JP5871160B2 - Earth leakage detector - Google Patents

Description

  The present invention relates to a leakage detection device that detects the presence or absence of leakage.

  Conventionally, there is a ground fault detection circuit disclosed in Patent Document 1, for example, as a leakage detection device that detects the presence or absence of leakage.

  The ground fault detection circuit includes a microcomputer, an oscillation output unit, an output impedance element, and a coupling capacitor. The microcomputer generates a pulse voltage having a predetermined frequency. The oscillation output unit amplifies and outputs the pulse voltage output from the microcomputer. The pulse voltage output from the oscillation output unit is applied to the high voltage battery via the output impedance element and the coupling capacitor. The high voltage battery has an insulation impedance composed of a ground insulation resistance and a ground parasitic capacitance. Therefore, a pulse voltage divided by the insulation impedance of the output impedance element and the high voltage battery is generated at the connection point between the output impedance element and the coupling capacitor. The peak value of the pulse voltage generated at the connection point between the output impedance element and the coupling capacitor varies depending on the insulation state of the high voltage battery. The microcomputer determines the presence or absence of a ground fault in the high-voltage battery based on the peak value of the pulse voltage generated at the connection point between the output impedance element and the coupling capacitor.

  By the way, the peak value of the pulse voltage generated at the connection point between the output impedance element and the coupling capacitor is changed not only by the insulation state of the high voltage battery but also by the deterioration of the elements constituting the ground fault detection circuit and the ambient temperature. Therefore, depending on the deterioration state of the elements that make up the ground fault detection circuit and the ambient temperature, it is judged that there is a ground fault despite the ground fault, or there is a ground fault despite the fact that there is no ground fault. There is a possibility that a ground fault may not be detected properly due to a false detection such as judging that the ground fault has occurred.

  On the other hand, a leakage detection device including an AC signal output circuit, an impedance circuit, a coupling capacitor, a first switching circuit, a reference impedance circuit, a second switching circuit, and a leakage determination circuit has been proposed. ing.

  One end of the impedance circuit is connected to the output end of the AC signal output circuit. One end of the coupling capacitor is connected to the other end of the impedance circuit, and the other end is connected to a leakage detection target. The first switching circuit is provided between the coupling capacitor and the leakage detection target, and connects or disconnects the other end of the impedance circuit to the leakage detection target. The second switching circuit is connected between the coupling capacitor and the first switching circuit, and connects or disconnects the other end of the impedance circuit from the reference impedance circuit. Prior to determining leakage, the leakage determination circuit controls the first switching circuit to disconnect the other end of the impedance circuit from the leakage detection target, and controls the second switching circuit to connect the other end of the impedance circuit to the reference impedance. Connect to the circuit and detect the peak value of the AC signal at the other end of the impedance circuit to obtain the reference peak value. Thereafter, the second switching circuit is controlled to disconnect the other end of the impedance circuit from the reference impedance circuit, and the first switching circuit is controlled to connect the other end of the impedance circuit to the leakage detection target and the other end of the impedance circuit. Based on the peak value of the alternating current signal and the detected reference peak value, the presence / absence of leakage of the leakage detection target is determined. Thereby, it is possible to appropriately detect the leakage without being affected by deterioration of the elements constituting the leakage detection device or the ambient temperature.

JP 2003-274504 A

  However, in the above-described leakage detection device, the reference peak value must be obtained by controlling the first switching circuit and the second switching circuit prior to determination of leakage. Therefore, there is a problem that the period during which leakage can actually be determined is shortened.

  This invention is made | formed in view of such a situation, and it aims at providing the leakage detection apparatus which can fully ensure the period which can determine leakage.

  Therefore, as a result of intensive research and trial and error to solve this problem, the present inventors can determine the leakage by obtaining the reference peak value when noise is applied to the leakage detection target. The inventors have found that a sufficient period can be secured and have completed the present invention.

That is, the leakage detection device according to claim 1 is configured such that an AC signal output circuit that outputs an AC signal, an impedance circuit that is set to a predetermined impedance, one end connected to the output end of the AC signal output circuit, and one end A coupling capacitor connected to the other end of the impedance circuit , one end connected to the other end of the coupling capacitor, the other end connected to the leakage detection target, and the other end of the impedance circuit connected to the leakage detection target via the coupling capacitor Connected to or disconnected from the leakage detection target, a reference impedance circuit set to a reference impedance, one end connected to the other end of the coupling capacitor, and the other end connected to the reference impedance circuit , reference impedance circuit and the other end of impedance circuit through a coupling capacitor A second switching circuit that disconnects from the connection or reference impedance, and controls the first switching circuit to disconnect the other end of the impedance circuit from the leakage detection target, and controls the second switching circuit to reference the other end of the impedance circuit. Connect to the impedance circuit, detect the peak value of the AC signal at the other end of the impedance circuit and set it as the reference peak value, and then control the second switching circuit to disconnect the other end of the impedance circuit from the reference impedance circuit, The first switching circuit is controlled to connect the other end of the impedance circuit to the leakage detection target, and the presence / absence of leakage of the leakage detection target is determined based on the peak value of the AC signal at the other end of the impedance circuit and the obtained reference peak value. in leakage detecting device comprising: the earth leakage determination circuit that, the electric leakage determination circuit is output from the external device A predetermined signal indicating whether noise leakage detection target is applied, when the noise leakage detection target becomes aware that it is applied, the other end of impedance circuit controls the first switch circuit leakage Disconnecting from the detection target, controlling the second switching circuit to connect the other end of the impedance circuit to the reference impedance circuit, and detecting the peak value of the AC signal at the other end of the impedance circuit to obtain the reference peak value Features.

  When noise is applied to the leakage detection target, the second switching circuit is controlled to disconnect the other end of the impedance circuit from the reference impedance circuit, and the first switching circuit is controlled to disconnect the other end of the impedance circuit. Even if it is connected to the detection target and the peak value of the AC signal at the other end of the impedance circuit is detected, the correct peak value cannot be detected due to the influence of noise. For this reason, it is not possible to correctly determine the leakage of the leakage detection target. According to this configuration, the reference peak value is obtained when noise is applied to the leakage detection target, in which the leakage of the leakage detection target cannot be correctly determined. Therefore, it is possible to sufficiently ensure a period during which leakage can be determined. Since the other end of the impedance circuit is disconnected from the leakage detection target by controlling the first switching circuit, the correct reference peak value can be obtained without being affected by noise.

  The leakage detection device according to claim 2, wherein the leakage determination circuit controls the first switching circuit based on a predetermined signal output from an external device and indicating whether noise is applied to the leakage detection target. The other end of the impedance circuit is disconnected from the leakage detection target, the second switching circuit is controlled to connect the other end of the impedance circuit to the reference impedance circuit, and the peak value of the AC signal at the other end of the impedance circuit is detected. It is characterized by a reference peak value. According to this configuration, it is possible to know whether or not noise is applied to the leakage detection target based on the predetermined signal output from the external device. Therefore, the reference peak value can be reliably obtained when noise is applied to the leakage detection target.

  In the leakage detection device according to claim 3, the leakage detection target is a battery, the external device has a switching element, controls the charging device that charges the battery by switching the switching element, and the predetermined signal is The external device controls the charging device to indicate whether or not the battery is being charged. According to this configuration, it is possible to surely know whether or not noise is applied to the leakage detection target by a predetermined signal output from the external device.

  The leakage detection device according to claim 4 is characterized in that the leakage detection target is mounted on the vehicle and insulated from the vehicle body. According to this configuration, it is possible to sufficiently ensure a period during which leakage can be determined in the leakage detection target that is mounted on the vehicle and insulated from the vehicle body.

It is a circuit diagram of the earth-leakage detection apparatus in this embodiment. It is a timing chart for demonstrating operation | movement of the leak detection apparatus shown in FIG. It is a flowchart for demonstrating operation | movement of the leak detection apparatus shown in FIG.

  Next, the present invention will be described in more detail with reference to embodiments. In this embodiment, the example which applied the earth-leakage detection apparatus which concerns on this invention to the earth-leakage detection apparatus which detects the earth-leakage of the high voltage battery mounted in the hybrid vehicle is shown.

  First, the configuration of the leakage detection device of the present embodiment will be described with reference to FIG. Here, FIG. 1 is a circuit diagram of the leakage detection device in the present embodiment.

  A leakage detection device 1 shown in FIG. 1 is a device that detects leakage of a high-voltage battery B1 (leakage detection target, battery) mounted on a hybrid vehicle.

  Here, the high voltage battery B1 is a power source that supplies electric power to a motor for traveling in the hybrid vehicle. The high voltage battery B1 is insulated from the vehicle body. Therefore, an insulation resistance Rg and a stray capacitance Cg exist between the high voltage battery B1 and the vehicle body. One end of the insulation resistance Rg is connected to the high voltage battery B1, and the other end is grounded to the vehicle body. One end and the other end of the stray capacitance Cg are connected to one end and the other end of the insulation resistance Rg, respectively.

  The high voltage battery B1 is provided with a charging device CHG1 and a control device ECU1 (external device) in order to charge the high voltage battery B1. The charging device CHG1 is a device that boosts the DC voltage and supplies it to the high voltage battery B1 to charge the high voltage battery B1. Charging device CHG1 has a switching element, and boosts the DC voltage by switching the switching element to charge high-voltage battery B1. The charging device CHG1 is connected to the high voltage battery B1 and the control device ECU1. The control device ECU1 is a device that controls the charging device CHG1. Specifically, switching of the switching element of the charging device CHG1 is controlled. The control device ECU1 is also a device that outputs a predetermined signal indicating whether or not switching noise (noise) is applied to the high voltage battery B1 to the leakage detection device 1. Specifically, the charging device CHG1 is controlled to output a charging signal indicating whether or not the high voltage battery B1 is being charged. The control device ECU1 is connected to the charging device CHG1 and the leakage detection device 1 respectively.

  As shown in FIG. 1, the leakage detection device 1 includes an AC signal output circuit 10, a resistor 11 (impedance circuit), a coupling capacitor 12, a first changeover switch 13 (first changeover circuit), and a reference impedance circuit. 14, a second changeover switch 15 (second changeover circuit), a filter circuit 16, and a leakage determination circuit 17.

  The AC signal output circuit 10 is a circuit that outputs an AC signal having a predetermined frequency. Specifically, it is a circuit for outputting a rectangular wave pulse signal. The output terminal of the AC signal output circuit 10 is connected to the resistor 11.

  The resistor 11 is an element that is set to a predetermined resistance value (predetermined impedance) and divides an AC signal. One end of the resistor 110 is connected to the output end of the AC signal output circuit 10, and the other end is connected to the coupling capacitor 12 and the filter circuit 16.

  The coupling capacitor 12 is an element for blocking a direct current component and insulating one end side and the other end side in a direct current manner. One end of the coupling capacitor 12 is connected to the other end of the resistor 110, and the other end is connected to the first changeover switch 13 and the second changeover switch 15.

  The first changeover switch 13 is an element for connecting the other end of the resistor 11 to the high voltage battery B1 or disconnecting from the high voltage battery B1. The first changeover switch 13 is provided between the coupling capacitor 12 and the high voltage battery B1. One end of the first changeover switch 13 is connected to the other end of the coupling capacitor 12, and the other end is connected to the high voltage battery B1. Further, the control end is connected to the leakage determination circuit 17.

  The reference impedance circuit 14 is a circuit set to an impedance that serves as a reference when determining that there is a leakage. The reference impedance circuit 14 includes a resistor 140 and a capacitor 141. One end of the resistor 140 is connected to the second changeover switch 15 and the other end is grounded to the vehicle body. One end and the other end of the capacitor 141 are connected to one end and the other end of the resistor 140, respectively. Here, the impedance of the reference impedance circuit 14 is set to a leakage determination impedance which is a combined impedance of the insulation resistance Rg and the stray capacitance Cg when it is determined that there is a leakage at normal temperature.

  The second changeover switch 15 is an element for connecting or disconnecting the other end of the resistor 11 to the reference impedance circuit 14. The second changeover switch 15 is connected between the coupling capacitor 12 and the first changeover switch 13. One end of the second changeover switch 15 is connected to the other end of the coupling capacitor 12, and the other end is connected to one end of the resistor 140 and the capacitor 141. Further, the control end is connected to the leakage determination circuit 17.

  The filter circuit 16 is a circuit for removing a high-frequency component contained in the AC signal at the other end of the resistor 11. The filter circuit 16 includes a resistor 160 and a capacitor 161. One end of the resistor 160 is connected to the other end of the resistor 11, and the other end is connected to the leakage determination circuit 17. One end of the capacitor 161 is connected to the other end of the resistor 160, and the other end is grounded to the vehicle body.

  The leakage determination circuit 17 is a circuit that determines whether or not the high-voltage battery B1 has a leakage based on the peak value of the AC signal at the other end of the resistor 11 from which the high-frequency component has been removed by the filter circuit 16. Specifically, when switching noise is applied to the high voltage battery B1, the first changeover switch 13 is controlled based on a predetermined signal output from the control device ECU1, and the other end of the resistor 11 is connected to the high voltage battery B1. While disconnecting from the battery B1, the second switch 15 is controlled to connect the other end of the resistor 11 to the reference impedance circuit 14 via the coupling capacitor 12, and the peak value of the AC signal at the other end of the resistor 11 is set. Detect and use as reference wave height value for leakage detection. Thereafter, the second changeover switch 15 is controlled to disconnect the other end of the resistor 11 from the reference impedance circuit 14, and the first changeover switch 13 is controlled to connect the other end of the resistor 11 to the high level via the coupling capacitor 12. Based on the comparison result between the peak value of the AC signal at the other end of the resistor 11 and the detected reference peak value for leak detection, the voltage battery B1 is connected to determine whether or not there is a leak in the high voltage battery B1. The input terminal of the leakage detection circuit 17 is connected to the other end of the resistor 160 and one end of the capacitor 161. The output ends are connected to the control end of the first changeover switch 13 and the control end of the second changeover switch 15, respectively.

  Next, the operation of the leakage detection device will be described with reference to FIGS. Here, FIG. 2 is a timing chart for explaining the operation of the leakage detecting apparatus shown in FIG. FIG. 3 is a flowchart for explaining the operation of the leakage detecting apparatus shown in FIG.

  As shown in FIG. 2, the control device ECU1 shown in FIG. 1 controls the charging device CHG1 to charge the high voltage battery B1, and turns on the charging signal. That is, the charging signal is turned on when switching the switching elements constituting the charging device CHG1.

  The AC signal output circuit 10 shown in FIG. 1 outputs a rectangular wave pulse signal having a predetermined frequency. As shown in FIG. 3, the leakage determination circuit 17 determines whether or not the charging signal is in an on state (S100). When the charging signal is on in step S100, the leakage determination circuit 17 turns off the first changeover switch 13 to disconnect the other end of the resistor 11 from the high-voltage battery B1, and turns on the second changeover switch 15. The other end of the resistor 11 is connected to the reference impedance circuit 14 via the coupling capacitor 12 (S101). Then, the peak value of the AC signal at the other end of the resistor 11 is detected and used as a reference peak value for determining leakage (S102).

  When the charging signal is turned off in step S100, the leakage determination circuit 17 turns off the second changeover switch 15 to disconnect the other end of the resistor 11 from the reference impedance circuit 14, and turns on the first changeover switch 13. The other end of the resistor 11 is connected to the high voltage battery B1 via the coupling capacitor 12 (S103). Then, the peak value of the AC signal at the other end of the resistor 11 is detected (S104).

  Thereafter, as shown in FIG. 3, the leakage determination circuit 17 shown in FIG. 1 determines the high voltage battery B <b> 1 based on the comparison result between the peak value detected in step S <b> 104 and the reference peak value for leakage determination obtained in step S <b> 102. The presence / absence of electric leakage is determined (step S105). Specifically, when the crest value detected in step S104 is equal to or less than the reference crest value for leakage detection obtained in step S102, it is determined that the insulation impedance composed of the insulation resistance Rg and the stray capacitance Cg is lowered and the leakage is occurring. To do.

  That is, as shown in FIG. 2, when the charging device CHG1 is in operation and the switching noise of the charging device CHG1 is applied to the high voltage battery B1, the reference peak value for determining leakage is obtained. Then, when the charging device CHG1 is stopped and the switching noise of the charging device CHG1 is not applied to the high voltage battery B1, the detected peak value is compared with the reference peak value for leakage detection, and the presence or absence of leakage is determined. judge.

  Next, the effect will be described.

  When noise is applied to the high voltage battery B1, the second changeover switch 15 is turned off to disconnect the other end of the resistor 11 from the reference impedance circuit 14, and the first changeover switch 13 is turned on to turn off the resistor 11. Even if the other end is connected to the high voltage battery B1 via the coupling capacitor 12 and the peak value of the AC signal at the other end of the resistor 11 is detected, the correct peak value cannot be detected due to the influence of noise. Therefore, it is not possible to correctly determine the leakage of the high voltage battery B1. According to this embodiment, when the noise is applied to the high-voltage battery B1 in which the leakage of the high-voltage battery B1 cannot be correctly determined, the reference peak value for leakage determination is obtained. Accordingly, it is possible to sufficiently ensure a period during which leakage can be determined in the high-voltage battery B1 mounted on the vehicle and insulated from the vehicle body. Since the first changeover switch 13 is turned off and the other end of the resistor 11 is disconnected from the high-voltage battery B1, the correct reference peak value for determining a leak can be obtained without being affected by noise.

  Further, according to the present embodiment, the control device ECU1 outputs a predetermined signal indicating whether switching noise is applied to the high voltage battery B1 to the leakage detection device 1. Therefore, it is possible to know whether or not noise is applied to the high voltage battery B1 by a predetermined signal output from the control device ECU1. Then, leakage determination circuit 17 obtains a reference peak value based on a predetermined signal output from control device ECU1. Therefore, when noise is applied to the high voltage battery B1, it is possible to reliably obtain the reference peak value for determining leakage.

  Further, according to the present embodiment, the predetermined signal output from the control device ECU1 is a charge signal indicating whether or not the control device ECU1 controls the charging device CHG1 to charge the high voltage battery B1. When the charging device CHG1 is controlled, the switching elements constituting the charging device CHG1 are switched. Along with that, switching noise is generated and applied to the high voltage battery B1. Therefore, it can be surely determined whether or not noise is applied to the high voltage battery B1 by the charge signal.

  In the present embodiment, an example is described in which leakage is determined based on a comparison result between the peak value of the AC signal at the other end of the resistor and the obtained reference peak value, but the present invention is not limited to this. A preset leakage judgment peak value may be corrected based on the obtained reference peak value, and leakage may be determined based on the peak value of the AC signal at the other end of the resistor and the corrected leakage judgment peak value. .

  In the present embodiment, an example is described in which the first changeover switch, the reference impedance circuit, and the second changeover switch are provided on the other end side of the coupling capacitor, that is, the high voltage battery side. However, the present invention is not limited to this. . A first changeover switch, a reference impedance circuit, and a second changeover switch may be provided on one end side of the coupling capacitor, that is, on the anti-high voltage battery side.

DESCRIPTION OF SYMBOLS 1 ... Electric leakage detection apparatus, 10 ... AC signal output circuit, 11 ... Resistance (impedance circuit), 12 ... Coupling capacitor, 13 ... 1st changeover switch (1st changeover circuit), 14 ... reference impedance circuit, 140 ... resistor, 141 ... capacitor, 15 ... second changeover switch (second changeover circuit), 16 ... filter circuit, 160 ... resistor, 161- ··· Capacitor, 17 ··· Leakage determination circuit, B1 · · · High voltage battery (leakage detection target, battery), Rg · · · Insulation resistance, Cg · · ..Control devices (external devices)

Claims (4)

An AC signal output circuit for outputting an AC signal;
An impedance circuit set to a predetermined impedance and having one end connected to the output end of the AC signal output circuit;
A coupling capacitor having one end connected to the other end of the impedance circuit;
One end is connected to the other end of the coupling capacitor and the other end is connected to the leakage detection target, and the other end of the impedance circuit is connected to the leakage detection target or disconnected from the leakage detection target via the coupling capacitor. A first switching circuit;
A reference impedance circuit set to a reference impedance;
One end is connected to the other end of the coupling capacitor and the other end is connected to the reference impedance circuit, and the other end of the impedance circuit is connected to the reference impedance circuit or disconnected from the reference impedance via the coupling capacitor. A second switching circuit that
Controlling the first switching circuit to disconnect the other end of the impedance circuit from the leakage detection target, and controlling the second switching circuit to connect the other end of the impedance circuit to the reference impedance circuit; The peak value of the AC signal at the other end of the impedance circuit is detected and set as a reference peak value, and then the other switching circuit is controlled to disconnect the other end of the impedance circuit from the reference impedance circuit. The switching circuit is controlled to connect the other end of the impedance circuit to the leakage detection target, and based on the peak value of the AC signal at the other end of the impedance circuit and the obtained reference peak value, A leakage determination circuit for determining presence or absence;
In the earth leakage detection device comprising
When the leakage detection circuit knows that noise is applied to the leakage detection target by a predetermined signal that is output from an external device and indicates whether noise is applied to the leakage detection target, Controlling the first switching circuit to disconnect the other end of the impedance circuit from the leakage detection target, and controlling the second switching circuit to connect the other end of the impedance circuit to the reference impedance circuit; A leakage detecting device, wherein a peak value of an AC signal at the other end of the impedance circuit is detected and used as the reference peak value. The earth leakage determination circuit, the other end of the output from an external device, the earth leakage detection target noise is based on the predetermined signal indicating whether it is applied by controlling the first switching circuit and the impedance circuit Is disconnected from the leakage detection target, and the second switching circuit is controlled to connect the other end of the impedance circuit to the reference impedance circuit and detect the peak value of the AC signal at the other end of the impedance circuit. The leakage detection device according to claim 1, wherein the reference peak value is used. The leakage detection target is a battery,
The external device has a switching element, and controls the charging device that charges the battery by switching the switching element.
The leakage detection device according to claim 2, wherein the predetermined signal indicates whether or not the external device controls the charging device to charge the battery.   The leakage detection device according to claim 1, wherein the leakage detection target is mounted on a vehicle and insulated from a vehicle body.

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