Electric leakage detection device and electric leakage detection method

Abstract

To provide an electric leakage detection device and an electric leakage detection method that can shorten a cycle for measuring a voltage across a detection resistor although common capacity exists.SOLUTION: An electric leakage detection device comprises a controller. The controller turns on one switch out of a first switch connected to a positive electrode side of a battery, and a second switch connected to a negative electrode side of the battery, turns off the other switch, and forms a series connection circuit with the battery and insulation resistance of the battery and a detection resistor for voltage measurement, in order to detect occurrence of electric leakage based on a voltage amount of the detection resistor. The controller conducts switching of both switches and measures a voltage value, in a cycle that is shorter than a cycle for completing electric discharge of common capacity, and detects occurrence of electric leakage based on the voltage value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The disclosed embodiments relate to an electric leakage detection device and an electric leakage detection method. [Background technology]

[0002] There is a leakage current detection device that detects the occurrence of leakage current due to a decrease in the insulation resistance of a battery. The leakage current detection device includes a first switch connected to the positive electrode side of the battery, a second switch connected to the negative electrode side, a detection resistor for measuring voltage, and a calculation processing circuit that detects the decrease in the insulation resistance of the battery based on the voltage across the detection resistor (see, for example, Patent Document 1).

[0003] The leakage current detection device turns on one of the first and second switches and turns off the other to form a series circuit of the battery, the battery's insulation resistance, and the detection resistor. The leakage current detection device then detects the occurrence of a leakage current based on the insulation resistance value calculated from the voltage across the detection resistor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2003-66090 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, for example, when there is a common capacitance between a battery and a charging control device, the conventional leakage detection device cannot accurately measure the voltage across the detection resistor until all the charges accumulated in the common capacitance are discharged and the voltage across the detection resistor stabilizes, making it difficult for the conventional leakage detection device to shorten the period for measuring the voltage across the detection resistor.

[0006] One aspect of the embodiment has been made in consideration of the above, and aims to provide a leakage current detection device and a leakage current detection method that can shorten the period for measuring the voltage across the detection resistor even when a common capacitance is present. [Means for solving the problem]

[0007] A leakage current detection device according to one aspect of the embodiment includes a controller. The controller turns on one of a first switch connected to the positive electrode of a battery and a second switch connected to the negative electrode of the battery and turns off the other switch to form a series connection circuit with the battery, an insulation resistance of a case that houses the battery, and a detection resistor for voltage measurement, and detects the occurrence of leakage current based on the voltage value of the detection resistor. The controller switches both switches at a period shorter than the period in which the discharge of a common capacitance is completed, measures the voltage value, and detects the occurrence of leakage current based on the voltage value. Effect of the Invention

[0008] Advantageous Effects of Invention An electric leakage detection device and an electric leakage detection method according to an aspect of an embodiment have an effect of shortening the period for measuring the voltage across the detection resistor even when a common capacitance is present. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram showing an example of the configuration of an electric leakage detection device according to an embodiment. [Diagram 2] FIG. 2 is an explanatory diagram showing an example of the operation of the electric leakage detection device according to the embodiment. [Diagram 3] FIG. 3 is an explanatory diagram showing an example of the operation of the electric leakage detection device according to the embodiment. [Figure 4] FIG. 4 is an explanatory diagram showing the influence of the common capacitance on the detection resistor voltage according to the embodiment. [Diagram 5] FIG. 5 is an explanatory diagram of the state of the electric leakage detection device 1 according to the embodiment. [Figure 6] FIG. 6 is an explanatory diagram of the state of the electric leakage detection device 1 according to the embodiment. [Figure 7] FIG. 7 is an explanatory diagram of the state of the electric leakage detection device 1 according to the embodiment. [Figure 8] FIG. 8 is an explanatory diagram of the state of the electric leakage detection device 1 according to the embodiment. [Figure 9A] FIG. 9A is an explanatory diagram showing a transition of VG according to the embodiment. [Figure 9B] FIG. 9B is an explanatory diagram showing a transition of VG according to the embodiment. [Figure 10] FIG. 10 is a flowchart showing the process executed by the controller according to the embodiment. [Figure 11] FIG. 11 is a flowchart showing the process executed by the controller according to the embodiment. [Figure 12] FIG. 12 is an explanatory diagram of a leakage determination method according to a modified example of the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of a leakage current detection device and a fault detection method will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiment. The leakage current detection device according to the embodiment is mounted on a vehicle that runs using the driving force of an electric motor, such as an electric vehicle or a hybrid vehicle.

[0011] A high-voltage secondary battery (such as a lithium-ion battery) that outputs a high voltage of several hundred volts or more is used as the battery that supplies power to the electric motor of a vehicle. Such a battery may pose a risk of electric shock if it leaks electricity.

[0012] For this reason, the battery is stored in an insulating case or the like and electrically insulated from the outside. When new, the battery case has a resistance value of several MΩ and barely conducts electricity. However, the insulating performance of the battery case may deteriorate due to, for example, aging. For this reason, the leakage detection device detects and monitors, for example, the insulation resistance of the case, which becomes the insulation resistance of the battery. The leakage detection device according to the embodiment is included in, for example, a charge control device that controls charging of the battery.

[0013] [1. Example of insulation detection device configuration] Fig. 1 is an explanatory diagram showing an example of the configuration of an electric leakage detection device 1 according to an embodiment. As shown in Fig. 1, the electric leakage detection device 1 is connected to a battery 10 via a high-voltage side insulation resistor (hereinafter referred to as "Rp12") and a low-voltage side insulation resistor (hereinafter referred to as "Rn13"). The battery 10 includes a plurality of battery cells 11 connected in series.

[0014] Rp12 and Rn13 are not resistive elements, but are parts of the insulating case that houses the above-mentioned battery 10. Note that Rp12 and Rn13 may be resistive elements provided to electrically insulate the battery 10 from the outside of the battery 10.

[0015] The leakage current detection device 1 includes a measurement unit 2 and a controller 3. The measurement unit 2 includes a first switch 21 connected to the positive electrode side of the battery 10, a second switch 22 connected to the negative electrode side of the battery 10, detection resistors 23 and 24, and a measurement circuit 25 that measures the voltage applied to the detection resistors 23 and 24. The measurement unit 2 further includes limiting resistors 26 and 27.

[0016] The controller 3 includes a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and various circuits. The controller 3 controls the first switch 21 and the second switch 22 by the CPU executing a program stored in the ROM using the RAM as a working area.

[0017] The controller 3 turns on one of the first switch 21 and the second switch 22 and turns off the other to form a series connection circuit of the battery 10, Rp12, Rn13 of the battery 10, and the detection resistors 23, 24. The controller 3 then calculates the resistance values ​​of Rp12 and Rn13 based on the voltage measured by the measurement circuit 25.

[0018] The controller 3 may be configured in part or in whole using hardware such as an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA).

[0019] [2. Example of leakage current detection device operation] Next, an operation example of the electric leakage detection device 1 will be described with reference to Fig. 2 and Fig. 3. Fig. 2 and Fig. 3 are explanatory diagrams showing an operation example of the electric leakage detection device 1 according to the embodiment.

[0020] [2-1. General insulation resistance calculation operation] 2, when calculating the resistance value of insulation resistor Rp∥Rn consisting of Rp12 and Rn13, the controller 3 turns off the first switch 21 and turns on the second switch 22 to form a series connection circuit of the battery 10, Rp12, detection resistor 24, and limiting resistor 27. Then, the measurement circuit 25 measures the voltage applied to the detection resistor 24 (the voltage difference across the detection resistor 24) VRP, and outputs the measurement result to the controller 3.

[0021] 3, the controller 3 turns on the first switch 21 and turns off the second switch 22 to form a series connection circuit of the battery 10, the limiting resistor 26, the detection resistor 23, and Rn13. Then, the measurement circuit 25 measures the voltage VRN applied to the detection resistor 23 (the voltage difference across the detection resistor 23) and outputs the measurement result to the controller 3.

[0022] Here, a typical controller calculates the resistance value Rp∥Rn (parallel resistance value of Rp and Rn) of the insulation resistance by performing a calculation process corresponding to the following formula (1). Rp||Rn=VB / (VRP+VRN)·RR´········(1) VB: voltage of the battery 10, R and R' are resistance values ​​calculated from the circuit resistance

[0023] A typical controller determines that there is no leakage (normal) if the resistance value Rp∥Rn is equal to or greater than a predetermined resistance value. Also, the controller 3 determines that there is leakage if the calculated resistance value Rp∥Rn is less than the predetermined resistance value. If the controller determines that there is leakage, it warns the user of this fact by a warning device such as a warning light.

[0024] 1 to 3, for example, a common capacitance C may occur between the leakage detection device 1 included in the charging control device and the battery 10. In this case, when the first switch 21 and the second switch 22 are on / off controlled, it takes time for the values ​​of VRP and VRN to stabilize.

[0025] 4, when the second switch 22 is turned on, the common capacitance C is charged, so VPR rises temporarily, and then VRP gradually drops as the common capacitance C is discharged, and converges to a certain value when the discharge is completed. After that, when the second switch 22 is turned off and the first switch 21 is turned on, the common capacitance C is charged, so VPN rises temporarily, and then VRN gradually drops as the common capacitance C is discharged, and converges to a certain value when the discharge is completed. For example, when the common capacitance is 1 μF, it takes 2 s from the start to the completion of the discharge of the common capacitance C.

[0026] The controller cannot calculate the accurate resistance value Rp||Rn of the insulation resistance until the values ​​of VRP and VRN converge. For this reason, when the common capacitance is 1 μF, for example, the controller takes 2 s to measure VRP and 2 s to measure VRN. For this reason, the controller cannot reduce the time it takes to measure VRP and VRN to less than 4 s. In other words, a typical controller cannot calculate the resistance value Rp||Rn of the insulation resistance in a period shorter than 4 s.

[0027] Therefore, the controller 3 of the leakage current detection device 1 according to the embodiment switches the first switch 21 and the second switch 22 and measures the voltage across the detection resistor 24 in a cycle shorter than the cycle in which the discharge of the common capacitance is completed. The controller 3 detects leakage current based on the voltage across the detection resistor 24, thereby making it possible to shorten the leakage current detection cycle. The leakage current detection device 1 according to the embodiment will be specifically described below.

[0028] [2-2. State of the earth leakage detection device according to the embodiment] Fig. 5 to Fig. 8 are explanatory diagrams showing the state of the earth leakage detection device 1 according to the embodiment. Fig. 9A and Fig. 9B are explanatory diagrams showing the transition of VG according to the embodiment. Note that in Fig. 5 to Fig. 8, the measurement circuit 25 and the controller 3 are omitted.

[0029] Fig. 5 shows the state of the earth leakage detection device 1 when measuring VRP without common capacitance C. Fig. 6 shows the state of the earth leakage detection device 1 when measuring VRN without common capacitance C. Fig. 7 shows the state of the earth leakage detection device 1 when measuring VRP with common capacitance C. Fig. 8 shows the state of the earth leakage detection device 1 when measuring VRN with common capacitance C.

[0030] Here, the case where the voltage of the battery 10 is 240V, Rp12 is 1.2MΩ, Rn13 is 100MΩ, and the detection resistor 24 is 2.3MΩ will be described. That is, Rn13, which is the insulation resistor on the low voltage side, is normal, and the resistance value of Rp12, which is the insulation resistor on the high voltage side, has decreased. Here, the potential difference between the high voltage ground (body earth GND of the vehicle) and the low voltage ground (negative electrode of the battery 10) is written as VG.

[0031] As shown in FIG. 5, in the absence of a common capacitance C, when the first switch 21 is turned off and the second switch 22 is turned on, the measured VRP(VG) becomes 156.4 V according to the following formula (2). VG=VB (Rn / / R) / (Rp+Rn / / R) (2) Detection resistor 24: R=2.3M, Rp=1.2M, Rn / / R=2.25M

[0032] Also, as shown in Figure 6, if there is no common capacitance C, and Rn>>Rp (Rn is significantly larger than Rp), the VG measured when measuring VRN will be VG ≒ 240 V. Conversely, if Rp>>Rn, then VG ≒ 0 V.

[0033] In contrast, when there is a common capacitance C, when switching control is repeated to alternately turn on the first switch 21 and the second switch 22 at a period of 150 ms, which is shorter than the discharge period (2 s) of the common capacitance C, VG gradually decreases from the initial value of 240 V.

[0034] Specifically, when there is no common capacitance C, when switching control is performed, VG alternates between 240V and 156.4V, as explained in Figures 5 and 6. In contrast, when there is common capacitance C, when switching control is performed, VG is smoothed by the common capacitance C and converges to approximately the midpoint between 240V and 156.4V. VG gradually decreases from 240V, the same as when VRN was measured without common capacitance, and converges and stabilizes at approximately the midpoint potential between 156.4V and 240V, which is the value when VRP was measured without common capacitance.

[0035] As a result, for example, as shown in FIG. 7 and FIG. 8, in the case where a common capacitance is present, when switching control is performed to alternately turn on the first switch 21 and the second switch 22 at 150 ms intervals, VG converges to 198.2V.

[0036] Therefore, the controller 3 can detect the occurrence of leakage current, for example, based on VG. For example, as shown in FIG. 9A, when VG is equal to or more than half the voltage VB (240V) of the battery 10, that is, when Rn>>Rp and leakage current of Rp is to be determined, VG is compared with a voltage threshold (first threshold) to detect the occurrence of leakage current. In this case, the controller 3 determines that leakage current has occurred if VG is equal to or more than the first threshold. If VG is less than the first threshold, the controller 3 determines that leakage current has not occurred and that the system is normal. This allows the controller 3 to determine the occurrence of leakage current at 300 ms intervals after VG has converged.

[0037] The first threshold is determined in the following manner. Let VB-(VB*Rn / (Rp / / R+Rn when normal)-VB*(Rn / / R) / (Rp+Rn / / R when normal)) / 2=A, VB-(VB*Rn / (Rp / / R+Rn when abnormal)-VB*(Rn / / R) / (Rp+Rn / / R when abnormal)) / 2=B, Between A and B a first threshold is set.

[0038] Furthermore, for example, when VG is lower than half the voltage VB (240V) of the battery 10, that is, when Rp>>Rn and a leakage current is detected for Rn, the controller 3 compares VG with a voltage threshold (second threshold) to detect the occurrence of a leakage current. In this case, if VG is equal to or greater than the second threshold, the controller 3 determines that there is no leakage current and that the system is normal. If VG is less than the second threshold, the controller 3 determines that a leakage current has occurred.

[0039] The second threshold is determined in the following manner. Let (VB*Rn when normal / (Rp / / R+Rn when normal)-VB*(Rn / / R when normal) / (Rp+Rn / / R when normal)) / 2=X, Let (VB*Rn when abnormal / (Rp / / R+Rn when abnormal)-VB*(Rn / / R when abnormal) / (Rp+Rn / / R when abnormal)) / 2=Y, A second threshold is set between Y and Y.

[0040] 9A and 9B show the control timing of the first switch 21 and the second switch 22. For example, a period when the square wave is at a high level is a period when the first switch 21 is on and the second switch 22 is off. A period when the square wave is at a low level is a period when the first switch 21 is off and the second switch 22 is on.

[0041] 9A shows a case where the resistance value of Rp12 is 1.2 MΩ and Rp12 is normal. In this case, VG converges to about 198.2 V, which is the middle between 240 V and 156.4 V. At this time, VG is lower than the first threshold value, and Rp12 is determined to be normal (no leakage current).

[0042] In contrast, for example, when the resistance value of Rp12 drops to 375 kΩ, as shown in Fig. 9B, it converges to about 223 V, which is the middle between 240 V and 206 V. At this time, VG is higher than the first threshold value, and Rp12 is determined to be abnormal (there is a leakage current).

[0043] 9A, VG converges at time T, and then takes a constant value (near 198.2 V). Therefore, the controller 3 can execute leakage current determination at 300 ms intervals after time T when the actual measurement value of VG converges. This allows the controller 3 to meet, for example, a request for leakage current detection at 1 s intervals, which is not possible with a general controller.

[0044] Furthermore, the controller 3 may be configured to detect the occurrence of a leakage current after a predetermined time has elapsed since the start of the switching control of the first switch 21 and the second switch 22. In the example shown in Fig. 9A, the VG converges 4 s after the start of the switching control of the first switch 21 and the second switch 22. In this case, the controller 3 executes the leakage current determination at a cycle of 300 ms, for example, when the controller 3 is next started, 4 s after the start of the switching control of the first switch 21 and the second switch 22. This eliminates the need for the controller 3 to perform VG measurement processing until the VG converges, thereby reducing the processing load.

[0045] The controller 3 may be configured to detect the occurrence of a leakage current after the number of times the first switch 21 and the second switch 22 are switched reaches a predetermined number. For example, the controller 3 stores the number of times the first switch 21 and the second switch 22 are switched from when the controller 3 starts switching control of the first switch 21 and the second switch 22 after startup until the VG converges. Then, the controller 3 switches the first switch 21 and the second switch 22 the number of times stored previously at the next startup, and thereafter executes the occurrence of a leakage current at a cycle of 300 ms. This eliminates the need for the controller 3 to perform VG measurement processing until the VG converges, thereby reducing the processing load.

[0046] The controller 3 may be configured to detect the occurrence of a leakage current after the difference between the current measurement value of VG and the previous measurement value (300 ms ago) becomes equal to or smaller than a predetermined value. This also enables the controller 3 to detect the occurrence of a leakage current at 300 ms intervals after the difference between the current measurement value of VG and the previous measurement value becomes equal to or smaller than a predetermined value.

[0047] [3. Processing performed by the controller] Next, the process executed by the controller 3 will be described with reference to Fig. 10 and Fig. 11. Fig. 10 and Fig. 11 are flowcharts showing the process executed by the controller 3 according to the embodiment.

[0048] When an ignition switch (hereinafter, referred to as "IG") of the vehicle is turned on, the controller 3 executes the process shown in Fig. 10. As shown in Fig. 10, when the IG is turned on, the controller 3 first starts a control to alternately turn on the first switch 21 and the second switch 22 at a period shorter than the discharge period of the common capacitance C (step S101).

[0049] Next, the controller 3 judges whether or not VG has converged (step S102). The controller 3 measures, for example, the actual value of VG, and judges that VG has converged when the actual value of VG has converged.

[0050] Furthermore, the controller 3 may be configured to determine that VG has converged when a predetermined time has elapsed since the controller 3 started to control the first switch 21 and the second switch 22 to be alternately turned on.

[0051] The controller 3 may be configured to determine that VG has converged when the difference between the current measurement value of VG and the previous measurement value becomes equal to or smaller than a predetermined value. The controller 3 may be configured to determine that VG has converged when the number of times the first switch 21 and the second switch 22 are switched reaches a predetermined number after the IG is turned on.

[0052] When it is determined that VG has not converged (step S102, No), the controller 3 repeats the determination in step S102 while continuing the control of alternately turning on the first switch 21 and the second switch 22 until VG converges.

[0053] If the controller 3 determines that VG has converged (Yes at step S102), it measures VG (step S103) and executes leakage determination processing (step S104). The details of the leakage determination processing will be described later with reference to FIG.

[0054] After executing the leakage current determination process, the controller 3 determines whether or not the IG has been turned off (step S105). If the controller 3 determines that the IG has not been turned off (step S105, No), the controller 3 moves the process to step S103. If the controller 3 determines that the IG has been turned off (step S105, Yes), the controller 3 ends the process.

[0055] Next, the contents of the leakage determination process will be described. As shown in Fig. 11, when the controller 3 starts the leakage determination process, it first judges whether VG is equal to or more than half of VB, which is the voltage of the battery 10 (step S201). That is, it judges whether or not there is a large difference between the values ​​of Rp and Rn. If the controller 3 judges that VG is equal to or more than half of VB (step S201, Yes), that is, if it judges that Rn>>Rp, it judges whether VG is equal to or more than a first threshold value (step S202).

[0056] When the controller 3 determines that VG is equal to or greater than the first threshold (step S202, Yes), it determines that a leak has occurred (Rp is leaking) (step S203) and ends the leak determination process. When the controller 3 determines that VG is not equal to or greater than the first threshold (step S202, No), it determines that no leak has occurred and that the system is normal (step S204) and ends the leak determination process.

[0057] Furthermore, when the controller 3 determines that VG is not equal to or greater than half of VB (step S201, No), that is, when it determines that Rp>>Rn, it determines whether VG is equal to or greater than the second threshold (step S205). When the controller 3 determines that VG is equal to or greater than the second threshold (step S205, Yes), it determines that no leakage has occurred and that the system is normal (step S206), and ends the leakage determination process. When the controller 3 determines that VG is not equal to or greater than the second threshold (step S205, No), it determines that a leakage has occurred (Rn is leaking) (step S207), and ends the leakage determination process.

[0058] As described above, when Rn>>Rp (Rn is significantly larger than Rp) or when Rp>>Rn (Rp is significantly larger than Rn), the controller 3 controls the switching of the switches at a period shorter than the period in which the discharge of the common capacitance C is completed.

[0059] For example, when there is a common capacitance C, the controller 3 alternately turns on and off the first switch 21 and the second switch 22 in a cycle of 150 ms, which is shorter than the cycle of 2 s in which the discharge of the common capacitance C is completed.

[0060] In other words, the controller 3 repeats switching control such that, for example, the second switch 22 is on and the first switch 21 is off for 150 ms, and then the first switch 21 is on and the second switch 22 is off for 150 ms.

[0061] As a result, after the common capacitance C is charged, charging begins before the discharge is completed. That is, the common capacitance C repeats charging and discharging for a very short time. Therefore, VB converges to a certain value a certain time after the on / off control of the first switch 21 and the second switch 22 is started. Thereafter, VB is maintained at the converged value as the on / off control of the first switch 21 and the second switch 22 continues.

[0062] Furthermore, after the value of VB has converged, the controller 3 can determine the presence or absence of an electric leakage by comparing VG with a threshold (the first threshold or the second threshold) at 300 ms intervals. Therefore, the controller 3 can shorten the period for determining the occurrence of an electric leakage compared to a general controller that can only determine the presence or absence of an electric leakage at a 4 s interval at the shortest.

[0063] However, the controller 3 cannot perform leakage current determination based on VG unless Rn>>Rp (Rn is significantly larger than Rp) or Rp>>Rn (Rp is significantly larger than Rn).

[0064] In other words, when both Rp12 and Rn13 are normal, or when both are abnormal (earth leakage), the controller 3 cannot perform earth leakage judgment based on VG. Although it is almost impossible for both Rp12 and Rn13 to become abnormal, it is preferable to assume this.

[0065] Therefore, the controller 3 may be configured to perform leakage determination taking into consideration the case where both Rp12 and Rn13 are abnormal. Fig. 12 is an explanatory diagram of a leakage determination method according to a modified example of the embodiment.

[0066] The VG determination shown in FIG. 12 is a process in which the controller 3 determines the occurrence of a leakage current based on the VG measured by alternately turning on and off the first switch 21 and the second switch 22 at a period shorter than the period in which the discharge of the common capacitance is completed.

[0067] Moreover, the VRP, VRN determination shown in FIG. 12 is a conventional process in which the controller 3 alternately turns on and off the first switch 21 and the second switch 22 at a period longer than the period in which the discharge of the common capacitance is completed, measures VRP and VRN after waiting for the discharge of the common capacitance to be completed, and determines whether a leakage current has occurred based on the measured VRP and VRN.

[0068] As shown in FIG. 12, in the leakage current determination method according to the modified example, the controller 3 repeatedly performs a series of processes, in which the controller 3 repeatedly performs a VG determination during a first period, and performs a VRP and VRN determination during a second period (a second period different from the first period) subsequent to the first period.

[0069] As a result, even if both Rp12 and Rn13 become abnormal, the controller 3 can accurately determine the occurrence of a leakage current by the VRP and VRN determinations performed in the second period.

[0070] Further advantages and modifications may readily occur to those skilled in the art. Thus, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and equivalents thereof. [Explanation of symbols]

[0071] 1. Electric leakage detection device 2. Measurement section 3. Controller 10 batteries 11 Battery Cell 12 Rp 13 Rn 21 First Switch 22 Second Switch 23 Detection resistor 24 Detector resistor 25 Measurement circuit 26 Limiting resistor 27 Limiting Resistor C Common capacitance GND Body Earth

Claims

1. a controller that turns on one of a first switch connected to a positive electrode of a battery and a second switch connected to a negative electrode of the battery and turns off the other switch to form a series connection circuit of the battery, the insulation resistance of the battery, and a detection resistor for voltage measurement, and detects the occurrence of a leakage current based on the voltage value of the detection resistor; The controller: Both switches are switched at a period shorter than the period in which the discharge of the common capacitance is completed, and the voltage value is measured, and the occurrence of a leakage current is detected based on the voltage value. Earth leakage detection device.

2. The controller: After the actual measured voltage value has converged, the occurrence of the leakage current is detected. The earth leakage detection device according to claim 1 .

3. The controller: The occurrence of the electric leakage is detected after a predetermined time has elapsed since the start of switching of the two switches, during which the actual measured values ​​of the voltage values ​​converge. The earth leakage detection device according to claim 1 .

4. The controller: The occurrence of the electric leakage is detected after the number of times the two switches are switched reaches a predetermined number at which the actual measured value of the voltage value converges. The earth leakage detection device according to claim 1 .

5. The controller: The occurrence of the electric leakage is detected after the difference between the current measurement value and the previous measurement value of the voltage value becomes equal to or less than a predetermined value. The earth leakage detection device according to claim 1 .

6. The controller: The occurrence of the electrical leakage is detected based on a comparison result between the voltage value and a voltage threshold value. The earth leakage detection device according to claim 1 .

7. The controller: During a first period, both switches are switched at a cycle shorter than the cycle in which the discharge of the common capacitance is completed, and the voltage value is measured, and the occurrence of a leakage current is detected based on the voltage value. During a second period different from the first period, the occurrence of a leakage current is detected based on the voltage value of the detection resistor that is measured after waiting for the discharge of the common capacitance to be completed. The earth leakage detection device according to claim 1 .

8. a controller which turns on one of a first switch connected to a positive electrode of a battery and a second switch connected to a negative electrode of the battery and turns off the other switch to form a series connection circuit of the battery, the insulation resistance of the battery, and a detection resistor for voltage measurement, and detects the occurrence of a leakage current based on the voltage value of the detection resistor; Both switches are switched at a period shorter than the period in which the discharge of the common capacitance is completed, and the voltage value is measured, and the occurrence of a leakage current is detected based on the voltage value. Earth leakage detection method.

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