Ground fault detection device, control method thereof, and control program

Abstract

To enable accurate detection of deterioration in insulation resistance.SOLUTION: An insulation resistance deterioration detection process for detecting deterioration in insulation resistance starts when a first time period T1 has elapsed after completion of a startup process for starting up a ground fault detection device 100.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a ground fault detection device, a control method thereof, and a control program. [Background technology]

[0002] Hybrid and electric vehicles are becoming increasingly popular. Hybrid and electric vehicles are equipped with an electric motor and a battery that supplies power to the electric motor. The batteries installed in hybrid and electric vehicles are high-voltage batteries of 200V or more, and to ensure safety, they must be electrically isolated from the vehicle body, which serves as the ground reference potential point. Therefore, vehicles such as hybrid and electric vehicles are also equipped with a ground fault detection device that detects a decrease in insulation resistance between the vehicle body and the system, including the battery, which is not grounded.

[0003] One example of a ground fault detection device is a flying capacitor type ground fault detection device (see, for example, Patent Document 1). A flying capacitor type ground fault detection device has a capacitor that operates as a flying capacitor, and switches between a first charging path in which the capacitor is connected between the positive and negative electrodes of a battery without going through ground, a second charging path in which the capacitor is connected between the positive electrode of the battery and ground, a third charging path in which the capacitor is connected between the negative electrode of the battery and ground, and a measurement path for measuring the charging voltage of the first capacitor, to charge the capacitor and measure the charging voltage of the capacitor, and detect a decrease in insulation resistance based on the measured charging voltage of the capacitor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-170103 Summary of the Invention [Problem to be solved by the invention]

[0005] Generally, a Y capacitor is connected to a system that includes a battery to reduce common-mode noise. In the second and third charging paths, the voltage of the Y capacitor becomes unbalanced. Insulation resistance measurements generally assume that the voltage of the Y capacitor is balanced. Therefore, insulation resistance values ​​measured based on the charging voltage of a capacitor charged when the voltage of the Y capacitor is unbalanced may have low measurement accuracy. For this reason, after measurements on the second or third charging path, the voltage of the Y capacitor is allowed to reach equilibrium before switching to another charging path.

[0006] In general, a ground fault detector performs a startup process before starting to detect a decrease in insulation resistance. During this startup process, the voltage of the Y capacitor may become unbalanced. However, this unbalanced state of the Y capacitor after the startup process has not been taken into consideration.

[0007] Therefore, an object of the present invention is to accurately detect a decrease in insulation resistance. [Means for solving the problem]

[0008] In order to solve the above problem, one embodiment of the present invention provides a ground fault detection device that detects a decrease in insulation resistance in a system that includes an ungrounded battery and a Y capacitor, and includes: a first capacitor; a first charging path in which the first capacitor is connected between the positive and negative electrodes of the battery without being grounded; a second charging path in which the first capacitor is connected between the positive electrode of the battery and ground; a third charging path in which the first capacitor is connected between the negative electrode of the battery and ground; and a measurement path for measuring the charging voltage of the first capacitor; and a control unit that controls the switching unit, measures the charging voltage of the first capacitor, and detects the decrease in insulation resistance based on the measured charging voltage of the first capacitor, and the control unit begins detecting the decrease in insulation resistance after a first period has elapsed since the end of the startup process for starting the ground fault detection device.

[0009] A control method according to one embodiment of the present invention is a control method for a ground fault detection device executed by a computer, the control method being for detecting a decrease in insulation resistance of a system including an ungrounded battery and a Y capacitor, the ground fault detection device having a first capacitor, a first charging path in which the first capacitor is connected between the positive and negative electrodes of the battery without being grounded, a second charging path in which the first capacitor is connected between the positive electrode of the battery and ground, a third charging path in which the first capacitor is connected between the negative electrode of the battery and ground, and a measurement path for measuring the charging voltage of the first capacitor, the control method having an insulation resistance decrease detection process that controls the switching unit to measure the charging voltage of the first capacitor and detects the decrease in insulation resistance based on the measured charging voltage of the first capacitor, the insulation resistance decrease detection process being started after a first period has elapsed since the end of the startup process for starting the ground fault detection device.

[0010] A control program according to an embodiment of the present invention causes a computer to execute the above information processing method. [Effects of the Invention]

[0011] According to the present invention, it is possible to accurately detect a decrease in insulation resistance. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing a ground fault detection device 100 according to an embodiment of the present invention. [Figure 2] 1 is a diagram illustrating an example of the configuration of a ground fault detection device 100. FIG. [Figure 3] FIG. 4 is a diagram illustrating a first charging path. [Figure 4] FIG. 10 is a diagram illustrating a second charging path. [Figure 5] FIG. 10 is a diagram illustrating a third charging path. [Figure 6]FIG. 2 is a diagram illustrating a measurement path. [Figure 7] FIG. 2 is a diagram illustrating a discharge path. [Figure 8] 3 is a diagram illustrating an example of a processing operation executed in the ground fault detection device 100 after the ground fault detection device 100 is started up. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Ground fault detection device 100> 1 is a diagram showing a ground fault detection device 100 according to one embodiment of the present invention. The ground fault detection device 100 is a flying capacitor type ground fault detection device that is connected to an ungrounded battery 200 and detects a decrease in insulation resistance in a system including the battery 200. Here, the insulation resistance between the positive electrode side of the battery 200 and the ground is taken as positive electrode side insulation resistance RLp, and the insulation resistance between the negative electrode side of the battery 200 and the ground is taken as negative electrode side insulation resistance RLn.

[0014] Battery 200 is, for example, a battery for supplying power to an electric motor of a vehicle, and is a high-voltage battery (for example, 200 V or higher). Battery 200 is, for example, composed of a plurality of rechargeable batteries (for example, lithium ion batteries). The positive electrode side of battery 200 is connected to positive electrode side power supply line 210, and the negative electrode side of battery 200 is connected to negative electrode side power supply line 220.

[0015] A Y capacitor is connected to a system including battery 200 to reduce common-mode noise. In the example shown in Fig. 1, a positive-side Y capacitor CYp is connected between positive-side power supply line 210 and ground, and a negative-side Y capacitor CYn is connected between negative-side power supply line 220 and ground. The positive-side Y capacitor CYp includes a stray capacitance between positive-side power supply line 210 and ground, and the negative-side Y capacitor CYn includes a stray capacitance between negative-side power supply line 220 and ground.

[0016] The ground fault detection device 100 is connected to the positive electrode of the battery 200 via a positive power supply line 210, and is connected to the positive electrode of the battery 200 via a negative power supply line 220. The ground fault detection device 100 has a first capacitor 110, a switching unit 120, and a control unit 130.

[0017] The first capacitor 110 is a capacitor having a first plate and a second plate, and operates as a flying capacitor.

[0018] The switching unit 120 switches between a first charging path in which the first capacitor 110 is connected between the positive and negative electrodes of the battery 200 without going through ground, a second charging path in which the first capacitor 110 is connected between the positive electrode of the battery 200 and ground, a third charging path in which the first capacitor 110 is connected between the negative electrode of the battery 200 and ground, and a measurement path for measuring the charging voltage of the first capacitor 110.

[0019] In the first charging path, the first capacitor 110 is charged by a current flowing through a closed circuit in which the positive electrode of the battery 200, the first capacitor 110, and the negative electrode of the battery 200 are connected in series in this order without being grounded. Therefore, in the first charging path, the first capacitor 110 is charged with a first charging voltage V0 corresponding to the charging voltage of the battery 200.

[0020] In the second charging path, the first capacitor 110 is charged by a current flowing through a closed circuit in which the positive electrode of the battery 200, the first capacitor 110, the negative electrode-side insulation resistance RLn, and the negative electrode of the battery 200 are connected in series in this order. Therefore, in the second charging path, the first capacitor 110 is charged with a second charging voltage VC1n that reflects the influence of the negative electrode-side insulation resistance RLn.

[0021] In the third charging path, the first capacitor 110 is charged by a current flowing through a closed circuit in which the positive electrode of the battery 200, the positive electrode side insulation resistance RLp, the first capacitor 110, and the negative electrode of the battery 200 are connected in series in this order. Therefore, in the third charging path, the first capacitor 110 is charged with a third charging voltage VC1p that reflects the influence of the positive electrode side insulation resistance RLp.

[0022] The control unit 130 measures the charging voltage of the first capacitor 110. The control unit 130 controls, for example, the switching unit 120 to measure, in the measurement paths, a first charging voltage V0 which is the charging voltage of the first capacitor 110 charged via the first charging path, a second charging voltage VC1n which is the charging voltage of the first capacitor 110 charged via the second charging path, and a third charging voltage VC1p which is the charging voltage of the first capacitor 110 charged via the third charging path.

[0023] Then, the control unit 130 detects a decrease in the insulation resistances RLp, RLn (detects a ground fault) based on this measured charging voltage of the first capacitor 110. The control unit 130 detects a decrease in the insulation resistances RLp, RLn, for example, based on the first charging voltage V0, the second charging voltage VC1n, and the third charging voltage VC1p. At this time, the control unit 130 measures the values ​​of the insulation resistances RLp, RLn, for example, based on the charging voltage of the first capacitor 110, and detects a decrease in the insulation resistances RLp, RLn based on the measured values ​​of the insulation resistances RLp, RLn. The control unit 130 is, for example, configured by a computer.

[0024] The control unit 130 detects a decrease in the insulation resistances RLp and RLn for each measurement cycle. That is, the control unit 130 repeats a measurement cycle in which the control unit 130 detects a decrease in the insulation resistances RLp and RLn. At this time, the control unit 130 detects a decrease in the insulation resistances RLp and RLn, for example, by measuring the values ​​of the insulation resistances RLp and RLn for each measurement cycle and comparing the values ​​of the insulation resistances RLp and RLn measured in the measurement cycle before the measurement cycle (for example, the measurement cycle immediately before the measurement cycle).

[0025] The measurement cycle includes a first measurement period (V0 measurement period) in which the first capacitor 110 is charged via a first charging path and discharged via a measurement path while measuring a first charging voltage V0, which is the charging voltage of the first capacitor 110 charged via this first charging path; a second measurement period (VC1n measurement period) in which the first capacitor 110 is charged via a second charging path and discharged via the measurement path while measuring a second charging voltage VC1n, which is the charging voltage of the first capacitor 110 charged via this second charging path; and a third measurement period (VC1p measurement period) in which the first capacitor 110 is charged via a third charging path and discharged via the measurement path while measuring a third charging voltage VC1p, which is the charging voltage of the first capacitor 110 charged via this third charging path. That is, the control unit 130 measures the first charging voltage V0, the second charging voltage VC1n, and the third charging voltage VC1p for each measurement cycle, and detects a decrease in insulation resistance based on the measured first charging voltage V0, the second charging voltage VC1n, and the third charging voltage VC1p. In a measurement cycle, the measurement periods are performed in the order of, for example, the first measurement period, the second measurement period, the first measurement period, and the third measurement period.

[0026] When an abnormality occurs (for example, when a decrease in insulation resistances RLp, RLn is detected), control unit 130 notifies the occurrence of the abnormality (for example, a decrease in insulation resistances RLp, RLn). At this time, control unit 130 may notify the occurrence of the abnormality by displaying information indicating the occurrence of the abnormality using a display device that displays information (for example, a display or a lamp), or may notify the occurrence of the abnormality by outputting a sound indicating the occurrence of the abnormality using a display device that outputs sound indicating the information (for example, a speaker), or may notify the occurrence of the abnormality by transmitting information indicating the occurrence of the abnormality to another device (for example, a higher-level ECU (Electronic Control Unit)) using a communication device that transmits information to another device.

[0027] The control unit 130 may be configured to notify the measured values ​​of the insulation resistances RLp and RLn. In this way, a decrease in the insulation resistances RLp and RLn can be detected not by the control unit 130 but by a person who receives information from the notification or by another device that receives information from the information.

[0028] <Configuration example of ground fault detection device 100> The switching unit 120 may have, for example, four switches (a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4) as shown in Fig. 2. These four switches are, for example, insulating switching elements (for example, optical MOSFETs).

[0029] The first switch S1 is connected between the positive electrode of the battery 200 and the first electrode plate of the first capacitor 110. At this time, the first switch S1 is connected to the first electrode plate of the first capacitor 110 via a first resistor R1, as shown in FIG. 2. Furthermore, a first diode D1 may be connected between the first switch S1 and the first resistor R1 or between the first resistor R1 and the first capacitor 110. The forward direction of the first diode D1 is from the positive electrode of the battery 200 to the first electrode plate of the first capacitor 110. In the configuration example shown in FIG. 2, the first diode D1 is connected between the first switch S1 and the first resistor R1.

[0030] The second switch S2 is connected between the negative electrode of the battery 200 and the second electrode plate of the first capacitor 110. A second resistor R2 may be connected between the second switch S2 and the second electrode plate of the first capacitor 110 or between the second switch S2 and the negative electrode of the battery 200. In the configuration example shown in FIG. 2, the second resistor R2 is connected between the second switch S2 and the second electrode plate of the first capacitor 110.

[0031] The third switch S3 is connected between the first plate of the first capacitor 110 and ground. In this case, the third switch S3 is connected to ground via a third resistor R3, as shown in FIG. 2 . Alternatively, a second diode D2 and a third diode D3 may be connected in parallel between the third switch S3 and the first plate of the first capacitor 110. The forward direction of the second diode D2 is from the first plate of the first capacitor 110 to the third switch S3. The forward direction of the third diode D3 is from the third switch S3 to the first plate of the first capacitor 110. A fifth resistor R5 may be connected in series with the second diode D2 between the third switch S3 and the first plate of the first capacitor 110. In the configuration example shown in FIG. 2 , the fifth resistor R5 is connected to the cathode side of the second diode D2.

[0032] The fourth switch S4 is connected between the second plate of the first capacitor 110 and ground. The fourth switch S4 is connected to ground through a fourth resistor R4, as shown in FIG.

[0033] 2, when the first switch S1 and the second switch S2 are on and the third switch S3 and the fourth switch S4 are off, a first charging path is established in which the first capacitor 110 is connected between the positive and negative electrodes of the battery 200 without being grounded, as shown in FIG. 3. In the configuration example shown in FIG. 2, the first capacitor 110 is charged through a closed circuit connected in series in the following order: the positive electrode of the battery 200, the first switch S1, the first diode D1, the first resistor R1, the first capacitor 110, the second resistor R2, the second switch S2, and the negative electrode of the battery 200. Therefore, in the first charging path, a first charging voltage V0 corresponding to the charging voltage of the battery 200 is charged to the first capacitor 110.

[0034] 2, when the first switch S1 and the fourth switch S4 are on and the second switch S2 and the third switch S3 are off, a second charging path is established in which the first capacitor 110 is connected between the positive electrode of the battery 200 and ground, as shown in FIG. 4. In the configuration example shown in FIG. 2, the second charging path charges the first capacitor 110 through a closed circuit connected in series in the following order: the positive electrode of the battery 200, the first switch S1, the first diode D1, the first resistor R1, the first capacitor 110, the fourth switch S4, the fourth resistor R4, the negative electrode insulation resistance RLn, and the negative electrode of the battery 200. Therefore, in the second charging path, a second charging voltage VC1n that reflects the influence of the negative electrode insulation resistance RLn of the battery 200 is charged to the first capacitor 110.

[0035] 2, when the second switch S2 and the third switch S3 are on and the first switch S1 and the fourth switch S4 are off, a third charging path is established in which the first capacitor 110 is connected between the negative electrode of the battery 200 and ground, as shown in FIG. 5. In the configuration example shown in FIG. 2, the first capacitor 110 is charged through a closed circuit connected in series in the following order: the positive electrode of the battery 200, the positive electrode-side insulation resistance RLp, the third resistor R3, the third switch S3, the third diode D3, the first capacitor 110, the second resistor R2, the second switch S2, and the negative electrode of the battery 200. Therefore, in the third charging path, a third charging voltage VC1p that reflects the influence of the positive electrode-side insulation resistance RLp of the battery 200 is charged to the first capacitor 110.

[0036] As shown in FIG. 2, the control unit 130 is connected to the first electrode plate of the first capacitor 110 via a third switch. Therefore, when the third switch S3 and the fourth switch S4 are on and the first switch S1 and the second switch S2 are off, current flows from the first electrode plate of the first capacitor 110 to the control unit 130, as shown in FIG. 6. This allows the control unit 130 to measure the charging voltage of the detection capacitor C1. In other words, when the third switch S3 and the fourth switch S4 are on and the first switch S1 and the second switch S2 are off, this becomes a measurement path for measuring the charging voltage of the first capacitor 110. The line connecting the third switch S3 and the control unit 130 may be grounded via the second capacitor C2, as shown in FIG. 2.

[0037] 6, a current flows from the first electrode plate to the second electrode plate of the first capacitor 110. Therefore, the first capacitor 110 is discharged in the measurement path.

[0038] The switching unit 120 may further include a measurement switch Sa as shown in FIG. 2. In this configuration, when the third switch S3, the fourth switch S4, and the measurement switch Sa are on and the first switch S1 and the second switch S2 are off, the path serves as a measurement path for measuring the charging voltage of the first capacitor 110 as shown in FIG. 6. When the third switch S3 and the fourth switch S4 are on and the first switch S1, the second switch S2, and the measurement switch Sa are off, the control unit 130 is disconnected from the first capacitor 110 as shown in FIG. 7, and the path serves as a discharge path for discharging the first capacitor 110. In the first charging path, the second charging path, and the third charging path, the measurement switch Sa is turned off as shown in FIGS. 3-5.

[0039] <Processing after startup> In the second and third charging paths, the voltages of the Y capacitors CYp and CYn are unbalanced. Generally, measurements of the insulation resistances RLp and RLn are based on the assumption that charging of the first capacitor 110 begins when the voltages of the Y capacitors CYp and CYn are balanced. Therefore, the accuracy of the insulation resistances RLp and RLn measured based on the charging voltage of the first capacitor 110, which begins charging when the voltages of the Y capacitors CYp and CYn are unbalanced, may be low. Therefore, after measuring the second charging voltage VC1n or the third charging voltage VC1p, the voltages of the Y capacitors CYp and CYn are allowed to reach equilibrium before switching to another charging path.

[0040] In the ground fault detection device 100, a startup process is generally performed to start the ground fault detection device 100 before starting to detect decreases in the insulation resistances RLp and RLn through repeated measurement cycles. During this startup process, the voltages of the Y capacitors CYp and CYn may become unbalanced. However, in the past, the capacitance of the Y capacitors CYp and CYn was not so large, and it was not necessary to wait for the voltages of the Y capacitors CYp and CYn to become balanced after the startup process. However, in recent years, the capacitance of the Y capacitors CYp and CYn has increased, and it has become longer to wait for the voltages of the Y capacitors CYp and CYn to become balanced after the voltages of the Y capacitors CYp and CYn become unbalanced.

[0041] Therefore, in this embodiment, the control unit 130 starts detecting a decrease in the insulation resistances RLp, RLn after a first period T1 has elapsed since the end of the startup process. At this time, the first period T1 is, for example, the time constant τ of the circuit consisting of the insulation resistances RLp, RLn and the Y capacitors CYp, CYn, and is calculated as follows based on the combined resistance value RL of the insulation resistances RLp, RLn and the combined capacitance CY of the Y capacitors CYp, CYn:

number

[0042] Therefore, in this embodiment, the values ​​of the insulation resistances RLn and RLp are measured when the Y capacitors CYp and CYn are in a balanced state, which improves the measurement accuracy of the values ​​of the insulation resistances RLn and RLp and makes it possible to accurately detect a decrease in the insulation resistance.

[0043] Alternatively, the first period T1 may be calculated as follows by multiplying the time constant τ by a predetermined constant A:

number

[0044] The predetermined constant A is set, for example, so that the voltages of the Y capacitors CYp and CYn are balanced by the start of the measurement period that is executed first among the measurement periods other than the first measurement period (V0 measurement period) of the first measurement cycle (the second measurement period (VC1n measurement period) or the third measurement period (VC1p measurement period). For example, if the measurement periods in the measurement cycle are executed in the order of the first measurement period, second measurement period, first measurement period, and third measurement period, the predetermined constant A is set, for example, so that the voltages of the Y capacitors CYp and CYn are balanced by the start of the second measurement period, which is the measurement period that is executed first among the measurement periods other than the first measurement period.

[0045] The startup process may include an insulation resistance measurement process (e.g., the measurement cycle described above) for measuring the insulation resistances RLp and RLn, and the combined resistance value of the insulation resistances RLp and RLn may be calculated based on the values ​​of the insulation resistances RLp and RLn measured by the insulation resistance measurement process.

[0046] 8 is a diagram showing an example of processing operations executed in the ground fault detection device 100 after the ground fault detection device 100 is started. The ground fault detection device 100 performs a start-up process (step S801). After a first period T1 has elapsed since the end of the start-up process (step S802, YES), detection of a decrease in the insulation resistances RLp and RLn (measurement cycle) is started, and detection of a decrease in the insulation resistances RLp and RLn (measurement cycle) is repeated (step S803) until a decrease in the insulation resistances RLp and RLn is detected (step S804, YES) or an end trigger is generated (step S805, YES).

[0047] The present invention has been described above in terms of preferred embodiments thereof. While the present invention has been described herein with reference to specific examples, various modifications and variations can be made to these examples without departing from the spirit and scope of the present invention as set forth in the claims. [Explanation of symbols]

[0048] 100 Earth fault detection device 110 First capacitor 120 Switching section 130 control section 200 Battery 210 Positive power supply line 220 Negative power supply line

Claims

1. A ground fault detection device that detects a decrease in insulation resistance of a system including an ungrounded battery and a Y capacitor, a first capacitor; a switching unit that switches among a first charging path in which the first capacitor is connected between the positive electrode and the negative electrode of the battery without being connected to ground, a second charging path in which the first capacitor is connected between the positive electrode of the battery and ground, a third charging path in which the first capacitor is connected between the negative electrode of the battery and ground, and a measurement path for measuring a charging voltage of the first capacitor; a control unit that controls the switching unit, measures a first charging voltage that is a charging voltage of the first capacitor charged through the first charging path, a second charging voltage that is a charging voltage of the first capacitor charged through the second charging path, and a third charging voltage that is a charging voltage of the first capacitor charged through the third charging path, for each measurement cycle, and detects a decrease in the insulation resistance based on the first charging voltage, the second charging voltage, and the third charging voltage; The measurement cycle comprises: a first measurement period in which the first capacitor is charged in the first charging path and the first charging voltage is measured in the measurement path; a second measurement period in which the first capacitor is charged in the second charging path and the second charging voltage is measured in the measurement path; a third measurement period in which the first capacitor is charged in the third charging path and the third charging voltage is measured in the measurement path; the control unit starts the measurement cycle after a first period has elapsed since completion of a startup process for starting the ground fault detection device; The ground fault detection device, wherein the startup process is a process performed by the ground fault detection device before the measurement cycle is started.

2. the first period is calculated based on a value of the insulation resistance and a capacitance of the Y capacitor; the startup process includes an insulation resistance measurement process for measuring a value of the insulation resistance, The ground fault detection device according to claim 1 , wherein the value of the insulation resistance used in calculating the first period is the value of the insulation resistance measured by the insulation resistance measurement process.

3. 3. The ground fault detection device according to claim 2, wherein the first period is calculated by multiplying a combined resistance value of a positive-side insulation resistance and a negative-side insulation resistance of the insulation resistor by a combined capacitance of a positive-side Y capacitor and a negative-side Y capacitor of the Y capacitor.

4. 4. The ground fault detection device according to claim 3, wherein the first period is a value obtained by multiplying a combined resistance value of a positive-side insulation resistance and a negative-side insulation resistance of the insulation resistor, a combined capacitance of a positive-side Y capacitor and a negative-side Y capacitor of the Y capacitor, and a predetermined constant.

5. 1. A computer-implemented control method for a ground fault detection device for detecting a decrease in insulation resistance of a system including an ungrounded battery and a Y capacitor, comprising: The ground fault detection device is a first capacitor; a switching unit that switches among a first charging path in which the first capacitor is connected between the positive electrode and the negative electrode of the battery without being connected to ground, a second charging path in which the first capacitor is connected between the positive electrode of the battery and ground, a third charging path in which the first capacitor is connected between the negative electrode of the battery and ground, and a measurement path for measuring a charging voltage of the first capacitor; The control method includes an insulation resistance decrease detection step of controlling the switching unit to measure, for each measurement cycle, a first charging voltage that is a charging voltage of the first capacitor charged through the first charging path, a second charging voltage that is a charging voltage of the first capacitor charged through the second charging path, and a third charging voltage that is a charging voltage of the first capacitor charged through the third charging path, and detecting a decrease in the insulation resistance based on the first charging voltage, the second charging voltage, and the third charging voltage; The measurement cycle comprises: a first measurement period in which the first capacitor is charged in the first charging path and the first charging voltage is measured in the measurement path; a second measurement period in which the first capacitor is charged in the second charging path and the second charging voltage is measured in the measurement path; a third measurement period in which the first capacitor is charged in the third charging path and the third charging voltage is measured in the measurement path; the measurement cycle starts after a first period has elapsed since the end of a startup process for starting the ground fault detection device; A control method, wherein the startup process is a process performed by the ground fault detection device before the measurement cycle is started.

6. An information processing program that causes a computer to execute the control method according to claim 5.

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