Insulation monitoring device and control method for the insulation monitoring device

Abstract

The present application is characterized by comprising: a signal generation section that applies a pulse signal to a power line; a signal measurement section that measures a voltage of the pulse signal applied to a ground when the pulse signal passes through an insulation resistance; an average voltage calculation section that calculates an average voltage of the voltage measured during a section according to a sampling interval; and a control section that calculates a sampling interval according to an initial sampling interval and a time multiple set in advance, calculates an average voltage during a sampling section according to the calculated sampling interval, detects the first average voltage as a normal state voltage according to whether a difference between the calculated first average voltage and a second average voltage measured before the first average voltage is within a first error range, or calculates the sampling interval using different time multiples from each other.

Description

Technical Field

[0001] This invention relates to an insulation monitoring device for preventing accidents by pre-detecting grounding faults and the like in an ungrounded (IT) power system, and a control method for the insulation monitoring device. Background Technology

[0002] IT (Insulation Terra) grounding is a grounding method where neither side of the power line is grounded, and grounding is achieved solely through the load's casing. With this IT grounding method, the system operation will not stop even if a ground fault occurs on any power line, allowing ample time to locate the fault and thus ensuring continuous system operation.

[0003] However, since the system can operate even in the event of a grounding fault, it is necessary to continuously monitor the insulation condition of the power lines while the system is in operation. IEC (International Electro-technical Commission) 61557 requires the installation of insulation monitoring devices capable of monitoring the insulation condition of power lines.

[0004] Therefore, on November 21, 2019, South Korea also announced the judgment criteria for electrical equipment technical standards in Ministry of Industry, Trade and Resources Announcement No. 2019-667, in order to install appropriate protection and control devices such as IMD in energy storage devices that use secondary batteries.

[0005] This insulation monitoring device includes: a pulse signal generating unit formed between a ground and a power line, which forms a circuit between the power line and the ground through an insulation resistance formed between the power line and the ground, and inputs a pulse signal to the formed circuit; and a detection resistor for detecting the voltage according to the pulse signal. Furthermore, the voltage under normal conditions (when the insulation is normal) is detected by measuring and analyzing the voltage across the detection resistor, and the magnitude of the insulation resistance is calculated based on the detected voltage, thereby enabling monitoring of the insulation condition of the power line.

[0006] However, this common insulation monitoring device has the following problem: in order to detect the voltage under normal conditions, the voltage measured from the detection resistor is analyzed according to a fixed time multiple. This results in the following problem: the time required to detect the voltage under normal conditions becomes longer, which in turn increases the time required to calculate and display the magnitude of the insulation resistance, i.e., the response time of the insulation monitoring device becomes longer.

[0007] Furthermore, in ordinary insulation monitoring devices, only an analog RC (Analog Resistor Capacitor) filter is used to remove noise generated in the pulse signal measured by the circuit formed between the power line and ground. Therefore, there are problems such as difficulty in removing noise from the insulation monitoring device itself or from the detection voltage after analog-to-digital conversion.

[0008] On the other hand, in order to detect the voltage under normal conditions, ordinary insulation monitoring devices determine the sampling interval by gradually increasing the sampling time according to a fixed time multiple. When the difference between the average voltages calculated in each sampling interval is below the preset error, the average voltage calculated in the current sampling interval will be detected as the voltage under normal conditions.

[0009] However, when detecting the voltage under normal conditions solely through the difference in average voltage as described above, the following problem exists: In the initial stages of detection, if the voltage value fluctuates with a short sampling time interval, causing the difference in average voltage to be calculated below the pre-set error, it may be misjudged as a stable voltage even when the voltage is unstable. In this case, due to the unstable voltage state, a voltage substantially higher than the stable voltage may be misjudged as a stable voltage, leading to incorrect measurement of the insulation resistance.

[0010] On the other hand, to accurately calculate the insulation resistance, the voltage under normal conditions needs to be calculated by reversing the polarity of the pulse signal. In this case, if the pulse signal polarity is reversed, a surge phenomenon caused by the voltage difference of the reversed pulse signal temporarily destabilizes the voltage. After a predetermined time, the voltage stabilizes again. The insulation resistance can then be calculated from the stable voltage. To detect the voltage under normal conditions, the insulation monitoring device determines sampling intervals by gradually increasing the sampling time according to a fixed time multiple. If the difference in the average voltage calculated across different sampling intervals is below a pre-set error, the average voltage calculated in the current sampling interval is detected as the voltage under normal conditions. This minimizes the time required to calculate the insulation resistance by minimizing the time spent detecting the normal voltage after the pulse signal is reversed.

[0011] On the other hand, ordinary insulation monitoring devices determine whether the voltage is stable based on the difference in average voltage. Therefore, the difference in average voltage is calculated regardless of the time elapsed after the pulse signal inversion. Thus, even when the voltage is highly unstable immediately after the pulse signal inversion, the process of calculating the difference in average voltage continues to be performed repeatedly. Furthermore, the calculated difference in average voltage is also larger during this highly unstable period, so the process of calculating the average voltage continues to be performed repeatedly even during this highly unstable voltage state.

[0012] As mentioned above, ordinary insulation monitoring devices calculate the difference in average voltage regardless of the time elapsed after the pulse signal inversion, thus repeating unnecessary measurement processes and resulting in increased power consumption. Summary of the Invention

[0013] The problem the invention aims to solve

[0014] The present invention addresses the aforementioned problems and aims to provide an insulation monitoring device that adjusts the time factor for detecting the normal state voltage based on the voltage analyzed from the detection resistor, thereby shortening the detection time of the normal state voltage and thus achieving a faster response speed. It also provides a control method for controlling the insulation monitoring device to improve its response speed.

[0015] In addition, the present invention is proposed to solve the above-mentioned problems, and its purpose is to provide an insulation monitoring device and a control method for the insulation monitoring device that removes noise from the internal components of the insulation monitoring device or from the detection voltage after analog-to-digital conversion, thereby enabling more accurate calculation of the insulation resistance.

[0016] In addition, the present invention was proposed to solve the above-mentioned problems, and its object is to provide an insulation monitoring device and a control method for the insulation monitoring device that can prevent the voltage in an unstable state from being identified as a voltage in a normal state.

[0017] In addition, the present invention was proposed to solve the above-mentioned problems, and its object is to provide an insulation monitoring device and a control method for the insulation monitoring device that can reduce power consumption by preventing the insulation monitoring device from repeatedly performing unnecessary measurement processes.

[0018] Furthermore, the present invention aims to provide an insulation monitoring device and a control method thereof that not only prevent unnecessary measurement processes from being performed based on changes in the measured voltage, but also calculate the optimal standby time of the insulation monitoring device that can detect the voltage of the stable state based on the applied pulse signal in the shortest possible time.

[0019] means for solving problems

[0020] An embodiment of the present invention for achieving the above-mentioned objective provides an insulation monitoring device, characterized in that it includes: a signal generation unit that applies a pulse signal having a predetermined voltage to the power line; a signal measurement unit connected to the ground, which measures the voltage of the applied pulse signal from the ground when the pulse signal applied to the power line is applied to the ground through the insulation resistance; an average voltage calculation unit that calculates the average voltage of the voltage measured by the signal measurement unit during a sampling interval according to a set sampling interval; and a control unit that calculates a sampling interval according to an initial sampling interval and a preset time multiple, calculates the average voltage during the sampling interval according to the calculated sampling interval, and detects the first average voltage as a normal state voltage based on whether the difference between the calculated first average voltage and a second average voltage calculated before the first average voltage is within a preset first error range, or updates the sampling interval using different time multiples based on the difference between the first average voltage and the second average voltage.

[0021] In one embodiment, when the difference between the first average voltage and the second average voltage exceeds a preset second error range, the control unit updates the sampling interval of the sampling interval from which the next average voltage will be calculated based on a first time multiple. When the difference between the first average voltage and the second average voltage is below the preset second error range, the control unit updates the sampling interval of the sampling interval from which the next average voltage will be calculated based on a second time multiple. The value of the second time multiple is less than the value of the first time multiple, and the value of the second error range is greater than the value of the first error range.

[0022] In one embodiment, the first time multiple is 1.66, the second time multiple is 1.33, the first error range is 1% of the second average voltage, and the second error range is 5% of the second average voltage.

[0023] In one embodiment, the control unit determines the initial sampling interval based on the larger of an initial value calculated from the internal resistance of the insulation monitoring device and the period of a preset noise frequency.

[0024] In one embodiment, the system further includes a memory that stores information about different sampling intervals corresponding to a plurality of different time constants.

[0025] The control unit calculates a first sampling interval based on the larger of an initial value calculated from the internal resistance of the insulation monitoring device and the period of a preset noise frequency. The control unit determines a plurality of interval setting time points for calculating the gradient of the voltage measured by the signal measurement unit based on the first sampling interval. The control unit calculates the ratio of the first gradient to the second gradient and determines any one of the different sampling intervals as the initial sampling interval based on the time constant corresponding to the calculated gradient ratio. The first gradient is based on the voltage difference between the interval setting time points including the plurality of first sampling intervals, and the second gradient is based on the voltage difference between other interval setting time points including the plurality of first sampling intervals.

[0026] In one embodiment, if the first average voltage is determined to be a normal state voltage based on the type of the applied pulse signal, the control unit controls the signal generation unit to invert the pulse signal into the other type of pulse signal based on whether there is a normal state voltage based on the type of other preset pulse signal, and controls the signal measurement unit and the average voltage calculation unit to detect the normal state voltage based on the other type of pulse signal.

[0027] In one embodiment, when there is a normal state voltage based on other types of pulse signals that are preset, the control unit calculates the magnitude of the insulation resistance based on the normal state voltage of the pulse signals that are different from each other.

[0028] In one embodiment, the control unit confirms whether a preset number of insulation resistance values ​​has been calculated. If the calculated insulation resistance value is less than the preset number, the control unit controls the signal generation unit, the signal measurement unit, and the average voltage calculation unit to calculate the insulation resistance value again. If the confirmation result is that the preset number of insulation resistance values ​​has been calculated, the final value of the insulation resistance value is determined by calculating the average value of the calculated insulation resistance values.

[0029] In one embodiment, if the value of the preset number of insulation resistances is calculated, the control unit calculates the difference between the calculated insulation resistance values, and if the calculated difference exceeds a preset threshold value, controls the signal generation unit, the signal measurement unit, and the average voltage calculation unit to change the interference frequency according to a preset ratio and recalculate the value of the preset number of insulation resistances according to the changed interference frequency.

[0030] In one embodiment, if the final value of the insulation resistance is determined based on the average value of the preset number of insulation resistances, the control unit confirms whether the value of the interference frequency is less than a preset minimum value, and if the value of the interference frequency is less than the preset minimum value, the control unit determines the value of the interference frequency as the minimum value.

[0031] In one embodiment, the signal measurement unit includes: a detection resistor; an amplifier for amplifying the voltage difference applied across the detection resistor; an ADC (Analog-to-Digital Converter) for converting the voltage difference amplified by the amplifier into a digital voltage value and inputting it to the control unit; and at least one of a first analog filter and a second analog filter, wherein the first analog filter is formed between the detection resistor and the amplifier for removing noise from the voltage applied across the detection resistor, and the second analog filter is connected between the amplifier and the ADC for removing noise from the voltage difference amplified by the amplifier.

[0032] In one embodiment, the ADC further includes: a conversion unit that converts the amplified voltage difference into a digital voltage value; and a digital filter formed between the conversion unit and the control unit to remove noise affecting the digital voltage value input to the control unit.

[0033] In addition, embodiments of the present invention provide a control method for an insulation monitoring device, the insulation monitoring device including an insulation resistance formed between a power line and a ground in a system, characterized in that the control method includes: a step of applying a pulse signal with a voltage of a predetermined magnitude to the power line; a step of determining an initial sampling interval; a step of calculating a sampling interval based on the determined initial sampling interval, calculating an average voltage during a sampling interval based on the calculated sampling interval, and calculating an average voltage during a sampling interval based on a sampling interval updated based on a first time multiple; a step of detecting whether the difference between a currently calculated first average voltage and a second average voltage measured before the first average voltage is within a preset first error range; a step of identifying the first average voltage as a normal state voltage based on the applied pulse signal, or updating the sampling interval using different time multiples based on the difference between the first average voltage and the second average voltage, based on the detection result; and repeatedly executing the step of calculating a sampling interval based on the updated sampling interval. The steps include: averaging the voltage over a period of time, and detecting whether the difference in voltage is within a pre-defined first error range until the normal state voltage is identified; updating the sampling interval using different time multiples; if the normal state voltage is identified, detecting whether a normal state voltage based on a pre-identified type of pulse signal exists; identifying a normal state voltage based on the other type of pulse signal by re-executing the steps of inverting the pulse signal to the other type of pulse signal and determining the initial sampling interval if the result of detecting whether a normal state voltage based on the other type of pulse signal exists is found to be present; and calculating the magnitude of the insulation resistance based on normal state voltages of different types of pulse signals if the result of detecting whether a normal state voltage based on the other type of pulse signal exists is found to be present.

[0034] In one embodiment, the step of updating the sampling interval using different time multiples includes: updating the sampling interval according to a first time multiple when the difference between the first average voltage and the second average voltage exceeds a preset second error range; and updating the sampling interval according to a second time multiple when the difference between the first average voltage and the second average voltage is below the preset second error range; wherein the value of the second time multiple is less than the value of the first time multiple, and the value of the second error range is greater than the value of the first error range.

[0035] In one embodiment, the step of determining the initial sampling interval is to calculate the initial sampling interval based on the larger of an initial value calculated based on the internal resistance of the insulation monitoring device and the period of a preset noise frequency.

[0036] Furthermore, embodiments of the present invention provide an insulation monitoring device, including an insulation resistance formed between a power line and a ground in a system, characterized in that it includes: a signal generation unit that applies a pulse signal with a predetermined voltage to the power line; a signal measurement unit connected to the ground, which measures the voltage of the applied pulse signal from the ground when the pulse signal applied to the power line is applied to the ground through the insulation resistance; an average voltage calculation unit that calculates the average voltage of the voltage measured by the signal measurement unit during a sampling interval according to a set sampling interval; and a control unit that executes an adjustment process, in which a sampling interval is calculated based on an initial sampling interval and a preset time multiple, the average voltage during the sampling interval according to the calculated sampling interval is calculated, and the difference between the calculated first average voltage and a second average voltage calculated before the first average voltage is compared; if the difference in the average voltage is within a preset error range, the second average voltage is detected as a normal state voltage or the adjustment process is executed again depending on whether the time elapsed from the sampling start time point is more than a predetermined time.

[0037] In one embodiment, the control unit performs an adjustment process based on a preset first time multiple. If the result of the first adjustment is that the difference between the first average voltage and the second average voltage is less than or equal to a preset first error, a secondary adjustment process is performed to determine the sampling interval of the sampling range for which the average voltage will be calculated based on a second time multiple different from the first time multiple. If the result of the secondary adjustment is that the difference between the first average voltage and the second average voltage is less than or equal to a preset normal voltage error, the second average voltage is detected as a normal state voltage based on whether the predetermined time has elapsed since the start of the secondary adjustment.

[0038] In one embodiment, when the result of the first adjustment is that the difference between the first average voltage and the second average voltage is below a preset first error, the control unit ends the first adjustment, determines at least one reference point based on the start time of the first adjustment, the initial sampling interval, and the end time of the first adjustment, calculates a plurality of voltage gradients based on the voltage difference based on the determined reference point, calculates a time constant based on the gradient ratio of the calculated voltage gradients, and determines the predetermined time based on the calculated time constant.

[0039] In one embodiment, if the adjustment ends, the control unit determines the start point of the adjustment, the time point elapsed from the start point corresponding to the initial sampling interval, the end point of the adjustment, and the time point before the end point of the adjustment in the initial sampling interval as the reference point, and calculates the gradient ratio based on the determined reference point and the following mathematical formula.

[0040] [Mathematical expression]

[0041]

[0042] Here, the start point represents the time point at which the sampling begins, the first reference point represents the time point after which the initial sampling interval has elapsed from the start point, the third reference point represents the time point at which the adjustment ends, and the second reference point represents the time point before the initial sampling interval prior to the third reference point.

[0043] The starting voltage represents the voltage at the starting point, the first voltage represents the voltage at the first reference point, the second voltage represents the voltage at the second reference point, and the third voltage represents the voltage at the third reference point.

[0044] In one embodiment, the control unit calculates a time constant (τ) based on the result of the natural logarithm (ln) of the gradient ratio and the time interval between the first reference point and the starting point, and the control unit determines the specified time based on a preset multiple of the calculated time constant.

[0045] In one embodiment, the control unit calculates the time constant based on whether the calculated gradient ratio is above a preset threshold. If the time constant is calculated, the control unit resets the initial sampling interval based on the calculated time constant and the following mathematical formula, and performs the secondary adjustment process based on the reset initial sampling interval.

[0046] [Mathematical expression]

[0047] t n = -ln(1-0.01)×τ

[0048] Here, tn is the newly set initial sampling interval, and τ is the time constant.

[0049] In one embodiment, if the time constant is not calculated based on the comparison between the calculated gradient ratio and the critical value, the control unit performs the secondary adjustment process based on the initial sampling interval.

[0050] In one embodiment, without calculating the time constant, the control unit increases the amplitude of the pulse signal by controlling the signal generation unit.

[0051] In one embodiment, a coupling resistor is further included, the coupling resistor comprising a plurality of resistors and a switch, the plurality of resistors being connected in parallel to the respective power lines of the system, the switch connecting a portion of the plurality of resistors to the respective power lines, and, without calculating the time constant, the control unit controlling the switch to connect the plurality of resistors in parallel to the respective power lines.

[0052] In one embodiment, the signal measurement unit includes a first detection resistor, a first circuit including a second detection resistor, a second circuit excluding the second detection resistor, and a switch that is connected to the first detection resistor through either the first circuit or the second circuit to form a loop. The signal measurement unit detects the voltage of the applied pulse signal based on the voltage applied to both ends of at least one detection resistor. If the time constant is not calculated, the control unit controls the switch to connect the first detection resistor to the second circuit to form a loop.

[0053] In one embodiment, when the calculated gradient ratio is less than the critical value, the control unit calculates a time constant based on the result of the natural logarithm (ln) of the preset minimum gradient ratio, the starting point of the first adjustment, and the time interval between the starting point and the time point corresponding to the initial sampling interval.

[0054] In addition, embodiments of the present invention provide a control method for an insulation monitoring device, the insulation monitoring device including an insulation resistance formed between a power line and a ground in a system, characterized in that the control method includes: a step of applying a pulse signal with a voltage of a predetermined magnitude to the power line; a step of determining an initial sampling interval; a step of performing a first adjustment, wherein in the first adjustment, a sampling interval is calculated based on the initial sampling interval and a first time multiple, an average voltage is calculated during the sampling interval based on the calculated sampling interval, and the difference between the calculated first average voltage and a second average voltage calculated before the first average voltage is compared; a step of detecting whether the result of the first adjustment is that the difference between the first average voltage and the second average voltage is within a predetermined first error range; and a step of ending the first adjustment based on whether the voltage difference is within the first error range, and performing a second adjustment, wherein in the second adjustment, the difference between the initial sampling interval and the second average voltage is determined based on the predetermined sampling interval; and a step of performing a second adjustment based on whether the voltage difference is within the first error range, the first adjustment is terminated, and a second adjustment is performed, wherein the second adjustment is performed based on the initial sampling interval and a first time multiple is calculated, the first average voltage is calculated, the ... The process involves: calculating the sampling interval using a second time multiple; calculating the average voltage during the sampling interval based on the calculated sampling interval; comparing the difference between the calculated third average voltage and a fourth average voltage calculated before the third average voltage; detecting whether the result of the secondary adjustment is that the difference between the third and fourth average voltages is within the normal voltage error range; if the difference between the third and fourth average voltages is within the normal voltage error range, detecting whether a predetermined time has elapsed since the start of the secondary adjustment; if the predetermined time has elapsed, detecting that the third average voltage is the normal state voltage based on the applied pulse signal; and repeatedly performing the secondary adjustment if the result of the secondary adjustment is that the difference between the third and fourth average voltages exceeds the normal voltage error range, or if a predetermined time has not elapsed since the start of the secondary adjustment.

[0055] In one embodiment, the step of performing secondary adjustment further includes: determining at least one reference point based on the start time of the primary adjustment, the initial sampling interval, and the end time of the primary adjustment; calculating a plurality of voltage gradients based on the voltage difference based on the determined reference point, and calculating a gradient ratio based on the calculated plurality of gradients; and calculating a time constant based on the calculated gradient ratio, and determining the predetermined time based on the calculated time constant.

[0056] In one embodiment, the step of determining the predetermined time further includes: detecting whether the calculated gradient ratio is above a preset threshold value; if the gradient ratio is above the threshold value, calculating the time constant; and if the time constant is calculated, resetting the initial sampling interval based on the calculated time constant and the following mathematical formula; the step of performing secondary adjustment is the step of performing the secondary adjustment process based on the reset initial sampling interval.

[0057] [Mathematical expression]

[0058] t n = -ln(1-0.01)×τ

[0059] Here, tn is the newly set initial sampling interval, and τ is the time constant.

[0060] In one embodiment, the step of performing secondary adjustment is to perform the second adjustment process based on the initial sampling interval without calculating the time constant.

[0061] In one embodiment, the step of detecting the normal state voltage based on the applied pulse signal further includes: if a normal state voltage based on the applied pulse signal is detected, then calculating the magnitude of the insulation resistance based on the detected normal state voltage; the step of calculating the magnitude of the insulation resistance further includes: if the time constant is not calculated, increasing the gradient ratio; the step of increasing the gradient ratio is the step of increasing the amplitude of the pulse signal.

[0062] In one embodiment, the insulation monitoring device further includes a coupler resistor comprising a plurality of resistors and a switch, the plurality of resistors being connected in parallel to the respective power lines of the system, the switch connecting a portion of the plurality of resistors to the respective power lines, and the step of increasing the gradient ratio further comprising controlling the switch to connect the plurality of resistors in parallel to the respective power lines.

[0063] In one embodiment, the insulation monitoring device further includes a signal measurement unit, which includes a first detection resistor, a first circuit including a second detection resistor, a second circuit excluding the second detection resistor, and a switch that is connected to the first detection resistor through either the first circuit or the second circuit to form a loop. The signal measurement unit detects the voltage of the applied pulse signal based on the voltage across at least one detection resistor, and the step of increasing the gradient ratio is to control the switch to connect the first detection resistor to the second circuit to form a loop.

[0064] In one embodiment, the step of calculating the time constant further includes: when the gradient ratio is less than the critical value, calculating the time constant based on the result of the natural logarithm (ln) of a preset minimum gradient ratio, the starting point of the first adjustment, and the time interval between the starting point and a time point equivalent to the initial sampling interval.

[0065] Furthermore, embodiments of the present invention provide an insulation monitoring device, including an insulation resistance formed between a power line and a ground in a system, characterized in that it includes: a signal generation unit that applies a pulse signal with a predetermined voltage to the power line; a signal measurement unit connected to the ground, which measures the voltage of the applied pulse signal from the ground when the pulse signal applied to the power line is applied to the ground through the insulation resistance; an average voltage calculation unit that calculates the average voltage of the voltage measured by the signal measurement unit during a sampling interval according to a set sampling interval; and a control unit that executes an adjustment process, wherein the adjustment process is based on an initial sampling interval and a pre-set sampling interval. The sampling interval is calculated using a set time multiple. The average voltage during the sampling interval based on the calculated sampling interval is calculated. The difference between the calculated first average voltage and the second average voltage calculated before the first average voltage is calculated. If the difference between the average voltages meets a preset normal voltage error, the first average voltage is detected as a normal state voltage. If the difference between the first average voltage and the second average voltage meets a preset error condition, the control unit switches the operation state to energy-saving mode during a preset standby time. If the standby time has elapsed, the adjustment process of recalculating the average voltage and detecting the normal state voltage is restarted.

[0066] In one embodiment, the control unit performs an adjustment process based on a preset first time multiple, and if the result of the first adjustment is that the difference between the first average voltage and the second average voltage is below a preset first error, the operation state is switched to energy-saving mode during the standby time. If the adjustment process restarts, the control unit performs a second adjustment process, in which the sampling interval of the sampling range for which the average voltage is to be calculated is determined based on a second time multiple different from the first time multiple.

[0067] In one embodiment, when the result of the first adjustment is that the difference between the first average voltage and the second average voltage is below a preset first error, the control unit ends the first adjustment. The control unit determines at least one reference point based on the start time of the first adjustment, the initial sampling interval, and the end time of the first adjustment, and calculates a plurality of voltage gradients based on the voltage difference of the voltages at the determined reference points. The control unit calculates a time constant based on the gradient ratio of the calculated voltage gradients, and determines the standby time based on the calculated time constant.

[0068] In one embodiment, the control unit determines whether to calculate the time constant based on a comparison between the calculated gradient ratio and a preset threshold value. If the insulation resistance is calculated based on the normal state voltage detected after the standby time determined according to the time constant, the control unit further calculates the leakage capacitance based on the calculated time constant using the following mathematical formula.

[0069] [Mathematical expression]

[0070]

[0071] Here, τ is the time constant, and R e It is the magnitude of the insulation resistance, R i It is the magnitude of the internal resistance of the insulation monitoring device, and the critical value is the minimum value of the calculated range of the leakage capacitance.

[0072] In one embodiment, the control unit determines whether to calculate the time constant based on a comparison between the calculated gradient ratio and a preset threshold value, and performs the secondary adjustment process based on the initial sampling interval and the second time multiple if the time constant is not calculated.

[0073] In one embodiment, if the insulation resistance is calculated based on the detected normal state voltage, the control unit controls the signal generation unit to increase the amplitude of the test pulse depending on whether the time constant has been calculated.

[0074] In one embodiment, a coupling resistor is also included, the coupling resistor comprising a plurality of resistors and a switch, the plurality of resistors being connected in parallel to the respective power lines of the system, the switch connecting a portion of the plurality of resistors to the respective power lines, and the control unit controlling the switch to connect the plurality of resistors in parallel to the respective power lines without calculating the time constant.

[0075] In one embodiment, the signal measurement unit includes a first detection resistor, a first circuit including a second detection resistor, a second circuit excluding the second detection resistor, and a switch that is connected to the first detection resistor through either the first circuit or the second circuit to form a loop. The signal measurement unit detects the voltage of the applied pulse signal based on the voltage across at least one detection resistor. If the time constant is not calculated, the control unit controls the switch to connect the first detection resistor to the second circuit to form a loop.

[0076] In one embodiment, the control unit determines whether to calculate the time constant based on a comparison between the calculated gradient ratio and a preset threshold value. If the time constant is not calculated, the control unit calculates the time constant based on the natural logarithm (ln) of the preset minimum gradient ratio, the start point of the first adjustment, and the time interval between the start point and the time point corresponding to the initial sampling interval.

[0077] In addition, embodiments of the present invention provide a control method for an insulation monitoring device, the insulation monitoring device including an insulation resistance formed between a power line and a ground in a system, characterized in that the control method includes: a step of applying a pulse signal with a voltage of a predetermined magnitude to the power line; a step of determining an initial sampling interval; a step of performing a first adjustment, wherein in the first adjustment, a sampling interval is calculated based on the initial sampling interval and a first time multiple, an average voltage during the sampling interval based on the calculated sampling interval is calculated, and the difference between the calculated first average voltage and a second average voltage calculated before the first average voltage is compared; if the result of the first adjustment is that the difference between the first average voltage and the second average voltage exceeds a preset first error range, the first adjustment step is repeated; if the result of the first adjustment is that the difference between the first average voltage and the second average voltage is within the first error range, at least one reference point is determined, and a gradient ratio is calculated based on a voltage gradient of the voltage difference based on the reference point; The steps include: calculating the time constant based on the calculated gradient ratio; switching the operating state of the insulation monitoring device to a standby state during the standby time determined by the calculated time constant; confirming whether the standby time has elapsed and switching the operating state to an active state based on the confirmation result; performing a secondary adjustment if the operating state is switched to an active state, wherein the sampling interval is calculated based on the reset initial sampling interval and the second time multiple, the average voltage during the sampling interval based on the calculated sampling interval is calculated, and the difference between the calculated third average voltage and the fourth average voltage calculated before the third average voltage is compared; detecting the third average voltage as the normal state voltage based on the applied pulse signal if the difference between the third average voltage and the fourth average voltage is within the normal voltage error range; and repeatedly performing the secondary adjustment if the difference between the third average voltage and the fourth average voltage exceeds the normal voltage error range.

[0078] In one embodiment, the step of switching the operating state of the insulation monitoring device to a standby state includes: determining the standby time based on a preset multiple of the calculated time constant; and switching the operating mode of the insulation monitoring device to an energy-saving mode during the determined standby time.

[0079] In one embodiment, the step of detecting the third average voltage as a normal state voltage based on the applied pulse signal further includes the step of calculating the size of the insulation capacitance based on the calculated time constant.

[0080] In one embodiment, the step of calculating the time constant further includes: when the gradient ratio is less than the critical value, calculating the time constant based on the result of the natural logarithm (ln) of a preset minimum gradient ratio, the starting point of the first adjustment, and the time interval between the starting point and a time point equivalent to the initial sampling interval.

[0081] Invention Effects

[0082] The effects of the insulation monitoring device and the control method of the insulation monitoring device according to the present invention will be described below.

[0083] According to at least one embodiment of the present invention, the present invention uses a time multiple with a smaller value based on the result of analyzing the voltage measured from the detection resistor, thereby having the effect of shortening the detection time of the normal state voltage.

[0084] According to at least one embodiment of the present invention, the present invention sets a more suitable initial time interval for the detected voltage based on the result of analyzing the gradient of the voltage measured from the detection resistor, thereby having the effect of shortening the detection time of the normal state voltage.

[0085] According to at least one embodiment of the present invention, the present invention additionally provides a filter capable of removing digital noise or obtaining noise from the analog-to-digital conversion detection voltage, thereby enabling a more accurate calculation of the insulation resistance by more effectively removing noise.

[0086] According to at least one embodiment of the present invention, the present invention calculates the average voltage from each sampling interval determined according to a preset time multiple, and determines the normal state voltage only when the average voltage that satisfies the normal voltage error condition is calculated after a predetermined time has elapsed from the sampling start time. This has the effect of preventing errors in determining the normal state voltage when the voltage is not stable.

[0087] Furthermore, the present invention calculates the first gradient and the second gradient based on the sampling start time, the preset sampling time interval, and the time point at which the preset error condition is met, and determines the length of the specified time for retaining the normal state voltage determination based on the time constant determined based on the ratio of the calculated gradients, thereby optimizing the effect of retaining the specified time for the normal state voltage determination.

[0088] According to at least one embodiment of the present invention, the present invention calculates the average voltage from each sampling interval determined according to a preset time multiple, and calculates a time constant when the calculated average voltage meets a preset error condition. Based on the calculated time constant, the operating state of the insulation monitoring device is switched to a standby state during a specified time period, thereby preventing unnecessary measurement processes from being performed during periods when the voltage is unstable. This results in a reduction in the power consumption of the insulation monitoring device.

[0089] Furthermore, the present invention calculates the first gradient and the second gradient based on the sampling start time, the preset sampling time interval, and the time point at which the preset error condition is met. Based on the time constant determined by the ratio of the calculated gradients, the length of time for the insulation monitoring device to switch to standby mode is determined. This not only minimizes the power consumption of the insulation monitoring device, but also minimizes the time required to detect the normal state voltage based on the pulse signal. Attached Figure Description

[0090] Figure 1 This is a block diagram illustrating the structure of an insulation monitoring device according to an embodiment of the present invention.

[0091] Figure 2 This is a flowchart illustrating the process of calculating the insulation resistance in the insulation monitoring device according to an embodiment of the present invention.

[0092] Figure 3 This is an example diagram illustrating an example of setting an initial measurement sampling interval for measuring normal state voltage in an insulation monitoring device according to an embodiment of the present invention.

[0093] Figure 4a This is a flowchart illustrating in more detail the process by which the insulation monitoring device of an embodiment of the present invention determines the sampling interval of the next sampling interval based on the difference between average voltages.

[0094] Figure 4b and Figure 4c It shows the press Figure 4a An example diagram illustrating the process of determining the sampling interval by different time multiples between average voltages.

[0095] Figure 5 This is a flowchart illustrating in more detail the process by which the insulation monitoring device of an embodiment of the present invention determines the initial sampling interval.

[0096] Figure 6 It shows according to the button Figure 5 An example diagram illustrating how the voltage gradient ratio calculated during the process determines the initial sampling interval.

[0097] Figure 7 This illustrates an insulation monitoring device according to an embodiment of the present invention, based on... Figure 2 The flowchart describes the process of calculating the final insulation resistance by using a pre-set initial insulation resistance.

[0098] Figure 8 This is a block diagram illustrating the configuration of an insulation monitoring device including a signal measurement unit further comprising an analog filter, according to an embodiment of the present invention.

[0099] Figure 9 This is a block diagram illustrating the configuration of an insulation monitoring device that includes an ADC further comprising a digital filter, according to an embodiment of the present invention.

[0100] Figure 10a This is a flowchart illustrating the operation process of calculating the insulation resistance in the insulation monitoring device of the second embodiment of the present invention.

[0101] Figure 10b It is used in the above Figure 10a Example diagram of how the gradient ratio is calculated during the process.

[0102] Figure 11 This is a flowchart illustrating a first adjustment process in the insulation monitoring device of the second embodiment of the present invention, in which the average voltage satisfying the preset error condition is detected from the sampling interval determined according to the initial sampling interval.

[0103] Figure 12 This is an example diagram showing the sampling interval set according to the initial sampling interval for measuring the normal state voltage in the insulation monitoring device of the second embodiment of the present invention.

[0104] Figure 13a This is a flowchart illustrating a secondary adjustment process in the insulation monitoring device of the second embodiment of the present invention, which calculates the time constant based on the calculated gradient ratio and detects the average voltage that meets the normal voltage error condition from the sampling interval determined based on the calculated time constant.

[0105] Figure 13b This is an example diagram showing the sampling interval set according to the secondary adjustment in the insulation monitoring device of the second embodiment of the present invention.

[0106] Figure 14 This is a flowchart illustrating the secondary adjustment process of detecting the average voltage that meets the normal voltage error condition from a sampling interval determined according to a preset time multiplier in the insulation monitoring device of the second embodiment of the present invention.

[0107] Figure 15 This illustrates an insulation monitoring device according to a second embodiment of the present invention, based on... Figure 10aThe flowchart describes the process of calculating the final insulation resistance by using a pre-set initial insulation resistance.

[0108] Figure 16 This is an example diagram illustrating a structural example of an insulation monitoring device according to a second embodiment of the present invention, configured to have a variable coupling resistance.

[0109] Figure 17 This is an example diagram illustrating a structural example of an insulation monitoring device according to a second embodiment of the present invention, configured to have a variable detection resistance.

[0110] Figure 18a and 18b This is a flowchart illustrating the process of calculating the insulation resistance in the insulation monitoring device according to the third embodiment of the present invention.

[0111] Figure 19a This is a flowchart illustrating the process of performing secondary adjustment based on a sampling interval calculated according to a time constant and a preset second time multiple in the insulation monitoring device of the third embodiment of the present invention.

[0112] Figure 19b This is an example diagram illustrating the secondary adjustment process performed in the insulation monitoring device according to the third embodiment of the present invention after a standby time determined according to a calculated time constant.

[0113] Figure 20 This is a flowchart illustrating the process of performing secondary adjustment based on the initial sampling interval and a preset second time multiple in the insulation monitoring device of the third embodiment of the present invention. Detailed Implementation

[0114] It should be noted that the technical terms used in this specification are for illustrative purposes only and are not intended to limit the technical concepts disclosed herein. Furthermore, unless the context clearly indicates a different meaning, singular expressions should include plural expressions. In this specification, terms such as "constituting" or "comprising" should not be construed as necessarily including all the various constituent elements or steps described in the specification, but should be interpreted as excluding some constituent elements or steps, or including additional constituent elements or steps.

[0115] In addition, in the process of describing the technology disclosed in this specification, when it is determined that a detailed description of the relevant known technology would obscure the essence of the technology disclosed in this specification, a detailed description thereof is omitted.

[0116] In describing the accompanying drawings, similar reference numerals have been assigned to similar constituent elements. Furthermore, terms such as "first," "second," etc., may be used when describing a wide variety of constituent elements, but the constituent elements are not limited by these terms. These terms are used only to distinguish one constituent element from another.

[0117] Terms defined in commonly used dictionaries should be interpreted as having the same meaning as in the context of the relevant technology, and should not be interpreted as having an idealized or overly formal meaning unless explicitly defined in this application.

[0118] Figure 1 This is a block diagram illustrating the structure of the insulation monitoring device 10 according to an embodiment of the present invention.

[0119] Reference Figure 1 The insulation monitoring device 10 of this embodiment may include: a coupling resistor 180Rc connected to the system's power line 170 (hereinafter referred to as the power line); a signal generation unit 130 that applies a square wave signal (hereinafter referred to as a pulse signal) to the power line 170 through the coupling resistor 180; an insulation resistor 140(Re) formed between the power line 170 and ground; a signal measurement unit 120 including a detection resistor Rm connected to the ground; and an ADC (Analog Converter for ADCs). A digital converter (ADC) 102, connected to the signal measurement unit 120, converts the voltage measured by the signal measurement unit 120 into a digital value; an average voltage calculation unit 110 receives the digital value converted by the ADC 102 and calculates the average voltage based on the pulse signal applied to the power line 170 during a preset sampling interval; a control unit 100 controls other connected components, calculates the sampling interval for determining the sampling interval, and detects a plurality of normal state voltages based on the plurality of average voltages calculated by the average voltage calculation unit 110, based on the applied pulse signal; and an insulation resistance calculation unit 108 calculates the magnitude of the insulation resistance 140 based on the plurality of normal state voltages detected by the control unit 100. Furthermore, it may include: a memory 104 storing various data input to or output from the control unit 100; and an interface 106.

[0120] On the other hand, in the Figure 1The diagram shows an example where the system's power line 170 is single-phase, but the system's power line 170 can be multi-phase. For example, the system's power line 170 can be three-phase (R, S, T). In this case, the coupling resistor 180 can be composed of resistors formed on the multi-phase power lines; for example, in the three-phase case, it can be composed of resistors formed on the R line, S line, and T line respectively.

[0121] Regarding the implementation of insulation monitoring device 10, Figure 1 The components shown are not essential; therefore, the components of the insulation monitoring device 10 described in this specification may be more or fewer than those listed above.

[0122] The following is a detailed explanation. First, the signal generation unit 130 can generate a pulse signal with a positive (+) voltage or a negative (-) voltage, depending on the control of the control unit 100. For example, the signal generation unit 130 can apply a signal with a positive voltage of a predetermined magnitude to the power line 170, or it can apply a signal with a negative voltage of the same magnitude to the power line 170, depending on the control of the control unit 100. Thus, a signal in which positive and negative voltages intersect, i.e., a pulse signal, can be applied to the power line 170 under the control of the control unit 100.

[0123] like Figure 1 As shown, the power line 170 and the ground can be connected to each other to form a circuit. Here, an insulation resistance 140 (Re) can be formed between the power line 170 and the ground.

[0124] Here, a capacitor 150 (Ce) may also be formed between the power line 170 and the ground, which together with the insulation resistance 140 can generate the insulation resistance 160 between the power line 170 and the ground.

[0125] On the other hand, the pulse signal applied from the signal generation unit 130 to the power line 170 can be input to the signal measurement unit 120 through a circuit formed between the power line 170 and ground. Here, the signal measurement unit 120 may include a detection resistor Rm, and the voltage of the pulse signal applied to the power line 170 according to the insulation resistance 160 can be detected based on the voltage across the detection resistor Rm. This voltage can then be amplified by an amplifier and applied to the ADC 102.

[0126] In this way, the ADC102 can convert the analog voltage detected by the signal measurement unit 120 into a digital value, and the converted digital voltage can be input to the control unit 100.

[0127] The average voltage calculation unit 110 can receive the digitized voltage value input from the ADC 102 under the control of the control unit 100. Furthermore, it can calculate the average voltage of the voltage measured by the signal measurement unit 120 during a sampling interval according to the sampling interval set by the control unit 100.

[0128] Furthermore, the control unit 100 can control other connected components and control the overall operation of the insulation monitoring device 10 of this embodiment. Additionally, the control unit 100 can provide suitable functions or information to the user, or process suitable functions or information, by processing signals, data, information, etc., input or output via the aforementioned components.

[0129] On the other hand, if the voltage changes from positive to negative or the pulse signal changes from negative to positive, a surge may occur due to the sudden change in the pulse signal. Therefore, the control unit 100 can determine whether the voltage has been stabilized by determining a sampling interval and detecting the voltage change measured by the signal measurement unit 120 based on the determined sampling interval. Furthermore, the voltage measured when the voltage is stable can be determined as the voltage under normal conditions based on the pulse signal applied to the power line 170, i.e., the voltage without surge effects.

[0130] Here, if the voltage is determined to be unstable, the control unit 100 can multiply the previous sampling interval by a preset time multiple greater than 1 to determine the next sampling interval, thereby gradually increasing the sampling interval. With this adaptive sampling interval setting, the sampling interval can increase as the voltage instability time increases.

[0131] On the other hand, when the sampling interval is determined as described above, since the sampling interval unconditionally increases according to a preset time multiple when the voltage difference detected between the sampling intervals deviates from the stable level, even if the voltage difference detected between the sampling intervals is not large, the sampling interval will be determined to be large according to the preset time multiple even if the difference slightly deviates from the stable level.

[0132] In response, the control unit 100 of the insulation monitoring device 10 of this embodiment can change the time multiple used to calculate the sampling interval based on the voltage difference detected between sampling intervals. Here, as the voltage approaches a stable state, i.e., when the voltage difference detected between the sampling intervals is less than a predetermined value, the next sampling interval can be determined based on a time multiple with a value less than the preset time multiple, thereby minimizing the increase in the sampling interval. Therefore, the size of this sampling interval (the time for measuring voltage based on the sampling interval, hereinafter referred to as the sampling interval) can be made smaller, shortening the time required for the voltage to stabilize.

[0133] However, the stable voltage reached at present may be based on the currently applied pulse signal, that is, the stable voltage based on either a positive pulse signal or a negative pulse signal. Therefore, the control unit 100 can control the signal generation unit 130 to reverse the pulse signal, and detect the stable voltage based on the reversed pulse signal by repeating the above process.

[0134] Furthermore, if a voltage under normal conditions based on a positive pulse signal (positive normal state voltage) and a voltage under normal conditions based on a negative pulse signal (negative normal state voltage) are detected, the control unit 100 can apply the detected positive and negative normal state voltages to the insulation resistance calculation unit 108.

[0135] Therefore, the insulation resistance calculation unit 108 can calculate the insulation resistance 140 between the power line 170 and the ground based on the positive and negative normal state voltages applied from the control unit 100, under the control of the control unit 100. To this end, the insulation resistance calculation unit 108 can calculate the amplitude of the voltage according to the pulse signal based on the applied positive and negative normal state voltages, and calculate the insulation resistance 140 based on the calculated voltage amplitude.

[0136] On the other hand, the memory 104 stores data supporting various functions of the insulation monitoring device 10. The memory 104 can store data and instructions for the operation of the insulation monitoring device 10. In addition, the memory 104 can temporarily or permanently store data input to the control unit 100 and data output from the control unit 100.

[0137] Interface 106 may include various components for interaction with the user. For example, interface 106 may include a display unit that displays various data based on the operation of the insulation monitoring device 10. For instance, the display unit may display the insulation resistance calculated by the insulation resistance calculation unit 108, or display information such as positive normal state voltage, negative normal state voltage, and calculated voltage amplitude. Furthermore, since the insulation monitoring device 10 continuously calculates the insulation resistance, the display unit can also display the change in insulation resistance over time in real time by representing the change in insulation resistance as a curve.

[0138] Additionally, the interface 106 may include at least one input section for receiving user input. As an example, the input section may be configured to include at least one hard key or touch key. Alternatively, if the display section is implemented as a touchscreen, the display section may also be used as the input section.

[0139] On the other hand, interface 106 may also include a communication unit (not shown) for performing wireless or wired communication with a pre-set user terminal. This communication unit can notify the user terminal of relevant information in the event of a grounding fault in the power line 170. Here, the grounding fault in the power line 170 can be detected by the control unit 100 of the insulation monitoring device 10, based on the calculated insulation resistance.

[0140] In the following description, referring to multiple flowcharts, the above... Figure 1 The operation process of the insulation monitoring device 10 of this embodiment of the invention, which calculates the insulation resistance between the power line 170 and the ground, will be described in more detail.

[0141] first, Figure 2 This is a flowchart illustrating the operation process of calculating the insulation resistance in the insulation monitoring device 10 of an embodiment of the present invention. Figure 3 This is an example diagram illustrating how an initial measurement sampling interval is set in the insulation monitoring device of an embodiment of the present invention for measuring the voltage under normal conditions.

[0142] First, refer to Figure 2 In this embodiment of the invention, the control unit 100 of the insulation monitoring device 10 first controls the signal generation unit 130 to generate a pulse signal with a predetermined voltage (S200). Thus, the signal generation unit 130 can generate a signal (pulse signal) with a predetermined positive or negative voltage according to the control of the control unit 100, and apply the generated signal to the power line 170 through the coupling resistor Rc.

[0143] If a pulse signal is generated in step S200, the control unit 100 can determine the initial sampling interval tn0 (S202). For example, the control unit 100 can determine the initial value tk according to the following mathematical formula 1, and determine the initial sampling interval tn0 according to the larger value between the period of the noise frequency and the initial value tk.

[0144] [Mathematical Expression 1]

[0145] t k = -ln(1-0.01)×R i ×C emax

[0146] Here, Ri is the internal resistance of the insulation monitoring device 10, and Cemax is the maximum capacitance of the capacitor 150 formed between the power line 170 and the ground.

[0147] Here, the internal resistance Ri of the insulation monitoring device 10 can be a predetermined value or determined based on the measured internal resistance of the insulation monitoring device 10. Additionally, Cemax is a value determined based on the capacitor 150 formed between the power line 170 and ground, which can be a value predetermined by the user. On the other hand, the noise frequency can also be a value estimated by the user beforehand.

[0148] On the other hand, if the initial sampling interval tn0 is determined in step S202, the control unit 100 can determine the starting point t0 for measuring the voltage URm detected by the resistance Rm of the signal measurement unit 120. The control unit 100 can determine the starting point t0 as the time point after a predetermined time has elapsed since the previous pulse signal was reversed.

[0149] On the other hand, if a starting point t0 is determined, the control unit 100 can determine the sampling interval from the starting point t0 to the time point t1, which corresponds to the initial sampling interval tn0, as the sampling interval according to the initial sampling interval, i.e., the initial sampling interval. Furthermore, the average voltage calculation unit 110 can be controlled to calculate the average voltages U1 and Ui by averaging the voltages detected during the initial sampling interval (S204).

[0150] On the other hand, if the average voltage U1 of the initial sampling interval is calculated, the control unit 100 can determine the next sampling interval tni+1 based on the initial sampling intervals tn0 and tni and a preset first time multiple. Here, the control unit 100 can determine the next sampling intervals tn1 and tni+1 by multiplying the initial sampling interval tn0 by the first time multiple. And the average voltage calculation unit 110 can be controlled to calculate the average voltages U2 and Ui+1 by averaging the voltages detected during the sampling interval from time point t1 to time point t2, which corresponds to the next sampling interval tn1 (S206).

[0151] On the other hand, in step S206, the control unit 100 can calculate the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltages U1 and Ui. Furthermore, it can determine whether the calculated difference is within a preset range, i.e., below a first error (S208). Here, the first error can be a relative error of the voltage used to determine whether the current voltage is in a stable state based on the result of comparing the magnitudes of the average voltages.

[0152] As an example, the first error may be a voltage equivalent to 1% of the currently calculated average voltage Ui+1. In this case, the control unit 100 may determine that the voltage detected by the signal measurement unit 120 is stable if the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltages U1 and Ui is less than 1% of the currently calculated average voltage Ui+1, and determine that the voltage detected by the signal measurement unit 120 is unstable if the difference exceeds 1% of the currently calculated average voltage Ui+1.

[0153] On the other hand, according to the judgment result of step S208, if the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui exceeds the first error and is judged to be a state of voltage instability, the control unit 100 can determine the next sampling interval based on the time multiple of the differences between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui.

[0154] As an example, if the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui exceeds a preset second error, the control unit 100 can determine the next sampling interval by multiplying the currently determined sampling interval by the first time factor.

[0155] On the other hand, such as Figure 3As shown, since voltage instability is caused by surges resulting from sudden voltage changes, the voltage immediately increases or decreases sharply after the pulse signal reverses. However, the voltage change gradually decreases over time and stabilizes. Therefore, if the voltage change is below a preset level, the voltage can be considered to be approaching a stable state.

[0156] Therefore, the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui can be used to determine whether the voltage is close to a stable state. Thus, if the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is less than or equal to a preset second error, the control unit 100 can determine that the voltage is close to a stable state and multiply the currently determined sampling interval by a second time multiple having a value less than the first time multiple to determine the next sampling interval.

[0157] As described above, when the next sampling interval is determined by multiplying by a second time factor, the increase in the sampling interval is smaller because the value of the second time factor is less than the value of the first time factor. Therefore, if the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is below a preset second error, the sampling time can be less than the sampling time determined according to the first time factor.

[0158] On the other hand, as described above, if the next sampling interval is determined by multiplying the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui by different time multiples, the control unit 100 can calculate the average voltage (i = i+1) during the sampling interval according to the determined next sampling interval. In this case, the newly calculated average voltage can become the currently calculated average voltage (Ui+2, (Ui+1, i = i+1)) (S210). Here, since the calculated average voltage is also negative when a voltage based on a negative pulse signal is measured, the difference in the average voltage can be the difference in the absolute values ​​of the average voltages.

[0159] Then, the control unit 100 can calculate the difference between the currently calculated average voltage Ui+2 and the previously calculated average voltage (Ui+1, (Ui, i=i+1)) by executing step S208 again, and execute step S210 again depending on whether the calculated difference is below the first error.

[0160] On the other hand, refer to the following Figure 4a to Figure 4b The process of calculating the sampling interval differently by using different time multiples based on the difference in the calculated average voltage in step S210 will be explained in more detail.

[0161] If the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is less than or equal to the first error, the control unit 100 can determine that the voltage detected by the signal measurement unit 120 is in a stable state.

[0162] Therefore, the control unit 100 can determine the currently calculated average voltage Ui+1 as the voltage of the stable state based on the currently generated pulse signal (S212). That is, if the currently generated pulse signal is a positive pulse signal, the control unit 100 can determine the currently calculated average voltage Ui+1 as a positive normal state voltage, and if the currently generated pulse signal is a negative pulse signal, the control unit 100 can determine the currently calculated average voltage Ui+1 as a negative normal state voltage (S212).

[0163] If the normal state voltage based on the currently generated pulse signal is determined in step S212, the control unit 100 can detect whether the normal state voltage based on both the positive and negative pulse signals has been determined (S214).

[0164] If the detection result of step S214 is that no normal state voltage based on either a positive or negative pulse signal is detected, the control unit 100 can reverse the pulse signal via the control signal generation unit 130 (S216). As a result, the signal generation unit 130 can apply a pulse signal with the same magnitude of the reversed voltage to the power line 170, and therefore, the voltage detected by the signal measurement unit 120 can become unstable again due to the surge caused by the voltage reversal.

[0165] Then, the control unit 100 can repeatedly execute the process from step S202 to step S212 based on the reversed pulse signal. Furthermore, if the detection result of step S214 is that the normal state voltage of both the positive and negative pulse signals is determined, the insulation resistance calculation unit 108 can be controlled to calculate the initial insulation resistance based on the determined normal state voltage (S218).

[0166] In step S218, the control unit 100 can calculate the average value of the currently determined normal state voltage according to the following mathematical formula 2. Furthermore, it can calculate the initial insulation resistance using the average normal state voltage calculated through mathematical formula 2, according to mathematical formula 3.

[0167] [Mathematical Expression 2]

[0168]

[0169] Here, Um is the average normal state voltage, Um1 is the normal state voltage based on a positive pulse signal, and Um2 is the normal state voltage based on a negative pulse signal.

[0170] [Mathematical Expression 3]

[0171]

[0172] Here, Re1 is the first initial insulation resistance, Up is the amplitude of the pulse signal, Rm is the detection resistance, and Ri is the internal resistance inside the insulation monitoring device.

[0173] On the other hand, if the initial insulation resistance (the magnitude of the initial insulation resistance) is calculated through step S218, the control unit 100 can confirm whether the preset number of initial insulation resistances has been calculated (S220). If the confirmation result of step S220 is that the preset number of initial insulation resistances has not been calculated, the control unit 100 can re-enter step S200 and repeat the process from step S200 to step S218.

[0174] Conversely, if the confirmation result of step S220 is that a predetermined number of initial insulation resistances have been calculated, the control unit 100 can calculate the final insulation resistance based on the predetermined number, i.e., a plurality of initial insulation resistances (S222). Here, step S222 may be the step of calculating the average value of the plurality of initial insulation resistances.

[0175] On the other hand, if the final insulation resistance is calculated in step S222, the control unit 100 can display the calculated final insulation resistance on the interface 106. Afterwards, by re-entering step S200 and repeating the process from step S200 to step S222, the insulation status between the power line 170 and the ground can be monitored based on the calculated insulation resistance.

[0176] on the other hand, Figure 4a This is a flowchart illustrating in more detail the process by which the insulation monitoring device 10 of an embodiment of the present invention determines the sampling interval of the next sampling interval based on the difference between average voltages.

[0177] Figure 4b This is an example diagram illustrating how the sampling interval is determined based on a second time multiple. Figure 4c This is an example diagram illustrating how the sampling interval is determined based on a second time multiple.

[0178] First, refer to Figure 4a ,if Figure 2If the determination result of step S208 is that the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui exceeds the first error, then the control unit 100 of the insulation monitoring device 10 of this embodiment can detect whether the difference of the calculated average voltage exceeds the second error or is less than the second error (S400).

[0179] Here, the second error can be a criterion used to determine whether the time point for calculating the current average voltage is close to the time point of voltage stability. That is, as... Figure 3 As shown, after the pulse signal reverses, the voltage immediately increases or decreases sharply. Then, the voltage change decreases over time and enters a stable state. Therefore, when the voltage change is below the preset level, it can be determined that the voltage is close to a stable state.

[0180] Therefore, the control unit 100 can determine whether the time point for calculating the current average voltage is close to the voltage stabilization time point based on whether the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is less than or equal to the second error. That is, if the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is less than or equal to the second error, the control unit 100 can determine that the time point for calculating the current average voltage is sufficiently close to the voltage stabilization time point.

[0181] Therefore, if the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is less than the second error, the control unit 100 can determine the next sampling interval (tni, i = i+1) by multiplying the sampling interval tni-1 of the sampling interval where the calculation of the current average voltage ends by a second time multiple having a value less than a preset first time multiple (S404).

[0182] The first time factor and the second time factor can have values ​​greater than 1 and can be determined based on a plurality of experimental results related to the present invention. Preferably, the first time factor can be set to 1.66, in which case the second time factor can be set to 1.33, which is less than the first time factor. In the following description, it is assumed that the first time factor is 1.66 and the second time factor is 1.33 for ease of explanation.

[0183] However, the present invention is not limited thereto. Therefore, the first time multiple can be any value as long as its value is greater than 1, and the second time multiple can also be any value as long as its value is greater than 1 and less than a different value of the first time multiple.

[0184] On the other hand, such as Figure 4bAs shown, this illustrates a case where the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is below the second error, provided that the first time factor is 1.66 and the second time factor is 1.33.

[0185] Reference Figure 4b If the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is less than or equal to the second error, the control unit 100 may execute... Figure 4a In step S404, the next sampling interval tni+2 is determined by multiplying the current sampling interval tni+1 by the second time multiplier, i.e., 1.33. Therefore, as... Figure 4b As shown, after sampling for a period of time according to the next sampling interval tni+2 and comparing the average voltage, the normal state voltage Um1 based on the positive pulse signal can be determined. In this way, since the control unit 100 can... Figure 2 Step S216 reverses the pulse signal, so the pulse signal can be reversed at the reversal time point 450.

[0186] On the other hand, with Figure 4b Differently, Figure 4c The case where the sampling interval is determined based on a fixed first time multiple is shown.

[0187] In this case, if the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is less than or equal to the second error, the control unit 100 can determine the next sampling interval tni+2 by multiplying the current sampling interval tni+1 by the first time factor, i.e., 1.66. Therefore, as Figure 4c As shown, the normal state voltage Um1 based on the positive pulse signal can be determined after sampling for a period of time according to the next sampling interval tni+2 and comparing the average voltage. In this case, as... Figure 4c As shown, since the value of the first time multiple is greater than the value of the second time multiple, the next sampling interval tni+2 is determined to be larger, thus forming a later inversion time point 450 for pulse inversion.

[0188] On the other hand, if the stated Figure 4a If the detection result of step S400 is that the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui exceeds the second error, then the control unit 100 can determine that the time point for calculating the current average voltage is not close to the time point of voltage stabilization. Then, the control unit 100 can determine the next sampling interval (tni, i = i+1) by multiplying the sampling interval tni-1 of the sampling interval where the calculation of the current average voltage ends by a preset first time multiple (S402).

[0189] On the other hand, if the next sampling interval (tni, i = i+1) is determined in step S402 or step S404, the control unit 100 can control the average voltage calculation unit 110 to calculate the average voltage Ui+1 (S406) from the time point ti according to the determined sampling interval to the time point ti+1 of the sampling interval determined in step S402 or step S404. Afterwards, it can be executed again... Figure 2 Step S208 is used to calculate the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui.

[0190] On the other hand, Figure 2 In step S208, it can be determined again whether the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is close to a voltage stable state. Therefore, if the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is less than or equal to a preset second error, the control unit 100 can determine that the voltage is close to a stable state, and determine the next sampling interval by multiplying the currently determined sampling interval by a second time multiple having a value less than the first time multiple.

[0191] On the other hand, the second error can have a ratio greater than the first error, thus having a value greater than the first error. For example, if the first error is determined to be 1% of the currently calculated average voltage Ui+1, the second error can be determined to be 5% greater than 1%. This second error is a value determined based on multiple experimental results related to the present invention, and therefore can certainly have a value greater than or less than 5%.

[0192] On the other hand, the control unit 100 of the insulation monitoring device 10 in this embodiment of the invention can also determine the initial sampling interval tn0 based on the voltage gradient measured by the signal measurement unit 120. Furthermore, since the measured voltage gradient can vary depending on the RC (Resister Capacitance) time constant, the RC time constant can be predicted by reflecting the gradient. That is, since the initial sampling interval tn0 can be determined differently from each other based on the predicted RC time constant, a more suitable initial sampling interval can be determined.

[0193] Figure 5 This is a flowchart illustrating in more detail the process by which the insulation monitoring device 10 of the present invention, as described above, determines the initial sampling interval by reflecting the gradient of the measured voltage. Figure 6 It shows according to the button Figure 5 An example diagram illustrating how the voltage gradient ratio calculated during the process determines the initial sampling interval.

[0194] First, refer to Figure 5 In this embodiment of the invention, the control unit 100 of the insulation monitoring device 10 can determine the initial value tk according to the mathematical formula 1 (S500). Furthermore, the period of the noise frequency can be calculated (S502). Here, the noise frequency can be a value predetermined by the user. And, if the period of the noise frequency is calculated, the control unit 100 can determine the larger of the initial value tk and the period of the noise frequency as the first sampling interval (S504).

[0195] On the other hand, if the first sampling interval is determined in step S504, the control unit 100 can determine the initial interval setting time point S0 for calculating the voltage gradient. Here, the initial interval setting time point can be a time point from the time point of pulse signal reversal after a predetermined time. In addition, the predetermined time can be a time determined as most suitable based on a plurality of experiments related to the present invention.

[0196] On the other hand, if the initial interval setting time point S0 is determined, the control unit 100 can set a plurality of interval setting time points (S0 to S3) based on the first sampling interval 600, including the initial interval setting time point S0 (S506).

[0197] Furthermore, the control unit 100 can calculate a first gradient (S508) based on a preset quantity, namely, the voltage difference between a plurality of preset time points including a plurality of first sampling intervals 600. Next, referring to... Figure 6 To explain (a), when the preset number is two, the control unit 100 can first detect a second interval setting time point S2 that includes two sampling intervals 600 from the initial interval setting time point S0. Furthermore, the first gradient 601 is calculated based on the difference between the voltage detected at the initial interval setting time point S0 and the voltage detected at the second interval setting time point S2.

[0198] Furthermore, the control unit 100 can calculate a second gradient (S510) based on a preset quantity, namely, the voltage difference between other time points including a plurality of first sampling intervals 600. Next, referring to... Figure 6In detail, when the preset number is two, the control unit 100 can detect other initial interval setting time points, namely, a third interval setting time point S3 that includes two sampling intervals 600 from the first interval setting time point S1. Furthermore, the second gradient 602 can be calculated based on the difference between the voltage detected at the first interval setting time point S1 and the voltage detected at the third interval setting time point S3.

[0199] On the other hand, if the first gradient 601 and the second gradient 602 are calculated through steps S508 and S510, the control unit 100 can calculate the ratio between the calculated gradients (gradient ratio, slope ratio) (S512). For example, the control unit 100 can calculate the ratio of the second gradient to the first gradient, thereby being able to calculate the gradient ratio.

[0200] On the other hand, if the gradient ratio is calculated in step S512, the control unit 100 detects one of the preset plurality of sampling intervals that corresponds to the gradient ratio calculated in step S512. Furthermore, the initial sampling interval tn0 can be determined based on the detected sampling interval (S514).

[0201] Here, the pre-set plurality of sampling intervals can be pre-set sampling intervals corresponding to a plurality of different RC time constants 610. Additionally, as... Figure 6 As shown in (b), the RC time constants that are different from each other can be predetermined. Figure 6 The gradient ratios corresponding to the gradient ratios τ are respectively. To this end, the memory 104 may include information on a complex number of RC time constants τ corresponding to gradient ratios that are different from each other, and information on a complex number of sampling intervals corresponding to information on RC time constants τ that are different from each other.

[0202] Therefore, the control unit 100 can detect the RC time constant τ corresponding to the gradient ratio calculated in step S512, and can determine the initial sampling interval tn0 by detecting any one of the preset plurality of sampling intervals that corresponds to the detected RC time constant τ.

[0203] On the other hand, in the above Figure 2 The document explains that if a plurality of initial insulation resistances are calculated, the final insulation resistance is calculated based on the plurality of insulation resistances in step S222. However, if the difference between the plurality of insulation resistances is above a predetermined threshold value, the control unit 100 may choose not to calculate the final insulation resistance based on the currently calculated initial insulation resistances.

[0204] Figure 7This illustrates the insulation monitoring device 10 of this embodiment of the invention according to... Figure 2 The flowchart describes the process of calculating the final insulation resistance by using a pre-set initial insulation resistance.

[0205] Reference Figure 7 The insulation monitoring device 10 of this embodiment can first calculate a preset quantity, that is, the difference between a plurality of initial insulation resistance values ​​(S700). For example, when the preset quantity is two, the control unit 100 can calculate the difference between a first initial insulation resistance Re1 and a second initial insulation resistance Re2 calculated after the first initial insulation resistance Re1 is calculated.

[0206] On the other hand, if the difference between the plurality of initial insulation resistance values ​​is greater than a preset threshold, the control unit 100 changes the interference frequency (S710) according to a preset ratio.

[0207] As an example, the control unit 100 can reduce the interference frequency by 50% and recalculate the initial insulation resistance based on the reduced interference frequency. In this case, since the period of the interference frequency increases to twice its normal value as the interference frequency decreases by 1 / 2, the initial sampling interval tn0 can be varied according to the magnitude of the interference frequency period.

[0208] As an example, by doubling the size of the interference frequency period, it may be greater than the initial value tk calculated according to Mathematical Formula 1. In this case, the initial sampling interval tn0 can be determined as the size of the interference frequency period.

[0209] Additionally, refer to Figure 5 and Figure 6 If the period of interference frequency becomes larger than the initial value tk, the first sampling interval 600 can be changed to the increased period of interference frequency. Therefore, the interval setting time point determined according to the first sampling interval 600 can be changed, and the gradient used to calculate the gradient ratio may change. Since the RC time constant can change if the gradient ratio is changed in this case, the initial sampling interval tn0, which is determined corresponding to the RC time constant, can also be changed.

[0210] On the other hand, if the interference frequency is changed, the control unit 100 can execute the above again. Figure 2 The process. Furthermore, if the predetermined initial insulation resistance is calculated again, then again in... Figure 7 Step S700 calculates the difference between the initial insulation resistances and then determines whether the difference exceeds the critical value.

[0211] On the other hand, in the above description, it was assumed that the reduction rate of the interference frequency was 50%, but this was only an assumption for the sake of explanation, and the present invention is not limited thereto. That is, the interference frequency can be reduced by any reduction rate other than 50%.

[0212] On the other hand, if the difference between a plurality of initial insulation resistance values ​​is below a preset threshold, the control unit 100 can calculate the final insulation resistance based on the currently calculated preset number of initial insulation resistances (S706). For example, the control unit 100 can calculate the final insulation resistance by calculating the average of the preset number of initial insulation resistances.

[0213] On the other hand, after calculating the final insulation resistance, the control unit 100 can confirm whether the magnitude of the currently set interference frequency is less than a preset minimum value (S706). For example, as explained in step S710, since the interference frequency is reduced when the difference between a preset number of initial insulation resistances exceeds a preset threshold, and the preset number of initial insulation resistances are re-detected based on the reduced interference frequency, the magnitude of the interference frequency can continue to decrease as the difference between the detected initial insulation resistances increases. Furthermore, the initial insulation resistance based on the reduced interference frequency can be detected.

[0214] On the other hand, if the confirmation result of step S706 is that the magnitude of the currently set interference frequency is less than the preset minimum value after calculating the final insulation resistance, the control unit 100 can determine the interference frequency based on the preset minimum value (S708). Therefore, in the insulation monitoring device 10 of this embodiment, when the final insulation resistance is calculated, the interference frequency can be determined to be a frequency greater than or equal to the preset minimum value. Furthermore, the control unit 100 can re-execute the... Figure 2 The process is used to continuously monitor the insulation status between power line 170 and ground.

[0215] On the other hand, the insulation monitoring device 10 of this embodiment may further include: a filter for removing noise from the voltage detected by the signal measurement unit 120; and at least one filter for removing noise from the detected voltage converted into a digital value within the insulation monitoring device 10. Figure 8 to Figure 9 This is a block diagram illustrating the structure of an insulation monitoring device in an embodiment that also includes at least one filter, as described above.

[0216] First, refer to Figure 8The signal measurement unit 120 may include a first analog filter 850 formed between the two ends of the detection resistor Rm and AMP810 as a filter for removing noise from the voltage detected across the detection resistor Rm. Additionally, a second analog filter 860 may be formed between AMP810 and ADC102.

[0217] In this case, the first analog filter 850 can remove noise from the voltage detected by the sensing resistor Rm, and the second analog filter 860 can remove the noise from the detected voltage of the signal measurement unit 120 amplified by the AMP810. Therefore, even if subtle noise is not removed by the first analog filter 850 and is amplified by the AMP810, it can be removed by the second analog filter 860, thereby inputting a more accurate measurement voltage to the ADC102.

[0218] On the other hand, the first analog filter 850 and the second analog filter 860 can be hardware filters, and can be filters with different characteristics such as band domain, blocking band domain, roll-off, and phase delay.

[0219] on the other hand, Figure 9 This is a block diagram illustrating the configuration of an insulation monitoring device including an ADC102 further comprising a digital filter, according to an embodiment of the present invention.

[0220] Below, refer to Figure 9 As can be explained, the ADC102 may include a digital filter 910 as a filter for removing noise present inside the insulation monitoring device 10. The digital filter 910 is formed between the conversion unit 900, which converts the analog measurement value amplified by the AMP810 into a digital value, and the control unit 100.

[0221] The digital filter 910 can remove noise within the insulation monitoring device 10 by removing noise from the voltage measurement value input to the control unit 100, between the conversion unit 900 and the control unit 100. The digital filter 910 can be a software filter, and its properties such as cutoff frequency and order can be changed according to the characteristics of the noise components present within the insulation monitoring device 10.

[0222] In the following description, with reference to a plurality of flowcharts, the operation process of the insulation monitoring device 10 of the second embodiment of the present invention calculating the insulation resistance between the power line 170 and the ground will be explained in more detail.

[0223] first, Figure 10a This is a flowchart illustrating the operation process of calculating the insulation resistance in the insulation monitoring device 10 of the second embodiment of the present invention.Figure 10b It is used to explain the above. Figure 10a Example diagram of how the gradient ratio is calculated during the process.

[0224] First, refer to Figure 10a In the second embodiment of the present invention, the control unit 100 of the insulation monitoring device 10 first controls the signal generation unit 130 to generate a pulse signal with a predetermined voltage (S1000). Thus, the signal generation unit 130 can generate a signal (pulse signal) with a predetermined positive or negative voltage according to the control of the control unit 100, and the generated signal can be applied to the power line 170 through the coupling resistor Rc.

[0225] If a pulse signal is generated in step S1000, the control unit 100 can determine the initial sampling interval tn0 (S1002). For example, the control unit 100 can determine the initial value tk according to the mathematical formula 1, and determine the initial sampling interval tn0 according to the initial value tk.

[0226] Here, the control unit 100 may also determine the initial sampling interval tn0 based on the larger of the period of the noise frequency and the initial value tk.

[0227] On the other hand, if the initial sampling interval tn0 is determined in step S1002, the control unit 100 can determine the starting point t0 of the voltage URm detected by the detection resistor Rm of the signal measurement unit 120, i.e., the initial sampling start point. In this case, the control unit 100 can determine the start point t0 as the time point after a predetermined time has elapsed since the previous pulse signal was reversed.

[0228] On the other hand, if the starting point t0 is determined, the control unit 100 can perform an adjustment process (S1004) starting from the starting point t0 according to the initial sampling interval tn0.

[0229] In step S1004, the control unit 100 can define a sampling interval as the time from the starting point t0 to the point corresponding to the initial sampling interval tn0. Furthermore, it can calculate the average voltage for the voltages measured during the defined sampling interval. The length of the next sampling interval can be determined based on the length of the current sampling interval and a preset first time multiple, and the next sampling interval is determined based on the determined length. Then, the average voltage for the voltages measured during the defined sampling interval can be calculated again. The difference between the currently calculated average voltage and the average voltage calculated in the previous sampling interval can be calculated.

[0230] Afterwards, depending on whether the calculated difference is below a pre-set first error, the next sampling interval can be determined again, the average voltage can be calculated again, and the calculated average voltage can be compared with the previously calculated average voltage again, or the adjustment process can be terminated. On the other hand, the value of the first time multiplier used in the adjustment process can be 1.

[0231] On the other hand, if the adjustment process ends, the control unit 100 can determine a reference point for calculating the gradient ratio based on the voltage measured at the end of the adjustment and the initial sampling interval (S1006). Furthermore, the gradient ratio can be calculated based on the determined reference point (S1008).

[0232] Figure 10b This is a diagram illustrating an example of determining a reference point and a voltage used to calculate the gradient ratio in order to calculate the gradient ratio as described above.

[0233] Reference Figure 10b If the first adjustment ends, the control unit 100 can determine the starting point t0 of the sampling start, the time point t1 (i.e., t1 = t0 + tn0) after the starting point t0, the time point t3 when the first adjustment ends as the difference in the average voltage is below the first error, and the time point t2 before the initial sampling interval from the time point t3 of the first adjustment end as the reference points (starting point t0, first reference point t1, second reference point t2, and third reference point t3) to be used to calculate the gradient ratio.

[0234] If the reference point is determined as described above, the control unit 100 can detect the voltage based on the determined reference point.

[0235] First, the control unit 100 can calculate the voltage difference between the voltage (starting voltage) 1050 measured at the starting point t0 and the voltage (second voltage) 1052 measured at the second reference point t2. Then, the first gradient can be calculated by dividing the voltage difference by the time between the starting point t0 and the second reference point t2.

[0236] Furthermore, the control unit 100 can calculate the voltage difference between the voltage (first voltage) 1051 measured at the first reference point t1 and the voltage (third voltage) 1053 measured at the third reference point t3. Then, the second gradient can be calculated by dividing the calculated voltage difference by the time between the first reference point t1 and the third reference point t3. Then, the gradient ratio can be calculated by calculating the ratio of the second gradient to the first gradient. The following mathematical formula 4 mathematically expresses this process of calculating the gradient ratio.

[0237] [Mathematical Expression 4]

[0238]

[0239]

[0240] Here, the start point represents the time point at which the initial sampling begins, the first reference point represents the time point from the start point that corresponds to the initial sampling interval, the third reference point represents the time point at which the adjustment ends, and the second reference point represents the time point from the third reference point before the initial sampling interval.

[0241] The starting voltage represents the voltage at the starting point, the first voltage represents the voltage at the first reference point, the second voltage represents the voltage at the second reference point, and the third voltage represents the voltage at the third reference point.

[0242] On the other hand, if the gradient ratio is calculated in step S1008, the control unit 100 can calculate the time constant τ based on the calculated gradient ratio. Here, the time constant can represent the expected time until the voltage reaches a normal state. For example, as in mathematical formula 5, the time constant τ can be calculated based on the ratio of the time interval between the first reference point and the starting point to the result of the natural logarithm (ln) operation on the calculated gradient ratio.

[0243] [Mathematical Expression 5]

[0244]

[0245] On the other hand, if the time constant τ is calculated according to the mathematical formula 5, the control unit 100 can reset the initial sampling interval based on the calculated time constant. Furthermore, a secondary adjustment can be performed based on the reset initial sampling interval and a second time multiple different from the first time multiple. This secondary adjustment can be an adjustment process using a time multiple different from the first adjustment process. Here, the value of the second time multiple can be greater than the value of the first time multiple. For example, the second time multiple can be 1.33; in this case, as the secondary adjustment time continues, the sampling interval set according to the second time multiple can gradually increase.

[0246] On the other hand, when performing the secondary adjustment, the control unit 100 can set the end time of the primary adjustment as the start point of the secondary adjustment. Furthermore, the time interval from the set start point of the secondary adjustment to a time point equivalent to the re-set initial sampling interval can be determined as the sampling interval for the secondary adjustment. The average voltage measured during the determined sampling interval can be calculated. The next sampling interval can be determined based on the time calculated using the length of the current sampling interval and the second time multiple, and the next sampling interval can be determined based on the determined length. The average voltage measured during the determined sampling interval can be calculated again. The difference between the currently calculated average voltage and the average voltage calculated in the previous sampling interval is calculated.

[0247] Afterwards, depending on whether the calculated difference is below the preset normal voltage error, the next sampling interval can be determined again, the average voltage can be calculated again, and the calculated average voltage can be compared with the previously calculated average voltage again, or the currently calculated average voltage can be determined as the normal state voltage of the pulse signal generated in step S1000.

[0248] On the other hand, once the normal state voltage is determined, the control unit 100 can determine whether a predetermined time, determined according to the time constant, has elapsed since the start of the secondary adjustment. If the predetermined time has not elapsed, the current normal state voltage determination result can be ignored, and the next sampling interval can be determined again, the average voltage can be calculated again, and the calculated average voltage can be compared with the previously calculated average voltage again. Conversely, if the predetermined time has elapsed, the currently calculated average voltage can be determined as the normal state voltage based on the pulse signal generated in step S1000.

[0249] That is, if the pulse signal generated in step S1000 is a positive pulse signal, the control unit 100 can determine the currently calculated average voltage as a positive normal state voltage. Conversely, if the pulse signal generated in step S1000 is a negative pulse signal, the currently calculated average voltage can be determined as a negative normal state voltage.

[0250] However, as described in mathematical formula 5, when the time constant τ is calculated, as the difference between the first and second gradients decreases, the ratio of the second gradient to the first gradient converges to 1. This makes it difficult to calculate the time constant τ because the denominator becomes 0, as it becomes ln1. Therefore, a process (S1010) can be included where the control unit 100 determines whether the ratio of the gradients calculated in step S1008 is above a preset threshold. Furthermore, the time constant τ can be calculated only if the gradient ratio is greater than the preset threshold.

[0251] In this case, the control unit 100 can reset the sampling interval for the secondary adjustment based on the calculated time constant, and execute the secondary adjustment process of determining the sampling interval and calculating the average voltage based on the reset sampling interval (S1012). Furthermore, if the difference between the calculated average voltage and the average voltage calculated in the previous sampling interval is below the normal voltage error, the currently calculated average voltage can be determined as the normal state voltage based on the pulse signal generated in step S1000, depending on whether a predetermined time determined according to the time constant has elapsed (S1016). Next, referring to... Figure 13a It explains in detail the process of calculating the time constant based on the calculated gradient ratio when the calculated gradient ratio is above the critical value, and then performing a secondary adjustment based on the calculated time constant.

[0252] Conversely, if the determination result of step S1010 is that the calculated gradient ratio is lower than a critical value, the control unit 100 may not calculate the time constant and execute a secondary adjustment process (S1014). In this case, the secondary adjustment process can be executed based on the initial sampling interval and the second time multiple set in step S1002. Furthermore, step S1016 can be executed based on whether the difference between the calculated average voltage and the average voltage calculated in the previous sampling interval is below the normal voltage error, and the currently calculated average voltage is determined as the normal state voltage based on the pulse signal generated in step S1000. Next, refer to... Figure 14 The process of performing secondary adjustment based on a pre-set initial sampling interval is explained in detail when the calculated gradient ratio is less than the critical value.

[0253] On the other hand, if the voltage of the stable state based on the currently generated pulse signal is determined in step S1016, the control unit 100 can detect whether the normal state voltage based on the positive pulse signal and the negative pulse signal has been determined (S1018).

[0254] If the detection result of step S1018 is that no normal state voltage based on either a positive or negative pulse signal is detected, the control unit 100 can reverse the pulse signal by controlling the signal generation unit 130 (S1020). As a result, the signal generation unit 130 can apply a pulse signal with the same magnitude of the reversed voltage to the power line 170, so the voltage detected by the signal measurement unit 120 may become unstable again due to the surge caused by the voltage reversal.

[0255] In this way, the control unit 100 can repeatedly execute the process from step S1002 to step S1016 based on the inverted pulse signal. If the detection result of step S1018 is that the normal state voltage of both the positive and negative pulse signals is determined, the insulation resistance calculation unit 108 can be controlled to calculate the initial insulation resistance based on the determined normal state voltage (S1022).

[0256] In step S1022, the control unit 100 can calculate the average value of the currently determined normal state voltage according to the mathematical formula 2. Furthermore, the initial insulation resistance can be calculated using the average normal state voltage calculated in the mathematical formula 2, according to the mathematical formula 3.

[0257] On the other hand, if the initial insulation resistance (the magnitude of the initial insulation resistance) is calculated through step S1022, the control unit 100 can confirm whether an initial insulation resistance equivalent to a preset quantity has been calculated (S1024). Furthermore, if the confirmation result of step S1024 is that an initial insulation resistance equivalent to a preset quantity has not been calculated, the control unit 100 can re-enter step S1000 and repeat the process from step S1000 to step S1022.

[0258] Conversely, if the confirmation result of step S1024 is that a predetermined number of initial insulation resistances have been calculated, the control unit 100 can calculate the final insulation resistance based on the predetermined number, i.e., a plurality of initial insulation resistances (S1026). Here, step S1026 may be the step of calculating the average value of the plurality of initial insulation resistances.

[0259] On the other hand, if the final insulation resistance is calculated in step S1026, the control unit 100 can display the calculated final insulation resistance value through the interface 106. Furthermore, the insulation resistance value can be calculated by re-entering step S1000 and repeating the process from step S1000 to step S1026. Therefore, the insulation status between the power line 170 and the ground can be monitored based on the calculated insulation resistance value.

[0260] on the other hand, Figure 11 This is a flowchart illustrating a first adjustment process in the insulation monitoring device 10 of the second embodiment of the present invention, in which the average voltage satisfying the preset error condition is detected from the sampling interval determined according to the initial sampling interval. Figure 12 This is an example diagram showing the sampling interval set according to the initial sampling interval for measuring the normal state voltage in the insulation monitoring device 10 of the second embodiment of the present invention.

[0261] First, refer to Figure 11 The control unit 100 can determine based on the above. Figure 10a In step S1002, the initial sampling interval tn0 is calculated and the voltage calculation unit 110 is controlled to calculate the average voltage U1 (=Ui) by averaging the voltage detected during the determined sampling interval (S1100).

[0262] On the other hand, if the average voltage U1 of the initial sampling interval is calculated, the control unit 100 can determine the next sampling interval tni+1 based on the initial sampling interval tn0 (=tni) and a preset first time multiple. Here, the control unit 100 can determine the next sampling interval tn1 (=tni+1) by multiplying the initial sampling interval tn0 by the first time multiple. Furthermore, the average voltage calculation unit 110 can be controlled to calculate the average voltage U2 (=Ui+1) by averaging the voltage detected during the sampling interval from time point t1 to time point t2, which corresponds to the next sampling interval tn1 (S1102).

[0263] Furthermore, the control unit 100 can calculate the difference between the currently calculated average voltage U2 (=Ui+1) and the previously calculated average voltage U1 (=Ui). Additionally, it can determine whether the calculated difference is below a preset value, i.e., a first error (S1104). Here, the first error can be a relative error used to determine whether the current voltage is in a stable state based on the result of comparing the magnitude of the average voltage. As an example, the first error can be a voltage equivalent to 1% of the currently calculated average voltage Ui+1.

[0264] On the other hand, if the determination result of step S1104 is that the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui exceeds the first error, the control unit 100 can determine the next sampling interval based on the first time multiplier. Furthermore, a sampling interval based on the determined sampling interval can be determined (S1106). Then, the average voltage of the voltage detected during the determined sampling interval can be calculated again (S1108). Furthermore, by re-entering step S1104, the difference between the current average voltage calculated in step S1108 and the average voltage calculated in the previous sampling interval can be calculated again, and it can be determined again whether the calculated difference is below the first error. That is, if the determination result of step S1104 is that the difference between the calculated average voltages exceeds the first error, the process of determining the sampling interval and calculating the average voltage can be repeatedly executed. In this case, as described above, if the first time multiplier is set to 1, then... Figure 12 As shown, sampling intervals of the same length can be set, and the average voltage detected during the same time period can be used as the average voltage of the sampling interval for calculation.

[0265] Conversely, if the determination result of step S1104 is that the difference between the currently calculated average voltage Ui+1 and the previously calculated average voltage Ui is less than or equal to the first error, the control unit 100 can execute... Figure 10a Step S1006 concludes the adjustment process. A reference point for calculating the gradient ratio can also be determined.

[0266] on the other hand, Figure 13a This is a flowchart illustrating a secondary adjustment process in the insulation monitoring device 10 of the second embodiment of the present invention, which calculates the time constant based on the calculated gradient ratio and detects the average voltage that meets the normal voltage error condition from the sampling interval determined based on the calculated time constant. Figure 13b This is an example diagram showing the sampling interval set according to the secondary adjustment in the insulation monitoring device 10 of the second embodiment of the present invention.

[0267] First, refer to Figure 13a In the Figure 10a If the gradient ratio calculated in step S1010 is above a preset critical value, the control unit 100 of the insulation monitoring device 10 of the second embodiment of the present invention can calculate the time constant based on the calculated gradient ratio (S1300). Step S1300 may be a step of calculating the time constant from the calculated gradient ratio according to the mathematical formula 5.

[0268] If the time constant is calculated in step S1300, the control unit 100 can then reset the initial sampling interval to be used in the secondary adjustment process (S1302) based on the calculated time constant. For example, the control unit 100 can determine the initial sampling interval tn to be reset according to the following mathematical formula 6.

[0269] [Mathematical Expression 6]

[0270] t n = -ln(1-0.01)×τ

[0271] Here, tn is the newly set initial sampling interval, and τ is the time constant.

[0272] Furthermore, the control unit 100 can set a sampling interval based on the reset initial sampling interval, and calculate the average voltage detected during the reset sampling interval (S1304). Additionally, the next sampling interval for secondary adjustment can be determined by multiplying the sampling interval based on the reset initial sampling interval by a preset second time factor, and the average voltage during the determined sampling interval can be calculated (S1305).

[0273] Figure 13b An example is shown where a second adjustment is performed after the first adjustment, as described above. As an example, such as... Figure 13b As shown, when the first time multiple used for the first adjustment is 1, the sampling interval set during the first adjustment can be an interval set according to the same time interval.

[0274] If, under these conditions, the initial time interval is reset after the first adjustment ends, the control unit 100 can set an initial sampling interval tn based on the reset initial sampling interval, and calculate the average voltage of the voltage detected during the initial sampling interval tn. Furthermore, it can set the next sampling interval tn+1 based on the time length of the initial sampling interval (i.e., the initial sampling interval) and a preset second time multiple, and calculate the average voltage of the voltage detected during the next sampling interval tn+1.

[0275] Therefore, the control unit 100 can calculate the difference between the currently calculated average voltage (the average voltage calculated during the tn+1 sampling interval) and the average voltage calculated during the previous sampling interval tn, and detect whether the difference in the calculated average voltage is below a preset normal voltage error (S1306). Furthermore, if the difference in the calculated average voltage is below the preset normal voltage error, it determines whether a predetermined time corresponding to a preset multiple of the currently calculated time constant has elapsed since the start time of the secondary adjustment, i.e., the start time of the secondary adjustment (S1308).

[0276] Furthermore, if the determination result of step S1308 is that the time has elapsed to a predetermined multiple of the time constant, then execution can proceed. Figure 10a Step S1016, the currently calculated voltage is determined according to the voltage described in the previous step. Figure 10a The stable voltage of the pulse signal generated in step S1000 is the normal state voltage.

[0277] Conversely, if the difference between the average voltages calculated in step S1306 exceeds the normal voltage error, or even if the difference between the average voltages calculated in step S1306 is below the normal voltage error, but the determination result in step S1308 is still that the predetermined time has not elapsed, the control unit 100 can update the sampling interval based on the length of the currently set sampling interval according to the second time multiple (S1310). Then, the next sampling interval tn+2 can be determined again based on the updated sampling interval (S1312).

[0278] In this case, the second time factor can be a value greater than 1 (e.g., 1.33). Thus, as... Figure 13b As shown, the length (time) of the next sampling interval tn+1 can be longer than the length of the initial sampling interval tn, and the length of the next sampling interval tn+2 can be longer than the length of the previous sampling interval tn+1.

[0279] On the other hand, the control unit 100 can recalculate the average voltage during the sampling interval tn+2 determined according to the updated sampling interval (S1314). Furthermore, by executing step S1306 again, the difference between the currently calculated average voltage (the average voltage calculated during the tn+2 sampling interval) and its previously calculated average voltage (the average voltage calculated during the tn+1 sampling interval) can be recalculated. Based on the difference in the calculated average voltage, step S1308 can be executed again to determine whether the predetermined time has elapsed, or step S1310 can be executed to update the sampling interval according to the length of the currently set sampling interval based on the second time multiple.

[0280] on the other hand, Figure 14 This is a flowchart illustrating the process of performing a secondary adjustment based on a preset initial time interval in the insulation monitoring device 10 of the second embodiment of the present invention, where the calculated gradient ratio is less than a critical value, making it difficult to calculate the time constant.

[0281] Reference Figure 14 If it is difficult to calculate the time constant because the calculated gradient ratio is less than the critical value, the control unit 100 may not perform the initial sampling interval reset, but directly perform the secondary adjustment process based on the second time multiple.

[0282] The control unit 100 can first determine the sampling interval based on the initial sampling interval tn0 (S1400). In this case, the initial sampling interval tn0 can be determined from the initial sampling interval tn0. Figure 10a The sampling interval is calculated in step S1002.

[0283] If the initial sampling interval is calculated in step S1400, the control unit 100 can calculate the average voltage during the sampling interval based on the calculated initial sampling interval (S1402). Furthermore, the next sampling interval can be determined based on the initial sampling interval tn0 and the second time multiple set for the second adjustment. Then, the average voltage can be calculated by averaging the voltage detected during the determined sampling interval (S1404).

[0284] On the other hand, if the average voltage is calculated in step S1404, the control unit 100 can determine whether the difference between the currently calculated average voltage and the average voltage calculated in the previous sampling interval is below the normal voltage error (S1406). If the determination result of step S1406 is that the difference between the calculated average voltage and the average voltage is below the normal voltage error, then execution can be performed. Figure 10a Step S1016, the currently calculated voltage is determined according to the voltage described in the previous step. Figure 10a The stable voltage of the pulse signal generated in step S1000 is the normal state voltage.

[0285] Conversely, if the difference between the average voltages calculated in step S1406 exceeds the normal voltage error, the control unit 100 updates the sampling interval based on the length of the currently set sampling interval according to the second time multiple (S1408). Then, the next sampling interval can be determined again based on the updated sampling interval (S1410). Then, the average voltage during the sampling interval determined in step S1410 can be calculated again based on the updated sampling interval (S1412).

[0286] On the other hand, if the average voltage during the newly determined sampling interval is calculated in step S1412, the control unit 100 can determine whether the difference between the currently calculated average voltage and the average voltage calculated in the previous sampling interval is below the normal voltage error by re-executing step S1406. Furthermore, steps S1408 to S1412 can be executed again based on the determination result.

[0287] On the other hand, in the above Figure 10a This explains that if a complex number of initial insulation resistances are calculated, then in Figure 10aIn step S1026, the final insulation resistance is calculated based on a plurality of insulation resistances. However, if the difference between the plurality of insulation resistances is above a preset threshold value, the control unit 100 may not calculate the final insulation resistance based on the currently calculated initial insulation resistance.

[0288] Figure 15 In this case, the insulation monitoring device 10 of the second embodiment of the present invention is based on... Figure 10a The flowchart shows the process of calculating the initial insulation resistance of a predetermined quantity and then calculating the final insulation resistance.

[0289] Reference Figure 15 In the second embodiment of the present invention, the insulation monitoring device 10 can first calculate a predetermined number, namely the difference between a plurality of initial insulation resistance values ​​(S1500). For example, when the predetermined number is two, the control unit 100 can calculate the difference between the first initial insulation resistance Re1 and the second initial insulation resistance Re2 calculated after the first initial insulation resistance Re1 is calculated.

[0290] On the other hand, if the difference between the plurality of initial insulation resistance values ​​exceeds a preset threshold, the control unit 100 can change the interference frequency (S1510) according to a preset ratio.

[0291] As an example, the control unit 100 can reduce the interference frequency by 50%, and can recalculate the initial insulation resistance based on the reduced interference frequency. In this case, the period of the interference frequency increases to twice its original value as the interference frequency decreases to half, so the initial sampling interval tn0 can change according to the magnitude of the interference frequency period.

[0292] As an example, when the interference frequency period increases, the initial sampling interval tn0 can be changed to the increased interference frequency period. Therefore, the reference point determined based on the initial sampling interval tn0 can be changed, thereby changing the gradient used to calculate the gradient ratio. In this case, if the gradient ratio changes, the time constant can also be changed.

[0293] On the other hand, if the interference frequency is changed in step S1510, the control unit 100 can execute the procedure again. Figure 10a The process. Furthermore, after recalculating the predetermined initial insulation resistance, it is possible to again... Figure 15 In step S1500, the difference between the initial insulation resistances is calculated, and it is determined again whether the difference exceeds the critical value.

[0294] On the other hand, although the above description assumes a 50% reduction rate in the interference frequency, this is merely an assumption for ease of explanation. The invention is not limited thereto. That is, the interference frequency can be reduced at any rate other than 50%.

[0295] On the other hand, if the difference between the plurality of initial insulation resistance values ​​is below a preset threshold, the control unit 100 can calculate the final insulation resistance based on the currently calculated preset number of initial insulation resistances (S1504). For example, the control unit 100 can calculate the final insulation resistance by calculating the average of the preset number of initial insulation resistances.

[0296] On the other hand, after calculating the final insulation resistance, the control unit 100 can confirm whether the magnitude of the currently set interference frequency is less than a preset minimum value (S1506). For example, as described in step S1510, since the interference frequency is reduced when the difference between a preset number of initial insulation resistances exceeds a preset threshold, and the preset number of initial insulation resistances is detected again based on the reduced interference frequency, the magnitude of the interference frequency can continuously decrease as the difference between the detected initial insulation resistances decreases. Then, the initial insulation resistance based on the reduced interference frequency can be detected.

[0297] On the other hand, if, when the final insulation resistance is calculated, the confirmation result of step S1506 is that the currently set interference frequency is less than a preset minimum value, then the control unit 100 can determine the interference frequency based on the preset minimum value (S1508). Therefore, in the insulation monitoring device 10 of the second embodiment of the present invention, when the final insulation resistance is calculated, the interference frequency can be determined to be a frequency greater than or equal to the preset minimum value. Furthermore, the control unit 100 can re-execute the... Figure 10a The process is used to continuously monitor the insulation status between power line 170 and ground.

[0298] On the other hand, according to the above description, it is proposed that the time constant can only be calculated when the gradient ratio is above a predetermined critical value. That is, since the gradient ratio calculated in step S1008 needs to be above a predetermined critical value in order to calculate the time constant, the insulation monitoring device 10 of the second embodiment of the present invention may further include a configuration that can increase the gradient ratio.

[0299] First, the relationship between the time constant and the voltage across the insulation resistance is shown in the following mathematical formula 7.

[0300] [Mathematical Expression 7]

[0301]

[0302] Here, U m Indicates normal voltage, R e R represents insulation resistance. m R represents the sensing resistor. c U represents the coupling resistance. P The amplitude of the test pulse is represented by t, and the normal voltage measurement time is represented by t.

[0303] Referring to the mathematical formula 7, it can be seen that when the test pulse U is increased... P The size, or increase the detection resistor R m The size, or reducing the coupling resistance R c In this case, the normal voltage U can be increased. m The gradient, i.e., U m In this embodiment, the insulation monitoring device 10 may further include a structure capable of reducing the magnitude of the coupling resistance or increasing the magnitude of the insulation resistance. Figure 16 to Figure 17 An example of this situation is shown.

[0304] first, Figure 16 This is an example diagram illustrating the structure of an insulation monitoring device according to a second embodiment of the present invention, which is configured to change the magnitude of the coupling resistance.

[0305] Reference Figure 16 The coupling resistor 180 of the insulation monitoring device 10 in the second embodiment of the present invention may include a plurality of resistors that can be connected in parallel to each power line. Furthermore, it has the following structure: a portion of the resistors can be connected via a switch, and the plurality of resistors can be connected in parallel to each power line 170 according to the control of the control unit 100.

[0306] In detail, such as Figure 16 As shown, when the system's power line 170 is single-phase, the first coupling resistor Rc1 and the second coupling resistor Rc2 can be connected in parallel to the second power line L2. The first coupling resistor Rc1 can be connected to the second power line L2 via the first switch 1600. Similarly, the third coupling resistor Rc3 and the fourth coupling resistor Rc4 can be connected in parallel to the first power line L1. The third coupling resistor Rc3 can be connected to the first power line L1 via the second switch 1602.

[0307] On the other hand, the first switch 1600 and the second switch 1602 can be linked together. That is, when the first switch 1600 is open, i.e., the connection of the first coupling resistor Rc1 is disconnected, the connection of the third coupling resistor Rc3 can also be disconnected by opening the second switch 1602. In addition, when the first switch 1600 is closed, i.e., the first coupling resistor Rc1 and the second power line L2 are connected, the connection between the third coupling resistor Rc3 and the first power line L1 can also be established by closing the second switch 1602.

[0308] On the other hand, if through the aforementioned Figure 10a If the final insulation resistance is calculated in step S1026, the control unit 100 can determine whether the current time constant has been calculated. Furthermore, if the time constant has not been calculated, the value of the coupling resistance can be reduced by controlling the first switch 1600 and the second switch 1602.

[0309] In this case, the first switch 1600 and the second switch 1602 can remain in an open state as an initial state. In this case, the control unit 100 can connect the first coupling resistor Rc1 to the second electric line L2 and the third coupling resistor Rc3 to the first electric line L1 by turning on the first switch 1600 and the second switch 1602. In this way, since the third coupling resistor Rc3 and the fourth coupling resistor Rc4 are connected in parallel to the first electric line L1, the value of the coupling resistance connected to the first electric line L1 can be reduced. Furthermore, since the first coupling resistor Rc1 and the second coupling resistor Rc2 are connected in parallel to the second electric line L2, the value of the coupling resistance connected to the second electric line L2 can also be reduced.

[0310] Therefore, by reducing the value of the coupling resistance, the gradient ratio can be increased. In this case, if the increased gradient ratio is above a critical value, the above procedure is performed again to calculate the insulation resistance. Figure 10a During the process, it can be done by executing the above. Figure 10a Step S1012 replaces step S1014, so that the time constant can be calculated and a secondary adjustment process based on the calculated time constant can be performed.

[0311] On the other hand, the Figure 16 This assumes a single-phase system, but the present invention is not limited thereto. That is, in the case of a three-phase system, multiple resistors can be connected in parallel to the respective power lines R, S, and T, and some of them can be connected by switches, with their connection to the power lines controlled by the control unit 100.

[0312] On the other hand, although, in the above Figure 16The description assumes two resistors connected in parallel to each electric field line, but the invention is not limited to this. That is, a greater number of resistors can be connected in parallel to each electric field line.

[0313] Figure 17 This is an example diagram showing a structural example of an insulation monitoring device according to a second embodiment of the present invention, which is configured to change the size of the detection resistance.

[0314] Reference Figure 17 The detection resistor of the signal measurement unit 120 of the insulation monitoring device 10 in the second embodiment of the present invention may include a plurality of resistors that can be connected in parallel to the signal generation unit 130. Furthermore, it may have a structure in which a portion of the plurality of resistors are connected by a switch and can be connected in parallel according to the control of the control unit 100.

[0315] More specifically, such as Figure 17 As shown, the sensing resistor may include: a first sensing resistor Rm1; a first circuit including a second sensing resistor Rm2 and a second circuit excluding the second sensing resistor Rm2; and a changeover switch 1700 connected to the first sensing resistor Rm1 through either the first circuit or the second circuit to form a circuit. In this case, the changeover switch 1700 can remain connected to the first circuit as an initial state. In this case, the first sensing resistor Rm1 and the second sensing resistor Rm2 are connected in parallel, thereby connecting the overall resistance of the first sensing resistor Rm1 and the second sensing resistor Rm2 in parallel, meaning the value of the sensing resistor can be less than the value of the first sensing resistor Rm1.

[0316] On the other hand, if through the aforementioned Figure 10a If the final insulation resistance is calculated in step S1026, the control unit 100 can determine whether it is currently in the state of calculating the time constant. Of course, if the time constant has not been calculated, a loop can be formed with the second circuit, which does not include the second detection resistor Rm2, by controlling the changeover switch 1700. In this case, the detection resistance can be increased by connecting the first detection resistor Rm1 in series.

[0317] In this way, the gradient ratio can be increased due to the increase in the value of the sensing resistance. If the increased gradient ratio in this case reaches a critical value, then the above process is repeated to calculate the insulation resistance. Figure 10a During the process, it can be done by executing the above. Figure 10a Step S1012 replaces step S1014, thereby calculating the time constant and performing a secondary adjustment process based on the calculated time constant.

[0318] Alternatively, to increase the gradient ratio, the control unit 100 can also control the signal generation unit 130 to further increase the amplitude of the test pulse. In this way, the gradient ratio can increase as the amplitude of the test pulse increases. In this case, if the increased gradient ratio reaches a critical value or higher, the process is repeated to calculate the insulation resistance. Figure 10a During the process, it can be done by executing the above. Figure 10a Step S1012 replaces step S1014, thereby allowing the time constant to be calculated and a secondary adjustment process to be performed based on the calculated time constant.

[0319] On the other hand, if the time constant is not calculated at the end of the final insulation resistance calculation, the control unit 100 can also control the gradient ratio to increase the gradient ratio. Figure 16 The first switch 1600 and the second switch 1602 mentioned in the description Figure 17 The description refers to at least one of the changeover switch 1700 and the amplitude of the test pulse. That is, in order to increase the gradient ratio, the control unit 100 may control only the first switch 1600 and the second switch 1602, or it may control only the changeover switch 1700. Alternatively, it may only increase the amplitude of the test pulse.

[0320] Furthermore, the control unit 100 can simultaneously control the first switch 1600, the second switch 1602, and the changeover switch 1700. Alternatively, it can control the first switch 1600 and the second switch 1602 while simultaneously increasing the amplitude of the test pulse. Alternatively, it can control the changeover switch 1700 while simultaneously increasing the amplitude of the test pulse. Alternatively, it can control the first switch 1600, the second switch 1602, and the changeover switch 1700 while simultaneously increasing the amplitude of the test pulse. That is, all three methods can be used together. As described above, when controlling two or more methods simultaneously, the gradient ratio can be increased more effectively compared to controlling only one method.

[0321] Alternatively, the control unit can first calculate the final insulation resistance using any method, and if the time constant is not calculated even using the stated method, the control unit 100 can simultaneously use multiple methods. That is, if the time constant is not calculated during the calculation of the final insulation resistance, the control unit 100 can first increase the gradient ratio by controlling any one of the following: the first switch 1600, the second switch 1602, the changeover switch 1700, or the test pulse amplitude. Nevertheless, if the time constant is still not calculated during the calculation of the next final insulation resistance, the control unit 100 can increase the gradient ratio by simultaneously using two methods. Furthermore, if the time constant is not calculated again during the calculation of the next final insulation resistance, the control unit 100 can also increase the gradient ratio by using three methods.

[0322] On the other hand, in the embodiments of the present invention described above, it is explained that in Figure 10a If the gradient ratio calculated in step S1008 is less than a preset threshold, a secondary adjustment is performed based on the initial sampling interval tn0. However, unlike this, if the calculated gradient ratio is less than the threshold, a preset minimum gradient ratio value can also be used. In this way, the time constant can be calculated based on the result of the natural logarithm (ln) operation on the minimum gradient ratio value and the time interval between the first reference point and the starting point, and the following can be performed based on the calculated time constant: Figure 13a The initial sampling interval is reset and the secondary adjustment is performed based on the reset initial sampling interval as described in the document.

[0323] In the following description, the operation process of the insulation monitoring device 10 of the third embodiment of the present invention calculating the insulation resistance between the power line 170 and the ground is explained in more detail with reference to a plurality of flowcharts.

[0324] first, Figure 18a and Figure 18b This is a flowchart illustrating the process of calculating the insulation resistance in the insulation monitoring device 10 according to the third embodiment of the present invention.

[0325] First, refer to Figure 18a In the third embodiment of the present invention, the control unit 100 of the insulation monitoring device 10 first controls the signal generation unit 130 to generate a pulse signal with a predetermined voltage (S1800). Thus, the signal generation unit 130 can generate a signal (pulse signal) with a predetermined positive or negative voltage according to the control of the control unit 100, and the generated signal can be applied to the power line 170 through the coupling resistor Rc.

[0326] If a pulse signal is generated in step S1800, the control unit 100 can determine the initial sampling interval tn0 (S1802). For example, the control unit 100 can determine the initial value tk according to the mathematical formula 1, and determine the initial sampling interval tn0 according to the initial value tk.

[0327] On the other hand, if the initial sampling interval tn0 is determined in step S1802, the control unit 100 can determine the starting point t0 of the voltage URm detected by the detection resistor Rm of the signal measurement unit 120 to be measured, i.e., the initial sampling start point. In this case, the control unit 100 can determine the starting point t0 as the time point after a predetermined time has elapsed since the previous pulse signal was reversed.

[0328] On the other hand, if the starting point t0 is determined, the control unit 100 can perform an adjustment process from the starting point t0 according to the initial sampling interval tn0 (S1804).

[0329] In step S1804, the control unit 100 can define a sampling interval as the time from the starting point t0 to the point corresponding to the initial sampling interval tn0. Furthermore, it can calculate the average voltage for the voltages measured during the defined sampling interval. It can also determine the length of the next sampling interval based on the length of the current sampling interval and a preset first time multiple, and determine the next sampling interval based on the determined length. The average voltage for the voltages measured during the defined sampling interval can be calculated again. Finally, the difference between the currently calculated average voltage and the average voltage calculated in the previous sampling interval can be calculated.

[0330] Furthermore, depending on whether the calculated difference is below a pre-set first error, the next sampling interval can be determined again, and the average voltage can be calculated again and compared with the previously calculated average voltage, or the adjustment process can be terminated. On the other hand, the value of the first time multiplier used in the adjustment process can be "1".

[0331] On the other hand, if the aforementioned adjustment process ends, then as in Figure 10bAs explained, the control unit 100 can determine a reference point for calculating the gradient ratio based on the voltage measured at the end of the first adjustment and the initial sampling interval (S1806). Furthermore, the gradient ratio can be calculated based on the determined reference point and mathematical formulas 4 and 5 (S1808). However, when the time constant τ is calculated as described in mathematical formula 5, as the difference between the first and second gradients decreases, the ratio of the second gradient to the first gradient converges to 1. This makes it difficult to calculate the time constant τ because the denominator becomes 0, since it becomes ln1. Therefore, the control unit 100 may also determine whether the gradient ratio calculated in step S1808 is above a predetermined threshold value (S1810). Furthermore, the time constant τ can only be calculated if the gradient ratio is greater than the predetermined threshold value.

[0332] On the other hand, when the time constant is calculated, the control unit 100 can determine the standby time based on the time constant. Here, the control unit 100 can determine the standby time as a time corresponding to a preset multiple of the calculated time constant. As an example, based on a plurality of experiments related to the present invention, it is most preferably that the standby time is determined to be a time corresponding to 5 times (5τ) of the time constant. In this case, the control unit 100 can determine the time corresponding to 5 times the calculated time constant as the standby time and switch the insulation monitoring device 10 to a standby state (S1812). In this way, the operation mode of the insulation monitoring device 10 can be switched to an energy-saving mode.

[0333] On the other hand, when switching to standby mode, the control unit 100 can determine whether a predetermined standby time has elapsed. That is, the control unit 100 can determine whether a time equivalent to the predetermined standby time has elapsed since the insulation monitoring device 10 switched to standby mode (S1814). Furthermore, if the time equivalent to the standby time has not elapsed, the standby mode is maintained; if the time equivalent to the standby time has elapsed, the insulation monitoring device 10 can be switched to active mode and the operation of setting the sampling interval and calculating the average voltage during the set sampling interval can be restarted.

[0334] As described above, when switching to the active state, the control unit 100 can reset the initial sampling interval based on the calculated time constant. Furthermore, a secondary adjustment (S1816) can be performed based on the reset initial sampling interval and a second time multiple different from the first time multiple. This secondary adjustment can be an adjustment process using a time multiple different from the first adjustment process. Here, the value of the second time multiple can be greater than the value of the first time multiple. For example, the value of the second time multiple can be 1.33, in which case the sampling interval set according to the second time multiple can gradually increase as the secondary adjustment time continues.

[0335] On the other hand, when performing the secondary adjustment, the control unit 100 can set the time point when the operating state is switched to the active state as the start point of the secondary adjustment. Furthermore, the time point from the set start point of the secondary adjustment to the time point corresponding to the re-set initial sampling interval can be determined as the sampling interval for the secondary adjustment. The average voltage measured during the determined sampling interval can be calculated. The next sampling interval can be determined based on the time calculated according to the length of the current sampling interval and the second time multiple, and the next sampling interval can be determined according to the determined length. The average voltage measured during the determined sampling interval can be calculated again. The difference between the currently calculated average voltage and the average voltage calculated in the previous sampling interval can be calculated.

[0336] Furthermore, if the calculated difference exceeds a preset normal voltage error, the next sampling interval can be determined again and the average voltage can be calculated again, and the calculated average voltage can be compared with the previously calculated average voltage again. However, if the calculated difference is below the normal voltage error, the currently calculated average voltage can be determined as the normal state voltage based on the pulse signal generated in step S1800 (S1820).

[0337] Here, if the pulse signal generated in step S1800 is a positive pulse signal, the control unit 100 can determine the currently calculated average voltage as a positive normal state voltage. Conversely, if the pulse signal generated in step S1800 is a negative pulse signal, the currently calculated average voltage can be determined as a negative normal state voltage.

[0338] Conversely, if the determination result of step S1810 is that the calculated gradient ratio is less than a critical value, the control unit 100 may not calculate the time constant. In this case, since the time constant is not calculated, the control unit 100 can directly execute the secondary adjustment process (S1818). In this case, the secondary adjustment process executed in step S1818 can be executed based on the initial sampling interval and the second time multiple set in step S1802. Furthermore, step S1820 can be executed based on whether the difference between the calculated average voltage and the average voltage calculated in the previous sampling interval is below the normal voltage error, and the currently calculated average voltage is determined as the normal state voltage of the pulse signal generated according to step S1800. Hereinafter, refer to Figure 20 The process of performing secondary adjustment based on a pre-set initial sampling interval when the calculated gradient ratio is less than the critical value is explained in more detail.

[0339] On the other hand, if the voltage of the stable state based on the currently generated pulse signal is determined in step S1820, the control unit 100 can detect whether the normal state voltage based on the positive pulse signal and the negative pulse signal has been determined (S1822).

[0340] If the detection result of step S1822 is that no normal state voltage based on either a positive or negative pulse signal is detected, the control unit 100 can reverse the pulse signal by controlling the signal generation unit 130 (S1824). In this way, the signal generation unit 130 can apply a pulse signal with the same magnitude of reversed voltage to the power line 170, thereby causing the voltage detected by the signal measurement unit 120 to become unstable again due to the surge caused by the voltage reversal.

[0341] Therefore, the control unit 100 can repeatedly execute the process from step S1802 to step S1820 based on the inverted pulse signal. Furthermore, if the detection result of step S1820 is that the normal state voltage is determined based on both the positive and negative pulse signals, the insulation resistance calculation unit 108 can be controlled to calculate the initial insulation resistance based on the determined normal state voltage (S1826).

[0342] In step S1826, the control unit 100 can calculate the average value of the currently determined normal state voltage according to the mathematical formula 2. Furthermore, it can calculate the initial insulation resistance based on the average normal state voltage calculated in the mathematical formula 2, according to the mathematical formula 3.

[0343] On the other hand, if the initial insulation resistance (the magnitude of the initial insulation resistance) is calculated through step S1826, the control unit 100 can confirm whether an initial insulation resistance equivalent to a preset quantity has been calculated (S1828). Furthermore, if the confirmation result of step S1828 is that an initial insulation resistance equivalent to a preset quantity has not been calculated, the control unit 100 can re-enter step S1800 and repeatedly execute the process from step S1800 to step S1826.

[0344] Conversely, if the confirmation result of step S1826 is that an initial insulation resistance equivalent to a preset number has been calculated, the control unit 100 can calculate the final insulation resistance based on the preset number, i.e., a plurality of initial insulation resistances (S1830). Here, step S1830 may be the step of calculating the average value of the plurality of initial insulation resistances.

[0345] On the other hand, if the final insulation resistance is calculated in step S1830, the control unit 100 can detect whether a calculated time constant exists (S1832). For example, if the gradient ratio calculated in step S1810 is above a preset threshold, a calculated time constant may exist. Conversely, if the determination result of step S1810 is that the calculated gradient ratio is less than a preset threshold, no calculated time constant may exist.

[0346] If the detection result of step S1832 indicates the existence of the calculated time constant, then as shown in mathematical formula 8, the control unit 100 can further calculate the capacitance of the insulating capacitor, i.e., the leakage capacitance C, based on the calculated time constant. e (S1834).

[0347] [Mathematical Expression 8]

[0348]

[0349] Here, τ is the time constant, and R e It is the magnitude of the insulation resistance, R i It refers to the magnitude of the internal resistance of the insulation monitoring device.

[0350] In this way, the control unit 100 can display the calculated final insulation resistance and leakage capacitance through the interface 106. Furthermore, the insulation resistance can be calculated by re-entering step S1800 and repeating the process from step S1800 to step S1830. Moreover, the insulation status between the power line 170 and the ground can be monitored based on the calculated insulation resistance.

[0351] Conversely, if the detection result of step S1832 is that no time constant has been calculated, that is, if the detection result of step S1808 is that the calculated gradient ratio is less than a preset threshold value, resulting in no time constant being calculated, then the control unit 100 can increase the range of the gradient ratio of the insulation capacitance that can be calculated, that is, the calculation range of the insulation capacitance (S1833).

[0352] Based on the above, the time constant can be calculated when the gradient ratio is above the critical value, and the insulation capacitance can only be calculated after calculating the time constant. Therefore, the minimum value of the range in which the insulation capacitance can be calculated can be the critical value.

[0353] In response, if the gradient ratio is less than the minimum value of the calculated range of the insulation capacitance, the control unit 100 can increase the gradient ratio. If the gradient ratio increases to a critical value or higher under these circumstances, the time constant can be calculated, and thus the insulation capacitance can be calculated. Hereinafter, as described above, the process by which the control unit 100 increases the gradient ratio will be explained as an operation process that increases the calculated range of the insulation capacitance.

[0354] On the other hand, in step S1833, the control unit 100 can use various means to increase the gradient ratio. For example, the control unit 100 can control the signal generation unit 130 to increase the amplitude of the pulse signal generated in step S1800. Alternatively, as described in... Figure 16 and Figure 17 As explained, the control unit 100 can reduce the coupling resistor 180 or increase the detection resistor Rm included in the signal measurement unit 120 in order to increase the gradient ratio.

[0355] However, unlike this, if the detection result of step S1832 is an uncalculated time constant, the control unit 100 can, of course, only display the calculated final insulation resistance value through the interface 106. Furthermore, the insulation resistance value can be calculated by re-entering step S1800 and repeating the process from step S1800 to step S1830. Moreover, the insulation status between the power line 170 and the ground can be monitored using the calculated insulation resistance value.

[0356] on the other hand, Figure 19a This is a flowchart illustrating the process of performing secondary adjustment based on the sampling interval calculated according to the time constant and the preset second time multiple in the insulation monitoring device 10 of the third embodiment of the present invention. Figure 19b This is an example diagram illustrating the secondary adjustment process performed in the insulation monitoring device 10 of the third embodiment of the present invention after a standby time determined according to a calculated time constant.

[0357] In the Figure 18a If the determination result of step S1810 is that the calculated gradient ratio is above a critical value, the control unit 100 of the insulation monitoring device 10 of the third embodiment of the present invention can calculate the time constant based on the gradient ratio in step S1812. Furthermore, it can switch to a standby state during the standby time determined based on the calculated time constant. If it switches to an active state after the standby time has elapsed, the control unit 100 can re-set the initial sampling interval to be used in the secondary adjustment process (S1900) based on the calculated time constant. For example, the control unit 100 can re-set the initial sampling interval tn based on the mathematical formula 6.

[0358] Then, the control unit 100 can set a sampling interval based on the reset initial sampling interval, and calculate the average voltage detected during the set sampling interval (S1902). Then, the next sampling interval for secondary adjustment can be determined by multiplying the sampling interval based on the reset initial sampling interval by a preset second time multiple, and the average voltage during the determined sampling interval can be calculated (S1904).

[0359] like Figure 19b This illustrates an example of performing a second adjustment after the first adjustment, as described above, ends and the system transitions to standby mode based on the calculated time constant. As an example, such as... Figure 19b As shown, when the first time multiple for the first adjustment is 1, the sampling interval set during the first adjustment can be an interval set according to the same time interval.

[0360] If the adjustment ends in this state and the standby time based on the calculated time constant is determined, the control unit 100 can switch the insulation monitoring device 10 to energy-saving mode (standby state) during the standby time. Furthermore, if the standby time has elapsed while the device is driven in the energy-saving mode, the initial sampling interval can be reset based on the time constant, and an initial sampling interval tn based on the reset initial sampling interval can be set. The average voltage detected during the initial sampling interval tn can be calculated. The next sampling interval tn+1 can be set based on the initial sampling interval, i.e., the time length during the initial sampling interval tn, and a preset second time multiple, and the average voltage detected during the next sampling interval tn+1 can be calculated.

[0361] In this way, the control unit 100 can calculate the difference between the currently calculated average voltage (the average voltage calculated during the tn+1 sampling interval) and the average voltage calculated during the previous sampling interval tn, and determine whether the difference in the calculated average voltage is below a preset normal voltage error (S1906). Furthermore, if the difference in the calculated average voltage is below the preset normal voltage error, it can be resolved by executing... Figure 18a Step S1820, the currently calculated voltage is determined according to the voltage described in the previous step. Figure 18a The stable voltage of the pulse signal generated in step S1800 is the normal state voltage.

[0362] Conversely, if the difference between the average voltages calculated in step S1906 exceeds the normal voltage error, the control unit 100 can update the sampling interval based on the length of the currently set sampling interval according to the second time multiple (S1908). Furthermore, the next sampling interval tn+2 can be determined again based on the updated sampling interval (S1910).

[0363] In this case, the second time factor can be a value greater than 1 (e.g., 1.33). Thus, as... Figure 19b As shown, the length (time) of the next sampling interval tn+1 can be greater than the length of the initial sampling interval tn, and the length of the next sampling interval tn+2 can be greater than the length of the previous sampling interval tn+1.

[0364] On the other hand, the control unit 100 can recalculate the average voltage during the sampling interval tn+2 determined according to the updated sampling interval (S1912). Furthermore, by re-executing step S1906, the difference between the currently calculated average voltage (the average voltage calculated during the tn+2 sampling interval) and the previously calculated average voltage (the average voltage calculated during the tn+1 sampling interval) can be calculated. And, based on the difference in the calculated average voltage, by executing... Figure 18a Step S1820 is used to determine if it is a normal state voltage, or step S1908 is used to update the sampling interval according to the second time multiple to determine the length of the currently set sampling interval.

[0365] on the other hand, Figure 20 This is a flowchart illustrating the process of performing secondary adjustment based on the initial sampling interval and a preset second time multiple in the insulation monitoring device 10 of the third embodiment of the present invention.

[0366] Reference Figure 20 If it is difficult to calculate the time constant because the calculated gradient ratio is less than the critical value, the control unit 100 may directly execute the secondary adjustment process based on the second time multiple without resetting the initial sampling interval.

[0367] The control unit 100 can first determine the sampling interval based on the initial sampling interval tn0. In this case, the initial sampling interval tn0 can be... Figure 18a The sampling interval is calculated in step S1802.

[0368] If the initial sampling interval is calculated, the control unit 100 can calculate the average voltage during the sampling interval based on the calculated initial sampling interval (S2000). Then, the next sampling interval can be determined based on the initial sampling interval tn0 and the second time multiple set for the second adjustment (S2002, S2004). Furthermore, the average voltage can be calculated by averaging the voltage detected during the determined sampling interval (S2006).

[0369] On the other hand, if the average voltage is calculated in step S2006, the control unit 100 can determine whether the difference between the currently calculated average voltage and the average voltage calculated in the previous sampling interval is below the normal voltage error (S2008). Furthermore, if the determination result of step S2008 is that the difference in the calculated average voltage is below the normal voltage error, then execution can be performed... Figure 18a Step S1816, the currently calculated voltage is determined according to the voltage described in the previous step. Figure 18a The stable voltage of the pulse signal generated in step S1800 is the normal state voltage.

[0370] Conversely, if the difference between the average voltages calculated in step S2008 exceeds the normal voltage error, the control unit 100 can update the sampling interval based on the length of the currently set sampling interval according to a second time multiple (S2010). Furthermore, the next sampling interval can be determined again based on the updated sampling interval (S2012). And, the average voltage during the sampling interval determined in step S2012 can be calculated again based on the updated sampling interval (S2014).

[0371] On the other hand, if the average voltage during the newly determined sampling interval is calculated in step S2014, the control unit 100 can determine whether the difference between the currently calculated average voltage and the average voltage calculated in the previous sampling interval is below the normal voltage error by re-executing step S2008. Furthermore, based on the determination result, the process of steps S2008 to S2014 is executed again.

[0372] On the other hand, although in the above Figure 18a The text explains that if a complex number of initial insulation resistances are calculated, then in... Figure 18aIn step S1826, the final insulation resistance is calculated based on a plurality of insulation resistances. However, if the difference between the plurality of insulation resistances is above a predetermined threshold, the control unit 100 may choose not to calculate the final insulation resistance based on the currently calculated initial insulation resistance.

[0373] On the other hand, referring to the above Figure 16 The operation of the insulation monitoring device 10 according to the third embodiment of the present invention will be described, and may also include the following: Figure 18b When the detection result of step S1832 is in a state where the time constant has not been calculated, the control unit 100 reduces the value of the coupling resistance by controlling the first switch 1600 and the second switch 1602 (not shown).

[0374] In this case, the first switch 1600 and the second switch 1602 can remain in an initially open state. In this case, the control unit 100 can turn on both the first switch 1600 and the second switch 1602, adding a first coupling resistor Rc1 to the second electric line L2 and a third coupling resistor Rc3 to the first electric line L1. Thus, the third coupling resistor Rc3 and the fourth coupling resistor Rc4 are connected in parallel to the first electric line L1, thereby reducing the value of the coupling resistance connected to the first electric line L1. Furthermore, since the first coupling resistor Rc1 and the second coupling resistor Rc2 are connected in parallel to the second electric line L2, the value of the coupling resistance connected to the second electric line L2 can also be reduced.

[0375] This reduces the value of the coupling resistance, thereby increasing the gradient ratio. In this case, if the increased gradient ratio exceeds a critical value, the above procedure is repeated to calculate the insulation resistance. Figure 18a During the process, it can be done by executing the above. Figure 18a In step S1812, the time constant is calculated, and the insulation monitoring device 10 can operate in energy-saving mode during the standby time determined according to the calculated time constant. Therefore, the power consumption of the insulation monitoring device can be reduced.

[0376] On the other hand, the Figure 16 This assumes a single-phase system, but the present invention is not limited thereto. That is, in the case of a three-phase system, multiple resistors can be connected in parallel to the respective power lines of the R, S, and T lines, and some of them can be connected by switches and their connection to the power lines can be controlled by the control unit 100.

[0377] On the other hand, in the Figure 16 The description assumes two resistors connected in parallel to each electric field line, but the invention is not limited to this. That is, a greater number of resistors can be connected in parallel to each electric field line.

[0378] Referring to the above Figure 17 The operation of the insulation monitoring device 10 according to the third embodiment of the present invention will be described. The detection resistor provided in the signal measurement unit 120 of the insulation monitoring device 10 may include a plurality of resistors that can be connected in parallel to the signal generation unit 130. Furthermore, it has the following structure: a portion of the plurality of resistors can be connected by a switch, and the plurality of resistors can be connected in parallel according to the control of the control unit 100.

[0379] In this case, it may also include the above. Figure 18b The step S1832, where the detection result is in a state where the time constant has not been calculated, involves the control unit 100 controlling the changeover switch 1700 to form a loop with the second circuit excluding the second detection resistor Rm2 (not shown). In this case, the detection resistance can be further increased by connecting the first detection resistor Rm1 in series.

[0380] In this way, the gradient ratio can be increased by increasing the value of the sensing resistance. In this case, if the increased gradient ratio reaches a critical value, the above process is repeated to calculate the insulation resistance. Figure 18a During the process, it can be done by executing the above. Figure 18a In step S1812, the time constant is calculated, and the insulation monitoring device 10 can operate in energy-saving mode during the standby time determined according to the calculated time constant. Therefore, the power consumption of the insulation monitoring device can be reduced.

[0381] On the other hand, in the Figure 18b In step S1833, the control unit 100 can simultaneously control the gradient ratio in order to increase the gradient ratio. Figure 16 The first switch 1600 and the second switch 1602 described herein, in Figure 17 At least one of the switching switch 1700 and the signal generation unit 130 described herein. That is, the control unit 100 may control only the first switch 1600 and the second switch 1602 to increase the gradient ratio, or it may control only the switching switch 1700. Alternatively, it may control only the signal generation unit 130 to increase the amplitude of the test pulse.

[0382] Furthermore, the control unit 100 can simultaneously control the first switch 1600, the second switch 1602, and the changeover switch 1700. Alternatively, it can control the first switch 1600 and the second switch 1602 simultaneously to increase the amplitude of the test pulse. Alternatively, it can control the changeover switch 1700 simultaneously to control the signal generation unit 130 to increase the amplitude of the test pulse.

[0383] Alternatively, the first switch 1600 and the second switch 1602 can be controlled, and the signal generation unit 130 can be controlled to increase the amplitude of the test pulse while controlling the switching switch 1700. That is, all three methods can be used together. As described above, when two or more methods are controlled simultaneously, the gradient ratio can be increased more effectively compared to controlling any one method.

[0384] Alternatively, the control unit 100 may first use only one means (e.g., controlling the first switch 1600 and the second switch 1602, the changeover switch 1700, and the signal generation unit 130) to calculate the final insulation resistance, and simultaneously use multiple means if the time constant cannot be calculated even though the above means are used.

[0385] That is, if the time constant is not calculated during the calculation of the final insulation resistance, the control unit 100 can increase the gradient ratio by controlling any one of the first switch 1600, the second switch 1602, the changeover switch 1700, and the signal generation unit 130. If the time constant is still not calculated during the calculation of the next final insulation resistance, the control unit 100 can increase the gradient ratio by using both methods simultaneously. Furthermore, if the time constant is still not calculated during the calculation of the next final insulation resistance, the control unit 100 can increase the gradient ratio by using all three methods.

[0386] On the other hand, the embodiments of the present invention described above illustrate that in Figure 18a In step S1808, if the calculated gradient ratio is less than a preset threshold, a secondary adjustment is performed based on the initial sampling interval tn0. However, unlike this, if the calculated gradient ratio is less than the threshold, a preset minimum gradient ratio value can also be used. In this way, the time constant can be calculated based on the result of the natural logarithm (ln) operation for the minimum gradient ratio value and the time interval between the first reference point and the starting point, and as in... Figure 19a As explained in the document, the initial sampling interval can also be reset and a secondary adjustment can be performed based on the calculated time constant.

[0387] On the other hand, although specific embodiments have been described in the above description of the present invention, various modifications can be made without departing from the scope of the present invention. In particular, in the embodiments of the present invention, examples are given of a first error of 1% of the currently calculated average voltage and a second error of 5% of the currently calculated average voltage, but this is only for the purpose of helping to understand the present invention, and the present invention is not limited thereto.

[0388] Furthermore, in the embodiments of the present invention, the first time multiple is assumed to be 1.66 and the second time multiple is assumed to be 1.33. However, this is only for the purpose of helping to understand the present invention, and the present invention is not limited thereto.

[0389] Furthermore, those skilled in the art can make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in this invention are not intended to limit the technical concept of the invention, but rather to illustrate that the scope of the technical concept of the invention is not limited by such embodiments. It should be interpreted that the scope of protection of the present invention should be interpreted by the claims, and all technical concepts within the same scope fall within the scope of protection of the present invention.

Claims

1. An insulation monitoring device, comprising an insulation resistance formed between the power line and ground of the system, characterized in that, include: The signal generation unit applies a pulse signal with a predetermined voltage to the power line; The signal measurement unit, connected to the ground, measures the voltage of the applied pulse signal from the ground when the pulse signal applied to the power line is applied to the ground through the insulation resistance; The average voltage calculation unit calculates the average voltage of the voltage measured by the signal measurement unit during a sampling interval according to a set sampling interval; and The control unit calculates a sampling interval based on an initial sampling interval and a preset time multiple, calculates the average voltage during the sampling interval based on the calculated sampling interval, and detects the first average voltage as a normal state voltage based on whether the difference between the calculated first average voltage and the second average voltage calculated before the first average voltage is within a preset first error range. If the difference between the first average voltage and the second average voltage exceeds the first error range, the control unit selectively updates the sampling interval using different time multiples based on the difference between the first average voltage and the second average voltage.

2. The insulation monitoring device according to claim 1, characterized in that, If the difference between the first average voltage and the second average voltage exceeds a preset second error range, the control unit updates the sampling interval of the sampling range from which the next average voltage will be calculated based on a first time multiple. If the difference between the first average voltage and the second average voltage is below a preset second error range, the control unit updates the sampling interval of the sampling range from which the next average voltage will be calculated based on a second time multiple. The value of the second time multiple is less than the value of the first time multiple. The value of the second error range is greater than the value of the first error range.

3. The insulation monitoring device according to claim 2, characterized in that, The first time multiple is 1.

66. The second time factor is 1.

33. The first error range is 1% of the second average voltage. The second error range is 5% of the second average voltage.

4. The insulation monitoring device according to claim 1, characterized in that, The control unit determines the initial sampling interval based on the larger of the initial value calculated from the internal resistance of the insulation monitoring device and the period of a pre-set interference frequency.

5. The insulation monitoring device according to claim 1, characterized in that, It also includes a memory that stores information about different sampling intervals corresponding to a plurality of different time constants. The control unit calculates the first sampling interval based on the larger of an initial value calculated from the internal resistance of the insulation monitoring device and the period of a preset interference frequency. The control unit determines a plurality of time intervals at which the gradient of the voltage measured by the signal measurement unit will be calculated, based on the first sampling interval. The control unit calculates the ratio of the first gradient to the second gradient, and determines any one of the different sampling intervals as the initial sampling interval based on the time constant corresponding to the calculated gradient ratio. The first gradient is based on the voltage difference between time points set at intervals including a plurality of first sampling intervals, and the second gradient is based on the voltage difference between other time points set at intervals including the plurality of first sampling intervals.

6. The insulation monitoring device according to claim 1, characterized in that, If the first average voltage is determined to be a normal state voltage based on the type of the applied pulse signal, the control unit controls the signal generation unit to invert the pulse signal into the other type of pulse signal based on whether there is a normal state voltage based on the type of other preset pulse signal, and controls the signal measurement unit and the average voltage calculation unit to detect the normal state voltage based on the other type of pulse signal.

7. The insulation monitoring device according to claim 6, characterized in that, In the presence of a normal state voltage based on other types of pulse signals that are preset, the control unit calculates the magnitude of the insulation resistance based on the normal state voltage of the pulse signals that are different from each other.

8. The insulation monitoring device according to claim 7, characterized in that, The control unit confirms whether the preset number of insulation resistances has been calculated. If the calculated number of insulation resistances is less than the preset number, the control unit controls the signal generation unit, the signal measurement unit, and the average voltage calculation unit to calculate the insulation resistances again. If the confirmation result is that the preset number of insulation resistances has been calculated, the final value of the insulation resistance is determined by calculating the average value of the calculated insulation resistances.

9. The insulation monitoring device according to claim 8, characterized in that, If the value of the preset number of insulation resistances is calculated, the control unit calculates the difference between the calculated insulation resistance values, and if the calculated difference exceeds a preset threshold value, controls the signal generation unit, the signal measurement unit, and the average voltage calculation unit to change the interference frequency according to a preset ratio and recalculate the value of the preset number of insulation resistances according to the changed interference frequency.

10. The insulation monitoring device according to claim 9, characterized in that, If the final value of the insulation resistance is determined based on the average value of the preset number of insulation resistances, the control unit confirms whether the value of the interference frequency is less than a preset minimum value, and if the value of the interference frequency is less than the preset minimum value, the control unit determines the value of the interference frequency as the minimum value.

11. The insulation monitoring device according to claim 1, characterized in that, The signal measurement unit includes: Detecting resistance; An amplifier for amplifying the voltage difference applied across the sensing resistor; The ADC converts the voltage difference amplified by the amplifier into a digital voltage value and inputs it to the control unit; and At least one of a first analog filter and a second analog filter, wherein the first analog filter is formed between the sensing resistor and the amplifier for removing noise from the voltage applied across the sensing resistor, and the second analog filter is connected between the amplifier and the ADC for removing noise from the voltage difference amplified by the amplifier.

12. The insulation monitoring device according to claim 11, characterized in that, The ADC also includes: The conversion unit converts the amplified voltage difference into a digital voltage value; and A digital filter is formed between the conversion unit and the control unit to remove noise from the digital voltage value input to the control unit.

13. A control method for an insulation monitoring device, the insulation monitoring device comprising an insulation resistance formed between a power line and ground in a system, characterized in that, The control method includes: The step of applying a pulse signal with a voltage of a specified magnitude to the power line; The steps for determining the initial sampling interval; The steps are as follows: calculate the sampling interval based on the determined initial sampling interval, calculate the average voltage during the sampling interval based on the calculated sampling interval, and calculate the average voltage during the sampling interval based on the sampling interval updated based on the first time multiple. The step of detecting whether the difference between the currently calculated first average voltage and the second average voltage measured before the first average voltage is within a preset first error range; The detection result includes the step of identifying the first average voltage as the normal state voltage based on the applied pulse signal when the difference between the first average voltage and the second average voltage is within a preset first error range, and selectively updating the sampling interval using different time multiples based on the difference between the first average voltage and the second average voltage when the difference between the first average voltage and the second average voltage exceeds the first error range. The steps include repeatedly performing the steps of calculating the average voltage during the sampling interval according to the updated sampling interval, and detecting whether the difference in the voltage is within a preset first error range until the normal state voltage is identified, up to the step of updating the sampling interval using different time multiples from each other; If the normal state voltage is identified, the step of detecting whether there is a normal state voltage based on other types of pulse signals that have been pre-identified; The step of identifying the normal state voltage based on the other type of pulse signal is achieved by repeatedly executing the step of inverting the pulse signal to the other type of pulse signal and determining the initial sampling interval, in the case that the result of detecting whether there is a normal state voltage based on the type of other pre-identified pulse signal is that other pre-identified pulse signal exists; and the step of identifying the normal state voltage based on the other type of pulse signal by repeating the step of detecting whether there is a normal state voltage based on the type of other pre-identified pulse signal. The step of calculating the magnitude of the insulation resistance based on the normal state voltage of the pulse signals of different types, in the case where the result of detecting whether there is a normal state voltage based on the other types of pulse signals is that other types of pulse signals are pre-identified.

14. The control method for the insulation monitoring device according to claim 13, characterized in that, The step of updating the sampling interval using different time multiples includes: The step of updating the sampling interval according to a first time factor when the difference between the first average voltage and the second average voltage exceeds a preset second error range; and The step of updating the sampling interval according to the second time multiple when the difference between the first average voltage and the second average voltage is below a preset second error range; The value of the second time multiple is less than the value of the first time multiple. The value of the second error range is greater than the value of the first error range.

15. The control method for the insulation monitoring device according to claim 13, characterized in that, The step of determining the initial sampling interval is to calculate the initial sampling interval based on the larger of the initial value calculated based on the internal resistance of the insulation monitoring device and the period of the preset interference frequency.

16. An insulation monitoring device, comprising an insulation resistance formed between a power line and a ground in a system, characterized in that, include: The signal generation unit applies a pulse signal with a predetermined voltage to the power line; The signal measurement unit, connected to the ground, measures the voltage of the applied pulse signal from the ground when the pulse signal applied to the power line is applied to the ground through the insulation resistance; The average voltage calculation unit calculates the average voltage of the voltage measured by the signal measurement unit during a sampling interval according to the set sampling interval; as well as The control unit executes an adjustment process, in which it calculates a sampling interval based on a preset time multiple, calculates the average voltage during the sampling interval based on the calculated sampling interval, compares the difference between the calculated first average voltage and a second average voltage calculated before the first average voltage; if the difference in the average voltage is within a preset error range, it detects the second average voltage as a normal state voltage or executes the adjustment process again based on whether the time elapsed from the sampling start time point is more than a predetermined time. If the time point at which the voltage difference between samples meets the preset error range is a time point that has elapsed more than the specified time since the sampling start time, the sampling interval is calculated based on the time point at which the voltage difference between samples meets the preset error range and the different time multiples thereof.

17. The insulation monitoring device according to claim 16, characterized in that, The control unit performs an adjustment process based on a preset first time multiple. If the difference between the first average voltage and the second average voltage is below a preset first error, the control unit performs a secondary adjustment process to determine the sampling interval of the sampling range from which the average voltage will be calculated based on a second time multiple different from the first time multiple. If the result of the secondary adjustment is that the difference between the first average voltage and the second average voltage is below a preset normal voltage error, the second average voltage is detected as a normal state voltage depending on whether the predetermined time has elapsed since the start of the secondary adjustment.

18. The insulation monitoring device according to claim 17, characterized in that, If the difference between the first average voltage and the second average voltage is below a preset first error as a result of the first adjustment, the control unit terminates the first adjustment. At least one reference point is determined based on the start time of the first adjustment, the initial sampling interval, and the end time of the first adjustment. A plurality of voltage gradients are then calculated based on the voltage difference between the voltages at the determined reference points. The time constant is calculated based on the gradient ratio of the calculated voltage gradient, and the specified time is determined based on the calculated time constant.

19. The insulation monitoring device according to claim 18, characterized in that, If the adjustment ends, the control unit determines the start point of the adjustment, the time point elapsed from the start point equivalent to the initial sampling interval, the end point of the adjustment, and the time point before the end point of the adjustment within the initial sampling interval as the reference point. Based on the determined reference point and the following mathematical formula, the gradient ratio is calculated. [Mathematical expression] Here, the start point represents the time point at which the sampling begins, the first reference point represents the time point from the start point after an initial sampling interval, the third reference point represents the time point at which the adjustment ends, the second reference point represents the time point from the third reference point before the initial sampling interval, the start voltage represents the voltage at the start point, the first voltage represents the voltage at the first reference point, the second voltage represents the voltage at the second reference point, and the third voltage represents the voltage at the third reference point.

20. The insulation monitoring device according to claim 19, characterized in that, The control unit calculates the time constant (τ) based on the natural logarithm (ln) of the gradient ratio and the time interval between the first reference point and the starting point. The control unit determines the specified time based on a preset multiple of the calculated time constant.

21. The insulation monitoring device according to claim 18, characterized in that, The control unit calculates the time constant based on whether the calculated gradient ratio is above a preset critical value. If the time constant is calculated, the control unit then resets the initial sampling interval based on the calculated time constant and the following mathematical formula, and performs the secondary adjustment process based on the reset initial sampling interval. [Mathematical expression] t n =-ln(1-0.01)×τ Here, tn is the newly set initial sampling interval, and τ is the time constant.

22. The insulation monitoring device according to claim 21, characterized in that, If the time constant is not calculated based on the comparison between the calculated gradient ratio and the critical value, the control unit performs the secondary adjustment process based on the initial sampling interval.

23. The insulation monitoring device according to claim 21, characterized in that, Without calculating the time constant, the control unit increases the amplitude of the pulse signal by controlling the signal generation unit.

24. The insulation monitoring device according to claim 21, characterized in that, It also includes coupling resistors, which comprise a plurality of resistors and a switch. The plurality of resistors are connected in parallel to the various power lines of the system, and the switch connects a portion of the plurality of resistors to each of the power lines. Without calculating the time constant, the control unit controls the switch to connect a plurality of resistors in parallel to each of the power lines.

25. The insulation monitoring device according to claim 21, characterized in that, The signal measurement unit includes a first detection resistor, a first circuit including a second detection resistor, a second circuit excluding the second detection resistor, and a switch connected to the first detection resistor via either the first circuit or the second circuit to form a loop. The signal measurement unit detects the voltage of the applied pulse signal based on the voltage applied across at least one detection resistor. Without calculating the time constant, the control unit controls the switch to connect the first detection resistor to the second circuit to form a loop.

26. The insulation monitoring device according to claim 21, characterized in that, If the calculated gradient ratio is less than the critical value, the control unit calculates the time constant based on the result of the natural logarithm (ln) of the preset minimum gradient ratio, the starting point of the first adjustment, and the time interval between the starting point and the time point corresponding to the initial sampling interval.

27. A control method for an insulation monitoring device, the insulation monitoring device comprising an insulation resistance formed between a power line and ground in a system, characterized in that, The control method includes: The step of applying a pulse signal with a voltage of a specified magnitude to the power line; The steps for determining the initial sampling interval; The step of performing an adjustment is as follows: in the adjustment, the sampling interval is calculated based on the initial sampling interval and the first time multiple; the average voltage during the sampling interval based on the calculated sampling interval is calculated; and the difference between the calculated first average voltage and the second average voltage calculated before the first average voltage is compared. The step of detecting whether the result of the first adjustment is that the difference between the first average voltage and the second average voltage is within a preset first error range; The first adjustment is terminated based on whether the voltage difference is within the first error range, and the second adjustment is performed. In the second adjustment, the sampling interval is calculated based on the preset sampling interval and the second time multiple, the average voltage during the sampling interval based on the calculated sampling interval is calculated, and the difference between the calculated third average voltage and the fourth average voltage calculated before the third average voltage is compared. The step of detecting whether the result of the secondary adjustment is that the difference between the third average voltage and the fourth average voltage is within the normal voltage error range; If the difference between the third average voltage and the fourth average voltage is within the normal voltage error range, the step of detecting whether a predetermined time has elapsed since the start of the secondary adjustment, and if the predetermined time has elapsed, then detecting the third average voltage as the normal state voltage according to the applied pulse signal; and If the result of the secondary adjustment is that the difference between the third average voltage and the fourth average voltage exceeds the normal voltage error range, or if the predetermined time has not elapsed since the start of the secondary adjustment, the secondary adjustment steps are repeatedly executed.

28. The control method for the insulation monitoring device according to claim 27, characterized in that, The step of performing secondary adjustment also includes: The step of determining at least one reference point based on the start time of the first adjustment, the initial sampling interval, and the end time of the first adjustment; The steps of calculating a complex number of voltage gradients based on the voltage difference at a determined reference point, and calculating the gradient ratio based on the calculated complex number of gradients; and The step of calculating the time constant based on the calculated gradient ratio, and determining the specified time based on the calculated time constant.

29. The control method for the insulation monitoring device according to claim 28, characterized in that, The step of determining the specified time also includes: The step of detecting whether the calculated gradient ratio is above a preset critical value; The step of calculating the time constant when the gradient ratio is above the critical value; and If the time constant is calculated, then the initial sampling interval is set according to the calculated time constant and the following mathematical formula; The step of performing the secondary adjustment is to perform the secondary adjustment process according to the newly set initial sampling interval. [Mathematical expression] t n =-ln(1-0.01)×τ Here, tn is the newly set initial sampling interval, and τ is the time constant.

30. The control method for the insulation monitoring device according to claim 29, characterized in that, The step of performing secondary adjustment is to perform a second adjustment process based on the initial sampling interval without calculating the time constant.

31. The control method for the insulation monitoring device according to claim 28, characterized in that, The step of detecting the normal state voltage based on the applied pulse signal further includes: If a normal state voltage is detected based on the applied pulse signal, then the step of calculating the magnitude of the insulation resistance based on the detected normal state voltage is... The step of calculating the insulation resistance also includes: The step of increasing the gradient ratio without calculating the time constant. The step of increasing the gradient ratio is the step of increasing the amplitude of the pulse signal.

32. The control method for the insulation monitoring device according to claim 31, characterized in that, The insulation monitoring device further includes a coupling resistor, which comprises a plurality of resistors and a switch. The plurality of resistors are connected in parallel to the various power lines of the system, and the switch connects a portion of the plurality of resistors to each of the power lines. The step of increasing the gradient ratio further includes: The step of controlling the switch to connect a plurality of resistors in parallel to the respective power lines.

33. The control method for the insulation monitoring device according to claim 31, characterized in that, The insulation monitoring device further includes a signal measurement unit, which comprises a first detection resistor, a first circuit including a second detection resistor, a second circuit excluding the second detection resistor, and a switch connected to the first detection resistor via either the first circuit or the second circuit to form a loop. The signal measurement unit detects the voltage of the applied pulse signal based on the voltage across at least one detection resistor. The step of increasing the gradient ratio is to control the switching switch to connect the first detection resistor to the second circuit to form a loop.

34. The control method for the insulation monitoring device according to claim 29, characterized in that, The steps for calculating the time constant also include: The step of calculating the time constant when the gradient ratio is less than the critical value is based on the result of the natural logarithm (ln) of the preset minimum gradient ratio, the starting point of the first adjustment, and the time interval between the starting point and the time point corresponding to the initial sampling interval.

35. The insulation monitoring device according to claim 16, characterized in that, If the difference between the first average voltage and the second average voltage satisfies a preset idle time error condition, the control unit switches the operation state to energy-saving mode during a preset standby time before calculating the sampling interval using the different time multiples. If the standby time has elapsed, the adjustment process of detecting the normal state voltage by calculating the inter-sample voltage difference based on the sampling interval updated using different time multiples is restarted.

36. The insulation monitoring device according to claim 35, characterized in that, The control unit performs an adjustment process according to a preset first time multiple, and if the difference between the first average voltage and the second average voltage is below a preset first error as a result of the adjustment, the operation state is switched to energy-saving mode during the standby time. If the adjustment process restarts, the control unit performs a secondary adjustment process, in which the sampling interval for calculating the average voltage is determined based on a second time multiple that is different from the first time multiple.

37. The insulation monitoring device according to claim 36, characterized in that, If the difference between the first average voltage and the second average voltage is below a preset first error as a result of the first adjustment, the control unit terminates the first adjustment. The control unit determines at least one reference point based on the start time of the first adjustment, the initial sampling interval, and the end time of the first adjustment, and calculates a plurality of voltage gradients based on the voltage difference between the voltages at the determined reference points. The control unit calculates a time constant based on the gradient ratio of the calculated voltage gradient, and determines the standby time based on the calculated time constant.

38. The insulation monitoring device according to claim 37, characterized in that, The control unit determines whether to calculate the time constant based on a comparison between the calculated gradient ratio and a preset threshold value. If the insulation resistance is calculated based on the normal state voltage detected after the standby time determined according to the time constant, the control unit also calculates the leakage capacitance according to the following mathematical formula based on the calculated time constant. [Mathematical expression] Here, τ is the time constant, and R e It is the magnitude of the insulation resistance, R i It is the magnitude of the internal resistance of the insulation monitoring device, and the critical value is the minimum value of the calculated range of the leakage capacitance.

39. The insulation monitoring device according to claim 37, characterized in that, The control unit determines whether to calculate the time constant based on the comparison result between the calculated gradient ratio and the preset critical value, and performs the secondary adjustment process based on the initial sampling interval and the second time multiple if the time constant is not calculated.

40. The control method for the insulation monitoring device according to claim 27, characterized in that, The step of detecting whether the difference between the first average voltage and the second average voltage is within a preset first error range includes: If the difference between the first average voltage and the second average voltage is within the first error range, at least one reference point is determined, and a gradient ratio is calculated based on the voltage gradient of the voltage difference according to the reference point. The steps to calculate the time constant based on the calculated gradient ratio; The step of switching the operating state of the insulation monitoring device to the standby state during the standby time determined according to the calculated time constant; The step involves confirming whether the standby time has elapsed and, based on the confirmation result, changing the action state to an active state.

41. The control method for the insulation monitoring device according to claim 40, characterized in that, The steps for switching the operating state of the insulation monitoring device to the standby state include: The step of determining the standby time based on a preset multiple of the calculated time constant; and The step of switching the operating mode of the insulation monitoring device to an energy-saving mode during the determined standby time.

42. The control method for the insulation monitoring device according to claim 40, characterized in that, The step of detecting the third average voltage as a normal state voltage based on the applied pulse signal further includes: The steps for calculating the size of the insulation capacitance based on the calculated time constant.

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