.

[0120] Therefore, the voltage division ratio α10 becomes larger relative to the voltage division ratio α, and the voltage division ratio α100 becomes larger relative to the voltage division ratio α10 (α<α10<α100). As the voltage division ratio becomes larger, the first voltage division value (voltage signal) becomes larger proportionally. In the second embodiment, the voltage division ratio α10 is about 10 times the voltage division ratio α, and the voltage division ratio α100 is about 10 times the voltage division ratio α10 (i.e., about 100 times the voltage division ratio α).

[0121] 20, in the second embodiment, a bypass circuit 190 made up of a series connection of a resistor R3 and a fourth switch S4 (changeover switch) is provided between the positive power supply path L1 and the vehicle-side ground FG. The fourth switch S4 is configured to be switched on and off by the control device 70. When the fourth switch S4 is turned on, electricity is conducted between the positive power supply path L1 and the vehicle-side ground FG via the resistor R3. When the fourth switch S4 is turned off, the bypass circuit 190 is brought into an electrical disconnection state, and electricity is no longer conducted between the positive power supply path L1 and the vehicle-side ground FG via the resistor R3.

[0122] The value of the resistor R3 is smaller than the positive side insulation resistance Rp between the positive side power supply path L1 and the vehicle side ground FG, and is larger than the value that is allowed as a normal value of the insulation resistance Rp.

[0123] 20, this bypass circuit 190 is connected in parallel with the positive-side insulation resistance Rp. Therefore, no matter how large the positive-side insulation resistance Rp becomes, the resistance Rp is prevented from actually increasing due to the resistor R3 connected in parallel. In other words, when the fourth switch S4 is turned on, the potential of the vehicle-side ground FG rises toward the positive side of the battery pack 10 (the side of the positive-side power supply path L1).

[0124] The control device 70 of the second embodiment can switch the detection range of the first divided voltage value between three stages by turning on and off the switches S3, S30, and S4. Specifically, as shown in FIG. 21, in the case of detection range LV1, the third switch S3 and the thirtieth switch S30 are turned on to obtain the first divided voltage value at a voltage division ratio α. At this time, the fourth switch S4 is turned off, so the potential of the vehicle-side ground FG is not raised. Therefore, in the case of detection range LV1, if the value of the positive-side insulation resistance Rp is larger than expected, this may have an effect.

[0125] In the detection range LV2, the third switch S3 is turned off while the thirtieth switch S30 is turned on to obtain the first divided voltage value at a voltage division ratio of α10. At this time, the fourth switch S4 is turned on, so the potential of the vehicle-side ground FG is raised. Therefore, in the detection range LV2, even if the value of the positive-side insulation resistance Rp is large, the effect can be substantially suppressed.

[0126] Similarly, in the case of the detection range LV3, the third switch S3 and the thirtieth switch S30 are turned off, and the first divided voltage value is acquired at a voltage division ratio of α100. At this time, the fourth switch S4 is turned on, so the potential of the vehicle-side ground FG is raised. Therefore, in the case of the detection range LV3, even if the value of the positive-side insulation resistance Rp is large, the effect can be substantially suppressed.

[0127] Next, the leakage detection process of the second embodiment will be described in detail with reference to Fig. 22 to Fig. 26. Fig. 26 also shows the resistance values ​​CK1, CK10, CK100 of the range change circuit 160, the resistance values ​​R1, R10, R100 of the first voltage divider circuit 130, the resistance value R2 of the second voltage divider circuit 40, the voltage division ratios α, α10, α100 of the first voltage divider circuit 130, the voltage division ratio β of the second voltage divider circuit 40, and the equations for the insulation resistances Rp, Rn, Rz (=Rp / / Rn). Fig. 26 shows the respective values ​​for each of the detection ranges LV1 to LV3.

[0128] The resistance value of the 1A detection resistor Rs1 is "Rs1," the resistance value of the 1B detection resistor Rk1 is "Rk1," the resistance value of the 1C detection resistor Rk10 is "Rk10," and the resistance value of the 1D detection resistor Rk100 is "Rk100." Furthermore, the resistance value of the resistor R3 is "R3."

[0129] The resistance value (combined resistance value) of the range change circuit 160 in the detection range LV1 is "CK1," the resistance value of the range change circuit 160 in the detection range LV2 is "CK10," and the resistance value of the range change circuit 160 in the detection range LV3 is "CK100." Since the other values ​​are the same as in the first embodiment, the first embodiment should be referred to and the description will be omitted.

[0130] 22 is performed at predetermined intervals (for example, every several tens of milliseconds) by the control device 70. When the leakage detection process is performed, the control device 70 first turns on the second switch S2 (step S301).

[0131] Next, the control device 70 determines whether it is immediately after startup (for example, immediately after the ignition switch is turned on) (step S302). If the result of this determination is positive, the control device 70 turns on the first switch S1 (step S303) and sets the detection range to "LV1" (step S304). When the detection range is set, the control device 70 switches on and off the switches S3, S30, and S4 according to the set detection ranges LV1 to LV3, as shown in FIG. 21. When the detection range LV1 is set, the voltage division ratio of the first voltage dividing circuit 130 becomes the voltage division ratio α.

[0132] After the process of step S304, or if the determination result of step S302 is negative, the control device 70 sets i to 1 after a predetermined time has elapsed (step S305).

[0133] Then, the control device 70 performs range switching processing of the detection range (step S306). Here, the range switching processing in step S306 will be described with reference to Fig. 23. Note that in the range switching processing of step S306, i is read as 1. For example, Vns0i in Fig. 23 is read as Vns01.

[0134] 23, the control device 70 inputs (detects) the first divided voltage value Vns0i from the first voltage dividing circuit 130 (step S401). Note that in the case of detection range LV1, the first divided voltage value Vns0i=α×Vni, in the case of detection range LV2, the first divided voltage value Vns0i=α10×Vni, and in the case of detection range LV3, the first divided voltage value Vns0i=α100×Vni.

[0135] Next, the control device 70 determines whether the detected first divided voltage value Vns0i is smaller than a threshold value Vth (step S402). The threshold value Vth is an arbitrary value, and is set according to the resolution of the control device 70, the required detection accuracy, etc.

[0136] If the determination result in step S402 is positive, the control device 70 determines whether the currently set detection range is detection range LV3 (step S403). If this determination result is positive, the control device 70 ends the switching process because there is no way to increase the detection range any further. On the other hand, if the determination result in step S403 is negative, the control device 70 increases the detection range setting by one level (step S404). For example, if the currently set detection range is detection range LV1, it is set to detection range LV2, and if the currently set detection range is detection range LV2, it is set to detection range LV3. Then, the control device 70 switches on and off the switches S3, S30, and S4 as shown in FIG. 21 in accordance with the changed detection ranges LV2 to LV3. Then, the control device 70 performs the process of step S401 again.

[0137] On the other hand, if the determination result in step S402 is negative, i.e., if the detected first divided pressure value Vns0i is equal to or greater than the threshold value Vth, the control device 70 determines whether the detected first divided pressure value Vns0i is equal to or greater than a limit value Vmax (step S405). The limit value Vmax is an arbitrary value, and is set depending on the resolution, withstand voltage, detection accuracy, etc. of the control device 70. If the determination result in step S405 is negative, the control device 70 ends the range switching process.

[0138] On the other hand, if the determination result in step S405 is positive, the control device 70 determines whether the currently set detection range is detection range LV1 (step S406). If this determination result is positive, there is no way to lower the detection range, so the control device 70 ends the switching process. On the other hand, if the determination result in step S406 is negative, the control device 70 lowers the detection range setting by one level (step S407). For example, if the currently set detection range is detection range LV3, it is set to detection range LV2, and if the currently set detection range is detection range LV2, it is set to detection range LV1. Then, the control device 70 switches on and off each of the switches S3, S30, and S4 as shown in FIG. 21 in accordance with the changed detection range LV1 to LV2. Then, the control device 70 performs the process of step S401 again.

[0139] As shown in Fig. 22, after the range switching process in step S306 is completed and a predetermined time has elapsed, the control device 70 performs detection processing for Vn1 (step S307). The detection processing for Vn1 will now be described with reference to Fig. 24. Note that in the detection processing in step S307, i is replaced with 1. For example, Vni in Fig. 24 is replaced with Vn1, and Vnsi is replaced with Vns1.

[0140] 24, when the detection process is started, the control device 70 inputs (detects) the first voltage division value Vnsi from the first voltage division circuit 130 (step S501). Next, the control device 70 determines whether the currently set detection range is the detection range LV3 (step S502). If the result of this determination is positive, the control device 70 calculates Vnsi / α100 to calculate Vni (step S503). Then, the detection process ends.

[0141] On the other hand, if the determination result in step S502 is negative, the control device 70 determines whether the currently set detection range is the detection range LV2 (step S504). If the determination result is positive, the control device 70 calculates Vnsi / α10 to calculate Vni (step S505). Then, the detection process ends.

[0142] On the other hand, if the determination result in step S504 is negative, that is, if the currently set detection range is the detection range LV1, the control device 70 calculates Vnsi / α to calculate Vni (step S506), and then ends the detection process.

[0143] 22, when a predetermined time has elapsed since the detection process in step S307 ended, the control device 70 turns off the second switch S2 (step S308). After that, when the predetermined time has elapsed, the control device 70 sets i to 2 (step S309).

[0144] Then, the control device 70 performs range switching processing (step S310). Note that the switching processing in step S310 is the same as that described above if i=2 is used in the switching processing in step S306 and the description of FIG. 23. For example, if Vns0i is replaced with Vns02, the same is true. Therefore, a description thereof will be omitted here.

[0145] As shown in Fig. 22, after the switching process in step S310 is completed, the control device 70 performs detection processing for Vn2 when a predetermined time has elapsed (step S311). Note that the detection processing in step S311 is the same as that described above if i=2 is used in the detection processing in step S307 and the description of Fig. 24. For example, if Vnsi is replaced with Vns2 and Vni is replaced with Vn2, the same is true. Therefore, a description thereof will be omitted here.

[0146] When the detection process of step S311 is completed, the control device 70 performs an insulation resistance calculation process to calculate the insulation resistance (step S312), as shown in Fig. 22. The insulation resistance calculation process will be described with reference to Fig. 25.

[0147] In the insulation resistance calculation process of step S312, the control device 70 determines whether the currently set detection range is detection range LV3 (step S601). If the result of this determination is positive, the control device 70 calculates the insulation resistance based on the detected Vn1 and Vn2 (step S602). In step S602, the control device 70 calculates the insulation resistance Rz in the detection range LV3 with reference to equation (13) shown in FIG. 26. Note that the insulation resistances Rp and Rn may also be found from equations (16) and (18) shown in FIG. 26, respectively. Then, the insulation resistance calculation process ends.

[0148] On the other hand, if the determination result in step S601 is negative, the control device 70 determines whether the currently set detection range is detection range LV2 (step S603). If the determination result is positive, the control device 70 calculates the insulation resistance based on the detected voltages Vn1 and Vn2 (step S604). In step S604, the control device 70 calculates the insulation resistance Rz in the detection range LV2 with reference to equation (12) shown in FIG. 26. Note that the insulation resistances Rp and Rn may also be calculated from equations (15) and (18) shown in FIG. 26, respectively. Then, the insulation resistance calculation process ends.

[0149] On the other hand, if the determination result in step S603 is negative, that is, if the currently set detection range is detection range LV1, the control device 70 calculates the insulation resistance based on the detected voltages Vn1 and Vn2 (step S605). In step S605, the control device 70 calculates the insulation resistance Rz in detection range LV1 with reference to equation (11) shown in FIG. 26. Alternatively, the insulation resistances Rp and Rn may be calculated from equations (14) and (17) shown in FIG. 26, respectively. Then, the insulation resistance calculation process ends.

[0150] 22, after the insulation resistance calculation process is completed, the control device 70 determines whether or not a leakage current has occurred based on the calculated insulation resistance (step S313). In step S313, for example, the determination as to whether or not a leakage current has occurred is based on whether or not the calculated insulation resistance Rz is within a predetermined normal range. Furthermore, when the insulation resistances Rp and Rn are calculated, the determination as to whether or not a leakage current has occurred may be based on whether or not the calculated insulation resistances Rp and Rn are equal to or less than the determination threshold values ​​Rp0 and Rn0, respectively.

[0151] If the determination result in step S313 is positive (if a leakage current is detected), the control device 70 performs processing to deal with the leakage current (step S314) and ends the leakage current detection processing. The processing to deal with the leakage current is, for example, processing to notify an external device of the leakage current and issue a warning. On the other hand, if the determination result in step S313 is negative (if a leakage current is not detected), the control device 70 determines that the device is normal and ends the leakage current detection processing.

[0152] Next, the detection timing of the first voltage dividing value and the switching timing of the detection ranges LV1 to L3 will be described with reference to Fig. 27. Fig. 27 will be described assuming that, initially (at time t10), both insulation resistances Rp and Rn are normal and that the detection range LV1 is being set. In the detection range LV1, the switches S1, S2, S3, and S30 are turned on, and the fourth switch S4 is turned off (at time t11). This causes the voltage dividing ratio of the first voltage dividing circuit 130 to become the voltage dividing ratio α. Furthermore, because the fourth switch S4 is off, the potential of the vehicle-side ground FG is not raised.

[0153] In order to stabilize the first divided voltage value, the control device 70 performs range switching processing when a predetermined time has elapsed (at time t12). That is, the control device 70 inputs the first divided voltage value Vns01 from the first voltage dividing circuit 130 and determines whether the first divided voltage value Vns01 is equal to or greater than the threshold value Vth and smaller than the limit value Vmax. As a result, the first divided voltage value Vns01 is equal to or greater than the threshold value Vth and smaller than the limit value Vmax, so the detection range LV1 is maintained. When a predetermined time has elapsed thereafter (at time t13), the control device 70 inputs the first divided voltage value Vns1 and calculates Vn1.

[0154] After calculating Vn1, the control device 70 turns off the second switch S2 when a predetermined time has elapsed (at time t14). In order to stabilize the voltage division value, the control device 70 performs range switching processing when a predetermined time has elapsed (at time t15). That is, the control device 70 inputs the first voltage division value Vns02 from the first voltage division circuit 130 and determines whether the first voltage division value Vns02 is equal to or greater than the threshold value Vth and smaller than the limit value Vmax. As a result, the first voltage division value Vns02 is equal to or greater than the threshold value Vth and smaller than the limit value Vmax, so the detection range LV1 is maintained.

[0155] Then, after a predetermined time has elapsed (time t16), the control device 70 inputs the first divided voltage value Vns2 and calculates Vn2. The control device 70 then calculates the insulation resistance Rz from the calculated Vn1 and Vn2 using equation (11) shown in Fig. 26, and determines whether or not there is a leakage current.

[0156] Then, at time t21, after a predetermined time has elapsed, the second switch S2 is turned on. Note that the following description is based on the assumption that, from time t20 onward between time t21 and time t22, the first divided voltage value becomes smaller than the threshold value Vth in the detection range LV1. That is, the following description is based on the assumption that, at time t20, in order to detect the first divided voltage value in the detection range LV1, the insulation resistance Rp has increased or the insulation resistance Rn has decreased.

[0157] The control device 70 performs range switching processing at a timing (time t22) when a predetermined time has elapsed since time t21. That is, the control device 70 inputs the first voltage division value Vns01 from the first voltage division circuit 130 and determines whether the first voltage division value Vns01 is equal to or greater than the threshold value Vth and smaller than the limit value Vmax. As a result, since the first voltage division value Vns01 is smaller than the threshold value Vth, the detection range is set to LV2. As a result, the third switch S3 is turned off and the voltage division ratio is changed to α10. In the detection value Vns column of FIG. 27, the detection voltage when the voltage division ratio remains at α is indicated by a dashed line. Furthermore, the fourth switch S4 is turned on and the potential of the vehicle-side ground FG is raised. In the physical value Vn column of FIG. 27, the voltage (potential) when the fourth switch S4 remains off is indicated by a dashed line.

[0158] The control device 70 then inputs the first divided voltage value Vns1 and calculates Vn1 when a predetermined time has elapsed (at time t23). After calculating Vn1, the control device 70 turns off the second switch S2 when a predetermined time has elapsed (at time t24). In order to stabilize the divided voltage value, the control device 70 performs range switching processing when a predetermined time has elapsed (at time t25). That is, the control device 70 inputs the first divided voltage value Vns02 from the first voltage dividing circuit 130 and determines whether the first divided voltage value Vns02 is equal to or greater than the threshold value Vth and smaller than the limit value Vmax. Because the first divided voltage value Vns02 is equal to or greater than the threshold value Vth and smaller than the limit value Vmax based on the premise, the detection range LV2 is maintained.

[0159] Then, after a predetermined time has elapsed (at time t26), the control device 70 receives the first divided voltage value Vns2 and calculates Vn2. The control device 70 then calculates the insulation resistance Rz from the calculated Vn1 and Vn2 using equation (12) shown in Fig. 26, and determines whether or not there is a leakage current.

[0160] Then, at time t31, after a predetermined time has elapsed, the second switch S2 is turned on. Note that the following description is based on the assumption that, from time t30 onward between time t31 and time t32, in detection range LV2, the first divided voltage value becomes smaller than threshold value Vth. That is, the following description is based on the assumption that, at time t30, the insulation resistance Rp becomes even larger or the insulation resistance Rn becomes even smaller, and the voltage division ratio becomes inappropriate in detection range LV2.

[0161] The control device 70 performs range switching processing at a timing (time t32) when a predetermined time has elapsed since time t31. That is, the control device 70 inputs the first voltage division value Vns01 from the first voltage division circuit 130 and determines whether the first voltage division value Vns01 is equal to or greater than the threshold value Vth and smaller than the limit value Vmax. Based on the premise, since the first voltage division value Vns01 is smaller than the threshold value Vth, the detection range LV3 is set. As a result, the voltage division ratio is changed to α100. In the detection value Vns column of FIG. 27, the detection voltage when the voltage division ratio remains α10 is indicated by a dashed line. Furthermore, the fourth switch S4 is turned on, and the potential of the vehicle-side ground FG is raised. In the physical value Vn column of FIG. 27, the voltage (potential) when the fourth switch S4 remains off is indicated by a dashed line.

[0162] The control device 70 then inputs the first divided voltage value Vns1 and calculates Vn1 when a predetermined time has elapsed (at time t33). After calculating Vn1, the control device 70 turns off the second switch S2 when a predetermined time has elapsed (at time t34). In order to stabilize the divided voltage value, the control device 70 performs detection range switching processing when a predetermined time has elapsed (at time t35). That is, the control device 70 inputs the first divided voltage value Vns02 from the first voltage dividing circuit 130 and determines whether the first divided voltage value Vns02 is equal to or greater than the threshold value Vth and smaller than the limit value Vmax. Because the first divided voltage value Vns02 is equal to or greater than the threshold value Vth and smaller than the limit value Vmax based on the premise, the detection range LV3 is maintained.

[0163] Then, after a predetermined time has elapsed (time t36), the control device 70 inputs the first divided voltage value Vns2 and calculates Vn2. The control device 70 then calculates the insulation resistance Rz from the calculated Vn1 and Vn2 using equation (13) shown in Fig. 26, and determines whether or not there is a leakage current.

[0164] The effects of the above embodiment will be described below.

[0165] (11) When the insulation resistance Rp increases, the first voltage dividing value decreases. Therefore, in the second embodiment, a bypass circuit 190 consisting of a series connection of a resistor R3 and a fourth switch S4 is provided between the positive power supply path L1 and the vehicle-side ground FG. When the detection range is expanded, that is, when the detection range is set to LV2 or LV3, the fourth switch S4 is turned on to raise the potential of the vehicle-side ground FG to the positive side of the battery pack 10 (the side of the positive power supply path L1). As a result, when the detection range is set to LV2 or LV3, no matter how large the positive-side insulation resistance Rp becomes, the parallel-connected resistor R3 can effectively suppress the effect.

[0166] (12) When the input first divided voltage values ​​Vns01, Vns02 of the first voltage divider circuit 130 are smaller than the threshold value Vth, the control device 70 turns on the fourth switch S4 to energize the positive power supply path L1 and the vehicle-side ground FG via the resistor R3. This allows the resistor R3 to be energized at an appropriate timing, thereby suppressing the influence of the insulation resistance Rp.

[0167] (13) The value of resistor R3 is smaller than the positive insulation resistance Rp between the positive power path L1 and the vehicle ground FG, but is larger than the allowable normal value of the insulation resistance Rp. Therefore, even if the positive insulation resistance Rp becomes large, the parallel connection of resistor R3 can substantially suppress the effect.

[0168] (Modification of the second embodiment) The second embodiment may be implemented in combination with the first embodiment or a modification thereof.

[0169] In the second embodiment, the range change circuit 160 is configured in two stages, and the voltage division ratio is configured to be changeable in two stages, but it may also be configured to be changeable in one stage, or three or more stages.

[0170] In the second embodiment, only the resistor Rk1 may be provided instead of the range change circuit 160. In other words, the voltage division ratio of the first voltage divider circuit 130 may be made unchangeable. In this case, when the input first voltage division values ​​Vns01, Vns02 of the first voltage divider circuit 130 are smaller than the threshold value Vth, the fourth switch S4 may simply be turned on.

[0171] In the second embodiment, the fourth switch S4 does not have to be provided. That is, current may be always conducted between the positive power supply path L1 and the vehicle ground FG via the resistor R3. In this case, the influence of an increase in the insulation resistance Rp can also be suppressed.

[0172] In the second embodiment, as shown in FIG. 12, when the first voltage-dividing circuit 130 and the second voltage-dividing circuit 40 are provided between the positive power supply path L1 and the vehicle-side ground FG, a bypass circuit 190 (resistor R3, etc.) may be provided between the negative power supply path L2 and the vehicle-side ground FG.

[0173] The following describes characteristic configurations extracted from the above-described embodiments. [Configuration 1] A leakage current detection device (20) for detecting a leakage current between a power supply path (L1, L2) connected to a terminal of a battery (10) and a ground (FG), a first voltage dividing circuit (30, 130) having one end connected to the power supply path side and the other end connected to the ground side; a resistor circuit (40) having one end connected to the power supply path side and the other end connected to the ground side and connected in parallel to the first voltage dividing circuit; a switch unit (S2) configured to be able to switch between a conducting state and a non-conducting state of the resistor circuit; a control unit (70) that controls switching of the switch unit to input a first divided voltage value (Vns1, Vns2) of the first voltage dividing circuit, calculates an insulation resistance from the input first divided voltage value, and detects a leakage current; the first voltage dividing circuit has a range changing circuit (60, 160) that changes the voltage dividing ratio of the first voltage dividing circuit; When the input first voltage division value (Vns01, Vns02) of the first voltage division circuit is smaller than a threshold value (Vth), the control unit changes the voltage division ratio of the first voltage division circuit using the range change circuit so that the first voltage division value becomes larger. [Configuration 2] The control unit a first input step of inputting a first divided voltage value (Vns1) from the first voltage dividing circuit when the resistor circuit is in a conducting state; a second input step of inputting a first divided voltage value (Vns2) from the first voltage dividing circuit when the resistor circuit is in a power-off state; a leakage current detection step of calculating an insulation resistance based on the first divided voltage value input in the first input step and the first divided voltage value input in the second input step, and detecting a leakage current; The leakage detection device according to Configuration 1, wherein the control unit inputs a first voltage division value (Vns01, Vns02) of the first voltage division circuit before the first input step or the second input step is performed, and changes the voltage division ratio of the first voltage division circuit if the input first voltage division value is smaller than a threshold value. [Configuration 3] the resistor circuit is a second voltage divider circuit, The control unit a voltage dividing circuit configured to be able to input voltage dividing values ​​from the first voltage dividing circuit and the second voltage dividing circuit; a first switching step of controlling the switch unit to switch the second voltage dividing circuit to a conducting state; a first input step of inputting a first divided voltage value (Vns1) from the first voltage divider circuit and a second divided voltage value (Vrs1) from the second voltage divider circuit when the second voltage divider circuit is in a conducting state after the first switching step; a second switching step of controlling the switch unit to switch the second voltage dividing circuit to an energization cut-off state after the first input step; a second input step of inputting a first divided voltage value (Vns2) from the first voltage dividing circuit when the second voltage dividing circuit is in a power-off state after the second switching step; a characteristic determination step of determining whether or not an abnormality has occurred in the first voltage dividing circuit and the second voltage dividing circuit based on the first voltage dividing value and the second voltage dividing value input in the first input step; and a leakage detection step of calculating insulation resistance based on the first divided voltage value input in the first input step and the first divided voltage value input in the second input step, and detecting leakage. [Configuration 4] the first voltage dividing circuit includes a firstA detection resistor (Rs1), a firstB detection resistor (Rk1'), a firstC detection resistor (Rk1), and a voltage dividing ratio changeover switch (S3) connected in series with the firstC detection resistor (Rk1) and switching between a conducting state and a non-conducting state of the firstC detection resistor (Rk1); a series connection of the first C detection resistor (Rk1) and the voltage division ratio changeover switch (S3) is connected in parallel to the first B detection resistor (Rk1') to form a parallel connection; The first A detection resistor (Rs1) is connected in series to the parallel connection body, 4. The leakage detection device according to any one of configurations 1 to 3, wherein the control unit changes the voltage division ratio of the first voltage dividing circuit by switching the voltage division ratio changeover switch. [Configuration 5] the first voltage dividing circuit includes a firstA detection resistor (Rs1), a firstB detection resistor (Rk1'), a firstC detection resistor (Rk1), and a voltage dividing ratio changeover switch (S3) connected in parallel to the firstB detection resistor (Rk1') and switching between a conducting state and a non-conducting state of the firstB detection resistor (Rk1'); the first A detection resistor (Rs1), the first B detection resistor (Rk1'), and the first C detection resistor (Rk1) are connected in series, 4. The leakage detection device according to any one of configurations 1 to 3, wherein the control unit changes the voltage division ratio of the first voltage dividing circuit by switching the voltage division ratio changeover switch. [Configuration 6] the first voltage dividing circuit has a firstA detection resistor (Rs1), a firstB detection resistor (Rk1'), and a firstC detection resistor (Rk1), which are connected in series; The control unit of the leakage current detection device of any one of configurations 1 to 3 inputs a first voltage division value from a connection point (P101) between the firstB detection resistor Rk1' and the firstC detection resistor Rk1 under normal conditions, and when the input first voltage division value is smaller than a threshold value, inputs the first voltage division value from a connection point (P102) between the firstA detection resistor Rs1 and the firstB detection resistor Rk1', thereby changing the voltage division ratio of the first voltage division circuit. [Configuration 7] The control unit detects that there is a leak without calculating the value of the insulation resistance when the voltage (Vn1, Vn2) across the first voltage divider circuit calculated using the first voltage divider value input from the first voltage divider circuit and the voltage division ratio is less than a judgment threshold value (TL1, TL2). [Configuration 8] The power supply path includes a positive power supply path (L1) connected to a positive terminal of the battery and a negative power supply path (L2) connected to a negative terminal of the battery, the first voltage dividing circuit and the resistance circuit are connected to a first power supply path which is either one of the positive power supply path and the negative power supply path, A leakage current detection device according to any one of configurations 1 to 7, wherein a resistor (R3) is provided between the ground and a second power supply path, which is different from the first power supply path, among the power supply path on the positive side and the power supply path on the negative side. [Configuration 9] A changeover switch (S4) is connected in series to the resistor, The leakage detection device according to configuration 8, wherein the control unit turns on the changeover switch to allow current to flow between the second power supply path and the ground via the resistor when the input first divided voltage value (Vns01, Vns02) of the first voltage divider circuit is smaller than a threshold value (Vth). [Configuration 10] A leakage current detection device according to configuration 8 or 9, wherein the resistance value is smaller than the insulation resistance between the second power supply path and the ground and is larger than the value that is allowed as a normal value of the insulation resistance. [Configuration 11] A leakage detection device (20) for detecting leakage between a positive power supply path (L1) connected to a positive terminal of a battery (10) and ground (FG), and between a negative power supply path (L2) connected to a negative terminal of the battery and ground (FG), a first voltage dividing circuit (130) having one end connected to a first power supply path, which is either one of the positive power supply path and the negative power supply path, and the other end connected to the ground side; a resistor circuit (40) having one end connected to the first power supply path side and the other end connected to the ground side and connected in parallel to the first voltage dividing circuit; a switch unit (S2) configured to be able to switch between a conducting state and a non-conducting state of the resistor circuit; a control unit (70) that controls switching of the switch unit to input a first divided voltage value (Vns1, Vns2) of the first voltage dividing circuit, calculates an insulation resistance from the input first divided voltage value, and detects leakage current; A leakage current detection device comprising: a resistor (R3) having one end connected to a second power supply path different from the first power supply path among the positive side power supply path and the negative side power supply path, and having the other end connected to the ground side. [Configuration 12] A changeover switch (S4) is connected in series to the resistor, The leakage detection device according to configuration 11, wherein the control unit turns on the changeover switch to allow current to flow between the second power supply path and the ground via the resistor when the input first voltage division value (Vns01, Vns02) of the first voltage division circuit is smaller than a threshold value (Vth). [Configuration 13] A leakage current detection device according to configuration 12 or 13, wherein the value of the resistance is smaller than the insulation resistance between the second power supply path and the ground and is larger than the value that is allowed as a normal value of the insulation resistance. [Explanation of symbols]

[0174] 10... battery pack, 20... leakage current detection device, 30, 130... first voltage dividing circuit, 40... second voltage dividing circuit, 60, 160... range change circuit, 70... control device, FG... vehicle side ground, L1... positive power supply path, L2... negative power supply path, Rn... insulation resistor, Rp... insulation resistor, S1... first switch, S2... second switch, S3... third switch, S4... fourth switch, S30... thirtieth switch.

Claims

1. A leakage current detection device (20) for detecting a leakage current between a power supply path (L1, L2) connected to a terminal of a battery (10) and a ground (FG), a first voltage dividing circuit (30, 130) having one end connected to the power supply path side and the other end connected to the ground side; a resistor circuit (40) having one end connected to the power supply path side and the other end connected to the ground side and connected in parallel to the first voltage dividing circuit; a switch unit (S2) configured to be able to switch between a conducting state and a non-conducting state of the resistor circuit; a control unit (70) that controls switching of the switch unit, inputs first divided voltage values ​​(Vns1, Vns2) of the first voltage dividing circuit, calculates insulation resistance from the input first divided voltage value, and detects leakage current; the first voltage dividing circuit has a range changing circuit (60, 160) that changes the voltage dividing ratio of the first voltage dividing circuit; When an input first divided voltage value (Vns01, Vns02) of the first voltage divider circuit is smaller than a threshold value (Vth), the control unit changes the voltage division ratio of the first voltage divider circuit by the range change circuit (60, 160) so that the first divided voltage value becomes larger; the resistor circuit is a second voltage divider circuit, The control unit a voltage dividing circuit configured to be able to input voltage dividing values ​​from the first voltage dividing circuit and the second voltage dividing circuit; a first switching step of controlling the switch unit to switch the second voltage dividing circuit to a conducting state; a first input step of inputting a first divided voltage value (Vns1) from the first voltage divider circuit and a second divided voltage value (Vrs1) from the second voltage divider circuit when the second voltage divider circuit is in a conducting state after the first switching step; a second switching step of controlling the switch unit to switch the second voltage dividing circuit to an energization cut-off state after the first input step; a second input step of inputting a first divided voltage value (Vns2) from the first voltage dividing circuit when the second voltage dividing circuit is in a power-off state after the second switching step; a characteristic determination step of determining whether or not an abnormality has occurred in the first voltage dividing circuit and the second voltage dividing circuit based on the first voltage dividing value and the second voltage dividing value input in the first input step; and a leakage current detection step of calculating insulation resistance and detecting leakage current based on the first divided voltage value input in the first input step and the first divided voltage value input in the second input step.

2. the first voltage dividing circuit includes a firstA detection resistor (Rs1), a firstB detection resistor (Rk1'), a firstC detection resistor (Rk1), and a voltage dividing ratio changeover switch (S3) connected in series with the firstC detection resistor (Rk1) and switching between a conducting state and a non-conducting state of the firstC detection resistor (Rk1); a series connection of the first C detection resistor (Rk1) and the voltage division ratio changeover switch (S3) is connected in parallel to the first B detection resistor (Rk1') to form a parallel connection; The first A detection resistor (Rs1) is connected in series to the parallel connection body, The leakage detection device according to claim 1 , wherein the control unit changes the voltage division ratio of the first voltage dividing circuit by switching the voltage division ratio changeover switch.

3. the first voltage dividing circuit includes a firstA detection resistor (Rs1), a firstB detection resistor (Rk1'), a firstC detection resistor (Rk1), and a voltage dividing ratio changeover switch (S3) connected in parallel to the firstB detection resistor (Rk1') and switching between a conducting state and a non-conducting state of the firstB detection resistor (Rk1'); The first A detection resistor (Rs1), the first B detection resistor (Rk1'), and the first C detection resistor (Rk1) are connected in series, The leakage detection device according to claim 1 , wherein the control unit changes the voltage division ratio of the first voltage dividing circuit by switching the voltage division ratio changeover switch.

4. A leakage current detection device (20) for detecting a leakage current between a power supply path (L1, L2) connected to a terminal of a battery (10) and a ground (FG), a first voltage dividing circuit (30, 130) having one end connected to the power supply path side and the other end connected to the ground side; a resistor circuit (40) having one end connected to the power supply path side and the other end connected to the ground side and connected in parallel to the first voltage dividing circuit; a switch unit (S2) configured to be able to switch between a conducting state and a non-conducting state of the resistor circuit; a control unit (70) that controls switching of the switch unit, inputs first divided voltage values ​​(Vns1, Vns2) of the first voltage dividing circuit, calculates insulation resistance from the input first divided voltage value, and detects leakage current; the first voltage dividing circuit has a range changing circuit (60, 160) that changes the voltage dividing ratio of the first voltage dividing circuit; When an input first divided voltage value (Vns01, Vns02) of the first voltage divider circuit is smaller than a threshold value (Vth), the control unit changes the voltage division ratio of the first voltage divider circuit by the range change circuit (60, 160) so that the first divided voltage value becomes larger; the first voltage dividing circuit has a first A detection resistor (Rs1), a first B detection resistor (Rk1'), and a first C detection resistor (Rk1), which are connected in series; The control unit, under normal circumstances, inputs a first voltage division value from a connection point (P101) between the first B detection resistor Rk1' and the first C detection resistor Rk1, and when the input first voltage division value is smaller than a threshold value, inputs the first voltage division value from a connection point (P102) between the first A detection resistor Rs1 and the first B detection resistor Rk1', thereby changing the voltage division ratio of the first voltage division circuit.

5. the first voltage dividing circuit has a first A detection resistor (Rs1), a first B detection resistor (Rk1'), and a first C detection resistor (Rk1), which are connected in series; The control unit normally inputs a first voltage division value from a connection point (P101) between the first B detection resistor Rk1' and the first C detection resistor Rk1, and when the input first voltage division value is smaller than a threshold value, changes the voltage division ratio of the first voltage division circuit by inputting the first voltage division value from a connection point (P102) between the first A detection resistor Rs1 and the first B detection resistor Rk1'.

6. A leakage current detection device (20) for detecting a leakage current between a power supply path (L1, L2) connected to a terminal of a battery (10) and a ground (FG), a first voltage dividing circuit (30, 130) having one end connected to the power supply path side and the other end connected to the ground side; a resistor circuit (40) having one end connected to the power supply path side and the other end connected to the ground side and connected in parallel to the first voltage dividing circuit; a switch unit (S2) configured to be able to switch between a conducting state and a non-conducting state of the resistor circuit; a control unit (70) that controls switching of the switch unit, inputs first divided voltage values ​​(Vns1, Vns2) of the first voltage dividing circuit, calculates insulation resistance from the input first divided voltage value, and detects leakage current; the first voltage dividing circuit has a range changing circuit (60, 160) that changes the voltage dividing ratio of the first voltage dividing circuit; When an input first divided voltage value (Vns01, Vns02) of the first voltage divider circuit is smaller than a threshold value (Vth), the control unit changes the voltage division ratio of the first voltage divider circuit by the range change circuit (60, 160) so that the first divided voltage value becomes larger; The control unit detects that there is a leak without calculating the value of the insulation resistance when the voltage (Vn1, Vn2) across the first voltage divider circuit calculated using the first voltage divider value input from the first voltage divider circuit and the voltage division ratio is less than a judgment threshold value (TL1, TL2).

7. 2. The leakage detection device according to claim 1, wherein the control unit detects that a leakage current has occurred without calculating an insulation resistance value when the voltage (Vn1, Vn2) across the first voltage divider circuit calculated using the first voltage divider value input from the first voltage divider circuit and the voltage division ratio is less than a judgment threshold value (TL1, TL2).

8. The control unit a first input step of inputting a first divided voltage value (Vns1) from the first voltage dividing circuit when the resistor circuit is in a conducting state; a second input step of inputting a first divided voltage value (Vns2) from the first voltage dividing circuit when the resistor circuit is in a power-off state; a leakage current detection step of calculating an insulation resistance based on the first divided voltage value input in the first input step and the second divided voltage value input in the second input step, and detecting a leakage current; 7. The leakage detection device according to claim 4, wherein the control unit inputs a first voltage division value (Vns01, Vns02) of the first voltage division circuit before performing the first input step or the second input step, and changes the voltage division ratio of the first voltage division circuit if the input first voltage division value is smaller than a threshold value.

9. The power supply path includes a positive power supply path (L1) connected to a positive terminal of the battery and a negative power supply path (L2) connected to a negative terminal of the battery, the first voltage dividing circuit and the resistance circuit are connected to a first power supply path which is either one of the positive power supply path and the negative power supply path, 2. The leakage detection device according to claim 1, wherein a resistor (R3) is provided between the ground and a second power supply path, which is one of the positive power supply path and the negative power supply path and is different from the first power supply path.

10. A changeover switch (S4) is connected in series to the resistor.

10. The leakage detection device according to claim 9, wherein when the first divided voltage value (Vns01, Vns02) of the first voltage divider circuit input is smaller than a threshold value (Vth), the control unit turns on the changeover switch to allow current to flow between the second power supply path and the ground via the resistor.

11. A leakage current detection device (20) for detecting a leakage current between a power supply path (L1, L2) connected to a terminal of a battery (10) and a ground (FG), a first voltage dividing circuit (30, 130) having one end connected to the power supply path side and the other end connected to the ground side; a resistor circuit (40) having one end connected to the power supply path side and the other end connected to the ground side and connected in parallel to the first voltage dividing circuit; a switch unit (S2) configured to be able to switch between a conducting state and a non-conducting state of the resistor circuit; a control unit (70) that controls switching of the switch unit, inputs first divided voltage values ​​(Vns1, Vns2) of the first voltage dividing circuit, calculates insulation resistance from the input first divided voltage value, and detects leakage current; the first voltage dividing circuit has a range changing circuit (60, 160) that changes the voltage dividing ratio of the first voltage dividing circuit; When an input first divided voltage value (Vns01, Vns02) of the first voltage divider circuit is smaller than a threshold value (Vth), the control unit changes the voltage division ratio of the first voltage divider circuit by the range change circuit (60, 160) so that the first divided voltage value becomes larger; The power supply path includes a positive power supply path (L1) connected to a positive terminal of the battery and a negative power supply path (L2) connected to a negative terminal of the battery, the first voltage dividing circuit and the resistance circuit are connected to a first power supply path which is either one of the positive power supply path and the negative power supply path, a resistor (R3) is provided between the ground and a second power supply path, which is one of the positive power supply path and the negative power supply path and is different from the first power supply path; A changeover switch (S4) is connected in series to the resistor. When the first voltage dividing value (Vns01, Vns02) of the first voltage dividing circuit input is smaller than a threshold value (Vth), the control unit turns on the changeover switch to allow current to flow between the second power supply path and the ground via the resistor.

12. 12. The leakage detection device according to claim 10, wherein the resistance value is smaller than the insulation resistance between the second power supply path and the ground and is larger than a value that is allowed as a normal value of the insulation resistance.

13. A leakage detection device (20) for detecting leakage between a positive power supply path (L1) connected to a positive terminal of a battery (10) and ground (FG), and between a negative power supply path (L2) connected to a negative terminal of the battery and ground (FG), a first voltage divider circuit (130) having one end connected to a first power supply path, which is either one of the positive power supply path and the negative power supply path, and the other end connected to the ground side; a resistor circuit (40) having one end connected to the first power supply path side and the other end connected to the ground side and connected in parallel to the first voltage dividing circuit; a switch unit (S2) configured to be able to switch between a conducting state and a non-conducting state of the resistor circuit; a control unit (70) that controls switching of the switch unit to input a first divided voltage value (Vns1, Vns2) of the first voltage dividing circuit, calculates an insulation resistance from the input first divided voltage value, and detects leakage current; a resistor (R3) having one end connected to a second power supply path different from the first power supply path among the positive power supply path and the negative power supply path, and having the other end connected to the ground side; A changeover switch (S4) is connected in series to the resistor. When the first voltage dividing value (Vns01, Vns02) of the first voltage dividing circuit input is smaller than a threshold value (Vth), the control unit turns on the changeover switch to allow current to flow between the second power supply path and the ground via the resistor.

14. 14. The leakage detection device according to claim 13, wherein the resistance value is smaller than an insulation resistance between the second power supply path and the ground and is larger than a value that is allowed as a normal value of the insulation resistance.

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