JP2014126382A - Insulation state detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable highly accurate measurement without inducing large increase in a device cost nor requiring a surplus work of an inspector even when a capacity such as a Y capacitor and the like affecting measurement is unknown.SOLUTION: A reference resistor Rref having a resistance value known is connected to power source lines 111, 112 and the like to implement a test mode. In the test mode, on the basis of the resistance value of the reference resistor Rref, an appropriate calculating formula or an appropriate capacity parameter is automatically grasped by a microcomputer 11. In consideration to a capacity, the appropriate calculating formula automatically selected from a plurality of calculating formulas or the appropriate capacity parameter is used to reduce a calculation error of a ground resistance value. A conversion map equivalent to the calculating formula is used. On the basis of the calculation error of the ground resistance value, an electrostatic capacity is calculated by a back calculation of the calculating formula.

Description

  The present invention relates to an insulation state detection device using a flying capacitor.

  For example, in a vehicle that uses electric power as propulsion energy, such as an electric vehicle, a DC power supply device that outputs a high voltage of about 200 V may be mounted. In the case of a vehicle equipped with such a high-voltage DC power supply device, it is used in a state where the positive and negative power supply lines of the DC power supply device and the vehicle body are electrically insulated. That is, the vehicle body is not used as a ground for a power source that outputs a high voltage.

  In such a vehicle, it is necessary to inspect and confirm that the high-voltage DC power output wiring and the vehicle body are sufficiently electrically insulated in order to ensure safety. For example, Patent Literature 1, Patent Literature 2, and Patent Literature 3 are known as related arts of an insulation state detection device used when performing such an inspection.

  This type of insulation state detection device uses a flying capacitor. That is, a detection capacitor (referred to as a flying capacitor) is connected between a high-voltage positive / negative power supply line and a ground electrode (vehicle body) for a certain period of time via a switching element. The charging voltage of the flying capacitor is monitored, and the ground fault resistance, that is, the insulation resistance between the power supply line and the ground electrode is calculated from the charging voltage.

  In addition, a capacitor (capacitor) called a Y capacitor (line bypass capacitor) is connected between the high-voltage positive and negative power supply lines and the ground electrode in order to eliminate high-frequency noise from the power supply and stabilize the operation. Often done.

JP 2008-89322 A JP 2009-281986 A JP 2011-21990 A

  In the above-described flying capacitor type insulation state detection device, the current and voltage when charging the detection capacitor are affected by the Y capacitor. Even when the Y capacitor does not exist, the charging current and voltage of the detection capacitor change due to the influence of the stray capacitance existing between the wiring of the high voltage DC power supply output and the vehicle body.

  When such an insulation state detecting device measures the insulation resistance, the voltage is measured while switching the charging / discharging of the flying capacitor by turning on and off the switching element connected to the flying capacitor. Then, the insulation resistance is calculated from the measured voltage using a predetermined calculation formula. However, since the influence of the capacitance such as the Y capacitor appears in the measured voltage value, a large calculation error occurs unless the influence of the capacitance is taken into consideration in the calculation formula. In particular, when the insulation resistance is large, the calculation error increases.

  However, the magnitude of the capacitance of the Y capacitor or the like is unknown, and the capacitance that affects the calculation result may vary greatly depending on the measurement situation such as the type of vehicle body to be inspected.

  Therefore, in order to reduce the calculation error of the insulation resistance, for example, the following processing is considered necessary. Before measuring the insulation resistance, the capacitance that affects the calculation results is measured using an appropriate measuring instrument in an actual measurement environment. Prepare a number of calculation formulas used for calculation of insulation resistance or capacitance parameters used by this calculation formula in advance, and select the calculation formula or parameters that match the actual capacitance by switching the switch. .

  However, extra work is required to measure the size of the capacitance, and it takes time to measure the insulation resistance. In addition, when switching the calculation formulas and parameters with switches that can be operated by the inspector, parts such as multiple switches must be added, and extra mounting space for the parts must be secured. It is disadvantageous in terms of cost and size. In addition, when software is rewritten in order to change a calculation formula or parameter, an extra interface must be added for rewriting, and rewriting work is also required.

  The present invention has been made in view of the above-described circumstances, and its purpose is to significantly increase the device cost even when the electrostatic capacitance such as a Y capacitor affecting the measurement of the insulation resistance is unknown. It is an object of the present invention to provide an insulation state detection device capable of measuring with high accuracy without incurring an extra work or an extra work by an inspector.

In order to achieve the above-described object, an insulation state detection device according to the present invention is characterized by the following (1) to (5).
(1) A positive-side input terminal and a negative-side input terminal connected to a positive-side power line and a negative-side power line for a predetermined high-voltage DC power output, respectively, and a ground electrode, and based on the charging voltage of the flying capacitor An insulation state detection device for grasping an insulation state between the positive electrode side power line and the negative electrode side power line and the ground electrode,
A ground fault resistance value calculation unit that outputs an insulation resistance value between the positive electrode side power supply line and the negative electrode side power supply line and the ground electrode based on a measured value related to the charging voltage of the flying capacitor and a predetermined calculation formula; ,
At least temporarily, a reference resistor having a known resistance value connected between the positive power line or the negative power line and the ground electrode;
In a test mode executed prior to normal measurement, based on the resistance value of the reference resistor, the positive-side capacitance between the positive-side power line and the ground electrode and the negative-side power line and the ground electrode A test mode control unit that grasps the influence of the negative electrode side capacitance between and a reflection of the influence of the capacitance on the processing content of the ground fault resistance value calculation unit,
Be provided.
(2) The insulation state detection device according to (1) above,
The ground fault resistance value calculation unit has a plurality of conversion maps having different capacitance sizes assumed by a calculation formula, and each of the plurality of conversion maps receives a measured value as a parameter. Output insulation resistance value,
The test mode control unit automatically selects one conversion map from the plurality of conversion maps according to the processing result of the test mode.
(3) The insulation state detection device according to (1) above,
The ground fault resistance value calculation unit has a conversion map for inputting the influence of the capacitance assumed by the measurement value and the calculation formula as a parameter and outputting the insulation resistance value,
The test mode control unit selects one influence amount from a plurality of influence amounts related to capacitance according to the processing result of the test mode, and gives the selected influence amount to the input of the conversion map.
(4) The insulation state detection device according to (1) above,
The reference resistor has a resistance value that is greater than a predetermined alarm threshold value that represents a criterion to be alarmed regarding leakage.
(5) The insulation state detection device according to (1) above,
The ground fault resistance value calculation unit has a conversion map for inputting a measurement value as a parameter and outputting an insulation resistance value based on a predetermined calculation formula,
The test mode control unit reversely calculates the calculation formula of the conversion map based on the error between the insulation resistance value obtained at the output of the conversion map in the test mode and the resistance value of the reference resistor, Capacitance for calculating a capacitance value corresponding to a positive-side capacitance between the positive-side power line and the ground electrode and a negative-side capacitance between the negative-side power line and the ground electrode Have a calculator.

According to the insulation state detection apparatus having the configuration (1), it is possible to perform highly accurate measurement without requiring an extra work by the inspector. That is, by connecting a reference resistor with a known resistance value in the test mode, the influence of the capacitance that is affected in the actual measurement environment is automatically reflected in the processing content of the ground fault resistance value calculation unit. The Therefore, even if the capacitance of the Y capacitor or the like is unknown, the measurement error of the insulation resistance can be reduced.
According to the insulation state detection device having the configuration (2), one conversion map suitable for the magnitude of the capacitance affected in the actual measurement environment is automatically selected. Even if the capacitance is unknown, the measurement error of the insulation resistance can be reduced.
According to the insulation state detection apparatus having the configuration (3), one influence amount suitable for the magnitude of the electrostatic capacitance affected in the actual measurement environment is automatically selected and input to the conversion map. Even if the capacitance of the Y capacitor or the like is unknown, the measurement error of the insulation resistance can be reduced.
According to the insulation state detection device having the configuration (4), since the reference resistor having a relatively large resistance value is used, the affected capacitance can be detected with higher sensitivity. Further, by making the resistance value of the reference resistor sufficiently larger than the alarm threshold value, it is possible to carry out normal measurement while the reference resistor is connected. Accordingly, it is possible to reduce the number of parts such as switches to be added, leading to cost reduction of the apparatus.
According to the insulation state detection device having the configuration of (5) above, an inspector or the like can know the magnitude of the electrostatic capacitance that is affected in the measurement of the insulation resistance. Therefore, this insulation state detection device can be used as a capacitance measuring device.

  According to the insulation state detection device of the present invention, even if the capacitance of the Y capacitor or the like that affects the measurement of insulation resistance is unknown, the cost of the device is significantly increased or the inspector's extra work is performed. High-precision measurement is possible without the need for That is, by connecting a reference resistor with a known resistance value in the test mode, the influence of the capacitance that is affected in the actual measurement environment is automatically reflected in the processing content of the ground fault resistance value calculation unit. The Therefore, even if the capacitance of the Y capacitor or the like is unknown, the measurement error of the insulation resistance can be reduced.

  The present invention has been briefly described above. Further, the details of the present invention will be further clarified by reading through a mode for carrying out the invention described below (hereinafter referred to as “embodiment”) with reference to the accompanying drawings. .

FIG. 1 is an electric circuit diagram illustrating a circuit configuration of an insulation state detection device according to an embodiment. FIG. 2 is a block diagram illustrating a configuration example (1) of the conversion map. FIG. 3 is a flowchart showing the main operation (1) of the insulation state detection device. FIG. 4 is a graph showing the relationship between the magnitude of the ground fault resistance value and the magnitude of the measurement error. FIG. 5 is a block diagram illustrating a configuration example (2) of the conversion map. FIG. 6 is a flowchart showing the main operation (2) of the insulation state detection device. FIG. 7 is a flowchart showing the main operation (3) of the insulation state detection device. FIG. 8 is a time chart showing a specific example of the switching timing of each switching element during measurement.

  Specific embodiments relating to the insulation state detection device of the present invention will be described below with reference to the drawings.

<Device configuration>
FIG. 1 shows an example of the configuration of the insulation state detection device 10 in this embodiment and a connection example at the time of measurement. A DC high-voltage power supply 50 shown in FIG. 1 is mounted on a vehicle such as an electric vehicle, and outputs high-voltage DC power of about 200V.

  The positive electrode side power supply line 111 of the output of the DC high voltage power supply 50 and the ground electrode 103 are electrically insulated. The negative power supply line 112 and the ground electrode 103 are also electrically insulated. The ground electrode 103 corresponds to an earth part such as a vehicle body. Here, the insulation state between the positive power line 111 and the ground electrode 103 can be expressed as a ground fault resistance (RLp). Further, the insulation state between the negative power supply line 112 and the ground electrode 103 can be expressed as a ground fault resistance (RLn).

  In order to reduce common mode noise, as shown in FIG. 1, a Y capacitor 101 is connected between the positive power line 111 and the ground electrode 103, and between the negative power line 112 and the ground electrode 103. A Y capacitor 102 is connected to this.

  The insulation state detection device 10 is used to detect ground fault resistances RLp and RLn at the output of the DC high-voltage power supply 50 and grasp the insulation state. When detecting the ground fault resistances RLp and RLn, as shown in FIG. 1, the positive side input terminal 13 and the negative side input terminal 14 of the insulation state detection device 10 are connected to the positive side power line 111 and the negative side power line 112, respectively. Connect with. Further, the ground electrode 15 of the insulation state detection device 10 is connected to the ground electrode 103.

  As shown in FIG. 1, the circuit of the insulation state detection device 10 is provided with a detection capacitor C1 that operates as a flying capacitor. Further, in order to control charging and discharging of the detection capacitor C1, five switching elements S1 to S5 are provided in the vicinity thereof. Each of these switching elements S1 to S5 is a switch such as an optical MOSFET capable of switching the open / close (off / on) state of the contact by controlling an insulated signal.

  One end of the switching element S1 is connected to the positive input terminal 13 via the wiring 31 and the resistor R11, and the other end is connected to the wiring 33. The switching element S2 has one end connected to the negative input terminal 14 via the wiring 32 and the resistor R12, and the other end connected to the wiring 34.

  The switching element S <b> 3 has one end connected to the wiring 33 and the other end connected to the wiring 35. The switching element S4 has one end connected to the wiring 34 and the other end connected to the ground electrode 15 via the resistor R4.

  The detection capacitor C <b> 1 has a negative terminal connected to the wiring 34. The positive terminal of the detection capacitor C1 is connected to the wiring 33 via a series circuit including a diode D0 and a resistor R1. The positive terminal of the detection capacitor C1 is connected to the wiring 33 via a series circuit including a diode D1 and a resistor R6.

  The switching element S5 has one end connected to the cathode of the diode D1 and the other end connected to the ground electrode 15 via the resistor R5. The wiring 35 is connected to the ground electrode 15 through the resistor R3.

  In the present embodiment, a reference resistor Rref is connected between the negative power supply line 112 and the ground electrode 103 as a characteristic component. The reference resistor Rref is an electric resistance whose resistance value is known, and is connected specifically for a test mode to be described later. The resistance value of the reference resistor Rref is, for example, a value sufficiently larger than the alarm threshold value shown in FIG. 4, and is practically set to a resistance value of about several hundred kΩ.

  In the circuit configuration of FIG. 1, the reference resistor Rref is directly connected to the negative power supply line 112, but may be connected via an appropriate switch. That is, only the test mode requires the reference resistor Rref, and the reference resistor Rref may be disconnected from the negative power supply line 112 during normal measurement. Further, the reference resistor Rref may be connected between the positive power supply line 111 and the ground electrode 103.

  The microcomputer 11 executes various controls required for the insulation state detection device 10 by executing a program incorporated in advance. Specifically, the microcomputer 11 controls the switching elements S1 to S5 individually to control charging and discharging of the detection capacitor C1. Further, the microcomputer 11 inputs an analog level corresponding to the charging voltage of the detection capacitor C1 through the input circuit 20 and the wiring 36, performs calculation based on the input level, and grasps the ground fault resistances RLp and RLn. To do.

  In the present embodiment, the microcomputer 11 is equipped with a conversion map 11a corresponding to a calculation formula for calculating the ground fault resistance based on the analog level input from the wiring 36 to the microcomputer 11. In this embodiment, a plurality of conversion maps are provided as shown in FIG. This conversion map is a memory that holds all calculation results calculated in advance for various input values as a set of data. By using the conversion map, the actual calculation can be omitted or simplified.

  A test mode switch 12 is connected to the input port of the microcomputer 11. When the user operates the test mode switch 12, the microcomputer 11 can start the test mode operation.

  Further, the output port of the microcomputer 11 is connected to the output connector 21 in order to output a measured value of ground fault resistance, an alarm, or the like. The output of the output connector 21 can be connected to, for example, a display for displaying numerical values or an alarm buzzer.

<Configuration example of conversion map (1)>
A configuration example of the conversion map 11a in the present embodiment is shown in FIG. In the example shown in FIG. 2, it is assumed that five conversion maps MP11, MP12, MP13, MP14, and MP15 that are independent from each other are provided. However, the number of conversion maps that are actually mounted is increased or decreased as necessary. be able to.

  The conversion maps MP11 to MP15 shown in FIG. 2 hold the results of calculating the calculation formulas assuming different capacitances C. The assumed capacitance C is the capacitance that affects the measurement of the ground fault resistances RLp and RLn, that is, in the vicinity of the Y capacitors 101 and 102, the positive power supply line 111, the negative power supply line 112, and the like. It means the capacitance of stray capacitance. Such a capacitance C is often unknown unless it is measured in advance using a dedicated measuring instrument, and may vary greatly depending on the environment. Therefore, a plurality of conversion maps MP11 to MP15 are prepared corresponding to the unknown capacitance C.

  That is, the conversion map MP11 holds data of calculation results corresponding to the calculation formula assuming the first capacitance C (1). Similarly, the conversion map MP12 corresponds to a calculation formula assuming the second capacitance C (2), and the conversion map MP13 corresponds to a calculation formula assuming the third capacitance C (3). The map MP14 corresponds to a calculation formula assuming the fourth capacitance C (4), and the conversion map MP15 corresponds to a calculation formula assuming the fifth capacitance C (5).

  The microcomputer 11 outputs the ground fault resistances RLp and RLn calculated by selectively using any one of the prepared conversion maps MP11 to MP15 as measurement results. Further, a test mode is executed in order to select an optimum conversion map from the plurality of conversion maps MP11 to MP15.

<Relationship between selected conversion map and measurement error>
A specific example of the relationship between the magnitude of the ground fault resistance value and the magnitude of the measurement error is shown in FIG. As shown in FIG. 4, when the selected conversion map is not appropriate, a large measurement error occurs.

  That is, when the capacitance C (n) assumed by the selected nth conversion map is larger than the actual capacitance of the Y capacitor 101 or the like, the plus side deviation is the ground fault resistance RLp. And appear in the measurement result of RLn. Conversely, when the capacitance C (n) assumed by the selected nth conversion map is smaller than the actual capacitance of the Y capacitor 101 or the like, the minus-side deviation is the ground fault resistance. It appears in the measurement results of RLp and RLn. Further, the amount of deviation that occurs tends to increase as the ground fault resistance value increases as shown in FIG.

  Therefore, it is important to select an optimal conversion map that assumes a capacitance C that matches the actual capacitance of the Y capacitor 101 or the like. Thereby, it can prevent that the measurement result of ground fault resistance RLp and RLn shifts from an actual value. As will be described later, in the present embodiment, one optimal conversion map can be automatically selected.

<Operation of the device>
<Description of Charging / Discharging of Capacitor for Detection (Flying Capacitor) C1>
<Timing for switching>
A specific example of the switching timing of the switching elements S1 to S5 at the time of measurement is shown in FIG. That is, when measuring the ground fault resistances RLp and RLn, the microcomputer 11 controls on / off of the switching elements S1 to S5 according to the basic measurement cycle as shown in FIG. 8 and is necessary for calculating the ground fault resistance. Get the measured value.

  The basic measurement cycle shown in FIG. 8 includes “V0 charge”, “measurement”, “discharge”, “Vc1-charge”, “measurement”, “discharge”, “V0 charge”, “measurement”, “discharge”, “Vc1 + charge”, “measurement”, and “discharge” are connected in series.

  In the “V0 charging” section at time t1-t2, the switching elements S1 and S2 are turned on (contacts closed), and the other switching elements are turned off (contacts open). In the “measurement” section at time t2-t3, the switching elements S3 and S4 are turned on, and the other switching elements are turned off.

  In the “discharge” section from time t3 to t4, the switching elements S4 and S5 are turned on, and the other switching elements are turned off. In the “Vc1-charge” section at time t4-t5, the switching elements S1 and S4 are turned on, and the other switching elements are turned off.

  The “measurement” section at time t5-t6 is the same as the “measurement” section at time t2-t3. Further, the “discharge” section at time t6-t7 is the same as the “discharge” section at time t3-t4. The “V0 charging” section from time t7 to t8 is the same as the “V0 charging” section from time t1 to t2. The subsequent “measurement” section from time t8 to t9 is the same as the “measurement” section from time t2 to t3. Further, the “discharge” section from time t9 to t10 is the same as the “discharge” section from time t3 to t4.

  In the “Vc1 + charge” section from time t10 to t11, the switching elements S2 and S3 are turned on, and the other switching elements are turned off. The “measurement” section at time t11-t12 is the same as the “measurement” section at time t2-t3. The “discharge” section from time t12 to t13 is the same as the “discharge” section from time t3 to t4.

<Energization path and operation in each section of measurement cycle>
"V0 charge" section:
Since the contact of the switching element S1 is closed, a current flows from the positive power supply line 111 to the positive terminal of the detection capacitor C1 through the positive input terminal 13, the wiring 31, the switching element S1, the diode D0, and the resistor R1. Flowing. Further, since the contact point of the switching element S2 is closed, a current flows from the negative terminal of the detection capacitor C1 to the wiring 34, the switching element S2, the wiring 32, the negative input terminal 14, and the negative power line 112. Therefore, the electric charge is charged in the detection capacitor C1 by this current.

“Measurement” section:
Since the contact of the switching element S4 is closed, the negative terminal of the detection capacitor C1 is connected to the ground electrode 15 via the resistor R4. Further, since the contact of the switching element S3 is closed, the positive terminal of the detection capacitor C1 is connected to the microcomputer 11 via the diode D1, the resistor R6, the switching element S3, the wiring 35, the input circuit 20, and the wiring 36. Connected to analog input port. Therefore, the microcomputer 11 can detect an analog level proportional to the charging voltage of the detection capacitor C1.

“Discharge” section:
Since the contact of the switching element S4 is closed, the negative terminal of the detection capacitor C1 is connected to the ground electrode 15 via the resistor R4. Further, since the contact of the switching element S5 is closed, the positive terminal of the detection capacitor C1 is connected to the ground electrode 15 via the diode D1, the switching element S5, and the resistor R5. Therefore, the electric charge accumulated in the detection capacitor C1 is discharged.

"Vc1-charge" section:
Since the contact of the switching element S1 is closed, a current flows from the positive power supply line 111 to the positive terminal of the detection capacitor C1 through the positive input terminal 13, the wiring 31, the switching element S1, the diode D0, and the resistor R1. Flowing. Further, since the contact of the switching element S4 is closed, the negative power supply line from the negative terminal of the detection capacitor C1 passes through the switching element S4, the resistor R4, the ground electrode 15, the ground electrode 103, and the ground fault resistor RLn. A current flows through 112. This current charges the detection capacitor C1. The charging voltage at this time is a result reflecting the influence of the ground fault resistance RLn.

“Vc1 + charging” section:
Since the contact point of the switching element S3 is closed, the positive side power line 111 passes through the ground fault resistance RLp, the ground electrode 103, the ground electrode 15, the resistor R3, the switching element S3, the diode D0, and the resistor R1 for detection. A current flows through the positive terminal of the capacitor C1. Further, since the contact point of the switching element S2 is closed, a current flows from the negative terminal of the detection capacitor C1 to the wiring 34, the switching element S2, the wiring 32, the negative input terminal 14, and the negative power line 112. This current charges the detection capacitor C1. The charging voltage at this time is a result reflecting the influence of the ground fault resistance RLp.

<Basic grounding resistance measurement operation>
Regarding the operation of the insulation state detection device 10 shown in FIG. 1, the following relational expression is basically established.
(RLp + RLn) / (RLp × RLn) = {(Vc1 +) + (Vc1-)} / Vc1
However,
Vc1: Charging voltage Vc1 of the detection capacitor C1 corresponding to the output voltage of the DC high-voltage power supply 50: Charge voltage Vc1 + of the detection capacitor C1 affected by the negative side ground fault resistance RLn: Positive side ground fault resistance RLp Voltage RLp, RLn of the detection capacitor C1 affected by the resistance: resistance value of the local resistance

  Therefore, the microcomputer 11 grasps each charging voltage “Vc1”, “Vc1−”, “Vc1 +” from the signal level input to the analog input port in each state, and the ground fault resistance RLp, RLn can be calculated.

<Explanation of measurement error>
On the other hand, the Y capacitors 101 and 102 connected to the output of the DC high-voltage power supply 50 and the stray capacitance existing between the positive-side power supply line 111 and the negative-side power supply line 112 and the ground electrode 103 are output from the DC high-voltage power supply 50. It is charged by the current that flows.

  The charged state of the Y capacitors 101, 102, etc. is stable and does not change in the steady state. However, in the “Vc1−charge” section, the charge on the positive Y capacitor 101 is discharged, and the charge including the discharged charge is charged on the detection capacitor C1. In the “Vc1 + charge” section, the charge on the negative Y capacitor 102 is discharged, and the charge including the discharged charge is charged into the detection capacitor C1.

  Therefore, the charging voltages “Vc1−” and “Vc1 +” detected by the microcomputer 11 include the influence of the Y capacitors 101 and 102 and the like. Therefore, a measurement error occurs unless calculation is performed on the assumption of the influence of the electrostatic capacity of the Y capacitors 101 and 102 and the like. However, since the actual capacitances such as the Y capacitors 101 and 102 and the stray capacitance are unknown, the capacitance assumed by the calculation formula does not necessarily match the actual capacitance. Therefore, a measurement error as shown in FIG. 4 occurs.

<Operation to reduce measurement error>
In the present embodiment, as shown in FIG. 2, the microcomputer 11 includes a plurality of independent conversion maps MP <b> 11 to MP <b> 15 having different assumed capacitances C (n). Therefore, the measurement error of the ground fault resistances RLp and RLn can be reduced by appropriately selecting and using any one of the conversion maps MP11 to MP15. However, in a situation where the actual capacitances such as the Y capacitors 101 and 102 and the stray capacitance are unknown, it is also unknown which of the conversion maps MP11 to MP15 is appropriate. A test mode described later is executed to automatically select an appropriate conversion map.

<Operation of Microcomputer 11>
The main operations of the insulation state detection apparatus 10 are shown in FIG. The microcomputer 11 shown in FIG. 1 can execute the operation shown in FIG. Each step in FIG. 3 will be described below.

  In step S11, a plurality of conversion maps having different capacitances assumed by the calculation formula are prepared so as to cope with differences in capacitances such as Y capacitors 101 and 102 and stray capacitances. In the present embodiment, since a plurality of conversion maps MP11 to MP15 as shown in FIG. 2 are prepared in advance on the internal memory of the microcomputer 11, the microcomputer 11 accesses the internal memory and converts the conversion maps MP11 to MP15. Can be obtained.

  Steps S12 to S16 correspond to an operation in a test mode specially provided for automatically selecting an appropriate conversion map. That is, prior to normal measurement, the microcomputer 11 performs an operation in a test mode in order to select a conversion map in accordance with an actual measurement environment. Actually, for example, when the user operates the test mode switch 12 shown in FIG. 1 and gives an instruction to the microcomputer 11, the test mode can be started.

  In step S <b> 12, as shown in FIG. 1, a reference resistor Rref having a known resistance value is connected between the negative power supply line 112 and the ground electrode 103. When the reference resistor Rref is connected from the beginning as shown in FIG. 1, nothing needs to be done in S12. The reference resistor Rref may be connected between the positive power supply line 111 and the ground electrode 103. Further, as shown in FIG. 4, the resistance value of the reference resistor Rref is set to a value sufficiently larger than the alarm threshold value of the ground fault resistance value.

  In step S <b> 13, the microcomputer 11 controls on / off of the switching elements S <b> 1 to S <b> 5 according to the basic measurement cycle as shown in FIG. 8 and acquires a measurement value necessary for calculating the ground fault resistance.

  In step S14, the microcomputer 11 sequentially selects a plurality of conversion maps MP11 to MP15, inputs the measured values acquired in the previous S13 to each selected conversion map, and calculates the ground fault resistance value for each map. To get.

  In step S15, the microcomputer 11 compares the plurality of ground fault resistance values obtained in S14 with the resistance value of the reference resistor Rref, and obtains a plurality of conversion maps in which the ground fault resistance value closest to Rref is obtained. The conversion maps MP11 to MP15 are selected.

  In step S16, the microcomputer 11 ends this test mode and shifts to the normal measurement mode while maintaining the selection state of the conversion map selected in S15.

  In the normal measurement mode, the user switches the measurement object as necessary. That is, the connection target object (vehicle or the like) of the positive electrode side input terminal 13 and the negative electrode side input terminal 14 of the insulation state detection device 10 is changed. For example, when the ground fault resistance of a large number of vehicles of the same vehicle type is inspected in order, the inspection can be continued in the normal mode without switching the conversion map to be used after one test mode is completed.

  In step S17, the microcomputer 11 controls on / off of the switching elements S1 to S5 according to the basic measurement cycle as shown in FIG. 8 in the same manner as in S13, and acquires a measurement value necessary for calculating the ground fault resistance.

  In step S18, the measured value acquired in S17 is input to one selected conversion map, and the ground fault resistance value Rx as a calculation result is acquired from the output of the conversion map.

  In step S19, the microcomputer 11 compares the ground fault resistance value Rx acquired in S18 with the alarm threshold value Rth (see FIG. 4). If the condition of “Rx <Rth” is satisfied, the process proceeds to S20, and if the condition is not satisfied, the process proceeds to S21.

  In step S <b> 20, the microcomputer 11 outputs a predetermined control signal to the output connector 21 in order to output an alarm regarding the ground fault resistance value.

  In step S <b> 21, the microcomputer 11 outputs information on the ground fault resistance value Rx acquired in S <b> 18 or information indicating “no ground fault (inspection OK)” to the output connector 21.

<Modification 1>
A configuration example (2) of the conversion map is shown in FIG. In this modification, the microcomputer 11 uses the single conversion map MP2 shown in FIG. Other circuit configurations are the same as those in FIG.

  As shown in FIG. 5, the conversion map MP2 is a map corresponding to a calculation formula using the capacity parameter Pc and the measured value as input parameters, and all the calculation results corresponding to each value of the parameter are collected as a set of data. Pre-held. That is, by inputting the capacitance parameter Pc and the measured value to the conversion map MP2, the ground fault resistance value as a calculation result can be immediately output.

  However, in a normal situation, as described above, the size of the capacitance including the influence of the Y capacitors 101 and 102 to be inspected and the stray capacitance is unknown. Therefore, when the conversion map MP2 of FIG. 5 is used, a correct value cannot be output as the ground fault resistance value unless an appropriate value is given as the capacitance parameter Pc.

  The main operation (2) of the insulation state detection device is shown in FIG. In this modification, the microcomputer 11 executes the operation shown in FIG. 6 and automatically determines an appropriate capacity parameter Pc in the test mode.

  Regarding the operation shown in FIG. 6, the steps of S11B, S14B, S15B, S16B, and S18B are different from the contents of FIG. Each step different from the content of FIG. 3 will be described below.

  In step S11B, a conversion map MP2 as shown in FIG. 5 corresponding to a calculation formula using the capacitance as one input parameter is prepared so as to cope with the difference in capacitance such as the Y capacitors 101 and 102 and the stray capacitance. Keep it. In the present embodiment, since the conversion map MP2 as shown in FIG. 5 is prepared in advance on the internal memory of the microcomputer 11, the microcomputer 11 can access the internal memory and acquire the conversion map MP2.

  In step S14B, the values of a plurality of capacitance parameters Pc prepared in advance are selected in order, and each capacitance parameter Pc and the measured value acquired in the previous S13 are input to the conversion map MP2, and the ground fault resistance value for each value of Pc. Get the calculation result of.

  In step S15B, the microcomputer 11 compares the plurality of ground fault resistance values obtained in S14B with the resistance value of the reference resistor Rref, and the ground fault resistance value closest to Rref among the plurality of Pc is obtained. One Pc value is selected.

  In step S16B, the microcomputer 11 ends this test mode and shifts to the normal measurement mode while maintaining the state where the value of the one capacitance parameter Pc selected in S15 is selectively input to the conversion map MP2.

  In step S18B, the microcomputer 11 inputs the selected capacitance parameter Pc and the measured value acquired in S17 to the conversion map MP2, and acquires the ground fault resistance value Rx as a calculation result from the output of the conversion map. .

<Modification 2>
A modified example in which a function of outputting the above-described Y capacitors 101 and 102 and a capacitance value such as stray capacitance is added will be described below.

  FIG. 7 shows the main operation (3) of the insulation state detection device 10 in this modification. In FIG. 7, each step of S21C, S31, and S32 is different from FIG. Each step different from the content of FIG. 3 will be described below. The configuration of the electric circuit assumed in this modification is the same as that shown in FIG.

  In step S31, the microcomputer 11 calculates the ground fault resistance value Rt output as a calculation result from one conversion map (any of MP11 to MP15) selected in the previous S15, and the resistance value of the reference resistor Rref. A difference (calculation error) ΔR is calculated.

  In step S32, the microcomputer 11 applies the difference (calculation error) ΔR obtained in S31 to the calculation formula corresponding to one conversion map (any of MP11 to MP15) selected in S15, and performs the calculation. The capacitance Cx is calculated by calculating back the equation.

  For example, when the conversion map MP13 shown in FIG. 2 is selected in S15, the calculation formula corresponding to MP13 has calculated the ground fault resistance value Rt based on the assumed capacitance C (3). The capacitance C (3) is also shifted by the difference (calculation error) ΔR of the ground fault resistance value. By reversely calculating the calculation formula of MP3, the deviation of the capacitance C (3) can be corrected by the difference (calculation error) ΔR, and the result can be calculated as the capacitance Cx.

  In step S21C, the microcomputer 11 outputs the information on the ground fault resistance value Rx acquired in S18 or the information indicating “no ground fault (inspection OK)” and the value of the capacitance Cx calculated in S32 on the output connector 21. Output to.

<Possibility of other deformations>
In the electric circuit shown in FIG. 1, the reference resistor Rref is directly connected to the negative power supply line 112 and the ground electrode 103, but may be connected via an appropriate switch. In addition, the microcomputer 11 controls the switch, and at a timing other than when the test mode is executed, the switch can be released to control the reference resistor Rref to be disconnected from the circuit.

  In the electric circuit shown in FIG. 1, the test mode switch 12 is provided to instruct the start of the test mode, but the test mode switch 12 can be omitted. For example, the microcomputer 11 can automatically start the test mode every time the operation of the microcomputer 11 is started, periodically, or when other specific conditions are satisfied.

<Supplementary explanation>
(1) The insulation state detection apparatus 10 shown in FIG. 1 includes a positive input terminal (111) connected to a positive power supply line (111) and a negative power supply line (112) of a predetermined high-voltage DC power supply (50). 13) and a negative electrode side input terminal (14), and a ground electrode (15), and based on the charging voltage of the flying capacitor (C1), between the positive electrode side power line and the negative electrode side power line and the ground electrode Grasping the insulation state. Moreover, based on the measured value regarding the charging voltage of the flying capacitor and a predetermined calculation formula, a ground fault resistance value for outputting an insulation resistance value between the positive power line and the negative power line and the ground electrode is calculated. A reference resistor (Rref) having a known resistance value connected at least temporarily between the positive power supply line or the negative power supply line and the ground electrode; In the test mode that is executed in advance, based on the resistance value of the reference resistor, the positive-side capacitance between the positive-side power line and the ground electrode and the negative-side power line and the ground electrode A test mode control unit (11, S12 to S16) that grasps the influence of the negative electrode side capacitance and reflects the influence of the capacitance on the processing content of the ground fault resistance value calculation unit.

  (2) Moreover, as shown in FIG. 2, the said ground fault resistance value calculation part has several different mutually the magnitude | sizes of the electrostatic capacitance (C (1) -C (5)) which the calculation formula assumes. Each of the plurality of conversion maps has a measured value as a parameter and outputs an insulation resistance value. Also, as shown in FIG. 3, the test mode control unit automatically selects one conversion map from the plurality of conversion maps according to the processing result of the test mode (S15, S16).

  (3) Further, as shown in FIG. 5, the ground fault resistance value calculation unit has a conversion map MP2 that inputs the measurement value and the influence of the capacitance assumed by the calculation formula as a parameter and outputs an insulation resistance value. . Further, as shown in FIG. 6, the test mode control unit selects one influence amount from a plurality of influence amounts related to the capacitance according to the processing result of the test mode, and gives it to the input of the conversion map ( S14B, S15B, S16B).

  (4) Further, as shown in FIG. 4, the reference resistor (Rref) has a resistance value that is larger than a predetermined alarm threshold value that indicates a criterion to be alarmed regarding electric leakage.

  (5) Moreover, the said ground fault resistance value calculation part has a conversion map which inputs a measured value as a parameter and outputs an insulation resistance value based on a predetermined | prescribed calculation formula. Further, as shown in FIG. 7, the test mode control unit performs the conversion based on an error between the insulation resistance value obtained in the output of the conversion map in the test mode and the resistance value of the reference resistor. By reversely calculating the map calculation formula, the electrostatic capacity corresponding to the positive-side capacitance between the positive-side power line and the ground electrode and the negative-side capacitance between the negative-side power line and the ground electrode is calculated. It has a capacitance calculation unit (11) that calculates a capacitance value (S31, S32).

DESCRIPTION OF SYMBOLS 10 Insulation state detection apparatus 11 Microcomputer 11a, MP11, MP12, MP13, MP14, MP15, MP2 Conversion map 12 Test mode switch 13 Positive side input terminal 14 Negative side input terminal 15 Ground electrode 20 Input circuit 21 Output connector 31-36 Wiring 50 DC high voltage power supply 101, 102 Y capacitor 103 Ground electrode 111 Positive power supply line 112 Negative power supply line C1 Detection capacitor (flying capacitor)
C2 Capacitor D0, D1 Diode Pc Capacitance parameter R1, R2, R3, R4, R5, R6, R11, R12 Resistor Rref Reference resistor RLp, RLn Ground fault resistance S1, S2, S3, S4, S5 Switching element

Claims (4)

A positive-side input terminal and a negative-side input terminal connected to a positive-side power line and a negative-side power line of a predetermined high-voltage DC power output, respectively, and a ground electrode, and the positive-side based on the charging voltage of the flying capacitor An insulation state detection device for grasping an insulation state between a power line and a negative side power line and the ground electrode,
A ground fault resistance value calculation unit that outputs an insulation resistance value between the positive electrode side power supply line and the negative electrode side power supply line and the ground electrode based on a measured value related to the charging voltage of the flying capacitor and a predetermined calculation formula; ,
At least temporarily, a reference resistor having a known resistance value connected between the positive power line or the negative power line and the ground electrode;
In a test mode executed prior to normal measurement, based on the resistance value of the reference resistor, the positive-side capacitance between the positive-side power line and the ground electrode and the negative-side power line and the ground electrode A test mode control unit that grasps the influence of the negative electrode side capacitance between and a reflection of the influence of the capacitance on the processing content of the ground fault resistance value calculation unit,
An insulation state detection device comprising: The ground fault resistance value calculation unit has a plurality of conversion maps having different capacitance sizes assumed by a calculation formula, and each of the plurality of conversion maps receives a measured value as a parameter. Output insulation resistance value,
The insulation state detection device according to claim 1, wherein the test mode control unit automatically selects one conversion map among the plurality of conversion maps according to a processing result of the test mode. The ground fault resistance value calculation unit has a conversion map for inputting the influence of the capacitance assumed by the measurement value and the calculation formula as a parameter and outputting the insulation resistance value,
The test mode control unit selects one influence amount from a plurality of influence amounts related to capacitance according to the processing result of the test mode, and gives the selected influence amount to the input of the conversion map. The insulation state detection apparatus of description. The insulation state detection device according to claim 1, wherein the reference resistor has a resistance value that is greater than a predetermined alarm threshold value that indicates a criterion to be alarmed regarding electric leakage.

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