Disclosure of Invention
The present disclosure has been made in view of the above circumstances, and provides an insulation test device and a method thereof capable of improving test accuracy.
As a first aspect, the present disclosure provides an insulation test device that tests an insulation state of each coating layer of a plurality of wires inserted into a slot (21) included in a core (2) of a rotating electrical machine in a state before a U-phase wire, a V-phase wire, and a W-phase wire are connected. The insulation testing device comprises a power supply unit (3), a switching unit (4), a discharge measuring unit (5), an insulation judging unit (6) and a control unit (7).
The power supply unit includes a first terminal (31) and a second terminal (32). The switching unit switches between an electrically connected state and an electrically disconnected state between the first terminal and the second terminal and the wires and the core of each phase U, V, W. The discharge measurement unit measures an amount of discharge generated between a first member electrically connected to the first terminal, the first member being selected from the wires and the cores of the U, V, W phases, and a second member electrically connected to the second terminal, the second member being selected from the wires and the cores of the U, V, W phases. An insulation judgment unit judges whether or not the coating of the wire rod satisfies a predetermined quality specification based on the discharge amount measured by the discharge measurement unit. The control unit controls the switching unit such that the wires and cores of each phase U, V, W are all electrically connected to the first terminal or the second terminal, while controlling the switching unit to avoid insulation of the wires and cores of each phase U, V, W from both the first terminal and the second terminal.
Therefore, the wires of U, V, W phases and the stator core 2 are all electrically connected to the first terminal or the second terminal, whereby floating potential can be avoided. Thus, it is possible to prevent discharge from being guided from a non-measurement portion where insulation test is not performed to a measurement portion where insulation test is performed. Accordingly, the insulation test device prevents the occurrence of overdetection of the wire rod that satisfies the predetermined quality specification, which is erroneously determined as not satisfying the predetermined quality specification. As a result, the accuracy of the insulation test is improved. Note that the discharge amount refers to the number of discharges measured in a predetermined period of time based on the discharge amount detected by the discharge measurement unit. The wires inserted into the slots of the armature (i.e., the stator core or the rotor core) are referred to as segmented coils.
The insulation test is sometimes performed under conditions of high ambient humidity or hygroscopicity (hereinafter simply referred to as humidity). In this case, a continuous discharge tends to occur, in which a discharge continuously occurs between the U, V, W-phase wire and the member in the core electrically connected to the first terminal and the U, V, W-phase wire and the member in the core electrically connected to the second terminal. The reason for this is that ionization is likely to occur in the gas atoms due to a large amount of moisture contained in the air or the coating, so that electron avalanches occur continuously. Therefore, as a countermeasure in the insulation test, the partial discharge start voltage (i.e., PD IV) is controlled to decrease at a constant rate with respect to the humidity increase rate. However, even with this countermeasure, if the humidity exceeds a predetermined value and causes frequent overdetection to lower the accuracy of the insulation test, continuous discharge may occur.
In view of this, as a sixth aspect, the present disclosure provides an insulation test device that tests an insulation state of each coating layer of a plurality of wires inserted into a groove (21) included in a core (2) of a rotating electrical machine in a state before a U-phase wire, a V-phase wire, and a W-phase wire are connected. The insulation testing device comprises a power supply unit (3), a switching unit (4), a discharge measuring unit (5), an insulation judging unit (6) and a humidity detecting unit (12).
The power supply unit includes a first terminal (31) and a second terminal (32). The switching unit switches between an electrically connected state and an electrically disconnected state between the wires and the core of each phase and the first and second terminals of U, V, W. The discharge measurement unit measures an amount of discharge generated between a first member electrically connected to the first terminal, the first member being selected from the wires and the cores of the U, V, W phases, and a second member electrically connected to the second terminal, the second member being selected from the wires and the cores of the U, V, W phases. An insulation judgment unit judges whether or not the coating of the wire rod satisfies a predetermined quality specification based on the discharge amount measured by the discharge measurement unit. The humidity detecting unit detects the ambient humidity around the wire rod and the core of each phase U, V, W or the hygroscopicity of the coating layer of the wire rod. Further, the insulation test device is configured to set a judgment period from a time when the power supply unit starts applying the voltage to the wire to a time when the insulation judgment unit judges whether or not the insulation state of the wire is acceptable, such that the judgment period in which the ambient humidity or hygroscopicity is higher than a predetermined value is set longer than the judgment period in which the ambient humidity or hygroscopicity is lower than the predetermined value.
Therefore, in the case where the humidity is higher than the predetermined value, the judgment period is set longer, whereby the number of discharges measured by the discharge measurement unit converges with time. Therefore, the insulation test apparatus 1 and the method thereof can avoid overdetection and improve the accuracy of insulation test without being affected by humidity. On the other hand, in the case where the humidity is lower than the predetermined value, the judgment period is set shorter, so that the time required for the insulation test can be shortened.
A seventh aspect of the present disclosure is an insulation test method for testing an insulation state of each coating layer of a plurality of wires inserted into a slot (21) included in a core (2) of a rotating electrical machine in a state before a U-phase wire, a V-phase wire, and a W-phase wire are connected. The method produces a state in which the wires and cores of the phases U, V, W are all electrically connected to the first terminal (31) or the second terminal (32) of the power supply unit (3), while also producing a state in which no element among the elements constituting the wires and cores of the phases U, V, W is insulated from the first terminal and the second terminal. Then, the method applies a voltage from a power supply unit to the wires and cores of the respective phases U, V, W, and measures an amount of discharge generated between a first member electrically connected to the first terminal, which is selected from the wires and cores of the respective phases U, V, W, and a second member electrically connected to the second terminal, which is selected from the wires and cores of the respective phases U, V, W.
According to the insulation test method, similarly to the first aspect, the floating potential is avoided, thereby preventing the occurrence of overdetection and improving the accuracy of the insulation test.
An eighth aspect of the present disclosure is an insulation test method for testing an insulation state of each coating layer of a plurality of wires inserted into a slot (21) included in a core (2) of an armature of a rotating electric machine in a state before a U-phase wire, a V-phase wire, and a W-phase wire are connected.
The method produces a state in which the wires and cores of the U, V, W phases are electrically connected to the first terminal (31) or the second terminal (32) of the power supply unit (3); detecting moisture absorption of the wires of U, V, W phases and ambient humidity around the core or the coating of the wires; the judgment period from the time when the power supply unit starts to apply the voltage to the wire to the time when the insulation judgment unit judges whether the insulation state of the wire is acceptable or not is set such that the judgment period in which the ambient humidity or hygroscopicity is higher than a predetermined value is set longer than the judgment period in which the ambient humidity or hygroscopicity is lower than the predetermined value.
Then, the method measures an amount of discharge generated between a first member electrically connected to the first terminal and a second member electrically connected to the second terminal, the first member selected from the wires and cores of the U, V, W phases, and the second member selected from the wires and cores of the U, V, W phases.
According to the insulation test method, similarly to the sixth aspect, occurrence of over-test is prevented and accuracy of insulation test is improved without being affected by humidity. On the other hand, in the case where the humidity is lower than the predetermined value, the judgment period is set shorter, so that the time required for the insulation test can be shortened.
Note that reference numerals applied to the respective elements denote examples of correspondence between the respective elements and specific elements described in embodiments to be described later.
Detailed Description
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In the following embodiments, elements having the same or substantially the same function are denoted by the same reference numerals, and description thereof is omitted or made as necessary.
(First embodiment)
The first embodiment will be described with reference to the accompanying drawings. As shown in fig. 1 to 3, an insulation test apparatus 1 according to a first embodiment is configured to test an insulation state of each coating layer of a plurality of wires inserted into a slot 21 included in a stator core 2 of a not-shown rotary electric machine. Note that a rotary electric machine is used in, for example, a motor generator mounted on an electric vehicle.
As shown in fig. 1, the insulation test apparatus 1 is provided with a power supply unit 3, a switching unit 4, a discharge measurement unit 5, an insulation judgment unit 6, and a control unit 7. The power supply unit 3 includes an ac power supply. The power supply unit 3 includes a first terminal 31 and a second terminal 32. The first terminal 31 is connected to the switching unit 4 via the wiring 8 on one side, and the second terminal 32 is connected to the switching unit 4 via the wiring 9 on the other side.
The wires of each phase of the switching units 4 and U, V, W are electrically connected to the stator core 2. As shown in fig. 2, U, V, W phases of wires are inserted into slots 21 included in the stator core 2. Fig. 2 schematically shows a part of the stator core 2 and a part of a plurality of wires constituting U, V, W phase wiring. Note that the wire is also referred to as a segmented coil.
Further, as shown in fig. 3, the wire of the U phase, the wire of the V phase, and the wire of the W phase are respectively connected in series. Further, the wires of U, V, W phases are in a state before the respective wires are connected to the neutral point.
As shown in fig. 1, the switching unit 4 can switch between the electrically connected state and the disconnected state of the wires of each phase U, V, W and the wiring 8 connected to one of the first terminals 31 and the wiring 9 connected to the other of the second terminals 32 to the stator core 2.
A choke coil 10 is provided in the wiring 8 connecting the first terminal 31 and the switching unit 4. The choke coil 10 prevents a discharge pulse signal (higher harmonic) caused by partial discharge generated in the wire or the stator core 2 from flowing backward to the power supply unit 3. Further, a coupling capacitor 11 is provided in a wiring 13 connected in parallel with the power supply unit 3 and the switching unit 4, and a discharge pulse signal generated in the wire or the stator core 2 flows into the coupling capacitor 11.
The discharge measurement unit 5 is arranged in series with a coupling capacitor 11. The discharge measurement unit 5 is configured to measure an amount of discharge generated in the wires of each phase U, V, W and the stator core 2 between a member electrically connected to the first terminal 31 via the switching unit 4 and a member electrically connected to the second terminal 32 via the switching unit 4. Specifically, the discharge measurement unit 5 detects a small amount of current flowing through the coupling capacitor 11 at the time of partial discharge, and calculates the discharge amount of the electric charge based on the amount of the small current. Then, the discharge measurement unit 5 measures the number of times of the detected discharge as the discharge amount based on the discharge amount for a predetermined period of time.
According to the present embodiment, the discharge measurement unit 5 measures the discharge amount based on the following two parameters. Specifically, the discharge measurement unit 5 is configured to detect the occurrence of discharge when the discharge amount of the electric charge is greater than or equal to a predetermined amount and the frequency of movement of the electric charge due to application of the alternating voltage is greater than or equal to a predetermined frequency. Then, the discharge measurement unit 5 determines the number of discharges measured in a predetermined period as the discharge amount.
The insulation judging unit 6 judges whether or not the coating layer of the wire rod satisfies a predetermined quality specification based on the discharge amount measured by the discharge measuring unit 5. Specifically, when the amount of discharge measured by the discharge measurement unit 5 is smaller than a predetermined threshold after a lapse of a certain time from the time of start of discharge, the insulation judgment unit 6 judges that the coating of the wire rod satisfies a predetermined quality specification. On the other hand, when the amount of discharge measured by the discharge measurement unit 5 is greater than the predetermined threshold after a lapse of a certain period of time from the start of discharge, the insulation judgment unit 6 judges that the coating of the wire does not satisfy the predetermined quality specification.
The information on the judgment result of the insulation judgment unit 6 is transmitted to the control unit 7. The control unit controls the respective parts of the insulation test apparatus 1. Specifically, the control unit 7 controls the output voltage of the power supply unit 3. Further, the control unit 7 can control the operation of the switching unit 4.
According to the present embodiment, the control unit 7 controls the operation of the switching unit 4 such that all the wires of each phase U, V, W and the stator core 2 are electrically connected to the first terminal 31 or the second terminal 32. Furthermore, the control unit 7 controls the operation of the switching unit 4 to avoid U, V, W each phase of wires and the stator core 2 being insulated from both the first terminal 31 and the second terminal 32.
Accordingly, the insulation test apparatus 1 electrically connects all the wires of each phase U, V, W and the stator core 2 with the first terminal 31 or the second terminal 32, whereby floating potential can be avoided. Thus, discharge is prevented from being guided from the non-measurement portion where insulation test is not performed to the measurement portion where insulation test is performed. Accordingly, the insulation test apparatus 1 prevents the occurrence of overdetection of the wire rod that satisfies the predetermined quality specification, which is erroneously determined as not satisfying the predetermined quality specification. As a result, the accuracy of the insulation test is improved.
Further, the insulation test apparatus 1 according to the first embodiment can test a plurality of portions of interphase insulation and insulation with respect to the ground simultaneously. Therefore, the number of tests becomes smaller as compared with the ordinary insulation test method. Thereby, the time required for the insulation test can be shortened.
Hereinafter, a comparison of an insulation test method according to a first comparative example and an insulation test method using the insulation test apparatus 1 according to the first embodiment will be described with reference to fig. 4. Note that the first comparative example illustrates a conventional wire insulation test in which the wires are connected in series in U, V, W phases. The insulation test sequence shown in the table of fig. 4 may be arbitrarily changed. The same applies to fig. 5 and 7 shown in the second and third embodiments.
First, an insulation test method according to a first comparative example will be described.
According to the first comparative example, the phase-to-phase insulation test is performed in the first test to the third test, and the insulation test with respect to the ground is performed in the fourth test. Specifically, insulation tests of the U-phase wire and the V-phase wire were performed in the first test. In the first insulation test, the first terminal 31 of the power supply unit 3 is electrically connected to the wire of the U phase and the second terminal 32 of the power supply unit 3 is electrically connected to the wire of the V phase by the operation of the switching unit. Then, the power supply unit 3 applies an alternating voltage between the U-phase wire and the V-phase wire, and the discharge amount generated between the U-phase wire and the V-phase wire is measured by the discharge measurement unit 5.
Note that in the first insulation test, the W-phase wire and the stator core 2 were non-measurement portions. Thus, in the case where there is a floating potential in the non-measurement portion, discharge will be induced from the non-measurement portion to the measurement portion, thereby increasing occurrence of discharge. Therefore, according to the configuration of the first comparative example, false detection of the wire rod that satisfies the predetermined quality specification is judged not to satisfy the quality specification may occur. Thus, the accuracy of the insulation test may be lowered.
Subsequently, in the second test, insulation test was performed on the V-phase wire and the W-phase wire. Note that since the second test and the third test differ from the first test only in the test phase, a description thereof will be omitted.
In the fourth test, an insulation test was performed between each wire of U, V, W phases and the stator core 2. In the fourth insulation test, the switching unit 4 electrically connects the wires of each phase of the first terminals 31 and U, V, W of the power supply unit 31, and electrically connects the second terminal 32 of the power supply unit 3 and the stator core 2. Then, the power supply unit 3 applies an alternating voltage between the wires of each phase U, V, W and the stator core 2, and the discharge measurement unit 5 measures the amount of discharge generated between the wires of each phase U, V, W and the stator core 2.
According to the first comparative example, in the case where it is determined that the coating layer of any one of the wires of U, V, W phases does not satisfy the predetermined quality specification during the first to fourth insulation tests, a product in which the coating layer of the wire does not satisfy the quality specification is regarded as a waste product.
Next, a method of insulation testing according to the first embodiment will be described. According to the first embodiment, an insulation test between phases (i.e., an inter-phase insulation test) and an insulation test with respect to ground (i.e., a ground insulation test) are simultaneously performed in the first test and the second test, and an insulation test with respect to ground is performed in the third test. Specifically, in the first test, an insulation test was performed between the U-phase wire and V, W-phase wire, the stator core 2. In the first insulation test, the switching unit 4 electrically connects the first terminal 31 of the power supply unit 3 with the U-phase wire, and the second terminal 32 of the power supply unit 3 with the V, W-phase wire and the stator core 2. Then, the power supply unit 3 applies an alternating voltage between the U-phase wire and V, W-phase wire, the stator core 2, and the discharge measurement unit 5 measures the amount of discharge generated between the U-phase wire and V, W-phase wire, the stator core 2.
Next, in the second test, an insulation test was performed between the V-phase wire and W, U-phase wire, the stator core 2. In the second insulation test, the switching unit 4 electrically connects the first terminal 31 of the power supply unit 3 with the V-phase wire, and electrically connects the second terminal 32 of the power supply unit 3 with the W, U-phase wire and the stator core 2. Then, the power supply unit 3 applies an alternating voltage between the V-phase wire and W, U-phase wire, the stator core 2, and the discharge measurement unit 5 measures the amount of discharge generated between the V-phase wire and W, U-phase wire, the stator core 2.
Finally, in the third test, the wires of each phase U, V, W and the stator core 2 were subjected to insulation test. In the third insulation test, the first terminals 31 and U, V, W phase wires of the power supply unit 3 are electrically connected and the second terminal 32 of the power supply unit 3 is electrically connected to the stator core 2 by the operation of the switching unit 4. Then, the power supply unit 3 applies an alternating voltage between the U, V, W-phase wire and the stator core 2, and the discharge measurement unit 5 measures the amount of discharge generated between the U, V, W-phase wire and the stator core 2.
According to the first embodiment, in the case where it is determined that at least one coating layer in the wires of U, V, W phases does not satisfy the predetermined quality specification during the first to third insulation tests, the product of the wire coating layer that does not satisfy the quality specification is regarded as a waste product.
Therefore, since the number of tests according to the insulation test method of the first embodiment is smaller than that of the first comparative example, the time required for the insulation test can be shortened. As a result, the number of insulation test devices, i.e., the capital investment, can be reduced.
Note that the connection state of the wirings in the first test and the second test according to the first embodiment described above is referred to as a first series connection measurement state. In other words, the first series connection measurement state refers to a state in which the wire of any one of U, V, W phases is electrically connected to the first terminal 31, and the wire of the other two phases is electrically connected to the stator core 2 and the second terminal 32.
Further, the wiring connection in the third test according to the first embodiment is referred to as a second series connection measurement state. In other words, the second series connection measurement state refers to a state in which all wires of U, V, W phases are electrically connected to the first terminal 31, and the stator core 2 and the second terminal 32 are electrically connected. Neither the first series connected measurement state nor the second series connected measurement state produces a non-measurement portion.
The insulation test apparatus 1 and the method thereof according to the first embodiment as described above have the following effects and advantages.
(1) According to the first embodiment, during the insulation test, the control unit 7 controls the switching unit 4 such that none of the wires of each phase U, V, W and the stator core 2 are insulated from the first terminal 31 and the second terminal 32. At this time, the control unit 7 controls the switching unit 4 such that all of the wires of each phase U, V, W and the stator core 2 are electrically connected to the first terminal 31 or the second terminal 32. Thus, when the insulation test is performed, the non-measurement portion can be eliminated. Thus, according to the first embodiment, unlike the first comparative example, discharge is not induced from the non-measurement portion to the measurement portion. Therefore, the insulation test apparatus 1 and the method thereof according to the first embodiment can prevent occurrence of overdetection and improve the accuracy of insulation test.
(2) According to the first embodiment, during the insulation test, the control unit 7 controls the switching unit 4 to generate the first series connection measurement state and the second series connection measurement state. Therefore, the insulation test apparatus 1 and the method thereof according to the first embodiment can reduce the number of tests as compared with the conventional test method described as the comparative example. Thereby, the insulation test apparatus 1 and the method thereof according to the first embodiment avoid having a floating potential, thereby improving the accuracy of insulation test and shortening the time required for insulation test.
(Second embodiment)
The second embodiment will be described below. The second embodiment is different from the first embodiment in that the test method of the insulation test device 1 is slightly modified from that of the first embodiment. Since other portions of the method are the same as those in the first embodiment, only the different portions will be described. Note that according to the second embodiment, wires in respective phases U, V, W are connected in series similarly to the first embodiment.
A method of performing insulation test using the insulation test apparatus 1 according to the second embodiment is shown in the table of fig. 5. Note that since the insulation test method of the first comparative example described in the table of fig. 5 is the same as that of the first embodiment, the description thereof will be omitted.
According to the second embodiment, the phase-to-phase insulation test and the ground insulation test are performed simultaneously in the first test and the second test. Specifically, at the time of the first test, insulation test was performed on U, V, W-phase wires and the stator core 2. In the first insulation test, the first terminal 31 of the power supply unit 3 is electrically connected to the wires of V, W phases and the second terminal of the power supply unit 3 is electrically connected to the wires of U phases and the stator core 2 by the operation of the switching unit 4. Then, the power supply unit 3 applies an alternating voltage between the V, W-phase wire and the U-phase wire and the stator core 2, and the discharge measurement unit 5 measures the amount of discharge generated between the V, W-phase wire and the U-phase wire and the stator core 2.
Next, in the second test, insulation test between W, U phase wires and V phase wires and the stator core 2 was performed. In the second test, the first terminal 31 of the power supply unit 3 is electrically connected to the wires of W, U phases and the second terminal 32 of the power supply unit 3 is electrically connected to the wires of V phases and the stator core 2 by the operation of the switching unit 4. Then, the power supply unit 3 applies an alternating voltage between the W, U-phase wire and the V-phase wire and the stator core 2, and the discharge measurement unit 5 measures the amount of discharge generated between the W, U-phase wire and the V-phase wire and the stator core 2.
According to the second embodiment, in the first insulation test and the second insulation test, in the case where it is judged that at least one coating layer in the U, V, W-phase wire does not satisfy the predetermined quality specification, the product having the wire coating layer that does not satisfy the quality specification is regarded as a waste product.
As described above, according to the second embodiment, the wires of any two phases in U, V, W phases are electrically connected to the first terminal 31, and the wires of the other phase and the stator core 2 are electrically connected to the second terminal 32. Therefore, the U, V, W-phase wires and the stator core 2 are all electrically connected to the first terminal 31 or the second terminal 32, whereby floating potential can be avoided. Therefore, the insulation test apparatus 1 and the method thereof according to the second embodiment can prevent occurrence of overdetection and improve the accuracy of insulation test.
Further, since the number of tests of the insulation test method according to the second embodiment is smaller than that of the first comparative example, the time required for the insulation test can be shortened. Further, the number of tests in the insulation test method according to the second embodiment is smaller than that of the first embodiment.
(Third embodiment)
Next, a third embodiment will be described. The third embodiment is different from the first embodiment in that the test method of the insulation test device 1 is slightly modified from that of the first embodiment. Since other portions of the method are the same as those in the first embodiment, only the different portions will be described.
As shown in fig. 6, according to the third embodiment, wires are connected in parallel in each of U, V, W phases. In the following description, one of the wires of the U phase connected in parallel is referred to as a U1 wire, and the other wire is referred to as a U2 wire. Similarly, one of the wires of the V phase connected in parallel is referred to as a V1 wire, and the other wire is referred to as a V2 wire. Further, one wire connected in parallel among the wires of the W phase is referred to as a W1 wire, and the other wire is referred to as a W2 wire.
Referring to fig. 7, a comparison between the insulation test method of the insulation test apparatus 1 according to the third embodiment and the insulation test method according to the second comparative example will be described. Note that the second comparative example illustrates a conventional wire insulation test method in which each of a U-phase wire, a V-phase wire, and a W-phase wire is connected in parallel.
First, an insulation test method according to a second comparative example will be described. In the second comparative example, the phase-to-phase insulation test was performed in the first test to the third test, the insulation test of each phase was performed in the fourth test to the sixth test, and the insulation test with respect to the ground was performed in the seventh test. Specifically, in the first test, the U1 and U2 wires and the V1 and V2 wires were subjected to insulation test. In the first insulation test, the first terminal 31 of the power supply unit 3 is electrically connected to the U1, U2 wires and the second terminal 32 of the power supply unit 3 is electrically connected to the V1, V2 wires by the operation of the switching unit 4. Then, the power supply unit 3 applies an alternating voltage between the U1, U2 wires and the V1, V2 wires, and the discharge amount generated between the U1, U2 wires and the V1, V2 wires is measured by the discharge measurement unit 5.
Note that in the first insulation test, the W1, W2 wires and the stator core 2 were non-measurement portions. Therefore, in the case where the floating potential exists in the non-measurement portion, discharge is induced from the non-measurement portion to the measurement portion, so that the probability of occurrence of discharge increases.
Subsequently, at the second time, insulation test was performed between the V1, V2 wires and the W1, W2 wires. At the third time, insulation tests were performed on the W1, W2 wires and the U1, U2 wires. Note that since the second and third insulation tests differ from the second and third insulation tests in the first embodiment only in the phase U, V, W, a description thereof will be omitted.
At the fourth test, the insulation test was performed on the U1, U2 wires. In the fourth insulation test, the first terminal 31 of the power supply unit 3 is electrically connected to the U1 wire and the second terminal 32 of the power supply unit 3 is electrically connected to the U2 wire by the operation of the switching unit 4. Then, the power supply unit 3 applies an alternating voltage between the U1 wire and the U2 wire, and the discharge amount generated between the U1 wire and the U2 wire is measured by the discharge measurement unit 5. Note that, in the fourth insulation test, the wires of V1, V2, W1, W2 phases and the stator core 2 are non-measurement portions. Therefore, in the case where the floating potential exists in the non-measurement portion, discharge is induced from the non-measurement portion to the measurement portion, so that the probability of occurrence of discharge increases.
Subsequently, in the fifth test, the V1 wire and the V2 wire were subjected to insulation test. In the sixth test, the insulation test was performed on the W1 wire and the W2 wire. Note that since the fifth and sixth insulation tests differ from the fourth insulation test only in the phase U, V, W of the wire to be tested differs from each other, a description thereof will be omitted.
In the seventh test, the wires of U, V, W phases and the stator core 2 were subjected to insulation test. In the seventh test, the first terminal 31 of the power supply unit 3 is electrically connected with the wires of U1, U2, V1, V2, W1, W2 and the second terminal 32 of the power supply unit 3 is electrically connected with the stator core 2 by the operation of the switching unit. Then, the power supply unit 3 applies an alternating voltage between the U1, U2, V1, V2, W1, W2 wires and the U2 wires, and the discharge amount generated between the U1, U2, V1, V2, W1, W2 wires and the stator core 2 is measured by the discharge measurement unit 5.
According to the second comparative example, in the first to seventh insulation tests, in the case where it is determined that at least one coating layer of the U1, U2, V1, V2, W1, W2 wires does not satisfy the predetermined quality specification, the product having the wire coating layer that does not satisfy the quality specification is regarded as a waste product.
Next, an insulation test method according to a third embodiment will be described. According to the third embodiment, the phase-to-phase insulation test and the ground insulation test are simultaneously performed in the first test and the second test, and the phase-to-phase insulation test and the ground insulation test are performed in the third test. Specifically, in the first test, an insulation test was performed between V, W phase wires and U phase wires and the stator core 2. In the first insulation test, the first terminal 31 of the power supply unit 3 is electrically connected with the V1, V2, W1, W2 wires, and the second terminal 32 of the power supply unit 3 is electrically connected with the U1, U2 wires and the stator core 2 by the operation of the switching unit 4. Then, the power supply unit 3 applies an alternating voltage between the V1, V2, W1, W2 wires and the U1, U2 wires and the stator core 2, and the discharge amount generated between the V1, V2, W1, W2 wires and the U1, U2 wires and the stator core 2 is measured by the discharge measurement unit 5.
Next, in the second test, insulation tests between the W1, W2, U1, U2 wires and the V1, V2 wires and the stator core 2 were performed. In the second test, the first terminal 31 of the power supply unit 3 is electrically connected with the W1, W2, U1, U2 wires, and the second terminal 32 of the power supply unit 3 is electrically connected with the V1, V2 wires and the stator core 2 by the operation of the switching unit 4. Then, the power supply unit 3 applies an alternating voltage between the W1, W2, U1, U2 wires and the V1, V2 wires and the stator core 2, and the discharge amount generated between the W1, W2, U1, U2 wires and the V1, V2 wires and the stator core 2 is measured by the discharge measurement unit 5.
Finally, in the third test, insulation tests were performed between the U1, V1, W1 wires and the U2, V2, W2 wires and the stator core 2. In the third insulation test, the first terminal 31 of the power supply unit 3 is electrically connected with the U1, V1, W1 wires and the second terminal 32 of the power supply unit 3 is electrically connected with the U2, V2, W2 wires, the stator core 2 by the operation of the switching unit 4. Then, the power supply unit 3 applies an alternating voltage between the U1, V1, W1 wire and the U2, V2, W2 wire, the stator core 2, and the discharge amount generated between the U1, V1, W1 wire and the U2, V2, W2 wire, the stator core 2 is measured by the discharge measurement unit 5.
According to the third embodiment, in the first to third insulation tests, in the case where it is determined that at least one coating layer of the U1, U2, V1, V2, W1, W2 wires does not satisfy the predetermined quality specification, the product having the wire coating layer that does not satisfy the quality specification is regarded as a waste product.
Therefore, since the number of tests of the insulation test method according to the third embodiment is smaller than that of the second comparative example, the time required for the insulation test can be shortened.
It should be noted that the connection state of the wirings in the first test and the second test according to the third embodiment is referred to as a first parallel connection measurement state. The first parallel connection measurement state refers to a state in which wires connected in parallel to any two of U, V, W phases are electrically connected to the first terminal 31, and wires connected in parallel to the other phase, the stator core 2, and the second terminal 32.
Further, the connection state of the wiring in the third test according to the third embodiment is referred to as a second parallel connection measurement state. In other words, the second parallel connection measurement state refers to a state in which wires connected in parallel in some phases of each phase U, V, W are electrically connected to the first terminal 31, and wires in other phases of each phase U, V, W, the stator core 2, and the second terminal 32 are electrically connected. Note that no non-measurement portion is generated in the first parallel connection measurement state and the second parallel connection measurement state.
According to the third embodiment described above, during the insulation test, the control unit 7 controls the switching unit 4 to generate the first parallel connection measurement state and the second parallel connection measurement state. Therefore, the insulation test apparatus 1 and the method thereof according to the third embodiment can reduce the number of tests as compared with the conventional test method described as the second comparative example. Thereby, the insulation test apparatus 1 and the method thereof according to the third embodiment eliminate the floating potential, thereby improving the accuracy of the insulation test and also shortening the time required for the insulation test.
(Fourth embodiment)
Next, a fourth embodiment will be described. The fourth embodiment is different from the first embodiment and the like in that the configuration of the insulation test device 1 and the test method thereof are slightly modified from those of the first embodiment. Since other portions are the same as those in the first embodiment, only different portions will be described.
As shown in fig. 8, the insulation test apparatus 1 according to the fourth embodiment is provided with a humidity detection unit 12. The humidity detection unit 12 detects the humidity of the environment around the wire rods of the U-phase, V-phase, W-phase and the stator core 2, or detects the hygroscopicity of the coating layer of the wire rods. In the following description, the ambient humidity or hygroscopicity may be referred to simply as humidity. Further, the humidity detected by the humidity detecting unit 12 may be referred to as simply detected humidity.
The insulation test apparatus 1 of the fourth embodiment sets a determination period from the time when the power supply unit 3 starts to apply a voltage to the wire to the time when the insulation determination unit 6 determines whether or not the insulation state of the wire is acceptable, based on the detected humidity. The judgment period is set to be longer than the judgment period in which the detected humidity is lower than the predetermined value. Note that the predetermined value is set to be in the range of 40% to 60% according to the experimental result or the like, for example.
Here, the importance of the determination period based on the detected humidity change will be described with reference to the graph shown in fig. 9. Fig. 9 is an experimental result showing the change in the number of discharge times due to the influence of humidity.
The vertical axis of fig. 9 indicates the number of discharges. The number of discharges is equal to the amount of discharges. In other words, assuming that the discharge is an event in which the discharge amount of the electric charge is greater than or equal to a predetermined amount and the movement frequency of the electric charge due to the application of the alternating voltage is greater than or equal to a predetermined frequency, the number of times of discharge is defined as the number of measurements of the discharge event in a predetermined period of time. The vertical axis of fig. 9 shows the time elapsed from the time when the power supply unit 3 applies the voltage to the wire. Note that in this experiment, the voltage applied to the wire by the power supply unit 3 was not changed by humidity.
In fig. 9, a change in the number of discharges when the humidity detection unit 12 detects low detected humidity is shown with a bar chart with cross hatching. Further, the change in the number of discharges when the humidity detection unit 12 detects the medium detected humidity is shown by a bar chart with cross hatching. The change in the number of discharges when the humidity detection unit 12 detects high detected humidity is shown by a hollow bar chart.
As shown by the cross-hatched bar graph, in the case of low humidity, the number of discharges is around a predetermined value at time t 1. After time t2, the number of discharges is small. Note that the predetermined value is set in consideration of the service life of the rotary electric machine.
As shown in the hatched bar graph and the open bar graph, in the case of high humidity and medium humidity, the number of discharges exceeds a predetermined value in a period from the start of voltage application by the power supply unit to time t 5. After time t6, the number of discharges is lower than the predetermined value, and the number of discharges appears very small at time t 10.
As shown by the cross-hatched bar chart in fig. 9, in the case where the humidity is low, the period from the time when the discharge starts to the time when the number of discharges becomes small is short. However, as shown in the cross-hatched bar graph and the open bar graph, in the case where the humidity is high, a long time is required from the start of discharge to the time when the number of discharge becomes small. In view of this, according to the fourth embodiment, the judgment period when the humidity is higher than the predetermined value is set longer than the judgment period when the humidity is lower than the predetermined value. Therefore, in the case where the humidity is higher than the predetermined value, the number of discharges measured by the discharge measurement unit 5 converges with time. Therefore, the insulation test apparatus 1 and the method thereof can avoid overdetection and improve the accuracy of insulation test without being affected by humidity. On the other hand, in the case where the humidity is lower than the predetermined value, the judgment period is set shorter, so that the time required for the insulation test can be shortened.
(Other embodiments)
The present disclosure is not limited to the embodiments described above, but may be modified in various ways within the scope of the claims. Furthermore, the embodiments described above are not independent of each other, and therefore, can be appropriately combined unless the case where combination is obviously impossible. Furthermore, in the respective embodiments, elements constituting each embodiment are not necessarily required unless the elements are specified as required or the elements are regarded as theoretically required.
Further, in the case where numerical values such as the number, value, amount, range, and the like of elements are mentioned in the embodiment, the numerical values are not limited to these numerical values except the case where numerical values are specified if necessary or the case where only the specified number is theoretically limited. Further, in each embodiment, when the shape of an element or the positional relationship between them is described, unless otherwise specified or the shape or the positional relationship is theoretically limited, the shape or the positional relationship is not particularly limited.
(1) According to the embodiment described above, the insulation test device 1 is configured to test the insulation state of the coating layer of the wire provided in the stator core 2 as the armature included in the rotary electric machine. However, it is not limited thereto. The insulation test device 1 may be configured to test an insulation state of a wire coating provided in a rotor core as an armature included in a rotary electric machine.
(2) According to the first embodiment described above, the insulation test is performed in a state before the plurality of wires constituting the U-phase, the plurality of wires constituting the V-phase, and the plurality of wires constituting the W-phase are connected in series, respectively, and are connected to the neutral point. However, it is not limited thereto. The insulation test may be performed in a state before the plurality of wires constituting the U phase, the plurality of wires constituting the V phase, and the plurality of wires constituting the W phase are connected in series, respectively, and are connected to the neutral point.
(3) According to the third embodiment described above, for the U-phase wire, the V-phase wire, and the W-phase wire, every two wires in each phase are connected in parallel. However, it is not limited thereto. For the wires of each phase, multiple parallel connection such as triple parallel connection or quadruple parallel connection may be employed.
(4) According to the embodiments described above, the wires may use a star connection. However, it is not limited thereto. For the wire, various connections such as a triangle connection, a triangle-star connection, a star-triangle connection, a triangle-triangle connection, and a star-star connection may be used.
(5) According to the fourth embodiment described above, the judgment period when the detected humidity is higher than the predetermined value is set longer than the judgment period when the detected humidity is lower than the predetermined value. However, it is not limited thereto. The applied voltage may be set such that the applied voltage when the detected humidity is higher than the predetermined value is set lower than the applied voltage when the detected humidity is lower than the predetermined value.