JP2003232825A - Detection method of insulation state of non-grounded power source, and insulation detection device using detection method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection method of the insulation state of a non- grounded power source capable of reducing the capacity of a data table used for determining a ground resistance value. <P>SOLUTION: In this detection method of the insulation state of the non- grounded power source, an address for referring to the data table of an insulation resistance value is calculated based on the number of data on the data table where data of a voltage value of a direct-current power source, a voltage value between both terminals of a capacitor when connecting the capacitor in series between the power source and a ground potential part during a time set beforehand, and the insulation resistance value of the power source to the ground potential part, and the insulation resistance value of the power source to the ground potential part is determined from the calculated address. Hereby, the ground resistance value RL can be determined by a single data table without requiring use of a plurality of data tables such as a threshold data table and a ground resistance value data table as before, to thereby reduce the capacity of the data table used for determining the ground resistance value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for detecting an insulation state of a non-grounded power source, and more particularly to a technique for detecting an insulation state suitable for a non-grounded DC power source mounted on a vehicle that uses electric propulsion. Regarding

[0002]

2. Description of the Related Art As a technique for detecting the insulation state of a non-grounded DC power source, the ground potential portion of the main circuit wiring on the positive and negative sides connected to the positive and negative terminals of the power source and insulated from the ground potential portion. Japanese Patent Application Laid-Open No. 8-226950 proposes a technique for detecting the insulation state with respect to the ground potential portion by detecting the insulation resistance to the ground, that is, the ground resistance. In such insulation state detection technology, the voltage between both terminals of the capacitor and the power source detected when the capacitor is connected in series between the positive terminal of the ungrounded DC power supply and the ground potential section for a preset time The insulation resistance to the ground potential portion of the power supply, that is, the ground fault resistance is calculated based on the voltage.

Here, the value RL of the ground fault resistance is obtained from an equation including logarithmic calculation such as the following equation (1) based on the voltage VC between both terminals of the capacitor and the power supply voltage V0. RL = −R−T / (C · ln (1−VC / V0)) (1) In the formula (1), R can connect a capacitor in series between the power supply and the ground potential portion. The value of the resistance provided between the power supply and the capacitor of the circuit, T is the time when the capacitor is connected in series between the power supply and the ground potential portion, C is the capacitance of the capacitor, and these resistance values R, The time T and the capacitance C of the capacitor are constants determined by the configuration of the insulation detecting device.

However, the equation including the logarithmic calculation such as the equation (1) takes a long time to perform the arithmetic operation, and this arithmetic operation time limits the time required for the detection cycle of the value of the ground fault resistance.
In some cases, the time required for the ground fault resistance detection cycle cannot be shortened to a desired time. Therefore, in equation (1), the value calculated by dividing the value of the voltage between both terminals of the capacitor, which is a variable that changes depending on the ground fault resistance value, by the value of the power supply voltage,
From the data table in which only the calculated value of / V0 is calculated and the ground fault resistance value calculated from equation (1) is arranged corresponding to the value of VC / V0, the ground fault resistance corresponding to the calculated value of VC / V0 is calculated. By calculating the value, it is possible to prevent logarithmic calculation and reduce the time required to calculate the ground fault resistance value.

In the conventional technique for detecting the insulation state of a non-grounded power source for obtaining the ground fault resistance value using such a data table, the threshold data table and the ground fault resistance value data table stored in the storage means are used. I am using. Then, first, by comparing the calculated value of VC / V0 with the threshold value, the threshold address which is an address for referring to the threshold data table is determined. Next, the ground fault resistance value address for referring to the ground fault resistance value data table is determined from the threshold value obtained from the threshold value data table by the determined threshold address, and the ground fault resistance value address is determined. The ground fault resistance value is obtained from the ground fault resistance value data table using the resistance value address.

[0006]

By the way, in the method for obtaining the ground fault resistance value using the data table in the conventional insulation state detection technique of the non-grounded power source as described above, the threshold data table and the ground fault resistance are used. You need multiple data tables, called value data tables. Therefore, in order to improve the detection accuracy of the insulation state, if the resolution of the detection of the ground fault resistance value is increased, the number of data in the threshold value data table and the ground fault resistance value data table is increased according to the resolution. There is a need. Therefore, as the number of data in the threshold value data table and the ground fault resistance value data table increases, the capacity required for the storage unit storing the threshold value data table and the ground fault resistance value data table increases. Will end up. Since the increase in the capacity of the storage means causes an increase in the cost of the storage means, it is desired to reduce the capacity of the data table used for obtaining the ground fault resistance value.

An object of the present invention is to reduce the capacity of the data table used for obtaining the ground fault resistance value.

[0008]

A method for detecting an insulation state of a non-grounded power supply according to the present invention is a method in which a capacitor is connected in series between a voltage value of a non-grounded DC power supply and a preset time between the power supply and a ground potential portion. Address for referencing the insulation resistance data table based on the voltage value between both terminals of this capacitor when connected to and the number of data on the data table in which the insulation resistance data for the ground potential part of the power supply is placed. Is solved and the insulation resistance value with respect to the ground potential portion of the power supply is calculated from the calculated address, thereby solving the above-mentioned problem.

Further, the insulation detecting apparatus of the present invention comprises a sensor unit having a circuit capable of connecting a capacitor in series between a non-grounded DC power source and a ground potential unit for a preset time, and a power source grounded. The sensor unit includes a storage unit that stores a data table in which data of insulation resistance values for the potential unit is stored, and a calculation unit that calculates an address for referring to the data table, and the sensor unit has a power supply for a preset time. When a capacitor is connected in series between the capacitor and the ground potential part, the voltage between both terminals of this capacitor is detected, and the calculation means is
The value of the voltage between both terminals of the capacitor detected by the sensor,
An address is calculated based on the voltage value of the power supply and the number of pieces of data in the data table stored in the memory, and the address calculated by the calculating means isolates the data table stored in the memory from the ground potential portion of the power supply. The above problem is solved by adopting a configuration for obtaining a resistance value.

With this configuration, one data table having the number of data corresponding to the resolution required according to the detection accuracy of the insulation state can be used to provide the insulation resistance value to the ground potential portion of the non-ground power source, that is, the ground fault. The resistance value can be calculated. Therefore, the capacity of the data table used to obtain the ground fault resistance value can be reduced.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an insulation detecting device to which the present invention is applied will be described below with reference to FIGS. FIG. 1 is a block diagram showing a schematic configuration and operation of an insulation detection device to which the present invention is applied. FIG. 2 is a diagram showing an example of a capacitor connection circuit of the sensor unit of the insulation detection device to which the present invention is applied. FIG. 3 is a time chart showing the charging / discharging state of the capacitor and the voltage reading timing with respect to the operation of each switch section in the sensor section of the insulation detecting device to which the present invention is applied. Figure 4
It is a flowchart which shows operation | movement of the insulation detection apparatus which applies this invention. FIG. 5 is a flow chart showing the process of detecting the insulation resistance value of the insulation detecting device to which the present invention is applied. Figure 6
FIG. 3 is a schematic diagram showing an example of a data table of an insulation detecting device to which the present invention is applied.

As shown in FIG. 1, the insulation detecting apparatus 1 of the present embodiment is applied to a DC power source 3 which is a power source of an electric propulsion vehicle or the like which uses electric power to obtain propulsive force. . The power source 3 is formed by connecting a plurality of storage batteries in series and is a non-grounded power source that is insulated from a ground potential portion such as a vehicle body. The insulation detection device 1 includes a sensor unit 9 having a capacitor connection circuit 5, A / D detection means 7, and the like,
The value detected by the sensor unit 9 is recorded, and the memory 11 for storing the table data in which the data of the insulation resistance value with respect to the ground potential part of the power supply 3, that is, the data of the ground fault resistance value is stored, the value recorded in the memory 11, etc. Based on the calculation means 13 for calculating an address for referring to the table data stored in the memory 11 based on the ground, and the occurrence of the ground fault by the ground fault resistance value obtained from the table data by the address calculated by the calculation means 13, that is, The ground fault detecting means 15 for detecting the insulation state is included.

As shown in FIG. 2, the power source 3 has a positive main circuit wiring 17a on the positive terminal side and a negative main circuit wiring 17b on the negative terminal side of the power source 3, each of which is at a ground potential portion 19, such as a vehicle body. It is insulated from and is a non-grounded power supply. The capacitor connection circuit 5 of the sensor unit 9 is connected to the positive terminal side of the power source 3 and the power source 3
, The first switch S1, the second switch S2, and the like are sequentially connected in series. Between the terminal located between the first switch S1 and the second switch S2 and the ground potential portion 19, the resistor R1 and the capacitor 21 are sequentially connected in series from this terminal side. Further, the sensor unit 9 has a first
It includes a switching control circuit (not shown) for closing the switch S1 and the second switch S2 at a preset timing for a preset time.

The A / D detecting means 7 of the sensor unit 9 is the power source 3
And the voltage between both terminals of the capacitor 21 of the capacitor connection circuit 5 are detected by analog / digital conversion, and are formed by, for example, a microcomputer having an A / D port. When the A / D detection means 7 is formed of a microcomputer having an A / D port, etc., the A / D port of this microcomputer is connected to the voltage of the power supply 3 and the capacitor 21 of the capacitor connection circuit 5 although not shown. Is appropriately connected to the capacitor connection circuit 5 via a circuit including a switch or the like that can detect the voltage between both terminals. Further, for example, a voltage detector that detects the voltage of the power supply 3 and a voltage detector that detects the voltage between both terminals of the capacitor 21 are separately connected to the power supply 3 and the capacitor connection circuit 5 as A / D detection means 7. It can also be configured.

When the A / D detecting means 7 is formed by a microcomputer, the calculating means 13, the ground fault detecting means 15, and a switching control circuit (not shown) as shown in FIG. The means 7 may be integrally formed in the formed microcomputer. In this way, the A / D detecting means 7, the calculating means 13, the ground fault detecting means 15, and the switching control circuit (not shown) are appropriately formed separately or integrally using a microcomputer or other circuits. it can.

The operation of the insulation detecting device having such a configuration and the characteristic part of the present invention will be described. As shown in FIGS. 3 and 4, the sensor unit 9 of the insulation detecting device 1 starts A / D detecting means when the first switch S1 and the second switch S2 are off, that is, when the insulation state is detected. The voltage value V0 of the power supply 3 is detected by 7 (step 101).
In step 101, for example, the A / D detection means 7 performs A / D
In the case of a microcomputer with a port, this microcomputer can be used for A / D
This is done by reading the conversion data.

After step 101, a switching control circuit (not shown) turns on or closes the first switch S1 for a preset closing time T, so that the power supply 3 and the ground potential part 19 are connected to each other. A circuit for connecting the capacitors 21 in series is formed. That is, as shown in FIG. 2, the positive side main circuit wiring 17a, the first switch S1, the resistor R
1, a capacitor 21, a ground potential portion 19, an insulation resistance, that is, a ground fault resistance Rn to the ground potential portion 19 on the negative terminal side, which is assumed to be at a position shown by a dotted line in FIG. 2, and a negative side main circuit wiring 17b are sequentially connected in series. A circuit connected to the power supply 3 is formed. As a result, the capacitor 21 is charged during the closing time T, and as shown in FIG.
The voltage between both terminals of the capacitor 21 increases according to the value of n. When the closing time T has elapsed, the first switch S1 is turned off, that is, cut off, and the voltage VC (−) between both terminals of the capacitor 21 at this time is read and detected by the A / D detection means 7 (step 102). .

After step 102, a switching control circuit (not shown) turns on or closes the second switch S2 for a preset closing time T, so that the power supply 3 and the ground potential portion 19 are connected. Capacitor 21 in between
A circuit for connecting the two in series is formed. That is, as shown in FIG. 1, the positive side main circuit wiring 17a, the ground potential portion 1 on the positive terminal side assumed at the position shown by the dotted line in FIG.
9. Insulation resistance to 9, that is, ground resistance Rp, ground potential section 1
A circuit is formed by sequentially connecting the capacitor 9, the resistor 21, the resistor R1, the second switch S2, and the negative side main circuit wiring 17b to the power supply 3 in series. As a result, the capacitor 21 is charged during the closing time T, and the voltage between both terminals of the capacitor 21 rises according to the value of the ground fault resistance Rp, as shown in FIG. After the closing time T has passed, the second switch S2 is turned off, that is, cut off, and the capacitor 21 at this time is turned off.
The voltage VC (+) between the two terminals is read and detected by the A / D detection means 7 (step 103).

In steps 101, 102 and 103, the voltage V0 of the power source 3 detected by the A / D detection means 7 and the voltages VC (-) and V between both terminals of the capacitor 21 are detected.
C (+) is recorded in the memory 11 as shown in FIG. As shown in FIGS. 1 and 4, the calculating means 13 calculates the ground fault from the voltages VC (−) and VC (+) between both terminals of the capacitor 21 recorded in the memory 11 according to the following equation (2). A voltage value VC used to obtain a ground fault resistance value RL representing the resistors Rn and Rp is calculated (step 10).
4). VC = VC (−) + VC (+) (2) After step 104, the voltage value V0 of the power supply 3 and step 1
Ground resistances Rn and R based on the voltage value VC calculated in 04.
A ground fault resistance value RL detection process for obtaining a ground fault resistance value RL representing p is performed (step 105).

In step 105, as shown in FIG. 5, when the address for referring to the ground fault resistance data table is a [b], the calculating means 13 calculates the following equation (3).
The address a [b] is calculated by obtaining b from (step 105a). b = INT ((VC * n) / V0) ... (3) In addition, in Formula (3), n is the number of data on a ground fault resistance data table.

After step 105a, step 105a
The ground fault resistance value RL is obtained from the ground fault resistance data table as illustrated in FIG. 6 by the address a [b] calculated in (step 105b). That is, in step 105b, the ground fault resistance value RL on the ground fault resistance value data table corresponding to the address a [b] calculated in step 105a is the ground fault resistance value RL detected in the process of detecting the insulation state. Becomes

After step 105, the ground fault detecting means 15
Depends on whether the ground fault resistance value RL obtained in step 105 is equal to or less than a preset resistance value for detecting the occurrence of the ground fault or higher than that, as shown in FIGS. 3 and 4. The occurrence of a ground fault, that is, the insulation state is determined (step 106). In step 106, when the ground fault resistance value RL obtained in step 105 is equal to or less than the preset resistance value, it is determined that the occurrence of the ground fault is detected, and, for example, the notification of the insulation failure or the insulation state Operations such as stop of detection are performed (step 107). On the other hand, in step 106, if the ground fault resistance value RL obtained in step 105 is higher than the preset resistance value, it is determined that the ground fault has not occurred, and the insulation state from step 101 to step 106 again. Repeat the detection cycle of (step 10
8).

Here, an example of the process of detecting the ground fault resistance value of the insulation detecting apparatus for obtaining the ground fault resistance value using the conventional data table will be shown. In the conventional insulation detecting device, as shown in FIG. 7, the ground fault resistance value R is determined by two kinds of data tables, that is, a threshold data table and a ground fault resistance value data table.
Seeking L. First, the voltage value V0 of the power source and the voltage value VC = VC between both terminals of the capacitor when the capacitor is connected in series between the power source and the ground potential portion for a set time.
VC / V0 is calculated from (−) + VC (+) (step 201). In the threshold address s [b], when b = 0 (step 202), the threshold corresponding to the threshold address s [0] is obtained from the threshold data table (step 203). The calculated threshold value is compared with the value of VC / V0 calculated in step 201 (step 204).

In step 204, when the value of VC / V0 is smaller than the obtained threshold value, the value of b is incremented by 1 (step 205), b = 1 is set, and step 2
Step 204 is performed from 03. If the value of VC / V0 is smaller than the obtained threshold value, steps 203 to 204 are repeated while increasing the value of b by 1 in step 205. Steps 203 to 204 are repeated while increasing the value of b by 1 in step 205, and in step 204, V
The ground fault resistance value address a [b] referring to the ground fault resistance data table is calculated from the threshold value when the value of C / V0 is equal to or higher than the obtained threshold value. That is, VC /
The ground fault resistance value address is calculated by using the threshold value when the value of V0 is equal to or greater than the obtained threshold value as b of the ground fault resistance value address a [b], and this ground fault resistance value address is calculated. The value of the data on the corresponding ground fault resistance value data table becomes the ground fault resistance value RL at this time (step 206).

As described above, the conventional insulation detecting device uses two data tables, that is, the threshold data table and the ground fault resistance data table. Therefore, in order to improve the detection accuracy of the insulation state, when trying to raise the resolution of the detection of the ground fault resistance value, the respective data of the threshold data table and the ground fault resistance value data table are The number will increase. Therefore, an increase in the number of data in the threshold value data table and the ground fault resistance value data table increases the capacity required for the storage means storing these data tables, and improves the detection accuracy of the insulation state. When trying to do so, it may be necessary to increase the capacity of the storage means used.

On the other hand, when the resolution of the calculated value of VC / V0 required when the detection accuracy of the ground fault resistance value RL is taken into consideration is 1 / n, the ground fault resistance value The number of ground fault resistance values RL arranged in the data table is n, and n corresponding to calculated values 1 / n of VC / V0 to n / n.
The ground fault resistance value RL is arranged on the data table. At this time, when the maximum integer that does not exceed the calculated value of (VC × n) / V0 is calculated, the value becomes 1 to n. That is, INT ((VC × n) /
Since the calculated value of V0) is 1 to n, the calculated value of this formula (3) corresponds to the first data arranged from the first data arranged in the data table for ground resistance value to the last data arranged in the nth data table. Can be made. Therefore, as in the insulation detection device 1 of the present embodiment, INT ((VC ×
By using the calculated value of n) / V0), it is possible to directly calculate the address for referring to the ground fault resistance data table without using the threshold data table.

As described above, the insulation detecting device 1 of the present embodiment
Corresponds to the voltage value V0 of the power supply, the voltage VC between both terminals of the capacitor when the capacitor is connected in series between the power supply and the ground potential portion for the set time, and the resolution according to the detection accuracy of the insulation state. It is possible to calculate an address for referencing the ground fault resistance value data table from the data number n of the ground fault resistance value RL, and obtain the ground fault resistance value RL from the data on the data table corresponding to the calculated address. it can. Therefore, it is possible to obtain the ground fault resistance value RL with one data table, and it is not necessary to use a plurality of data tables having the number of data corresponding to the resolution as in the conventional case. Therefore, the data used to obtain the ground fault resistance value can be obtained. The capacity of the table can be reduced.

Further, the insulation detecting apparatus 1 of the present embodiment does not use two data tables as in the conventional case, and further has no process for sequentially comparing the data on the threshold data table with the threshold. Therefore, the processing time required to detect the ground fault resistance value RL can be shortened.

Further, the present invention is not limited to the insulation detecting device having the configuration shown in the present embodiment, but a capacitor can be connected in series between the power source and the ground potential portion for a preset time, and the power source It is applied to insulation detection devices of various configurations that obtain the ground fault resistance based on the voltage value and the voltage between both terminals of this capacitor when a capacitor is connected in series between the power supply and the ground potential part for a preset time. be able to. In addition, the present invention provides the ground fault resistors Rn and Rp as in the present embodiment.
The present invention is not limited to the case of obtaining the ground fault resistance value RL representing the above, but can be applied to the case of separately obtaining the values of the ground fault resistances Rn and Rp.

[0030]

According to the present invention, the capacity of the data table used for obtaining the ground fault resistance value can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration and operation of an embodiment of an insulation detection device to which the present invention is applied.

FIG. 2 is a diagram showing an example of a capacitor connection circuit of a sensor section in an embodiment of an insulation detection device to which the present invention is applied.

FIG. 3 is a time chart showing a charge / discharge state of a capacitor and a voltage reading timing with respect to an operation of each switch unit in a sensor unit of an embodiment of an insulation detection device to which the present invention is applied.

FIG. 4 is a flowchart showing the operation of an embodiment of the insulation detection device to which the present invention is applied.

FIG. 5 is a flowchart showing a process of detecting an insulation resistance value in an embodiment of an insulation detection device to which the present invention is applied.

FIG. 6 is a schematic view showing an example of a data table in one embodiment of the insulation detection device to which the present invention is applied.

FIG. 7 is a diagram showing an example of a threshold value data table and a ground fault resistance value data table included in a conventional insulation detection device.

FIG. 8 is a flowchart showing an example of a process of detecting an insulation resistance value in a conventional insulation detection device.

[Explanation of symbols]

1 Insulation detector 3 power supplies 5 Capacitor connection circuit 7 A / D detection means 9 Sensor section 11 memory 13 Computing means 15 Ground fault detection means 19 Ground potential part 21 capacitor

Claims (2)

[Claims] 1. A voltage value of a non-grounded DC power source, a voltage value between both terminals of the capacitor when the capacitor is connected in series between the power source and a ground potential portion for a preset time,
And an address for referring to the data table of the insulation resistance value based on the number of data on the data table in which the data of the insulation resistance value with respect to the ground potential part of the power source is arranged, and the address is calculated from the calculated address. A method for detecting an insulation state of a non-grounded power supply, which comprises obtaining an insulation resistance value of the power supply from the ground potential portion. 2. A sensor unit having a circuit capable of connecting a capacitor in series between a non-grounded DC power source and a ground potential unit for a preset time, and an insulation resistance value of the power source with respect to the ground potential unit. Storage means for storing a data table in which the data of (1) are arranged, and a calculation means for calculating an address for referring to the data table, wherein the sensor unit is configured to operate the power supply and the ground for a preset time. The voltage between both terminals of the capacitor when the capacitor is connected in series with the potential part is detected, and the calculating means detects the value of the voltage between both terminals of the capacitor detected by the sensor part and the power supply. The address is calculated on the basis of the voltage value of the data and the number of data on the data table stored in the memory, and the address is stored in the memory by the address calculated by the arithmetic means. Insulation detecting apparatus comprising seeking insulation resistance from the data table for the ground potential portion of the power source.