Insulation resistance detection device and insulation resistance detection method

Abstract

To provide an insulation resistance detection device capable of reducing the time required to determine insulation resistance abnormalities, and an insulation resistance detection method.SOLUTION: A disclosed insulation resistance detection device includes a controller and a promotion circuit. The controller forms a series circuit with a battery, an insulation resistance of the battery, and a detection resistor by turning on one switch and turning off the other switch out of a first switch connected on the positive side of the battery and a second switch connected to the negative side thereof and detects abnormalities in the insulation resistance based on the voltage value applied to the detection resistor. The promotion circuit is connected to the detection resistor in parallel therewith to increase the rate at which the voltage value applied to the detection resistor decreases when one switch is turned on. The controller detects an insulation resistance abnormality based on the voltage value lowered by the promotion circuit.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an insulation resistance detecting device and an insulation resistance detecting method. [Background technology]

[0002] Conventionally, there has been an insulation resistance detection device that forms a series circuit with a battery, the battery's insulation resistance, and a resistor for insulation detection (hereinafter referred to as the detection resistor), measures the voltage of the detection resistor, and detects an abnormality in the insulation resistance based on the measured voltage (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-66090 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional technology, if a common capacitance exists between the battery and the insulation resistance detection device, the charge accumulated in the common capacitance flows into the above-mentioned series circuit, causing an error in the voltage of the detection resistor. In this regard, a method can be considered in which the voltage of the detection resistor is measured after the charge accumulated in the common capacitance is completely discharged, but in that case, it is necessary to wait until the charge is completely discharged, which takes time to determine whether there is an abnormality in the insulation resistance.

[0005] The present application has been made in view of the above, and has an object to provide an insulation resistance detection device and an insulation resistance detection method that can shorten the time required to determine whether or not there is an abnormality in insulation resistance. [Means for solving the problem]

[0006] The insulation resistance detection device according to the present application includes a controller and a promotion circuit. The controller turns on one of a first switch connected to the positive electrode side of a battery and a second switch connected to the negative electrode side of the battery and turns off the other switch to form a series circuit with the battery, the insulation resistance of the battery, and a detection resistor, and detects an abnormality in the insulation resistance based on a voltage value applied to the detection resistor. The promotion circuit is connected in parallel to the detection resistor, and increases a rate of reduction in the voltage value applied to the detection resistor when the one switch is turned on. The controller detects an abnormality in the insulation resistance based on the voltage value reduced by the promotion circuit. Effect of the Invention

[0007] According to one aspect of the embodiment, an effect is achieved in that the time required for determining an abnormality in insulation resistance can be shortened. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is an explanatory diagram showing an example of the configuration of an insulation resistance detecting device according to the first embodiment. [Diagram 2] FIG. 2 is an explanatory diagram showing an example of the operation of the insulation resistance detecting device according to the first embodiment. [Diagram 3] FIG. 3 is an explanatory diagram showing an example of the operation of the insulation resistance detecting device according to the first embodiment. [Figure 4A] FIG. 4A is a diagram for explaining the insulation abnormality detection process according to the first embodiment. [Figure 4B] FIG. 4B is a diagram for explaining the process of detecting an insulation abnormality according to the modified example of the first embodiment. [Diagram 5] FIG. 5 is a flowchart illustrating an example of the first detection process executed by the control unit according to the first embodiment. [Figure 6] FIG. 6 is a flowchart illustrating an example of the second detection process executed by the control unit according to the first embodiment. [Figure 7] FIG. 7 is an explanatory diagram showing an example of the configuration of an insulation resistance detecting device according to the second embodiment. [Figure 8] FIG. 8 is an explanatory diagram showing an example of the operation of the insulation resistance detecting device according to the second embodiment. [Figure 9] FIG. 9 is an explanatory diagram showing an example of the operation of the insulation resistance detecting device according to the second embodiment. [Figure 10] FIG. 10 is a diagram showing a voltage applied to a detection resistor. [Figure 11] FIG. 11 is a diagram showing another example of the configuration of the promotion circuit. [Figure 12] FIG. 12 is a flowchart illustrating an example of a detection process executed by the control unit according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of an insulation resistance detection device, an insulation resistance detection method, and an insulation resistance detection program will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiment. An insulation resistance 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.

[0010] The vehicle in which the power supply control device according to the embodiment is installed may be an engine vehicle that runs on an internal combustion engine. The power supply control device according to the embodiment is a device that is installed in a vehicle with an automatic driving function and supplies power to a load.

[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, batteries are stored in insulating cases or the like to be electrically insulated from the outside. When new, a battery case has a resistance value of several MΩ and barely conducts electricity. However, the insulating performance of a battery case may deteriorate due to, for example, aging. For this reason, an insulation resistance detection device detects and monitors the insulation resistance of the case, which becomes the insulation resistance of the battery, for example.

[0013] [Example of insulation detection device configuration] Fig. 1 is an explanatory diagram showing an example of the configuration of an insulation resistance detection device 1 according to a first embodiment. As shown in Fig. 1, the insulation resistance detection device 1 is connected to a battery 10 via a high-voltage side insulation resistor 12 and a low-voltage side insulation resistor 13. The battery 10 includes a plurality of battery cells 11 connected in series.

[0014] The high-voltage side insulation resistor 12 and the low-voltage side insulation resistor 13 are not resistive elements, but are part of the insulating case that houses the above-mentioned battery 10. Note that the high-voltage side insulation resistor 12 and the low-voltage side insulation resistor 13 may be resistive elements provided to electrically insulate the battery 10 from the outside of the battery 10.

[0015] The insulation resistance detection device 1 includes a measurement unit 2 and a control unit 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, a measurement circuit 25 that measures the voltage applied to the detection resistors 23 and 24, limiting resistors 26 and 27, and smoothing capacitors 28 and 29 that smooth the voltage applied to the detection resistors 23 and 24.

[0016] The control unit 3 is a controller and includes a microcomputer having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and various circuits. The control unit 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 control unit 3 turns on one of the first switch 21 and the second switch 22 and turns off the other switch to form a series circuit of the battery 10, the insulation resistors 12, 13 of the battery 10, and the detection resistors 23, 24, and calculates the insulation resistances 12, 13 based on the voltage measured by the measurement circuit 25.

[0018] The control unit 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] [Example of insulation resistance detection device operation] Next, an operation example of the insulation resistance detecting device 1 according to the first embodiment 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 insulation resistance detecting device 1 according to the first embodiment.

[0020] [Operation when insulation resistance is detected] For example, when detecting the resistance value of the low-voltage side insulation resistor 13, as shown in Fig. 2, the control unit 3 turns on the first switch 21 and turns off the second switch 22 to form a first series circuit R1 including the battery 10, the limiting resistor 26, the detection resistor 23, and the low-voltage side insulation resistor 13. Then, the measurement circuit 25 measures the voltage applied to the detection resistor 23 (the voltage difference across the detection resistor 23) and outputs the measurement result to the control unit 3. Note that hereinafter, the voltage applied to the detection resistor 23 is referred to as "VRN."

[0021] At this time, if the resistance value of the low-voltage side insulation resistor 13 is sufficiently high, almost no current flows through the first series circuit R1. In this case, the voltage measured by the measurement circuit 25 will be close to 0V. In contrast, if the resistance value of the low-voltage side insulation resistor 13 has decreased, current will flow through the first series circuit R1. And the lower the resistance of the low-voltage side insulation resistor 13, the higher the voltage measured by the measurement circuit 25 will be.

[0022] For this reason, the control unit 3 calculates the resistance value of the insulation resistor 13 on the low voltage side based on the voltage measured by the measurement circuit 25, and if the calculated resistance value is equal to or greater than the threshold resistance value indicating a leakage current, it determines that there is no leakage current. Furthermore, if the calculated resistance value is less than the threshold resistance value, the control unit 3 determines that there is a leakage current. If the control unit 3 determines that there is a leakage current, it outputs a signal to a warning device such as a warning light to notify the user of the leakage current. The warning device that receives this signal outputs a sound or light to notify the user of the leakage current. As a result, the user can recognize that there is a leakage current.

[0023] Furthermore, for example, when detecting the resistance value of the high-voltage side insulation resistor 12, as shown in Fig. 3, the control unit 3 turns off the first switch 21 and turns on the second switch 22 to form a second series circuit R2 of the battery 10, the high-voltage side insulation resistor 12, the detection resistor 24, and the 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) and outputs the measurement result to the control unit 3. Note that hereinafter, the voltage applied to the detection resistor 24 is referred to as "VRP".

[0024] At this time, if the resistance value of the high-voltage side insulation resistor 12 is sufficiently high, almost no current flows through the second series circuit R2. In this case, the voltage measured by the measurement circuit 25 will be close to 0V. In contrast, if the resistance value of the high-voltage side insulation resistor 12 is low, current will flow through the second series circuit R2. And the lower the resistance of the high-voltage side insulation resistor 12, the higher the voltage measured by the measurement circuit 25 will be.

[0025] Therefore, the control unit 3 calculates the resistance value of the insulation resistor 12 on the high voltage side based on the voltage measured by the measurement circuit 25, and if the calculated resistance value is equal to or greater than a predetermined resistance value indicating a leakage current, it determines that there is no leakage current. Moreover, if the calculated resistance value is less than the predetermined resistance value, the control unit 3 determines that there is a leakage current. If the control unit 3 determines that there is a leakage current, it warns the user of this fact by a warning device such as a warning light.

[0026] In addition, the control unit 3 may calculate the parallel resistance value of the high-voltage side insulation resistors 12 and 13 based on VRP and VRN, and determine that there is no leakage if the parallel resistance value is equal to or greater than a predetermined resistance value, and determine that there is leakage if the parallel resistance value is less than the predetermined resistance value.

[0027] Here, as shown in FIG. 1, in addition to the insulation resistors 12, 13, common capacitances 14, 15 may exist between the battery 10 and the insulation resistance detection device 1. The common capacitances 14, 15 may be unintentional floating capacitances or may be capacitor components installed to suppress noise generated by a vehicle control device or the like. The common capacitances 14, 15 have charges stored therein before the first switch 21 or the second switch 22 is turned on. Therefore, when the first switch 21 or the second switch 22 is turned on, the charges stored in the common capacitances 14, 15 flow to the detection resistors 23, 24. As a result, the voltage measured by the detection resistors 23, 24 increases by the amount of the charges of the common capacitances 14, 15, which may make it difficult to accurately determine an insulation abnormality.

[0028] Specifically, when the first switch 21 is turned on, the charge of the high-voltage side common capacitance 14 flows to the detection resistor 23, causing the voltage of the detection resistor 23 to rise by the charge of the common capacitance 14. When the second switch 22 is turned on, the charge of the low-voltage side common capacitance 15 flows to the detection resistor 24, causing the voltage of the detection resistor 24 to rise by the charge of the common capacitance 15.

[0029] In order to reduce the voltage error of the detection resistors 23, 24 due to the common capacitances 14, 15, for example, a method of measuring the voltage of the detection resistors 23, 24 after the charge accumulated in the common capacitances 14, 15 is completely discharged is conceivable. However, if the measurement of the voltage of the detection resistors 23, 24 is delayed until the charge is completely discharged, the determination of an abnormality in the insulation resistors 12, 13 will inevitably be delayed. Note that the above expression "the charge is completely discharged" is not limited to the case where the charge becomes zero. For example, the case where the voltage value becomes equal to or lower than a threshold value (for example, 10% or less) from a peak voltage value measured in advance may be regarded as "the charge is completely discharged."

[0030] Therefore, in the first embodiment, the voltages of the detection resistors 23, 24 are measured while the charges of the common capacitances 14, 15 are being discharged to determine whether or not there is an abnormality in the insulation resistances 12, 13. This eliminates the need to wait until the charges of the common capacitances 14, 15 are completely discharged, thereby shortening the time required to determine whether or not there is an abnormality in the insulation resistances 12, 13.

[0031] Here, the insulation abnormality detection process according to the first embodiment will be described with reference to Fig. 4A. Fig. 4A is a diagram for explaining the insulation abnormality detection process according to the first embodiment. Fig. 4A shows a graph of the change in voltage over time in the detection resistors 23 and 24. In the graph of Fig. 4A, the solid line indicates the voltage taking into account the common capacitances 14 and 15, and the dashed line indicates the voltage excluding the common capacitances 14 and 15. The voltage values ​​in Fig. 4A are shown in absolute values.

[0032] 4A, the voltages of the detection resistors 23 and 24 taking into account the common capacitances 14 and 15 are highest when the first switch 21 or the second switch 22 is turned on, and gradually decrease over time. In other words, the charges accumulated in the common capacitances 14 and 15 are gradually discharged after the first switch 21 or the second switch 22 is turned on.

[0033] In the first embodiment, an abnormality determination is performed for the insulation resistors 12, 13 using voltages (VRP1, VRN1) measured while charges accumulated in the common capacitors 14, 15 are being discharged. Specifically, in the first embodiment, the insulation resistance detecting device 1 performs a first detection process and a second detection process.

[0034] In the first detection process, the insulation resistance detection device 1 measures the first voltage values ​​VRP1, VRN1 when a first time has elapsed since one of the first switch 21 or the second switch 22 was turned on, and measures the second voltage values ​​VRP2, VRN2 when a second time has elapsed thereafter. In the first detection process, after measuring the second voltage values ​​VRP2, VRN2, the insulation resistance detection device 1 turns off the one switch and turns on the other switch. Note that, although FIG. 4A shows an example in which the VRP measurement is performed followed by the VRN measurement, the VRP measurement may also be performed followed by the VRN measurement.

[0035] The first time is, for example, the time from when one of the first switch 21 or the second switch 22 is turned on until the voltage increased by the common capacitances 14, 15 drops by a predetermined rate (for example, 60%). The second time is the time until the voltage increased by the common capacitances 14, 15 disappears, in other words, the time until the voltage becomes stable or until the discharge of the electric charge of the common capacitances 14, 15 is almost completed. The first time and the second time are set in advance, for example, by measuring the voltage through an experiment or the like. Therefore, the second voltage values ​​VRP2, VRN2 are voltages excluding the influence of the common capacitance. Note that the second time may be the time until the rate of change of the voltage increased by the common capacitances 14, 15 over time becomes stable, in particular, the time until the rate of change becomes equal to or less than a threshold value.

[0036] In the first detection process, the insulation resistance detection device 1 detects an abnormality in the insulation resistors 12 and 13 based on the measured second voltage values ​​VRP2 and VRN2. Specifically, in the first detection process, the insulation resistance detection device 1 determines that there is no abnormality (no leakage) when the resistance values ​​of the insulation resistors 12 and 13 calculated based on the second voltage are equal to or greater than a threshold resistance value, and determines that there is an abnormality (electric leakage) when the resistance values ​​are less than the threshold resistance value. Then, in the first detection process, when the insulation resistance detection device 1 determines that there is no abnormality, it stores the measured first and second voltage values ​​in a storage unit (not shown). Also, in the first detection process, when the insulation resistance detection device 1 determines that there is an abnormality, it does not store the voltage values, but outputs a signal to a warning device such as a warning light to notify the user of the electric leakage.

[0037] Note that, although FIG. 4A shows a case where the VRP measurement and the VRN measurement are each performed once in the first detection process, they may each be performed multiple times, and a representative value (average value, mode value, median value, etc.) of the second voltage value may be stored in the memory unit.

[0038] The second detection process is a process performed after the first detection process is completed, and the insulation resistance detection device 1 measures the third voltage values ​​VRP3, VRN3 when a first time has elapsed since one of the first switch 21 or the second switch 22 was turned on. In the second detection process, after measuring the third voltage values ​​VRP3, VRN3, the insulation resistance detection device 1 turns off the one switch and turns on the other switch. That is, in the second detection process, the insulation resistance detection device 1 does not perform a voltage measurement equivalent to the second voltage value of the first detection process, and switches the switches while the common capacitances 14, 15 are discharging.

[0039] In the second detection process, the insulation resistance detection device 1 compares the measured third voltage values ​​VRP3, VRN3 with the first voltage values ​​VRP1, VRN1 stored in the storage unit, and detects an abnormality in the insulation resistances 12, 13 based on the comparison result. Specifically, in the second detection process, the insulation resistance detection device 1 determines that there is no abnormality (no leakage) if the third voltage values ​​VRP3, VRN3 and the first voltage values ​​VRP1, VRN1 do not deviate by more than a set value. That is, in the second detection process, it is assumed that the third voltage values ​​VRP3, VRN3 are measured when a first time has elapsed, and then the second voltage values ​​VRP2, VRN2 are measured when a second time has elapsed, as in the first detection process. If the third voltage values ​​VRP3, VRN3 and the first voltage values ​​VRP1, VRN1 are substantially equal, the second voltage values ​​VRP2, VRN2 of the second first detection process in Fig. 4A will also be substantially equal to the second voltage values ​​VRP2, VRN2 of the first first detection process in Fig. 4A. Therefore, in the second detection process, if the third voltage values ​​VRP3, VRN3 and the first voltage values ​​VRP1, VRN1 do not deviate by a set value or more, the second voltage values ​​VRP2, VRN2 of the second first detection process in Fig. 4A are not measured, and an abnormality determination is performed using an insulation resistance value calculated from the stored second voltage values ​​VRP2, VRN2 or using an abnormality determination result based on the second voltage values ​​VRP2, VRN2.

[0040] In this way, the insulation resistance detection device 1 of the first embodiment can quickly determine whether or not the insulation resistors 12 and 13 are abnormal by using the third voltage value measured while the common capacitances 14 and 15 are discharging in the second detection process.

[0041] On the other hand, in the second detection process, if the third voltage values ​​VRP3, VRN3 and the first voltage values ​​VRP1, VRN1 deviate by more than the set value (see the last "VRN" in the first "second detection process" in FIG. 4A), the insulation resistance detection device 1 performs the first detection process again to detect an abnormality in the insulation resistances 12, 13. In other words, if the third voltage values ​​VRP3, VRN3 and the first voltage values ​​VRP1, VRN1 deviate by more than the set value, it can be assumed that a change has occurred in the battery voltage or the insulation resistance. Therefore, the insulation resistance detection device 1 performs the first detection process again to make a re-evaluation based on the insulation resistance from which the influence of the common capacitance has been eliminated. Specifically, in the first detection process (second first detection process) performed after the second detection process, the insulation resistance detection device 1 measures the first voltage values ​​VRP1, VRN1 when a first time has elapsed since one of the first switch 21 or the second switch 22 was turned on, and measures the second voltage values ​​VRP2, VRN2 when a second time has elapsed thereafter. Then, in the second first detection process, the insulation resistance detection device 1 detects an abnormality in the insulation resistors 12, 13 based on the measured second voltage values ​​VRP2, VRN2. Specifically, in the second first detection process, the insulation resistance detection device 1 determines that there is no abnormality (no leakage) when the resistance values ​​of the insulation resistors 12, 13 calculated based on the second voltage are equal to or greater than a threshold resistance value, and determines that there is an abnormality (there is leakage) when the resistance values ​​are less than the threshold resistance value. Then, in the second first detection process, if the insulation resistance detection device 1 determines that there is no abnormality, it stores the measured first and second voltage values ​​in a storage unit (not shown). Also, in the second first detection process, if the insulation resistance detection device 1 determines that there is an abnormality, it does not store the voltage values, but outputs a signal to a warning device such as a warning light to notify the user of a leakage current.

[0042] That is, after determining whether there is an insulation abnormality in the second detection process, the insulation resistance detection device 1 determines whether there is an insulation abnormality in the insulation resistors 12, 13 based on the second voltage value measured in a state in which the charges of the common capacitances 14, 15 are completely discharged in a second re-run of the first detection process, thereby determining whether there is an insulation abnormality. In this way, by performing the first detection process after the second detection process to re-determine whether there is an insulation abnormality, it is possible to detect an abnormality in the insulation resistors 12, 13 with high accuracy.

[0043] Next, as shown in FIG. 4A, when it is determined that there is no abnormality in the detected deviation as a result of the re-determination in the second first detection process, the insulation resistance detection device 1 performs the second detection process again (second second detection process). Specifically, in the second second detection process, the insulation resistance detection device 1 measures the third voltage values ​​VRP3, VRN3 when a first time has elapsed since one of the first switch 21 or the second switch 22 was turned on. In the second detection process, after measuring the third voltage values ​​VRP3, VRN3, the insulation resistance detection device 1 turns off the one switch and turns on the other switch. Then, in the second second detection process, the insulation resistance detection device 1 compares the measured third voltage values ​​VRP3, VRN3 with the first voltage values ​​VRP1, VRN1 measured in the immediately preceding first detection process (second first detection process), and detects an abnormality in the insulation resistances 12, 13 based on the comparison result.

[0044] In addition, in the second detection process, the insulation resistance detection device 1 continues to perform the second detection process as long as the deviation between the third voltage values ​​VRP3, VRN3 and the first voltage values ​​VRP1, VRN1 does not exceed the set value.

[0045] 4A, the first detection process is performed when one of the two third voltage values ​​VRP3, VRN3 deviates from the first voltage value once, but the first detection process may be performed when one of the voltage values ​​deviates from the first voltage value multiple times in succession, thereby stabilizing the accuracy of detecting an insulation abnormality.

[0046] In addition, in FIG. 4A, an example is described in which the insulation resistance detection device 1 switches to the first detection process to determine an abnormality when the third voltage value deviates from the first voltage value in the second detection process, but this is not limited to the example.

[0047] For example, when the third voltage value deviates from the first voltage value in the second detection process, the insulation resistance detection device 1 may measure the second voltage value in the second detection process and determine an abnormality. Specifically, when the third voltage value deviates from the first voltage value in the VRN measurement (the last VRN measurement in FIG. 4A), the insulation resistance detection device 1 may measure the second voltage value by continuing the VRN measurement (the last "VRN" in the first "second detection process" in FIG. 4A) until the second time has elapsed, without switching over.

[0048] In this way, by performing the insulation abnormality determination and re-determination in the second detection process, it is not necessary to switch from the second detection process to the first detection process, so that an abnormality in the insulation resistors 12, 13 can be detected earlier.

[0049] Furthermore, the insulation resistance detection device 1 may determine whether or not the deviation of the third voltage value in the second detection process is due to a voltage abnormality of the battery 10. Specifically, the insulation resistance detection device 1 includes in the first detection process a battery voltage measurement process in which both the first switch 21 and the second switch 22 are turned on and the voltage of the battery 10 (hereinafter, battery voltage) is measured by the measurement circuit 25. For example, in the first detection process, the insulation resistance detection device 1 first measures the battery voltage, and then measures VRP and VRN. Note that the insulation resistance detection device 1 may measure the battery voltage after measuring VRN (hereinafter, the battery voltage measured in the first detection process is referred to as the first battery voltage). Then, the insulation resistance detection device 1 associates the first battery voltage with the first voltage value in the first detection process and stores it.

[0050] The insulation resistance detection device 1 also includes the battery voltage measurement process in the second detection process. For example, the insulation resistance detection device 1 repeats a set of battery voltage measurement process-VRP measurement-VRN measurement as the second detection process (hereinafter, the battery voltage measured in the second detection process is referred to as the second battery voltage). Then, when the third voltage value deviates from the first voltage value by a set value or more in the second detection process, the insulation resistance detection device 1 calculates the difference voltage between the second battery voltage measured immediately before and the first battery voltage associated with the first voltage value. Based on the difference voltage, the insulation resistance detection device 1 calculates the deviation of the third voltage value from the first voltage value. When the calculated deviation of the third voltage value and the deviation of the actual third voltage value are substantially equal, the insulation resistance detection device 1 determines that the deviation of the third voltage value is caused by the battery voltage, and determines that there is no abnormality in the insulation resistances 12 and 13. That is, when a deviation in the third voltage value caused by the battery voltage occurs in the second detection process, the insulation resistance detection device 1 does not switch to the first detection process.

[0051] On the other hand, when there is a difference between the calculated deviation of the third voltage value and the actual deviation of the third voltage value that is equal to or greater than a threshold value, the insulation resistance detection device 1 switches to the first detection process because the deviation of the third voltage value may be due to an insulation abnormality.

[0052] In this way, by comparing the voltages of the batteries 10, the insulation resistance detection device 1 can determine whether the deviation in the third voltage value is caused by the battery voltage, and if it is caused by the battery voltage, it continues the second detection process without switching to the first detection process, thereby preventing the abnormality detection time from being extended by switching to the first detection process.

[0053] Note that the process flow shown in Fig. 4A is an example, and is not limited thereto. For example, as shown in Fig. 4B, the second detection process may be started first. This point will be described with reference to Fig. 4B.

[0054] Fig. 4B is a diagram for explaining the insulation abnormality detection process according to the modified example of the first embodiment. Fig. 4A shows the process starting from the first detection process, whereas Fig. 4B shows the process starting from the second detection process.

[0055] Specifically, the insulation resistance detection device 1 measures the third voltage value VRP3 when a first time has elapsed since turning on one of the first switch 21 or the second switch 22. The insulation resistance detection device 1 stores the measured third voltage VRP3, and determines that there is no abnormality (no leakage) when the resistance value of the insulation resistor 12 calculated based on the third voltage VRP3 is equal to or greater than a threshold resistance value, and determines that there is a possibility of an abnormality (possibility of leakage) when the resistance value is less than the threshold resistance value.

[0056] That is, since the third voltage VRP3 is the voltage of the common capacitance during discharging, the insulation resistance detection device 1 cannot calculate an accurate resistance value of the insulation resistor 12 when the common capacitance voltage is fully discharged from the third voltage VRP3. However, the resistance value of the insulation resistor 12 calculated based on the third voltage VRP3 is smaller than the accurate resistance value of the insulation resistor 12 when the common capacitance voltage is fully discharged. Therefore, if the resistance value of the insulation resistor 12 calculated based on the third voltage VRP3 is equal to or greater than the threshold resistance value, the accurate resistance value of the insulation resistor 12 when the common capacitance voltage is fully discharged is also equal to or greater than the threshold resistance value. Therefore, if the resistance value of the insulation resistor 12 calculated based on the third voltage VRP3 is equal to or greater than the threshold resistance value, it can be determined that there is no abnormality (no leakage).

[0057] On the other hand, if the resistance value of the insulation resistor 12 calculated based on the third voltage VRP3 is less than the threshold resistance value, the accurate resistance value of the insulation resistor 12 when the voltage of the common capacitance is completely discharged may be equal to or greater than the threshold resistance value (i.e., not greater than). Therefore, when the insulation resistance detecting device 1 determines that there is a possibility of an abnormality, it proceeds to the first detection process.

[0058] Furthermore, if the insulation resistance detection device 1 determines that there is no abnormality, it turns off one of the switches and turns on the other switch to perform a VRN measurement (measurement of the third voltage VRN3). The insulation resistance detection device 1 stores the measured third voltage VRN3 as a reference voltage, and determines that there is no abnormality (no leakage) if the resistance value of the insulation resistance 13 calculated based on the third voltage VRN3 is equal to or greater than a threshold resistance value, and determines that there is a possibility of an abnormality (possibility of leakage) if it is less than the threshold resistance value. If it determines that there is a possibility of an abnormality, the insulation resistance detection device 1 proceeds to a first detection process.

[0059] Moreover, when the insulation resistance detection device 1 determines that there is no abnormality, it switches the switch and performs VRP measurement again. The insulation resistance detection device 1 compares the measured third voltage value VRP3 with the third voltage value VRP3 stored in the storage unit, and detects an abnormality in the insulation resistance 12 based on the comparison result. Specifically, if the difference between the two third voltage values ​​VRP3 is less than a threshold, the insulation resistance detection device 1 determines that there is no abnormality (no leakage) and continues the second detection process, and if the difference is equal to or greater than the threshold, it determines that there is a possibility of an abnormality and moves to the first detection process. In the first detection process, the insulation resistance detection device 1 measures the first voltage values ​​VRP1, VRN1 and the second voltage values ​​VRP2, VRN2 to perform an abnormality determination. In this way, in FIG. 4B, the second detection process is started, in other words, the first detection process is omitted, and the time required for an abnormality determination can be shortened by the amount of time required for the first detection process not to be performed as in FIG. 4A.

[0060] [Processing performed by the control unit] Next, the processing executed by the control unit 3 will be described with reference to Fig. 5 and Fig. 6. Fig. 5 is a flowchart showing an example of a first detection processing executed by the control unit 3 according to the first embodiment. Fig. 6 is a flowchart showing an example of a second detection processing executed by the control unit 3. The processing shown in Fig. 5 is repeatedly executed from when the IG (ignition switch) of the vehicle is turned on until it is turned off.

[0061] First, the first detection process will be described with reference to FIG. 5. As shown in FIG. 5, the control unit 3 first determines whether the flag F is 1 or not (step S101). The flag F is a flag indicating whether the first detection process has been completed or not, and is "0" when the first detection process is not being performed. When the flag F is 1 (step S101: Yes), the control unit 3 terminates the first detection process from step S102 onward since the first detection process has been completed, and proceeds to the second detection process. On the other hand, when the flag F is zero, that is, when the first detection process is not being performed (step S101: No), the control unit 3 executes the first detection process. That is, the control unit 3 turns off the first switch 21 and turns on the second switch 22 to start VRP measurement (step S102).

[0062] Next, the control unit 3 measures the first voltage value VRP1 of the detection resistor 24 when the first time has elapsed since the second switch 22 was turned on (step S103). Specifically, the control unit 3 acquires the first voltage value VRP1 measured by the measurement unit 2 when the first time has elapsed.

[0063] Next, the control unit 3 measures the second voltage value VRP2 of the detection resistor 24 when a second time has elapsed since the second switch 22 was turned on (step S104). Specifically, the control unit 3 acquires the first voltage value VRP2 measured by the measurement unit 2 when the second time has elapsed.

[0064] Next, the control unit 3 calculates the insulation resistance value of the insulation resistor 12 based on the measured second voltage value VRP2, and determines whether the insulation resistance value is equal to or greater than a predetermined resistance value (step S105). In other words, the control unit 3 determines whether the insulation resistance value is sufficiently high (whether insulation is achieved).

[0065] If the insulation resistance value is equal to or greater than a predetermined resistance value (step S105: Yes), the control unit 3 determines that there is no leakage (step S106), and stores the acquired first voltage value VRP1 and second voltage value VRP2 in the memory unit (step S107).

[0066] Next, the control unit 3 turns on the first switch 21 and turns off the second switch 22 to start VRN measurement (step S108).

[0067] Next, the control unit 3 measures the first voltage value VRN1 of the detection resistor 23 when the first time has elapsed since the second switch 22 was turned on (step S109). Specifically, the control unit 3 acquires the first voltage value VRN1 measured by the measurement unit 2 when the first time has elapsed.

[0068] Next, the control unit 3 measures the second voltage value VRN2 of the detection resistor 23 when a second time has elapsed since the second switch 22 was turned on (step S110). Specifically, the control unit 3 acquires the second voltage value VRN2 measured by the measurement unit 2 when the second time has elapsed.

[0069] Next, the control unit 3 calculates the insulation resistance value of the insulation resistor 13 based on the measured second voltage value VRN2, and determines whether the insulation resistance value is equal to or greater than a predetermined resistance value (step S111). In other words, the control unit 3 determines whether the insulation resistance value is sufficiently high (whether insulation is achieved).

[0070] If the insulation resistance value is equal to or greater than the predetermined resistance value (step S111: Yes), the control unit 3 determines that there is no leakage (step S112) and stores the acquired first voltage value VRN1 and second voltage value VRN2 in the storage unit (step S113). Next, the control unit 3 sets a flag F=1, ends the first detection process, and transitions to the second detection process.

[0071] On the other hand, if the insulation resistance value is less than the predetermined resistance value in steps S105 and S111 (step S105: No, step S111: No), the control unit 3 determines that there is a leakage current (step S114). If the control unit 3 determines that there is a leakage current, it warns the user of that fact by a warning device such as a warning light (step S115). Next, the control unit 3 sets flag F=1, ends the first detection process, and transitions to the second detection process.

[0072] Next, the second detection process will be described with reference to Fig. 6. As shown in Fig. 6, the control unit 3 first judges whether or not the flag F is 1 (step S201). If the flag F is 1 (step S201: Yes), the control unit 3 executes the second detection process. That is, the control unit 3 turns off the first switch 21 and turns on the second switch 22 to start VRP measurement (step S202). On the other hand, if the flag F is zero, that is, if the first detection process has not ended (step S201: No), the control unit 3 ends the second detection process.

[0073] Next, the control unit 3 measures the third voltage value VRP3 of the detection resistor 24 when the first time has elapsed since the second switch 22 was turned on (step S203). Specifically, the control unit 3 acquires the third voltage value VRP3 measured by the measurement unit 2 when the first time has elapsed.

[0074] Next, the control unit 3 reads out the voltage VRP1 measured in the first detection process from the storage unit (step S204), and determines whether the difference between the voltage VRP1 measured in the first detection process and the third voltage value VRP3 measured in the second detection process is within a predetermined range (step S205). In other words, the control unit 3 determines whether the third voltage value VRP3 measured in the second detection process deviates from the voltage VRP1 measured in the first detection process.

[0075] If the difference between the voltage VRP1 measured in the first detection process and the third voltage value VRP3 measured in the second detection process is within a predetermined range (step S205: Yes), the control unit 3 determines that there is no leakage (step S206).

[0076] Next, the control unit 3 turns on the first switch 21 and turns off the second switch 22 to start VRN measurement (step S207).

[0077] Next, the control unit 3 measures the third voltage value VRN3 of the detection resistor 23 when the first time has elapsed since the second switch 22 was turned on (step S208). Specifically, the control unit 3 acquires the third voltage value VRN3 measured by the measurement unit 2 when the first time has elapsed.

[0078] Next, the control unit 3 reads out the voltage VRN1 measured in the first detection process from the storage unit (step S209), and determines whether the difference between the voltage VRN1 measured in the first detection process and the third voltage value VRN3 measured in the second detection process is within a predetermined range (step S210). In other words, the control unit 3 determines whether the third voltage value VRN3 measured in the second detection process deviates from the voltage VRN1 measured in the first detection process.

[0079] If the difference between the voltage VRN1 measured in the first detection process and the third voltage value VRN3 measured in the second detection process is within a predetermined range (step S210: Yes), the control unit 3 determines that there is no leakage (step S211) and returns to step S201.

[0080] On the other hand, if the voltage difference is within the predetermined range in steps S205 and S210 (step S205: No, step S210: No), the control unit 3 sets the flag F to 0, transitions to the first detection process (step S212), and ends the second detection process. Note that the flag F is reset (F=0) when the vehicle is started (IG-ON) or shut down (IG-OFF).

[0081] As described above, the insulation resistance detection device 1 according to the first embodiment includes a controller (control unit 3). The controller turns on one of the first switch 21 connected to the positive electrode side of the battery 10 and the second switch 22 connected to the negative electrode side, and turns off the other switch, thereby forming a series circuit with the battery 10, the insulation resistances 12, 13 of the battery 10, and the detection resistances 23, 24, and detects an abnormality in the insulation resistances 12, 13 based on the voltage value applied to the detection resistances 23, 24. The controller stores in a memory unit a first voltage value detected when a first time has elapsed since one of the switches was turned on during which the voltage value of the detection resistors 23, 24 has been decreasing, and a second voltage value detected when a second time has elapsed, which is longer than the first time, during which the rate of change in the voltage value of the detection resistors 23, 24 over time is equal to or lower than a threshold value. The controller is capable of performing a first detection process for detecting an abnormality in the insulation resistors 12, 13 based on the second voltage value, and a second detection process for detecting an abnormality in the insulation resistors 12, 13 based on a comparison result between a third voltage value detected when the first time has elapsed since one of the switches was turned on again and the first voltage value stored in the memory unit. After startup, the controller detects an abnormality in the insulation resistors 12, 13 by the first detection process, and thereafter detects an abnormality in the insulation resistors 12, 13 by the second detection process.

[0082] This allows the insulation resistance detection device 1 to calculate the insulation resistance and determine an abnormality using the voltage value acquired during the discharge without waiting for the charge accumulated in the common capacitance to be discharged below a certain value, thereby shortening the time required to determine an abnormality in the insulation resistance.

[0083] Next, an insulation resistance detecting device 1 according to a second embodiment will be described with reference to Fig. 7 to Fig. 12. Fig. 7 is an explanatory diagram showing an example of the configuration of an insulation resistance detecting device 1 according to the second embodiment. As shown in Fig. 7, the second embodiment is different from the first embodiment in that it further includes promotion circuits 31 and 32.

[0084] The acceleration circuits 31 and 32 are connected in parallel to the detection resistors 23 and 24, and accelerate the decrease in the voltage value applied to the detection resistors 23 and 24. In other words, the acceleration circuits 31 and 32 increase the discharge speed of the common capacitance voltage, that is, increase the rate of decrease in the voltage value applied to the detection resistors 23 and 24. Specifically, the first acceleration circuit 31 is connected in parallel to the detection resistor 23 on the high-voltage side of the battery 10, and accelerates the decrease in the voltage value applied to the detection resistor 23. The second acceleration circuit 32 is connected in parallel to the detection resistor 24 on the low-voltage side of the battery 10, and accelerates the decrease in the voltage value applied to the detection resistor 24. As shown in FIG. 7, the acceleration circuits 31 and 32 are connected in series with resistors 311 and 321 and third switches 312 and 322.

[0085] [Example of insulation resistance detection device operation] Next, an operation example of the insulation resistance detecting device 1 according to the second embodiment will be described with reference to Fig. 8 and Fig. 9. Fig. 8 and Fig. 9 are explanatory diagrams showing an operation example of the insulation resistance detecting device 1 according to the second embodiment.

[0086] [Operation when insulation resistance is detected] For example, when detecting the resistance value of the low-voltage side insulation resistor 13, as shown in Fig. 8, the control unit 3 turns on the first switch 21 and turns off the second switch 22 to detect the resistance value of the low-voltage side insulation resistor 13 using the first series circuit R1 formed by the battery 10, the limiting resistor 26, the detection resistor 23, and the low-voltage side insulation resistor 13. The control unit 3 also turns on the third switch 312 of the first promotion circuit 31 for a certain time, and then turns it off. Then, the measurement circuit 25 measures the voltage applied to the detection resistor 23 (the voltage difference across the detection resistor 23) a certain time after the switch 312 of the first promotion circuit 31 is turned off, and outputs the measurement result to the control unit 3.

[0087] That is, in the second embodiment, the combined resistance of the parallel resistance of the detection resistor 23 and the resistor 311 is smaller than the resistance value of the detection resistor 23. As a result, the charge accumulated in the common capacitance 14 can be discharged by the combined resistance of the detection resistor 23 and the resistor 311 more quickly than when the charge is discharged by only the detection resistor 23.

[0088] 9, when detecting the resistance value of the high-voltage side insulation resistor 12, the control unit 3 turns off the first switch 21 and turns on the second switch 22 to detect the resistance value of the high-voltage side insulation resistor 12 using the second series circuit R2 formed by the battery 10, the high-voltage side insulation resistor 12, the detection resistor 24, and the limit resistor 27. The control unit 3 turns on the third switch 322 of the second promotion circuit 32 for a certain time, and then turns it off. Then, the measurement circuit 25 measures the voltage applied to the detection resistor 24 (the voltage difference across the detection resistor 24) a certain time after the third switch 322 of the second promotion circuit 32 is turned off, and outputs the measurement result to the control unit 3.

[0089] That is, in the second embodiment, the combined resistance of the parallel resistance of the detection resistor 24 and the resistor 321 is smaller than the resistance value of the detection resistor 24. As a result, the charge accumulated in the common capacitance 15 can be discharged by the combined resistance of the detection resistor 24 and the resistor 321 more quickly than when the charge is discharged by only the detection resistor 24.

[0090] FIG. 10 is a diagram showing the voltage applied to the detection resistors 23 and 24 for each elapsed time. FIG. 10 shows a graph showing the voltage change when the promotion circuits 31 and 32 are not provided, and a graph showing the voltage change when the promotion circuits 31 and 32 are provided. In the graph of FIG. 10, time t0 is the timing when the first switch 21 or the second switch 22 is turned on, and is the timing when the third switch 312 (or the switch 322) of the promotion circuit 31 (or the promotion circuit 32) is turned on. Time t1 is the timing when the switch 312 (or the switch 322) of the promotion circuit 31 (or the promotion circuit 32) is turned off. Time t2 is the timing of voltage measurement when the promotion circuits 31 and 32 are provided, and time t3 is the timing of voltage measurement when the promotion circuits 31 and 32 are not provided.

[0091] As shown in FIG. 10, when the acceleration circuits 31, 32 are present, the time to approach the steady state (the state in which the common capacitances 14, 15 are completely discharged) is earlier during the period from time t0 to time t1 than when the acceleration circuits 31, 32 are not present. In other words, the acceleration circuits 31, 32 are circuits that reduce the time constant of the series circuits R1, R2. As a result, as shown in FIG. 10, the voltages of the detection resistors 23, 24 reach the steady state at time t2. In other words, the time to reach the steady state is earlier by Δt than when the acceleration circuits 31, 32 are not present. In this way, the timing to measure the voltages of the detection resistors 23, 24 can be made earlier by Δt, so that insulation abnormality can be determined early.

[0092] The timing (time t1) for turning off the facilitating circuits 31, 32 is, for example, the timing when the rate of change of the voltage of the detection resistors 23, 24 becomes less than the threshold value. This allows the facilitating circuits 31, 32 to be turned off after the charges accumulated in the common capacitances 14, 15 are sufficiently discharged, and the facilitating circuits 31, 32 can prevent the voltage from being excessively lowered. Here, the timing when the rate of change of the voltage of the detection resistors 23, 24 becomes less than the threshold value is the timing when the voltage and the rate of change of the detection resistors 23, 24 are measured at short intervals by the measuring circuit 25 and the rate of change of the voltage of the detection resistors 23, 24 become less than the threshold value. Note that the time until the rate of change of the voltage of the detection resistors 23, 24 becomes less than the threshold value may be obtained in advance by experiment for various common capacitances, and the average time may be stored in memory for use.

[0093] In the above, an example has been shown in which the facilitating circuits 31 and 32 are configured by the resistors 311 and 321 and the switches 312 and 322, but the configuration of the facilitating circuits 31 and 32 is not limited to this.

[0094] Fig. 11 is a diagram showing another configuration example of the facilitating circuits 31 and 32. As shown in Fig. 11, the facilitating circuits 31 and 32 may be configured as constant current circuits 41 and 42. Specifically, the first constant current circuit 41 is connected in parallel to the detection resistor 23. Moreover, the second constant current circuit 42 is connected in parallel to the detection resistor 24.

[0095] When turning on the first switch 21, the control unit 3 turns on the first constant current circuit 41. This allows the charge accumulated in the common capacitance 14 to be discharged via the first constant current circuit 41. In particular, in addition to discharging through the detection resistor 23, the constant current circuit 41 discharges at a constant current. This allows the charge accumulated in the common capacitance 14 to be discharged by the detection resistor 23 and the first constant current circuit 41 more quickly than when discharging through only the detection resistor 23.

[0096] Furthermore, when the control unit 3 turns on the second switch 22, it turns on the second constant current circuit 42. This allows the charge accumulated in the common capacitance 15 to be discharged via the second constant current circuit 42. In particular, in addition to discharging through the detection resistor 24, the constant current circuit 42 discharges at a constant current. This allows the charge accumulated in the common capacitance 15 to be discharged by the detection resistor 24 and the second constant current circuit 42, making it possible to discharge the charge more quickly than when discharging through only the detection resistor 24.

[0097] Furthermore, by using constant current circuits 41 and 42 as the promotion circuits 31 and 32, the current flowing through the constant current circuits 41 and 42 can be adjusted according to the resistance values ​​of the insulation resistors 12 and 13, thereby making it possible to always keep a constant resistance division ratio with the insulation resistors 12 and 13. This makes it possible to keep the discharge amounts of the common capacitances 14 and 15 constant.

[0098] [Processing performed by the control unit] Next, the process executed by the control unit 3 will be described with reference to Fig. 12. Fig. 12 is a flowchart showing an example of the detection process executed by the control unit 3 according to the second embodiment. The process shown in Fig. 12 is repeatedly executed from when the IG (ignition switch) of the vehicle is turned on until it is turned off. In the following, "turning the promotion circuit on or off" refers to turning on or off the switches 312, 322 shown in Fig. 7, or turning on or off the constant current circuits 41, 42 shown in Fig. 11.

[0099] 12, the control unit 3 first starts VRP measurement by turning off the first switch 21, turning on the second switch 22, and turning on the second promotion circuit 32 (step S301). Next, after a certain period of time has elapsed, the control unit 3 turns off the second promotion circuit 32 (step S302).

[0100] Next, the control unit 3 measures the voltage VRP of the detection resistor 24 at a timing when a certain time has elapsed since the second promotion circuit 32 was turned off (step S303). Specifically, the control unit 3 acquires the voltage VRP measured by the measurement unit 2.

[0101] Next, the control unit 3 calculates the insulation resistance value of the insulation resistor 12 based on the measured voltage VRP, and determines whether the insulation resistance value is equal to or greater than a predetermined resistance value (step S304). In other words, the control unit 3 determines whether the insulation resistance value is sufficiently high (whether insulation is achieved).

[0102] If the insulation resistance value is equal to or greater than the predetermined resistance value (step S304: Yes), the control unit 3 determines that there is no leakage (step S305).

[0103] Next, the control unit 3 starts VRN measurement by turning on the first switch 21, turning off the second switch 22, and turning on the first facilitating circuit 31 (step S306). Next, after a certain period of time has elapsed, the control unit 3 turns off the first facilitating circuit 31 (step S307).

[0104] Next, the control unit 3 measures the voltage VRN of the detection resistor 23 at a timing when a certain time has elapsed since the first promotion circuit 31 was turned off (step S308). Specifically, the control unit 3 acquires the voltage VRN measured by the measurement unit 2.

[0105] Next, the control unit 3 calculates the insulation resistance value of the insulation resistor 13 based on the measured voltage VRN, and determines whether the insulation resistance value is equal to or greater than a predetermined resistance value (step S309). In other words, the control unit 3 determines whether the insulation resistance value is sufficiently high (whether insulation is achieved).

[0106] If the insulation resistance value is equal to or greater than the predetermined resistance value (step S309: Yes), the control unit 3 determines that there is no leakage (step S310) and ends the detection process.

[0107] On the other hand, if the insulation resistance value is less than the predetermined resistance value in steps S304 and S309 (step S304: No, step S309: No), the control unit 3 determines that there is a leakage current (step S311). If the control unit 3 determines that there is a leakage current, it warns the user of the leakage current by a warning device such as a warning light (step S312), and ends the detection process.

[0108] As described above, the insulation resistance detection device 1 according to the second embodiment includes a controller (control unit 3) and promotion circuits 31 and 32. The controller turns on one of the first switch 21 connected to the positive electrode side of the battery 10 and the second switch 22 connected to the negative electrode side, and turns off the other switch, thereby forming series circuits R1 and R2 with the battery 10, the insulation resistances 12 and 13 of the battery 10, and the detection resistances 23 and 24, and detects an abnormality in the insulation resistances 12 and 13 based on the voltage value applied to the detection resistances 23 and 24. The promotion circuits 31 and 32 are connected in parallel to the detection resistances 23 and 24, and increase the rate of decrease in the voltage value applied to the detection resistances 23 and 24 when one switch is turned on. The controller detects an abnormality in the insulation resistances 12 and 13 based on the voltage value decreased by the promotion circuits 31 and 32. As a result, the combined resistance of the parallel resistance of the detection resistors 23, 24 and the acceleration circuits 31, 32 can be made smaller than the resistance value of the detection resistors 23, 24. As a result, the charge accumulated in the common capacitances 14, 15 can be discharged by the combined resistance of the detection resistors 23, 24 and the acceleration circuits 31, 32, and can be discharged faster than when the charge is discharged only by the detection resistors 23, 24. In other words, the time required to determine an abnormality in the insulation resistors 12, 13 can be shortened.

[0109] In the above-described second embodiment, a processing example is shown in which the abnormality determination of the insulation resistors 12, 13 is performed after the promotion circuits 31, 32 are turned off, but the abnormality determination of the insulation resistors 12, 13 may also be performed with the promotion circuits 31, 32 turned on.

[0110] [Note] As an appendix, the features of the present invention are as follows: (1) a controller that turns on one 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 and turns off the other switch to form a series circuit with the battery, the battery's insulation resistance, and a detection resistor, and detects an abnormality in the insulation resistance based on a voltage value applied to the detection resistor; a promotion circuit connected in parallel to the detection resistor and configured to increase a rate of decrease in a voltage value applied to the detection resistor when the one switch is turned on; Equipped with The controller: An abnormality in the insulation resistance is detected based on the voltage value that has been reduced by the acceleration circuit. Insulation resistance detection device. (2) The facilitation circuit includes: A circuit that reduces the time constant of the series circuit. An insulation resistance detection device as described in (1). (3) The facilitation circuit includes: a third switch and a resistor connected in series; The controller: When the one switch is turned on, the third switch of the facilitating circuit is turned on. An insulation resistance detection device according to (1) or (2). (4) The facilitation circuit includes: Includes a constant current circuit, The controller: When the one switch is turned on, the constant current circuit is turned on. The insulation resistance detection device according to any one of (1) to (3). (5) The controller: When a rate of change of the voltage value applied to the detection resistor becomes less than a threshold value, the operation of the promotion circuit is stopped. The insulation resistance detection device according to any one of (1) to (4). (6) An insulation resistance detection method performed by an insulation resistance detection device, comprising: a first switch connected to the positive electrode side of a battery and a second switch connected to the negative electrode side of the battery are turned on and the other switch is turned off to form a series circuit with the battery, the battery's insulation resistance, and a detection resistor, and an abnormality in the insulation resistance is detected based on a voltage value applied to the detection resistor; a promotion circuit connected in parallel to the detection resistor increases a rate of decrease in a voltage value applied to the detection resistor when the one switch is turned on; An abnormality in the insulation resistance is detected based on the voltage value that has been reduced by the acceleration circuit. Insulation resistance detection method.

[0111] 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]

[0112] 1. Insulation resistance detector 2. Measurement section 3. Control Unit 10 batteries 11 Battery Cell 12, 13 Insulation resistance 14, 15 Common capacitance 21 First Switch 22 Second Switch 23, 24 Detect resistor 25 Measurement circuit 26, 27 Limiting resistor 31 First Promotion Circuit 32 Second Promotion Circuit 41 First constant current circuit 42 Second constant current circuit 311, 321 Resistance 312, 322 Switch R1 First series circuit R2 2nd series circuit

Claims

1. a controller that turns on one 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 and turns off the other switch to form a series circuit with the battery, an insulation resistance of the battery, and a detection resistor, and detects an abnormality in the insulation resistance based on a voltage value applied to the detection resistor; a promotion circuit connected in parallel to the detection resistor and configured to increase a rate of decrease in a voltage value applied to the detection resistor when the one switch is turned on; The controller: An abnormality in the insulation resistance is detected based on the voltage value that has been reduced by the acceleration circuit. Insulation resistance detection device.

2. The facilitation circuit includes: A circuit that reduces the time constant of the series circuit.

2. An insulation resistance detection device according to claim 1.

3. The facilitation circuit includes: a third switch and a resistor connected in series; The controller: When the one switch is turned on, the third switch of the facilitating circuit is turned on.

2. An insulation resistance detection device according to claim 1.

4. The facilitation circuit includes: Includes a constant current circuit, The controller: When the one switch is turned on, the constant current circuit is turned on.

2. An insulation resistance detection device according to claim 1.

5. The controller: When a rate of change of the voltage value applied to the detection resistor becomes less than a threshold value, the operation of the promotion circuit is stopped.

2. An insulation resistance detection device according to claim 1.

6. An insulation resistance detection method performed by an insulation resistance detection device, comprising: 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, one of which is turned on and the other is turned off to form a series circuit with the battery, the insulation resistance of the battery, and a detection resistor, and an abnormality in the insulation resistance is detected based on a voltage value applied to the detection resistor; a promotion circuit connected in parallel to the detection resistor increases a rate of decrease in a voltage value applied to the detection resistor when the one switch is turned on; An abnormality in the insulation resistance is detected based on the voltage value that has been reduced by the acceleration circuit. Insulation resistance detection method.

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