JP2024008014A - Insulation resistance detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an insulation resistance detection device capable of performing correction during an insulation resistance detection operation and satisfying system requirement accuracy.

SOLUTION: An insulation resistance detection device 30 comprises: a controller 33; a pulse generator 31; a detection resistor Rd; a leakage resistor Rx connected to a measurement node M; and a switch SW controlled in an off-state in which the leakage resistor Rx and a ground are cut off and in an on-state in which the leakage resistor and the ground are connected. The controller 33 has a parameter map indicative of parameters including a relation between voltages and insulation resistance values of a master article. The controller calculates an insulation resistance value from voltage results when the switch SW is turned on and a first-time pulse is applied and a parameter map indicative of characteristics on the insulation resistance, and corrects a candidate of the insulation resistance value to calculate the insulation resistance value using a saturation voltage when the switch SW is kept in an on-state until it is saturated for a second time longer than a fist time and the saturation voltage of the master article.

SELECTED DRAWING: Figure 10

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present invention relates to an insulation resistance detection device.

In many cases, electrical circuits mounted on a vehicle are electrically insulated from the vehicle body (hereinafter referred to as vehicle frame). For example, a fuel cell vehicle is equipped with a high voltage circuit including a fuel cell, a DC/DC converter, and a load. In this case, this high voltage circuit is isolated from the vehicle frame. Moreover, such a vehicle is equipped with an insulation resistance detection device for detecting insulation resistance. Note that the insulation resistance detection device is sometimes called an earth leakage detection device.

The insulation resistance detection device includes, for example, a pulse generator, a detection resistor, a decoupling capacitor, and a controller. In this case, the pulse signal generated by the pulse generator is transmitted to the ground of a high voltage circuit mounted on the vehicle via a detection resistor, a decoupling capacitor, and an insulation resistor. Then, the controller measures the peak value of the pulse signal using the detection resistor, and determines whether the insulation resistance is normal based on the peak value.

This is an insulation resistance detection device that can detect insulation resistance without making the vehicle body (vehicle frame) the same potential as the reference side of the electric circuit. connected via. Equipped with a pulse wave generator and voltage detection circuit for measuring insulation resistance. Then, the detected voltages are integrated inside the controller 33 (for example, "inside the microcomputer"), the insulation resistance value is calculated based on the internal map, and a decrease in insulation resistance is detected.

The purpose of such insulation resistance detection is failure detection. The required accuracy of the insulation resistance detection threshold is calculated mainly from the following two viewpoints. (1) The insulation resistance value should not be erroneously detected, and (2) it should be detected that the insulation resistance value poses a risk of electric shock.

Therefore, the insulation resistance detection device may be provided with a self-diagnosis function. The self-diagnosis function determines whether the insulation resistance detection device is operating normally. For example, during self-diagnosis, a pseudo electrical leakage condition is caused. Then, the controller measures the peak value of the pulse signal in the pseudo earth leakage state, and determines whether the insulation resistance detection device is operating normally based on the peak value.

Note that an insulation resistance detection device that can perform self-diagnosis is described in, for example, Patent Document 1.

Japanese Patent Application Publication No. 2007-187454

However, the accuracy of the insulation resistance detection device is affected by physical variations (hereinafter also referred to as "monovariations") in the circuit elements inside the controller (ECU) and the 12V DC/DC converter that supplies the power supply voltage to the controller (ECU). , will be affected by temperature variations (hereinafter also referred to as "temperature variations"). Therefore, improvements are needed to meet the accuracy required for the system.

An object of one aspect of the present invention is to provide an insulation resistance detection device that performs correction during insulation resistance detection operation and satisfies the accuracy required by the system.

An insulation resistance detection device according to one aspect of the present invention is an insulation resistance detection device that detects insulation resistance between a frame of a vehicle and a high voltage circuit mounted on the vehicle, and includes a controller and a predetermined cycle. a pulse generator that generates a pulse, a detection resistor provided between the pulse generator and the frame, a leakage resistor connected to a measurement node between the detection resistor and the frame, and the leakage resistor. and a switch that is controlled to be in an off state to cut off the connection between the earth leakage resistor and the ground, or an on state to connect the earth leakage resistor and the ground, and the controller is configured to control the relationship between the voltage and the insulation resistance value of the master product. The insulation resistance value is calculated from the voltage result when the switch is turned on and a first time pulse is applied, and the parameter map showing characteristics related to insulation resistance. , correct the insulation resistance value candidate using the saturation voltage when the switch is kept on until it is saturated for a second time longer than the first time, and the saturation voltage of the master product, and determine the insulation resistance. Calculate the value.

In this way, the insulation resistance detection device calculates the insulation resistance value from the voltage result when the switch is turned on and the first time pulse is applied, and the parameter map showing the characteristics related to insulation resistance. Then, the insulation resistance value is calculated by correcting the insulation resistance value candidate using the saturation voltage when the switch is kept on until it is saturated for a second time longer than the first time and the saturation voltage of the master product. The insulation resistance can then be detected. Therefore, correction can be made during the operation of insulation resistance detection to meet the required accuracy of the system.

In the embodiment described above, the vehicle has a cooling water ion exchanger. Insulation resistance varies through cooling water passing through the frame. The controller may detect the state of the ion exchanger by calculating the insulation resistance value.

In this way, the state of the ion exchanger can be detected by calculating the insulation resistance value. Therefore, failure detection of the ion exchanger, which is particularly important in a fuel cell system, can be performed quickly and accurately, and adverse effects caused by a failure of the fuel cell system can be suppressed to a minimum.

In the above aspect, the controller may calculate the insulation resistance value based on the integrated value of the voltage obtained by integrating the voltage results when the switch is turned on and the pulse is applied for the first time every predetermined unit time. .

In this way, by calculating the insulation resistance value using the integrated voltage value, noise can be absorbed and the insulation resistance value can be calculated accurately.

According to the above-mentioned aspect, correction can be performed during the operation of insulation resistance detection, and the required accuracy of the system can be satisfied.

1 shows an example of an insulation resistance detection device according to an embodiment of the present invention. It is a figure which shows an example of the flowchart of advance preparation of a prior art. An example of a pulse waveform generated by a pulse generator is shown. An example of a waveform of a voltage at a measurement node measured by a voltage sensor is shown. FIG. 3 is a diagram showing an example of a voltage integrated value calculated by integrating voltages measured by a voltage sensor. FIG. 3 is a diagram showing a parameter map. It is a figure which shows an example of the flowchart of actual operation of a prior art. It is a figure which shows an example of the flowchart of advance preparation performed by the insulation resistance detection apparatus of embodiment of this invention. FIG. 3 is a diagram showing an example of a waveform of a voltage value at saturation. FIG. 3 is a diagram illustrating an example of a flowchart of actual operation of the embodiment of the present invention.

FIG. 1 shows an example of an insulation resistance detection device according to an embodiment of the present invention. The insulation resistance detection device 30 according to the embodiment of the present invention is mounted on the vehicle 1 and measures the resistance value of the insulation resistance Ri between the high voltage circuit 10 and the vehicle frame 20 (hereinafter also referred to as "insulation resistance value"). To detect. The vehicle 1 is, for example, an industrial vehicle such as a forklift, although it is not particularly limited. However, the vehicle 1 is not limited to an industrial vehicle, and may be a passenger car or the like.

The high voltage circuit 10 is mounted on the vehicle 1 and includes a fuel cell 11, a DC/DC converter 12, a radiator 13, an ion exchanger 14, and a load 15. Note that the high voltage circuit 10 may include other circuits or functions not shown in FIG. High voltage circuit 10 constitutes an example of a fuel cell system.

The fuel cell 11 generates electric power using fuel gas (for example, hydrogen). The DC/DC converter 12 steps up and/or steps down the output voltage of the fuel cell 11. The load 15 is, for example, a motor for driving the vehicle 1, and a DC voltage is applied to the load 15 via the DC/DC converter 12. That is, the load 15 is driven by the power generated by the fuel cell 11.

The radiator 13 exchanges heat between the cooling water heated by the heat generated by the fuel cell 11 and the outside air.

The ion exchanger 14 is provided in parallel with the fuel cell 11. For example, impurity ions are removed from a portion of the cooling water flowing through the radiator 13 by the ion exchange resin housed in the ion exchanger 14 . The insulation resistance of the ion exchanger 14 via cooling water may decrease due to changes in performance.

High voltage circuit 10 is electrically insulated from vehicle frame 20. That is, an insulation resistance Ri is provided between the high voltage circuit 10 and the vehicle frame 20. Here, the minimum resistance value of the insulation resistance Ri is determined by standards and the like. The insulation resistance of the insulation resistance Ri that mounts the fuel cell 11 and the vehicle frame 20 may deteriorate due to aging or the like. Therefore, the insulation resistance detection device 30 monitors the resistance value of the insulation resistance Ri.

The insulation resistance detection device 30 includes a pulse generator 31, a detection resistor Rd, a decoupling capacitor C, a leakage resistor Rx, a switch SW, a voltage sensor 32, and a controller (also referred to as "ECU") 33. Note that the insulation resistance detection device 30 may include other circuits or functions not shown in FIG. 1.

The pulse generator 31 generates a pulse having a predetermined peak value at a predetermined period T. The period T is set so that the pulse train can pass through the decoupling capacitor C. Further, it is assumed that the peak value of the pulse is proportional to the power supply voltage Vcc. Note that the pulse is, for example, a rectangular wave, although it is not particularly limited. In this case, the duty of the pulse is not particularly limited. The pulse generated by the pulse generator 31 is then applied to one terminal of the detection resistor Rd.

The other terminal (output side terminal) of the detection resistor Rd is electrically connected to one terminal of the decoupling capacitor C. The other terminal of the decoupling capacitor C is electrically connected to the vehicle frame 20. Decoupling capacitor C is provided to remove DC voltage components.

One terminal of the leakage resistor Rx is electrically connected to the output terminal of the detection resistor Rd. The other terminal of the leakage resistance Rx is electrically connected to ground via a switch SW. That is, a leakage resistor Rx and a switch SW are provided in series between the output terminal of the detection resistor Rd and the ground. The state of the switch SW is controlled by the controller 33. Specifically, the switch SW is controlled by the controller 33 to be in an OFF state that disconnects the earth leakage resistor Rx and the ground, or an ON state that connects the earth leakage resistor Rx and the ground.

Voltage sensor 32 measures the voltage at the output terminal of detection resistor Rd. The voltage value measured by the voltage sensor 32 is then sent to the controller 33. Note that in the following description, a node whose voltage is measured by the voltage sensor 32 may be referred to as a "measurement node M."

The controller 33 detects the resistance value of the insulation resistance Ri. Further, the controller 33 determines whether the insulation resistance detection device 30 is operating normally. That is, the controller 33 performs a self-diagnosis of the insulation resistance detection device 30. Note that the controller 33 is realized by, for example, a processor and a memory. In this case, the memory stores a program for detecting the resistance value of the insulation resistance Ri and a self-diagnosis program for diagnosing the insulation resistance detection device 30. Then, when the processor executes these programs, the resistance value of the insulation resistance Ri is detected, and self-diagnosis of the insulation resistance detection device 30 is realized.

In the vehicle 1 having the above configuration, when detecting the resistance value of the insulation resistance Ri, the controller 33 controls the switch SW to be in the off state. That is, the leakage resistance Rx and the ground are cut off. Further, the controller 33 causes the pulse generator 31 to generate pulses at a predetermined period T. Then, the pulse train generated by the pulse generator 31 is applied to the vehicle frame 20 via the detection resistor Rd and the decoupling capacitor C. Furthermore, this pulse train reaches the high voltage circuit 10 via the insulation resistor Ri and is terminated at the ground of the high voltage circuit 10.

The controller 33 performs advance preparation and actual operation.

<Advance preparation>
An example of advance preparation in the prior art will be described with reference to FIG. 2. FIG. 2 is a diagram illustrating an example of a flowchart of advance preparation in the prior art. As a preliminary preparation, the controller 33 is a master product that is connected between the frame and GND, calculates the integrated voltage value at each resistance value, creates a parameter map (insulation resistance value VS integrated voltage value), and connects the controller 33 with a master product. Incorporate it into the software inside the microcontroller. Specifically, a parameter map is created in each of the following steps S11 to S13. The parameter map is information that includes data indicating various parameters used to calculate insulation resistance based on the results of the master product. A master product is a standard product that serves as a sample for which the actual insulation resistance value, etc., such as the diode characteristics of an ECU, is connected to a known resistor and the origin of the value is known. The master product is used for the purpose of minimizing the effects of mono-variability and temperature variation of the DC/DC converter 12. Using a master product, a parameter map can be created by plotting multiple voltages measured when the insulation resistance value is set to an arbitrary value. Preparation for creating a parameter map created using this master product is a process performed in advance preparation described later.

Specifically, voltage sensor 32 measures the voltage at measurement node M. Then, the controller 33 acquires the voltage value measured by the voltage sensor 32 at predetermined sampling intervals. It is assumed that the sampling interval is sufficiently short with respect to the pulse period T.

FIG. 3 shows an example of a pulse waveform generated by the pulse generator 31. In this embodiment, the peak value of the pulse generated by the pulse generator 31 is V1. When a predetermined pulse is applied by the pulse generator 31, a waveform having a peak is measured by the voltage sensor 32. In the graph of FIG. 3, the horizontal axis indicates elapsed time, and the vertical axis indicates raw voltage.

The controller 33 detects the voltage using the voltage sensor 32 (step S11). FIG. 4 shows an example of the waveform of the voltage at the measurement node M measured by the voltage sensor 32. In the graph of FIG. 4, the horizontal axis indicates elapsed time, and the vertical axis indicates raw voltage. In this embodiment, the peak value of the pulse produced by the voltage sensor 32 is V2. The peak value V2 is proportional to the voltage obtained by dividing the power supply voltage Vcc by the detection resistor Rd and the insulation resistor Ri. In this embodiment, for example, a pulse of 100 to 999 ms (first time) is applied by the pulse generator 31 and the measured voltage is measured. In the example shown in FIG. 4, the resistance value of the insulation resistance Ri is reduced. In this case, the influence of the inductance component included in the high voltage circuit 10 becomes dominant, and the voltage waveform becomes rounded. Therefore, compared to the case shown in FIG. 3, the timing at which the peak value of the pulse appearing at the measurement node M exceeds the threshold value Vth is delayed.

The controller 33 calculates the integrated value of the voltage shown in FIG. 3 (step S12). FIG. 5 is a diagram showing an example of a voltage integrated value calculated by integrating the voltages measured by the voltage sensor 32. In the graph of FIG. 5, the horizontal axis indicates elapsed time, and the vertical axis indicates total value voltage. As shown in FIG. 5, the controller 33 can calculate the voltage integrated value shown in FIG. 5 by plotting the integrated values of the voltage shown in FIG. 4 at predetermined time intervals.

Then, the controller 33 creates a parameter map shown in FIG. 6 by plotting the relationship between the voltage integrated values according to the resistance value of the insulation resistance Ri (step S13). FIG. 6 is a diagram showing a parameter map. In the graph of FIG. 6, the horizontal axis shows the insulation resistance value, and the vertical axis shows the voltage integrated value. The parameter map shows the relationship between the voltage integrated value according to the resistance value of the insulation resistance Ri.

<Actual operation>
An example of the actual operation of the conventional technology will be described with reference to FIG. FIG. 7 is a diagram showing an example of a flowchart of the actual operation of the prior art. As an actual operation, the fuel cell system constituted by the high voltage circuit 10 shifts to the termination phase after the key of the vehicle 1 is turned off, and the controller 33 measures the insulation resistance in each of the following steps S21 to S23.

The controller 33 applies a first time pulse and measures the voltage with the voltage sensor 32 (step S21).

The controller 33 calculates the voltage integrated value inside the microcomputer of the controller 33 (step S22).

The controller 33 calculates the insulation resistance value by applying the voltage integrated value to the parameter map inside the microcomputer of the controller 33 (step S23). When calculating the insulation resistance value using the conventional method of steps S11 to S13 described above, it is not possible to correct variations such as mono-dimensional variations and temperature variations between the master product and the target product, so it is necessary to calculate the insulation resistance value separately. Calibration etc. are required.

Therefore, in the embodiment of the present invention, the saturation voltage is also acquired when creating the parameter map in advance, and is incorporated into the software, and the integrated voltage value is corrected before measuring the insulation resistance during actual operation.

<Advance preparation>
Preparation for the embodiment of the present invention will be described below. In advance preparation, the microcomputer of the controller 33 was a master product, and the pulse-on time was lengthened when creating the insulation resistance parameter map.

An example of advance preparation performed by the insulation resistance detection device 30 according to the embodiment of the present invention will be described with reference to FIG. 8 . FIG. 8 is a diagram showing an example of a flowchart of advance preparation performed by the insulation resistance detection device 30 according to the embodiment of the present invention. As a preliminary preparation, the controller 33 is a master product that is connected between the frame and GND, calculates the integrated voltage value at each resistance value, creates a parameter map (insulation resistance value VS integrated voltage value), and connects the controller 33 with a master product. Incorporate it into the software inside the microcontroller. Specifically, a parameter map is created in each of the following steps S31 to S34.

Specifically, the controller 33 continues to turn on the pulse for a second time until the voltage value is saturated, and incorporates (obtains) the voltage value at the time of saturation into the software of the controller 33 as the saturation voltage (step S31).

FIG. 9 is a diagram showing an example of the waveform of the voltage value at saturation. In the graph of FIG. 9, the horizontal axis shows elapsed time, and the vertical axis shows raw voltage. In FIG. 9, the solid line shows the waveform L1 of the voltage value when not saturated, and the dotted line shows the waveform L2 of the voltage value when saturated. In this example, the waveform L2 of the voltage value at saturation exceeds the peak value V2 of the waveform L1 of the voltage value when not saturated, and becomes higher than the waveform L1 of the voltage value when not saturated to a predetermined value. becomes constant at the value (peak value V3). This constant peak value V3 at saturation is acquired as the saturation voltage. Therefore, the pulse at saturation can minimize the influence of monochromatic variations and temperature variations of the DC/DC converter 12.

The controller 33 detects the voltage using the voltage sensor 32 (step S32). FIG. 4 shows an example of the waveform of the voltage at the measurement node M measured by the voltage sensor 32. In the graph of FIG. 4, the horizontal axis indicates elapsed time, and the vertical axis indicates raw voltage. In this embodiment, the peak value of the pulse produced by the voltage sensor 32 is V2. The peak value V2 is proportional to the voltage obtained by dividing the power supply voltage Vcc by the detection resistor Rd and the insulation resistor Ri. In this embodiment, for example, a pulse of 100 to 999 ms (first time) is applied by the pulse generator 31 and the measured voltage is measured.

The controller 33 calculates the integrated value of the voltage shown in FIG. 4 (step S33). FIG. 5 is a diagram showing an example of calculation by integrating the voltage integrated values shown in FIG. 4. In the graph of FIG. 5, the horizontal axis indicates elapsed time, and the vertical axis indicates total value voltage. As shown in FIG. 5, the controller 33 can calculate the voltage integrated value shown in FIG. 5 by plotting the integrated values of the voltage shown in FIG. 4 at predetermined time intervals. For example, the voltage integrated value shown in FIG. 5 is calculated by plotting the integrated value of the voltage shown in the graph of FIG. 4 for a period of time until the peak value V2 is reached every predetermined time.

Then, the controller 33 creates a parameter map shown in FIG. 5 by plotting the relationship between the voltage integrated values according to the resistance value of the insulation resistance Ri (step S34). FIG. 6 is a diagram showing a parameter map. In the graph of FIG. 6, the horizontal axis shows the insulation resistance value, and the vertical axis shows the voltage integrated value. The parameter map shows the relationship between the voltage integrated value according to the resistance value of the insulation resistance Ri. The parameter map created in the embodiment of the present invention is created based on the voltage obtained by keeping the switch SW on until it is saturated. The time during which the switch SW was kept on until saturation continued (second time) was created by keeping the switch SW on for a longer time than the result of applying a pulse for the time when it was conventionally on (first time). Therefore, by using the integrated voltage value at saturation created by keeping the switch SW on for a second time longer than the first time, the effects of mono-variability and temperature variation of the DC/DC converter 12 are minimized. can do.

<Actual operation>
An example of the actual operation of the embodiment of the present invention will be described with reference to FIG. FIG. 10 is a diagram showing an example of a flowchart of the actual operation of the embodiment of the present invention. As an actual operation, the fuel cell system constituted by the high voltage circuit 10 shifts to the termination phase after the key of the vehicle 1 is turned off, and the controller 33 calculates the insulation resistance value in each of the following steps S41 to S45.

The controller 33 turns on the switch SW of the DC/DC converter 12, applies a pulse for a second time until it is saturated, and measures the voltage with the voltage sensor 32 (step S41). A time longer than the first time is set as the second time. For example, 1000 to 10000 ms can be set as the second time.

The controller 33 turns on the switch SW of the DC/DC converter 12, applies a first time pulse, and measures the voltage with the voltage sensor 32 (step S42). A time shorter than the second time is set as the first time. For example, 100 to 999 ms can be set as the first time.

The controller 33 calculates a voltage integrated value by integrating the voltage values measured by the voltage sensor 32 in step S42 at predetermined time intervals within the microcomputer of the controller 33 (step S43).

The controller 33 refers to the parameter map created in advance, compares it with the saturation voltage of the master product, and corrects the integrated voltage value (step S44). The corrected voltage integrated value is calculated using Equation 1 below.

Corrected voltage integration value = voltage integration value x (master product saturation voltage/measured saturation voltage)...Equation 1

For example, if it is known from the parameter map that the saturation voltage of the master product is 12.5V, the saturation voltage measured in step S41 is 12.0V, and the voltage integrated value calculated in step S43 is 14000. By substituting each value into Equation 1, the corrected voltage integrated value=14000×(12.5/12.0)=“14583.3” is calculated.

The controller 33 corrects the insulation resistance value candidates and calculates the insulation resistance value by applying the voltage integrated value correction calculated in step S44 to the parameter map inside the microcomputer (step S45). The controller 33 can detect the insulation resistance Ri based on the calculated insulation resistance value.

In this way, the insulation resistance detection device 30 according to the embodiment of the present invention can perform insulation from the voltage result when the switch SW is turned on and the first time pulse is applied, and the parameter map showing the characteristics related to insulation resistance. Calculate the resistance value. Then, the candidate insulation resistance value is corrected using the saturation voltage when the switch SW is kept on until it is saturated for a second time longer than the first time, and the saturation voltage of the master product. can be calculated to detect insulation resistance. Therefore, correction can be made during the operation of insulation resistance detection to meet the required accuracy of the system.

Further, in this way, the insulation resistance varies through the cooling water passing through the vehicle frame 20, and the controller 33 can detect the state of the ion exchanger 14 by calculating the insulation resistance value. Therefore, the state of the ion exchanger 14 can be detected by detecting the insulation resistance. Thereby, failure detection of the ion exchanger 14, which is particularly important in a fuel cell system, can be performed quickly and accurately, and adverse effects caused by a failure of the fuel cell system can be suppressed to a minimum.

In addition, in this way, the insulation resistance detection device 30 calculates the insulation resistance value based on the integrated value of the voltage obtained by integrating the voltage results obtained when the switch SW is turned on and the pulse of the first time is applied every predetermined unit time. be done. Thereby, noise can be absorbed and calculation can be performed using the integrated value of voltage, and the insulation resistance value can be accurately determined.

1: Vehicle 10: High voltage circuit 11: Fuel cell 12: DC/DC converter 13: Radiator 14: Ion exchanger 15: Load 20: Vehicle frame 30: Insulation resistance detection device 31: Pulse generator 32: Voltage sensor 33 : Controller C : Decoupling capacitor Rd : Detection resistor Ri : Insulation resistance Rx : Leakage resistance

Claims (3)

An insulation resistance detection device that detects insulation resistance between a vehicle frame and a high voltage circuit mounted on the vehicle,
controller and
a pulse generator that generates pulses at a predetermined period;
a detection resistor provided between the pulse generator and the frame;
an earth leakage resistor connected to a measurement node between the detection resistor and the frame;
a switch that is controlled to be in an off state that cuts off between the earth leakage resistor and ground or an on state that connects between the earth leakage resistor and ground;
The controller includes:
It has a parameter map that shows parameters including the relationship between voltage and insulation resistance value of the master product.
Calculating an insulation resistance value from the voltage result when the switch is turned on and a first time pulse is applied and the parameter map showing characteristics related to insulation resistance;
The insulation resistance value candidate is corrected by using the saturation voltage when the switch is kept on until it is saturated for a second time longer than the first time and the saturation voltage of the master product. An insulation resistance detection device characterized by calculating. The vehicle has a cooling water ion exchanger,
the insulation resistance varies through the cooling water passing through the frame;
The insulation resistance detection device according to claim 1, wherein the controller detects the state of the ion exchanger by calculating the insulation resistance value. The controller includes:
The insulation resistance value is calculated based on the integrated value of the voltage obtained by integrating the voltage results obtained when the switch is turned on and the pulse of the first time is applied every predetermined unit time. 1. The insulation resistance detection device according to 1.

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