JP2021056150A - Insulation inspection method - Google Patents

Abstract

To provide an insulation inspection method with which it is possible to prevent an overcurrent from flowing into a circuit that includes a power supply and a test object.SOLUTION: An insulation inspection method inspects the insulation of a test object using a power supply device for insulation inspection equipped with a power supply that can set a voltage rise time. This insulation inspection method sets a first voltage rise time and detects a current in a circuit that includes the power supply and the test object at a time when the first voltage rise time has elapsed. This insulation inspection method determines that abnormality has occurred to the circuit when the detected current is larger than a prescribed level, and sets a second voltage rise time and inspects the insulation of the test object when the detected current is lower than or equal to the prescribed level. The second voltage rise time is set to be shorter than the first voltage rise time.SELECTED DRAWING: Figure 1

Description

The present invention relates to an insulation inspection method.

Patent Document 1 describes an insulation inspection method for inspecting the insulation of a test object by using a power supply device for insulation inspection. In the insulation inspection method described in Patent Document 1, the insulation of the test object is inspected by individually setting the rise time of the voltage of the power supply and the time for maintaining the voltage having a predetermined magnitude or more.

Japanese Unexamined Patent Publication No. 2017-219352

However, in the insulation inspection method described in Patent Document 1, when the load of the circuit including the DC voltage generating portion serving as the power source and the test object is short-circuited, an overcurrent flows in the circuit, so that the insulation inspection is performed. The high-voltage switch (high-voltage switch) provided in the power supply may be damaged. This high-voltage switch is a switch in which one end is connected to the positive electrode terminal of the DC voltage generating portion and the other end is connected to a variable inductor for changing the rise time of the test voltage.

Therefore, an object of the present invention is to provide an insulation inspection method capable of preventing an overcurrent from flowing in a circuit including a power supply and a test object.

One aspect of the present invention for achieving the above object is an insulation inspection method for inspecting the insulation of a test object by using an insulation inspection power supply device provided with a power source capable of setting a voltage rise time. The insulation inspection method includes a step of setting a rise time of a first voltage and a step of detecting a current in a circuit including the power supply and the test object when the rise time of the first voltage has elapsed. When the detected current is larger than the predetermined level, a step of determining that an abnormality has occurred in the circuit, and when the detected current is equal to or lower than the predetermined level, a second voltage rises. It includes a step of setting a time to inspect the insulation of the test object. In the insulation inspection method, the rise time of the second voltage is set shorter than the rise time of the first voltage.

In the insulation inspection method according to this aspect, by lengthening the rise time of the first voltage of the power supply device for insulation inspection, it is possible to suppress the sudden flow of current through the circuit. In the insulation inspection method according to this aspect, when the current is generated above a predetermined level, the circuit abnormality is determined, and when it is determined that there is no abnormality, the rise time is shorter than the first voltage. The insulation of the object to be inspected is inspected with a second voltage. Therefore, according to this aspect, it is possible to prevent an overcurrent from flowing in the circuit including the power supply and the test object.

According to the present invention, it is possible to provide an insulation inspection method capable of preventing an overcurrent from flowing in a circuit including a power supply and a test object.

It is a flow diagram for demonstrating an example of the insulation inspection method which concerns on embodiment. It is a figure which shows an example of the short circuit check voltage used in the insulation inspection method of FIG. It is a figure which shows the example of the current value when the short circuit check is performed by the short circuit check voltage of FIG. It is a figure which shows an example of the inspection voltage used in the insulation inspection method of FIG. It is a figure which shows the example of the current value at the time of inspecting the insulation state by the inspection voltage of FIG. It is a block diagram which shows one configuration example of the power supply device for insulation inspection used in the insulation inspection method of FIG. It is a block diagram which shows the other structural example of the power-source device for insulation inspection used in the insulation inspection method of FIG. It is a block diagram which shows the other structural example of the power-source device for insulation inspection used in the insulation inspection method of FIG.

Hereinafter, the present invention will be described through embodiments of the invention, but the invention according to the claims is not limited to the following embodiments. Moreover, not all of the configurations described in the embodiments are indispensable as means for solving the problem. Hereinafter, embodiments will be described with reference to the drawings. In each drawing, the same elements are designated by the same reference numerals, and duplicate description is omitted as necessary.

(Embodiment)
The insulation inspection method according to the present embodiment is a method of inspecting the insulation of a test object by using an insulation inspection power supply device provided with a power source capable of setting a voltage rise time. This insulation inspection method includes a first setting step, a detection step, a determination step, and an inspection step as described later.

Hereinafter, an example of this insulation inspection method will be described with reference to FIGS. 1 to 5. FIG. 1 is a flow chart for explaining an example of the insulation inspection method according to the present embodiment. Further, FIG. 2 is a diagram showing an example of a short-circuit check voltage, and FIG. 3 is a diagram showing an example of a current value when a short-circuit check is performed at the short-circuit check voltage. FIG. 4 is a diagram showing an example of an inspection voltage used in the insulation inspection method of FIG. 1, and FIG. 5 is a diagram showing an example of a current value when an insulation state is inspected with the inspection voltage. An example of the power supply device for insulation inspection will be described later with reference to FIGS. 6 and 6 and thereafter.

In the insulation inspection method according to the present embodiment, first, in the insulation inspection power supply device, a load is connected to the internal power supply (step S1), and a first voltage as a short-circuit check voltage is applied (step S2). Further, the above load can be composed of a load due to a test object connected to the power supply device for insulation inspection and an internal load of the power supply device for insulation inspection. Then, prior to the application of the first voltage in step S2, the rise time (first rise time) for the first voltage is set as the first setting step. The first rise time may be set before the start of the inspection. The first voltage can be set so that the voltage value gradually increases with the passage of time as illustrated in FIG.

Next, as the detection step, when the first rise time has elapsed, the current in the circuit including the power supply and the test object is detected (step S3). Here, the circuit including the power supply and the test object can be a circuit in which the power supply device for insulation inspection including the power supply and the test object are connected. Further, the object to be tested is not limited, and examples thereof include equipment that requires an insulating portion such as a motor.

Next, it is determined whether or not the current detected in step S3 is equal to or less than a predetermined level of current (step S4). This determination can be performed, for example, by detecting whether or not the detected current value is equal to or less than a predetermined value.

Further, the current of a predetermined level may be set to be smaller than the current at which the circuit is damaged (damaged current). For example, in step S4, it is determined whether or not the current is less than or equal to the breaking current. Although it is possible to detect the current before the first rise time elapses, the determination in step S4 is basically determined when the elapsed time.

As the determination step, if NO in step S4, that is, if the detected current is larger than a predetermined level, it means that the circuit has been short-circuited. Therefore, it is determined that an abnormality has occurred in the circuit, and the process is terminated. (Step S5). Step S5 means that the inspection was abnormally completed due to the short circuit.

In FIG. 3, graph 31 is a graph showing a change in the current value at the time of a short circuit, and graph 32 is a graph showing a change in the current value at the time of non-short circuit (when the load is normal). The predetermined level may be determined so that the values of graphs 31 and 32 at the time when the first rise time has elapsed can be distinguished.

As the inspection step, if YES in step S4 (when the detected current is equal to or less than the predetermined level as illustrated in Graph 32), a second voltage as the inspection voltage is applied (step S6). ), It is determined whether or not a discharge due to dielectric breakdown is detected (step S7). The threshold value for the determination in step S7 may be set to such that the discharge due to dielectric breakdown can be detected. In the above detection step, the insulation of the test object is inspected by such a discharge detection determination. However, the method of inspection of insulation (inspection of insulation state) is not limited to this.

In the above inspection step, the rise time (second rise time) for the second voltage is set prior to the application in step S6, but the second rise time is set shorter than the first rise time. I will do it. In other words, in the first setting step, the first rise time is set longer than the second rise time. The second voltage is set so that the voltage value increases sharply as illustrated in FIG. 4 as compared with the first voltage having a long rise time illustrated in FIG.

When the inspection voltage as shown in FIG. 4 is used, if a short circuit occurs, the current value becomes as shown in Graph 51 and the switch inside the power supply device for insulation inspection (described later) is located near the apex. The high voltage switch) will be damaged. However, in the present embodiment, since the rise time is already shortened only when the determination in step S4 is YES, this high voltage is shown as shown in Graph 52 which illustrates the current value at the time of non-short circuit (normal load). It is possible to avoid damage to the switch.

If NO in step S7, it is determined that there is no problem in the insulation state of the test object (OK), and the process ends (step S8). On the other hand, if YES in step S7, it is determined that there is a problem in the insulation state of the test object (NG), and the process is terminated (step S9). Note that steps S8 and S9 mean that the inspection could be completed normally without a short circuit.

Further, the results of steps S5, S8, and S9 may be notified to the inspector by a display device (which may be a simple display lamp) provided or connected to the power supply device for insulation inspection.

Next, a configuration example of the power supply device for insulation inspection used in the insulation inspection method of FIG. 1 will be described with reference to FIG. FIG. 6 is a block diagram showing a configuration example of the power supply device for insulation inspection.

As shown in FIG. 6, the insulation inspection power supply device 10 includes a DC voltage generator (hereinafter, exemplified by the DC high voltage generator 11), a switch (hereinafter, exemplified by the high voltage switch 12), and a pulse generator (pulse oscillator). 12, the variable inductor 14, and the discharge detector 15 can be provided.

Further, the power supply device 10 for insulation inspection includes a first connection terminal TT1, a second connection terminal TT2, switches SW1 to SW4, a resistance element (hereinafter, exemplified by a terminating resistor Rs), and an overcurrent protection circuit 16. Can be done. The switches SW1 to SW4 are switches used for switching the polarities of the first connection terminal TT1 and the second connection terminal TT2.

In FIG. 6, a motor is assumed as an example of the object 20 to be tested, and only two terminals to be tested that are connected to the power supply device 10 for insulation inspection are shown among the terminals of the motor. The first connection terminal TT1 is connected to one of the terminals under test (first terminal under test TM1), and the second connection terminal TT2 is connected to the other of the terminals under test (second terminal under test TM2). Will be done.

The DC high voltage generator 11 outputs a DC voltage (for example, a DC high voltage). Further, the DC high voltage generation unit 11 has a function of changing the rise time of the voltage by an instruction from the outside.

One end of the high voltage switch 12 is connected to the positive electrode terminal of the DC high voltage generating unit 11, and the other end is connected to the variable inductor 14 via the overcurrent protection circuit 16. Further, the high voltage switch 12 is turned on during the period when the pulse signal output by the pulse generator 13 is at a high level, and turned off during the period when the pulse signal is at a low level. The pulse generator 13 outputs a pulse signal for switching the open / closed state of the high-voltage switch 12. Further, the pulse generator 13 can change the pulse width of the pulse signal by setting, which makes it possible to change the peak maintenance time.

One end of the variable inductor 14 is connected to the other end of the high voltage switch 12 via the overcurrent protection circuit 16, and the other end is connected to the first connection terminal TT1. In the example shown in FIG. 6, the other end of the high-voltage switch 12 is connected to the first connection terminal TT1 when the switch SW3 is in the on state and the switch SW1 is in the off state. On the other hand, the other end of the high-voltage switch 12 is connected to the second connection terminal TT2 when the switch SW3 is in the off state and the switch SW1 is in the on state. Further, the high voltage switch 12 changes the inductance value according to the set value.

As shown in the figure, the variable inductor 14 may be mounted as one component whose inductance value can be changed. For example, the inductance value can be switched by switching the number of inductors that effectively function among a plurality of inductors. It can also be configured.

The insulation inspection power supply device 10 has a negative electrode wiring that connects the second connection terminal TT2 and the negative electrode terminal of the DC high voltage generating unit 11. The discharge detector 15 is provided on the negative electrode wiring. The discharge detector 15 detects the current output from the first connection terminal TT1 and returned via the test object 20. The capacitor C is connected between the positive electrode terminal and the negative electrode terminal of the DC high voltage generation unit 11. The terminating resistors Rs are connected between the first connection terminal TT1 and the second connection terminal TT2.

The overcurrent protection circuit 16 is on the same path as the high-voltage switch 12, and includes a current sensor, a comparator that compares its output with the current value at which the high-voltage switch is damaged, and a switch that opens and closes according to the comparison result of the comparator. , Can have. When a current that damages the high-voltage switch 12 flows, the output of the current sensor increases, and the switch is opened by the output of the comparator to cut off the circuit. The overcurrent protection circuit 16 has a function of monitoring the circuit, and at the time of such interruption, the function detects an abnormal state and notifies the outside of the insulation inspection power supply device 10 of the abnormal state.

In the insulation inspection power supply device 10 having the above configuration, the test object 20 is connected in step S1, and the DC high voltage generator 11 corresponding to the internal power supply is loaded by the control of the switches SW1 to SW4. Will be connected. The first voltage and the second voltage applied in steps S2 and S6, respectively, can be set together with their rise time by controlling the DC high voltage generating unit 11 from the outside or the like. Then, in the insulation inspection power supply device 10, in step S3, the current is detected by using the current sensor in the overcurrent protection circuit 16, and the determination in step S4 can also be performed there. Further, in the insulation inspection power supply device 10, in step S7, the discharge is detected by using the discharge detector 15.

Then, the results of steps S5, S8, and S9 can be notified to the inspector by the display device provided or connected to the insulation inspection power supply device 10.

As described above, in the insulation inspection method according to the present embodiment, the rise time of the first voltage of the insulation inspection power supply device 10 is lengthened to suppress the sudden flow of current through the circuit. In this insulation inspection method, at the same time, when the current is generated above a predetermined level, the circuit abnormality is determined, and when it is determined that there is no abnormality, the second voltage has a shorter rise time than the first voltage. Inspect the insulation of the object to be inspected with. Therefore, according to the insulation inspection method according to the present embodiment, it is possible to prevent an overcurrent from flowing in the circuit including the power supply and the test object, and it is possible to prevent the high voltage switch 12 from being damaged.

Here, the effect when the test object 20 is used as a motor mounted on a vehicle such as a hybrid vehicle or an electric vehicle will be described. The voltage waveform of the power supply used for insulation inspection in the manufacturing line of the stator included in the motor is closer to that when it is used in the vehicle equipped with the motor, so the voltage rise time is shorter than that of the existing power supply.

Therefore, when the voltage rise time is not controlled as in the present embodiment, the following events occur. That is, when the load is short-circuited and the impedance is extremely low, the circuit is interrupted by the overcurrent even if an overcurrent protection function such as a fuse is provided in the circuit as illustrated in the overcurrent protection circuit 16. The high pressure switch 12 may be damaged before. This is because the rise time of the voltage waveform used for the insulation inspection reaches a high voltage in a short time of, for example, about 40 kV / μsec. If the high-voltage switch 12 is damaged, the power supply device 10 for insulation inspection cannot be restored, it takes time and money to repair, and the power supply device 10 for insulation inspection cannot be used for a period of time.

However, in the insulation inspection power supply device 10 according to the present embodiment, first, by using the function of the power supply capable of varying the voltage rise time, a large rise time is set and it is confirmed whether or not the load is short-circuited. .. Even if the load is short-circuited, if the voltage rise time is increased, the current rise time is also increased, and the overcurrent protection function can be secured for a certain period of time. Therefore, the circuit is connected before the high voltage switch 12 is damaged. It can be blocked.

Then, after it is confirmed that the overcurrent protection function does not work and the load is not short-circuited, the insulation inspection can be performed without damaging the high-voltage switch 12 even if the rise time is reduced.

(Alternative example)
In the above-described embodiment, the insulation inspection power supply device 10 has been described as an example of the insulation inspection power supply device used in the insulation inspection method, but an insulation inspection power supply device having another configuration can also be adopted. .. For example, the power supply device 10 for insulation inspection has an example in which the power supply waveform has a power supply capable of changing the two values of the rise time and the voltage maintenance time (peak maintenance time) separately. It is also possible to use a power supply device for insulation inspection that is fixed.

Further, the power supply device for insulation inspection may adopt a configuration example as illustrated in FIG. 7 or FIG. 7 and 8 are block diagrams showing another configuration example of the power supply device for insulation inspection used in the insulation inspection method of FIG. 1, and FIGS. 7 and 8 are configuration examples different from each other.

The power supply used in the insulation inspection power supply device 10 shown in FIG. 6 has a function of changing the voltage rise time as illustrated by the DC high voltage generation unit 11. Therefore, when the rise time is set to a large value and the short-circuit state of the load is confirmed, the current output of the discharge detector 15 is used without using the overcurrent protection circuit 16, and the current output becomes large. The output of the pulse generator 13 can be reduced and the high voltage switch 12 can be opened to interrupt the circuit.

An example of such a configuration is the insulation inspection power supply device 10a shown in FIG. 7. The insulation inspection power supply device 10a is the insulation inspection power supply device 10 shown in FIG. 6 from which the overcurrent protection circuit 16 has been removed. Naturally, it takes more time to cut off the circuit after the overcurrent occurs than when the overcurrent protection circuit 16 is used, but if the voltage rise time is set in anticipation of that time, the high voltage switch The circuit can be interrupted without damaging the twelve. By adopting such a configuration, the same function can be realized without mounting the overcurrent protection circuit 16.

The insulation inspection power supply device 10b shown in FIG. 8 is the insulation inspection power supply device 10a shown in FIG. 7 in which a current sensor 17 is provided between one end of the terminating resistor Rs and one end of the test object 20. That is, in the insulation inspection power supply device 10b, the current sensor 17 for detecting the current is installed in the vicinity of the test object 20 in the insulation inspection power supply devices 10 and 10a.

In the insulation inspection power supply device 10b, use the overcurrent protection circuit 16 and the discharge detector 15 when checking the short-circuit state of the load by setting a large rise time by using the function that can change the rise time of the voltage. Instead, the current sensor 17 is used. Then, when the current output from the current sensor 17 becomes large, the insulation inspection power supply device 10b reduces the output of the pulse generator 13 and opens the high voltage switch 12 to cut off the circuit.

By adopting such a configuration, when the load is in the released state, no current is generated to pass through the current sensor 17, so that it is possible to detect the release of the load. When the load is released, an overcurrent will not occur and damage the other internal circuits of the power supply device 10b for insulation inspection and the object 20 to be tested, but it is meaningless to carry out the inspection, so before the inspection. It is possible to output a signal such as a test object abnormality, and it is possible to reduce unnecessary test time.

Although the present embodiment has been described above, the above-described embodiment has the following features.
That is, in the insulation inspection method according to the above embodiment, the insulation of the test object is inspected by using a power supply device for insulation inspection provided with a power source capable of setting a voltage rise time. This insulation inspection method includes a first setting step, a detection step, a determination step, and an inspection step. The first setting step sets the rise time of the first voltage. The detection step detects the current in the circuit including the power supply and the test object when the rise time of the first voltage has elapsed. The determination step determines that an abnormality has occurred in the circuit when the detected current is larger than a predetermined level. In the above inspection step, when the detected current is equal to or less than a predetermined level, the rise time of the second voltage is set to inspect the insulation of the test object. Here, the rise time of the second voltage is set shorter than the rise time of the first voltage.

In the above insulation inspection method, the rise time of the first voltage of the power supply device for insulation inspection is lengthened to suppress the sudden flow of current through the circuit, and when the current is generated above a predetermined level, the circuit is used. Judge the abnormality of. Then, in this insulation inspection method, when it is determined that there is no abnormality, the insulation of the object to be inspected is inspected with a second voltage having a shorter rise time than the first voltage. Therefore, according to the above insulation inspection method, it is possible to prevent an overcurrent from flowing in the circuit including the power supply and the test object.

10, 10a, 10b Power supply for insulation inspection 11 DC high voltage generator 12 High voltage switch 13 Pulse generator 14 Variable inductor 15 Discharge detector 16 Overcurrent protection circuit 17 Current sensor 20 Test object Rs Termination resistance SW1, SW2, SW3 , SW4 switch TM1 1st test terminal TM2 2nd test terminal TT1 1st connection terminal TT2 2nd connection terminal

Claims (1)

This is an insulation inspection method that inspects the insulation of a test object using a power supply device for insulation inspection equipped with a power supply that can set the voltage rise time.
The step of setting the rise time of the first voltage and
A step of detecting a current in a circuit including the power supply and the test object when the rise time of the first voltage has elapsed, and a step of detecting the current.
When the detected current is larger than a predetermined level, a step of determining that an abnormality has occurred in the circuit and a step of determining that an abnormality has occurred.
When the detected current is equal to or lower than the predetermined level, a step of setting a rise time of the second voltage and inspecting the insulation of the test object, and
Including
The rise time of the second voltage is set shorter than the rise time of the first voltage.
Insulation inspection method.

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