JP4248480B2 - Leakage detection method - Google Patents

Description

  The present invention is based on the state of charge of the capacitor when the DC power source insulated from the ground potential portion and the other end side of the charging capacitor whose one end side is connected to the ground potential portion, The present invention relates to a leakage detection method for determining whether or not a leakage has occurred with a ground potential portion.

  Examples of the DC power source insulated from the ground potential section as described above include, for example, an electric vehicle that is driven by an electric motor, or a hybrid vehicle that is driven by using an engine and an electric motor in combination. There is a direct current power source for supplying driving electric power to the electric motor. A DC power source mounted in such a hybrid vehicle has a configuration in which a number of low-voltage batteries are connected in series to drive an electric motor at a high voltage of, for example, 200 V or more. The vehicle is electrically insulated from the ground potential portion of the vehicle.

  By the way, in the DC power supply as described above, if a leakage occurs with respect to the ground potential portion of the vehicle, useless current flows through the ground potential portion, so safety in use cannot be ensured. In such a case, the leakage occurs between the DC power supply and the ground potential part in order to take safety measures such as notifying the driver or cutting off the power supply. It has been conventionally performed to determine whether or not.

Conventionally, as a method for determining whether or not a leakage has occurred between the DC power source and the ground potential unit as described above, there has been the following method.
That is, either the positive electrode or negative electrode portion of the DC power source insulated from the ground potential portion and the other end side of the charging capacitor are connected for a set time, and the capacitor when the connection is terminated is connected. A voltage detection operation for detecting the voltage between terminals is executed, and the voltage between the terminals of the capacitor detected in the voltage detection operation is applied to a preset judgment table to cause a leakage between the DC power source and the ground potential part. In some cases, it is determined whether or not the above has occurred (for example, see Patent Document 1).

  In the determination table, the relationship between the voltage (power supply voltage) between the positive electrode and the negative electrode of the DC power supply and the voltage between the terminals of the capacitor detected by the voltage detection operation described above is normal, and the insulation resistance is not lowered. It is expressed as map data so that it is possible to determine whether the state is in the normal state or the state in which the insulation resistance has deteriorated to cause the insulation abnormality. Further, the DC power supply as described above supplies power to a load such as an electric motor, and the voltage (power supply voltage) between the positive electrode and the negative electrode of the DC power supply is the power to the load. May vary depending on supply conditions. Therefore, when it is determined whether or not a leakage has occurred between the DC power supply and the ground potential portion, a plurality of leakages with respect to the voltage across the terminals of the capacitor when the power supply voltage of the DC power supply is variously changed. The reference value for determination is stored as map data.

JP-A-8-226950 (paragraph 0010, paragraph 0012, FIG. 1, FIG. 4)

  In the conventional method as described above, when determining whether or not a leakage has occurred between the DC power supply and the ground potential portion, the power supply voltage of the DC power supply was variously changed as the determination table. It is necessary to create and store a plurality of reference values for determining leakage current with respect to the voltage between terminals of the capacitor as map data, which has the disadvantage that it takes time and effort to create such a determination table. It was. In addition, when applying to another DC power supply having a different power supply voltage, a new determination table must be recreated for each device corresponding to the other DC power supply having a different power supply voltage. There was also a disadvantage that it was not possible to use a plurality of different DC power supplies with versatility.

  The object of the present invention is not to bother the troublesome task of mapping a plurality of determination data corresponding to a plurality of voltages as reference information for determining a leakage current, and is also affected by voltage fluctuations of the DC power supply. It is possible to determine whether or not a leakage has occurred between the DC power supply and the ground potential portion even when the plurality of DC power supplies have different power supply voltages. It is in providing a leakage detection method.

  The leakage detection method according to claim 1 is a state in which the capacitor is charged when a DC power source insulated from the ground potential portion is connected to the other end side of the charging capacitor whose one end side is connected to the ground potential portion. A leakage detection method for determining whether or not a leakage has occurred between the DC power supply and the ground potential portion, wherein the detection set time elapses between the DC power supply and the other end of the capacitor. The voltage detection operation for detecting the voltage between the terminals of the capacitor when the connection is completed and the connection is terminated is performed with the detection setting time being varied, and the detection setting time is varied. By comparing the voltage ratio between the terminals obtained in the voltage detection operation with a preset reference value for determination, it is determined whether or not a leakage has occurred between the DC power supply and the ground potential portion. How to That.

According to the above method, the voltage detection operation of detecting the voltage between the terminals of the capacitor when the DC power source and the other end of the capacitor are connected only for the detection set time elapses and the connection is terminated. It is executed with different detection set times.
In other words, if the DC power supply is connected to the other end of the capacitor when the DC power supply is connected to the other end of the capacitor when the insulation resistance of the DC power supply is reduced with respect to the ground potential, A current flows and is charged. In other words, when the DC power supply and the other end of the capacitor are connected, the connection point to the capacitor of the DC power supply, the capacitor, the ground potential section, the insulation resistance, and the leakage point of the DC power supply are electrically connected to each other to form a charging circuit. And a charging current flows through the charging circuit to charge the capacitor. At that time, the voltage between the terminals of the capacitor increases exponentially, but the increasing tendency of the voltage between the terminals of the capacitor depends on the magnitude of the voltage applied to the charging circuit and the time constant of the charging circuit. It is determined by Sato. The time constant of the charging circuit is determined by the capacitance of the capacitor and the insulation resistance between the DC power supply and the ground potential portion. When the power supply voltage of the DC power supply is changed, the charging circuit is applied to the charging circuit. The magnitude of the voltage will change.

  Therefore, the voltage detection operation is performed with the detection setting time being different, and the ratio between the terminals of the capacitor obtained in the voltage detection operation performed with the detection setting time being different is set in advance. By comparing with the reference value for determination, it is determined whether or not a leakage occurs between the DC power supply and the ground potential portion. At this time, if the insulation resistance is sufficiently large and no leakage has occurred, the voltage between the terminals of the capacitor will hardly change or rise very slowly even if the DC power supply is connected to the other end of the capacitor. become. On the other hand, when leakage occurs and the insulation resistance is small, the voltage between the terminals of the capacitor rises in a short time. The ratio of the voltage between the terminals obtained by performing the voltage detection operation with different detection set times is not affected by the magnitude of the voltage applied to the charging circuit as described above, and is insulated. This corresponds to the magnitude of the resistance.

  That is, by comparing the ratio of the voltage between the terminals as described above with a predetermined reference value for determination, for example, whether or not the insulation resistance is smaller than a value corresponding to the reference value for determination, that is, the DC power supply and It is possible to determine whether or not a leakage has occurred between the ground potential portion. That is, prior to the determination process, it is only necessary to set and store the determination reference value in advance, and there is no troublesome process of mapping a plurality of determination data corresponding to a plurality of voltages. Can be handled with simple processing.

  Moreover, since the ratio of the voltage between the terminals as described above corresponds to the magnitude of the insulation resistance regardless of the magnitude of the voltage applied to the charging circuit, the power supply voltage of the DC power supply fluctuates. Even if it exists, it can be discriminate | determined appropriately whether it is leaking. Moreover, even when the leakage detection method is applied to another system having a DC power supply having a different power supply voltage, it is possible to appropriately determine whether or not the DC power supply is leaking.

  Therefore, prior to executing the leakage determination process, there is no troublesome trouble of creating and storing map data using a plurality of determination data corresponding to a plurality of voltages, and It is possible to detect leakage without being affected by fluctuations in the voltage of the DC power supply, and whether there is a leakage between the DC power supply and the ground potential even with multiple DC power supplies with different power supply voltages It has become possible to provide a leakage detection method that makes it possible to determine whether or not.

  In addition to the leakage detection method according to claim 1, the leakage detection method according to claim 2 is an intermediate potential obtained by dividing a voltage between a positive electrode and a negative electrode in the DC power supply by a plurality of resistors in the voltage measurement operation. And the other end side of the capacitor.

  According to the leakage detection method of claim 2, in the voltage measurement operation, the intermediate potential portion obtained by dividing the positive electrode and the negative electrode of the DC power supply by a plurality of resistors is connected to the other end side of the capacitor. Therefore, the process of determining whether or not the DC power supply is leaking by comparing the ratio of the voltage between the terminals and the reference value for determination is performed only once between the DC power supply and the ground potential portion. Thus, it is possible to determine whether or not a leakage has occurred.

  In addition, when the other end side of the capacitor is connected to either the positive electrode or the negative electrode in the DC power source, for example, when connecting the other end side of the capacitor to the positive electrode in the DC power source, There is a disadvantage that it is not possible to detect even if the leakage current at the positive electrode in the DC power supply is generated. When the other end of the capacitor is connected to the negative electrode in the DC power supply, the leakage current at the negative electrode in the DC power supply occurs. However, according to the leakage detection method according to claim 2, when there is a leakage on the negative electrode side of the DC power supply and on the positive electrode side of the DC power supply, In any case, the capacitor is charged when the intermediate potential portion is connected to the other end of the capacitor. Can be a DC power source, it is determined whether or not the leakage by measuring the terminal voltage of the capacitor when.

[First Embodiment]
Hereinafter, an embodiment of a leakage detection method according to the present invention will be described with reference to the drawings.
FIG. 1 shows a leakage detection apparatus for carrying out the leakage detection method. This leakage detection device is for detecting leakage to a ground potential portion of a DC power source mounted in a hybrid vehicle (not shown) configured to drive a traveling device with an engine and an electric motor as a power source. Is provided.

  As shown in FIG. 1, this leakage detection device is charged with an intermediate potential portion obtained by dividing a voltage between a positive electrode and a negative electrode in a DC power source 2 insulated from a ground potential portion 1 by two voltage dividing resistors R1 and R2. The leakage detecting switch means SW1 that can be connected to and separated from the other end of the capacitor 3 for use, and the other end of the discharge resistor 4 whose one end is connected to the ground potential portion 1 are connected to the other end of the capacitor 3. It comprises a discharge switch means SW2 that can be connected and disconnected, a control device 5 using a microcomputer that constitutes the control means, and the like.

  Further, as shown in FIG. 1, the DC power source 2 has a configuration in which a number of low voltage batteries B are connected in series and a high voltage of about 200 V is output between the positive terminal and the negative terminal. The DC power source 2 is in a state of being electrically insulated from the ground potential unit 1 and is configured to supply power to a load F such as a traveling electric motor. One end side of the charging capacitor 3 is connected to the ground potential portion 1, and the leakage detecting switch means SW1 divides between the positive electrode and the negative electrode in the DC power source 2 by two voltage dividing resistors R1 and R2. Between the other end side of the capacitor 3 to which the leakage detecting switch means SW1 is connected and the ground potential portion 1. The discharge switch means SW2 and the discharge resistor 4 are provided in series.

  Each of the leakage detection switch means SW1 and the discharge switch means SW2 is composed of a photoelectric semiconductor relay H as shown in FIG. That is, the light-emitting diode 8 and the photo MOSFET 9 are arranged in a light-shielding package so as to face each other so as to be optically coupled, and a control signal is input to the control input terminals 10 and 11 so that the light-emitting diode 8 When light is emitted, the photo MOSFET 9 is turned on and the pair of switch terminals 12 and 13 are switched to a conductive state. When no control signal is input, the photo MOSFET 9 is turned off and the pair of switching output terminals 12 and 13 are cut off. It becomes the composition which switches to.

  Therefore, when the photo MOSFET 9 in the leakage detection switch means SW1 is turned off, the leakage detection switch means SW1 is cut off, and the intermediate potential portion and the other end side of the capacitor 3 are switched to each other. When the photo MOSFET 9 in the switch means SW1 is turned on, it is switched to a connection state in which the intermediate potential portion and the other end side of the capacitor 3 are connected. Similarly, when the photo MOSFET 9 in the discharge switch means SW2 is turned off, the state is switched to a state in which the other end side of the capacitor 3 and the other end side of the discharge resistor 4 are separated, and the photo switch 9 in the discharge switch means SW2 is switched. When the MOSFET 9 is turned on, it switches to a state in which the other end side of the capacitor 3 and the other end side of the discharging resistor 4 are connected.

  Next, a leakage detection method using this leakage detection apparatus will be described. That is, the voltage detection operation for detecting the voltage between the terminals of the capacitor 3 when the DC power source 2 and the other end of the capacitor 3 are connected only for the detection set time elapses and the connection is terminated, The DC power supply 2 is executed by executing twice at different set times, and comparing the ratio of the voltages between the two terminals obtained in the two voltage detection operations with a preset reference value for determination. This is a method for determining whether or not a leakage has occurred between the ground potential portion 1 and the ground potential portion 1. If it adds explanation, the processing which determines whether such a leak has generate | occur | produced will be performed by the control apparatus 5. FIG.

  That is, the control device 5 shuts off the discharge switch means SW2 and places the leakage detection switch means SW1 in a connected state while the set time for detection elapses, after the detection connection process. A voltage detection process for detecting the voltage between the terminals of the capacitor 3 by switching the discharge switch means SW2 to a connected state, and determining whether or not the DC power supply 2 is leaking based on the detection result of the voltage detection process. Each of the detection connection process and the voltage detection process is configured to be executed twice at different detection set times. And it is comprised so that it may be discriminate | determined whether the DC power supply 2 is leaking based on the detection information of the voltage detection value detected by the voltage detection process performed twice. That.

Hereinafter, the processing operation in the earth leakage state determination control of the control device 5 will be specifically described.
The control device 5 is configured to execute the leakage state determination control when a start of processing is instructed from, for example, a management unit (not shown) that manages the overall driving state of the hybrid vehicle. The leakage state determination control is configured to execute processing as shown in FIG.
That is, when the process is started, if it is not determined that the leakage has occurred in the previous determination operation, it is first determined whether or not the charging capacitor 3 is discharged, in other words, the voltage V _C0 between the terminals of the capacitor 3. Is confirmed to be 0V (steps 1 and 2). If the inter-terminal voltage V _C0 of the capacitor 3 is not ₀ V, the discharging switch means SW2 is switched to the connected state and the capacitor 3 is discharged by the discharging resistor 4 (step 3). If it is determined in step 1 that the current has been leaked in the previous determination operation, it is not appropriate to charge the capacitor 3 in the state where the leakage has occurred. Like that.

  Next, the leakage detection switch means SW1 in the cut-off state is switched to the connection state only for 10 msec as the set time for detection and then switched to the cut-off state (step 4). Then, the discharging switch means SW2 is switched to the connected state, the electric charge of the capacitor 3 is discharged by the discharging resistor 4, and the first terminal voltage Vc1 as the terminal voltage of the capacitor 3 is measured (step 5). ). After discharging the capacitor 3 until the inter-terminal voltage becomes substantially zero while maintaining the discharging switch means SW2 in the connected state, the discharging switch means SW2 is switched to the cut-off state (steps 6 and 7).

  Next, the leakage detecting switch means SW1 in the cut-off state is switched to the connected state only during the lapse of 20 msec as the detection set time and then switched to the cut-off state (step 8). Then, the discharging switch means SW2 is switched to the connected state, and the electric charge of the capacitor 3 is discharged by the discharging resistor 4, and the second terminal voltage Vc2 as the terminal voltage of the capacitor 3 is measured (step 9). After discharging the capacitor 3 until the voltage between the terminals becomes substantially zero while maintaining the discharging switch means SW2 in the connected state, the discharging switch means SW2 is switched to the cut-off state (steps 10 and 11).

Next, the voltage increase rate V _RATE = (Terminal voltage V _C1 when the discharge switch means SW2 is connected for 10 msec and the terminal voltage V _C2 when the discharge switch means SW2 is connected for 20 msec. V _C2 / V _C1 ) is obtained (step 12). This voltage increase rate V _RATE corresponds to the ratio between the two inter-terminal voltages obtained by the two voltage detection operations, that is, the inter-terminal voltage V _C1 and the inter-terminal voltage V _C2 .

Then, the voltage increase rate V _RATE is compared with a determination reference value V _REF set in advance based on experimental data. If the voltage increase rate V _RATE is equal to or higher than the determination reference value V _REF , It is determined that the insulation resistance is larger than the reference insulation resistance and the insulation resistance has not deteriorated, in other words, a normal state in which no leakage has occurred (steps 13 and 14). If the voltage increase rate V _RATE is smaller than the determination reference value V _REF , the insulation resistance is smaller than the reference insulation resistance, that is, the insulation resistance is deteriorated, that is, between the DC power supply 2 and the ground potential portion. It is determined that an electric leakage has occurred (step 15).

  The control device 5 determines whether the leakage point is on the positive electrode side or the negative electrode side of the DC power supply 2 depending on whether the polarity of the voltage between the terminals of the capacitor 3 is the forward direction or the reverse direction. be able to. If this discrimination process is further explained, as shown in FIG. 4 (a), when the leakage resistance is reduced on the negative electrode side of the DC power source 2 and the insulation resistance is lowered, the leakage detection switch means SW1 is brought into a connected state. A series circuit is formed by each of the positive electrode of the DC power source 2, the voltage dividing resistor R1, the leakage detection switch means SW1, the capacitor 3, the ground potential unit 1, the insulation resistance unit Rp, and the negative electrode of the DC power source 2. A voltage is applied to the series circuit, and a current flows to charge the capacitor 3. At this time, the capacitor 3 is charged in a state where the terminal on the ground potential portion 1 side is a negative voltage and the opposite terminal is a positive voltage. Therefore, when the discharging switch means SW2 is switched to the connected state, current flows as shown in FIG. 4B, and the electric charge is discharged, so that the voltage polarity of the capacitor 3 becomes positive.

  On the other hand, as shown in FIG. 5 (a), when the leakage resistance is reduced on the positive electrode side of the DC power supply 2 and the insulation resistance is reduced, the leakage detection switch means SW1 is connected as in the above case. In this way, a series circuit is configured, and the voltage in the DC power supply 2 is applied to the series circuit. From the positive electrode of the DC power supply 2, the insulation resistance portion Rp, the ground potential portion 1, the capacitor 3, the leakage detection switch means SW1, A current flows in the order of the pressure resistor R2, and the capacitor 3 is charged. At this time, the capacitor 3 is charged in a state where the terminal on the ground potential portion 1 side is a positive voltage and the opposite terminal is a negative voltage. Therefore, when the discharging switch means SW2 is switched to the connected state, current flows as shown in FIG. 5B, and the electric charge is discharged, so that the polarity of the voltage of the capacitor 3 is reversed.

  Therefore, it is possible to determine whether or not a leakage has occurred by one determination process, and to determine whether or not the leakage point is on the positive electrode side or the negative electrode side of the DC power supply 2. It can be done. In addition, since the leakage detecting switch means SW1 can be dealt with by one connected to the intermediate potential portion in the DC power supply 2, it is possible to simplify the circuit configuration.

When it is configured to determine whether or not a leakage has occurred using the voltage increase rate V _RATE as described above, the determination is performed with high accuracy in a state where an error due to fluctuation of the voltage of the DC power supply 2 does not occur. be able to. This will be described below.

FIG. 6 shows an equivalent circuit in the case where a leakage occurs in the ground potential portion 1 through the insulation resistance RL at an intermediate potential in the DC power supply 2. In this figure, V _E1 is the potential difference between the positive electrode of the DC power supply 2 and the intermediate potential portion at the leakage point, and V _E2 is the potential difference between the intermediate potential portion and the negative electrode at the leakage point of the DC power supply 2. C is the capacity of the capacitor 3. The leakage detection switch means SW1, the control device 5 and the like are omitted. The voltage across the capacitor 3 with respect to the passage of time t in a transitional state until the capacitor 3 is saturated when the leakage detection switch means SW1 is in the connected state and the charging current flows through the capacitor 3 through the insulation resistance RL. Vc (t) can be expressed by the following equation (1).

  In the above equation 1, “Vc (0)” is the voltage between the terminals of the capacitor 3 in the initial state, but in this embodiment, it is always 0 V before the leakage detection switch means SW1 is in the connected state. Therefore, the second term of Equation 1 is zero (0).

The voltage increase rate V _{RATE at} two times t1 (10 msec) and t2 (20 msec) with different elapsed times can be expressed by the following equation 2.

As is clear from Equation 2, the voltage increase rate V _RATE is not influenced by the power supply voltage V _E1, V _E2, since a monotonically increasing function of the insulation resistance RL and variable, the voltage increase rate V _RATE By comparing with the determination reference value V _REF , it can be determined whether or not the insulation resistance is reduced. The value of the insulation resistance RL can be obtained by calculation using the voltage increase rate V _RATE from _Equation 2.

[Second Embodiment]
Next, a second embodiment of the leakage detection device used in the leakage detection method according to the present invention will be described with reference to the drawings.
In this second embodiment, the leakage detecting switch means SW1 in the first embodiment is for charging the intermediate potential portion obtained by dividing the voltage between the positive electrode and the negative electrode of the DC power source 2 by two voltage dividing resistors R1 and R2. As shown in FIG. 7, this leakage detection switch means SW1 uses the positive electrode in the DC power supply 2 and the other end side of the charging capacitor 3 as a load. The second embodiment is different from the first embodiment in that the connection is separable through the resistor R1. The other configurations are the same as those in the first embodiment. The operation is the same. Here, the same members as those in the first embodiment are denoted by the same reference numerals and described in the drawings, but the description of the same components will be omitted, and only the components different from those in the second embodiment will be described.

Next, it will be described below that the leakage detection method according to the present invention can also be used in this circuit configuration.
FIG. 8 shows an equivalent circuit in the second embodiment in the case where a leakage occurs in the ground potential portion 1 through the insulation resistance RL at an intermediate potential in the DC power source 2. The voltage across the capacitor 3 with respect to the passage of time t in a transitional state until the capacitor 3 is saturated when the leakage detection switch means SW1 is in the connected state and the charging current flows through the capacitor 3 through the insulation resistance RL. Vc (t) can be expressed by the following equation (4).

  In Equation 3, “Vc (0)” is the voltage between the terminals of the capacitor 3 in the initial state, as in Equation 1, but in this embodiment, the leakage detection switch means SW1 is brought into the connected state. Since the voltage is always set to 0V before the operation, the second term of Equation 1 is zero (0).

The voltage increase rate V _{RATE at} two times t1 (10 msec) and t2 (20 msec) with different elapsed times can be expressed by the following equation (4).

Accordingly, in this circuit arrangement, the voltage increase rate V _RATE is not influenced by the power supply voltage V _E1, V _E2, since a monotonically increasing function of the insulation resistance RL and variable, the voltage increase rate V _RATE By comparing with the determination reference value V _REF , it can be determined whether or not the insulation resistance is reduced.

[Third Embodiment]
Next, a third embodiment of the leakage detection device used in the leakage detection method according to the present invention will be described with reference to the drawings.
In the third embodiment, the leakage detection switch means SW1 is not configured to connect the positive electrode of the DC power source 2 and the other end of the charging capacitor 3 as in the second embodiment, but is shown in FIG. As described above, this leakage detection switch means SW1 is different from the second embodiment in that the negative electrode of the DC power supply 2 and the other end of the charging capacitor 3 are connected and separated. The rest of the configuration is the same as that of the second embodiment, and the processing operation by the control device 5 is the same. Here, the same members as those in the second embodiment are denoted by the same reference numerals and described in the drawings. However, the description of the same components will be omitted, and only components different from those in the second embodiment will be described.

Next, the point that the leakage detection method according to the present invention can be used also in this circuit configuration will be described below.
FIG. 10 shows an equivalent circuit in the second embodiment in the case where a leakage occurs in the ground potential portion 1 through the insulation resistance RL at an intermediate potential in the DC power supply 2. The voltage across the capacitor 3 with respect to the passage of time t in a transitional state until the capacitor 3 is saturated when the leakage detection switch means SW1 is in the connected state and the charging current flows through the capacitor 3 through the insulation resistance RL. Vc (t) can be expressed by the following equation (6).

  In equation (5), “Vc (0)” is the voltage across the capacitor 3 in the initial state, as in equation (1), but in this embodiment, the leakage detection switch means SW1 is brought into the connected state. Since the voltage is always set to 0V before the operation, the second term of Equation 1 is zero (0).

The voltage increase rate V _{RATE at} two times t1 (10 msec) and t2 (20 msec) with different elapsed times can be expressed by the following equation (6).

Accordingly, in this circuit arrangement, the voltage increase rate V _RATE is not influenced by the power supply voltage V _E1, V _E2, since a monotonically increasing function of the insulation resistance RL and variable, the voltage increase rate V _RATE By comparing with the determination reference value V _REF , it is possible to determine whether or not the insulation resistance RL has decreased.

[Another embodiment]
Hereinafter, other embodiments are listed.

(1) In each of the above embodiments, the DC power source and the other end side of the capacitor are connected only during the set time for detection, and the voltage for detecting the terminal voltage of the capacitor when the connection is terminated Whether or not a leakage has occurred using the ratio of the two terminal voltages obtained by executing the detection operation twice with different detection set times and executing the voltage detection operation twice. However, instead of such a configuration, for example, the voltage detection operation is executed three or more times with different detection set times, and any one of the plurality of terminal voltages is selected. Alternatively, a ratio of two objects may be used.

  Also, instead of such a configuration, two types of time are set as the detection set time, and the voltage detection operation is executed a plurality of times with one detection set time, and the average of the voltages between the terminals is averaged. The value is obtained as the first average value, and further, the voltage detection operation is executed a plurality of times with the other detection set time, and the average value of the plurality of terminal voltages is obtained as the second average value. You may make it determine whether the electric leakage has generate | occur | produced using the ratio of an average value and a 2nd average value.

(2) In each of the above embodiments, the leakage detection switch means SW1 and the discharge switch means SW2 are each configured by the semiconductor relay H. However, the invention is not limited to the semiconductor relay H. A relay or the like may be used.

(3) In each of the above-described embodiments, the leakage detection device is mounted on a hybrid vehicle. However, the present invention is not limited to a hybrid vehicle, and may be an electric vehicle that is driven only by an electric motor or other electric vehicle, It is not limited to such an electric vehicle, and any device having a DC power supply that is not grounded is acceptable, and a device on which the DC power supply is mounted is not limited.

The circuit block diagram of the earth-leakage detection apparatus of 1st Embodiment The figure which shows the structure of the semiconductor relay of 1st Embodiment. Flowchart of control operation of the first embodiment Action explanatory diagram of the first embodiment Action explanatory diagram of the first embodiment Equivalent circuit diagram of the first embodiment Circuit configuration diagram of leakage detection device of second embodiment Equivalent circuit diagram of the second embodiment Circuit configuration diagram of leakage detection device of third embodiment Equivalent circuit diagram of the third embodiment

Explanation of symbols

1 Ground potential part 2 DC power supply 3 Capacitor R1, R2 Resistance V _RATE ratio V Reference value for _REF judgment

Claims (2)

Based on the state of charge of the capacitor when the DC power source insulated from the ground potential portion and the other end side of the charging capacitor whose one end side is connected to the ground potential portion are connected, the DC power source and the ground potential portion A leakage detection method for determining whether or not a leakage has occurred between
A voltage detection operation for detecting the voltage between the terminals of the capacitor when the DC power source and the other end side of the capacitor are connected only during the detection set time elapses and the connection is terminated. The DC power supply by comparing the ratio of the voltage between the terminals obtained in the voltage detection operation executed with the detection setting time being different from the preset reference value for determination. Leakage detection method for determining whether or not a leakage has occurred between the ground and the ground potential portion.   The leakage detection method according to claim 1, wherein, in the voltage detection operation, an intermediate potential portion obtained by dividing a positive electrode and a negative electrode in the DC power source by a plurality of resistors is connected to the other end side of the capacitor.

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