JP7196297B2 - Winding short-circuit diagnostic device and winding short-circuit diagnostic method - Google Patents

Description

The present invention provides a winding short-circuit diagnosis apparatus and a winding short-circuit diagnosis method for diagnosing a winding short circuit in a stator or rotor of a rotating machine in which a plurality of teeth arranged at approximately equal intervals in the circumferential direction are subjected to concentrated winding. Regarding.

In Japanese Patent Application Laid-Open No. 2009-115505 (Patent Document 1), an impulse voltage is applied between terminals of windings of an arbitrary phase among windings inside a rotating machine such as an electric motor or a generator, and the impulse voltage is applied. The waveform of the oscillating voltage generated between the terminals of the winding due to the voltage application is detected, and the oscillating voltage of the normal winding (winding with no short circuit) is created in advance with the waveform of the detected oscillating voltage. is described.

In the winding short-circuit diagnosis device, it is possible to determine which phase winding has a short-circuit. You can identify what is happening.

By the way, if it is possible to specify in what manner the windings inside a rotating machine such as an electric motor or a generator are short-circuited, the winding manner of the windings can be determined by feeding back the short-circuited manner information to the design stage. Since countermeasures can be taken for the structure of teeth for winding windings, etc., it leads to a reduction in the rate of short circuit occurrence in rotating machines such as electric motors and generators, which is a great advantage. Here, as a form of short-circuiting of windings, for example, a form in which short-circuiting occurs between windings adjacent to each other in the length direction of a tooth, and a form in which short-circuiting occurs between layers of windings can be considered.

From the viewpoint of reducing the rate of occurrence of short circuits in rotating machines such as electric motors and generators, the applicant also proposed in Japanese Patent No. 6404424 (Patent Document 2) that a stator or rotor of a rotating machine in which concentrated winding is applied to teeth. We have proposed a winding short-circuit diagnosis device that can identify where in the winding of a child a short-circuit has occurred.

JP 2009-115505 A Japanese Patent No. 6404424

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and is a winding short-circuit diagnosis device that can easily identify a winding short-circuit in a stator or rotor of a rotating machine in which concentrated winding is applied to teeth. A main object of the present invention is to provide a method for diagnosing winding short circuits.

According to a preferred embodiment of the winding short-circuit diagnosis device according to the present invention, short-circuiting of windings in a stator or rotor of a rotating machine in which concentrated winding is applied to a plurality of teeth arranged at approximately equal intervals in the circumferential direction is diagnosed. A winding short circuit diagnostic device is configured. The winding short circuit diagnostic device includes a voltage oscillator, a magnetic field sensor, a memory, and a processor. The voltage oscillator is configured to apply an alternating voltage across the terminals of the winding. The magnetic field sensor measures the strength of the magnetic field generated in the winding wound on each tooth in accordance with the application of the AC voltage at predetermined intervals along the extending direction of the tooth. The memory stores the alternating voltage or the alternating current flowing through the windings due to the alternating voltage and the strength of the magnetic field. The processor determines the orientation of the magnetic field stored in memory for each measurement location based on the alternating voltage or current and the strength of the magnetic field. Further, in the case of the first pattern in which all of the determined directions of the magnetic field are in the first direction, the processor determines that no short-circuit has occurred in the winding, and the direction of the magnetic field is changed from the first direction to the first direction. In the case of the second pattern, which changes from the second direction to the first direction after changing to the second direction opposite to the first direction, a short circuit occurs between windings adjacent to each other in the extending direction of the teeth. In the case of a third pattern in which the direction of the magnetic field changes from the first direction or the second direction to the second direction or the first direction and then remains in the second direction or the first direction, and the magnetic field In the case of the fourth pattern in which all the directions of the windings are in the second direction, it is determined that a short circuit has occurred between the winding layers.

Here, the "strength of the magnetic field" in the present invention corresponds to the magnitude of the magnetic flux density generated in the winding wound for each tooth, or the voltage proportional to the magnitude of the magnetic flux density.

As a result of intensive research on short-circuiting of the windings in the stator or rotor of a rotating machine in which the teeth are subjected to concentrated winding, the present inventor found that the strength of the magnetic field obtained at predetermined intervals along the extending direction of the teeth. It was found that the pattern of changes in the strength and direction of the magnetic field differs depending on the mode of winding short circuit. Based on such research results, in the present invention, in the case of the first pattern, it is determined that no short-circuit has occurred in the winding, and in the case of the second pattern, It is determined that a short circuit has occurred between the windings, and in the case of the third pattern and the fourth pattern, it is determined that a short circuit has occurred between the layers of the windings. can be specified. As a result, it is possible to feed back short-circuit state information to the design stage, and to take countermeasures regarding the winding method of the windings, the structure of the teeth for winding the windings, and the like. As a result, the rate of occurrence of short circuits in rotating machines such as electric motors and generators can be reduced, which can contribute to quality improvement.

According to a further aspect of the turn short circuit diagnosis device according to the present invention, the processor, in the case of the third pattern, determines the direction of the magnetic field from the first direction or the second direction to the second direction or the first direction. If the change occurs at the ends of the teeth in the extending direction, the strength of the magnetic field in the second direction is compared with a threshold, and if the strength of the magnetic field is equal to or greater than the threshold, and/or The absolute value of the rate of change in the strength of the magnetic field when the orientation of the magnetic field changes from the first direction or the second direction to the second direction or the first direction is compared with the reference rate of change, and the absolute value of the rate of change is If it is equal to or greater than the reference rate of change, it is determined that a short circuit has occurred between the windings adjacent in the longitudinal direction of the tooth, and if the strength of the magnetic field is less than the threshold and/or the absolute value of the rate of change is If it is less than the reference rate of change, it is determined that a short circuit has occurred between the winding layers.

According to this embodiment, a short circuit in the windings that occurs at the end of the tooth in the extending direction and at the measurement start position or the measurement end position of the magnetic field may be a short circuit between the windings adjacent in the tooth extending direction. , a short circuit between the layers of the winding. Even if there is a short circuit between windings adjacent to each other in the extending direction of the tooth, if the winding short circuit occurs at the end of the extending direction of the tooth and at the magnetic field measurement start position or the measurement end position. by comparing the strength of the magnetic field in the second direction with a preset threshold, since the direction of the magnetic field remains changed from the first direction or the second direction to the second direction or the first direction, and / Or by comparing the absolute value of the change rate of the strength of the magnetic field when the direction of the magnetic field changes from the first direction or the second direction to the second direction or the first direction with a preset reference change rate It is then determined whether the short circuit that has occurred is a short circuit between adjacent windings in the extending direction of the tooth or a short circuit between winding layers. Here, under the same conditions, the magnetic field strength of the short circuit between the layers of the winding is weaker than the short circuit between the windings adjacent in the extension direction of the teeth, or the magnetic field strength Since the absolute value of the rate of change is small, the strength of the magnetic field when a short circuit occurs between the layers of the winding, or the absolute value of the rate of change in the strength of the magnetic field and the windings adjacent in the extending direction of the teeth By setting the threshold value or reference rate of change to an appropriate value between the strength of the magnetic field when a short circuit occurs between them, or the absolute value of the rate of change in the strength of the magnetic field, the extending direction of the teeth It is possible to distinguish between a short circuit between adjacent windings and a short circuit between winding layers.

According to a further aspect of the winding short-circuit diagnosis device according to the present invention, the memory can store the strength of the magnetic field in association with the measurement position. Then, if the processor determines that a short circuit has occurred between layers of the winding, it determines that the short circuit has occurred in the winding at the measurement position where the direction of the magnetic field first becomes the second direction.

According to this embodiment, when a short circuit occurs between winding layers, it is possible to specify where in the winding wound around the teeth the short circuit has occurred. As a result, it is possible to obtain information on locations where short circuits tend to occur, and by feeding this information back to the design stage, structural or strength measures can be taken at locations where short circuits tend to occur. , leading to a reduction in the rate of occurrence of short circuits in rotating machines such as electric motors and generators, which can contribute to quality improvement.

According to a further aspect of the winding short-circuit diagnosis device according to the present invention, the memory can store the strength of the magnetic field in association with the measurement position. Then, when the processor determines that a short circuit has occurred between the windings adjacent to each other in the longitudinal direction of the teeth, the processor compares the strength of the magnetic field in the second direction with the second threshold, It is determined that a short circuit has occurred in the winding at the measurement position associated with the strength of the magnetic field determined to be present.

According to the present embodiment, when a short circuit occurs between windings adjacent to each other in the longitudinal direction of the teeth, it is possible to identify where in the windings wound around the teeth the short circuit has occurred. . As a result, it is possible to obtain information on locations where short circuits tend to occur, and by feeding this information back to the design stage, structural or strength measures can be taken at locations where short circuits tend to occur. , leading to a reduction in the rate of occurrence of short circuits in rotating machines such as electric motors and generators, which can contribute to quality improvement.

According to a further aspect of the winding short-circuit diagnosis device according to the present invention, the voltage oscillator applies an AC voltage having a frequency higher than the commercial frequency between the terminals of the winding.

The inventors of the present invention found that as the frequency of the AC voltage applied by the voltage oscillator increases, the measured magnetic flux density decreases due to the influence of the inductance component of the winding. It was found that the rate of decrease in magnetic flux density measured at a location where a short circuit occurs tends to be greater than the rate of decrease in magnetic flux density measured at a location where a short circuit does not occur. That is, when the frequency of the AC voltage applied by the voltage oscillator is increased, the value of the magnetic flux density measured at a normal location where a short circuit does not occur in the winding and the value measured at a location where a short circuit occurs. It was found that there is a large difference between the value of the magnetic flux density Based on these research results, in this embodiment, the frequency of the AC voltage applied between the terminals of the winding is set to a frequency higher than the commercial frequency, so it is easy to identify whether a short circuit has occurred. .

According to a further aspect of the winding short-circuit diagnosis device according to the present invention, the voltage oscillator applies an AC voltage of 200 volts or less between terminals of the winding.

According to this aspect, it is possible to reduce the size of the power supply to be supplied to the voltage oscillator, and to finish the electronic circuit of the voltage oscillator at a low cost. As a result, it is possible to reduce the size and cost of the winding short-circuit diagnosis device itself.

According to a further aspect of the winding short circuit diagnosis device according to the present invention, the magnetic field sensor has a search coil for measuring the strength of the magnetic field. The magnetic field sensor is arranged so that the axial direction of the search coil is parallel to the axial direction of the wire wound around the teeth when measuring the strength of the magnetic field.

According to this aspect, it is possible to accurately measure the strength of the magnetic field generated in the winding by the AC voltage applied between the terminals of the winding by the voltage oscillator.

According to a further aspect of the winding short circuit diagnosis device according to the present invention, the magnetic field sensor has a search coil for measuring the strength of the magnetic field. When the magnetic field sensor measures the strength of the magnetic field, the axis of the search coil on the virtual projection plane when viewed from one side in the axial direction of the stator or rotor is the winding wound around the teeth. are arranged so as to overlap the axis of

According to this embodiment, the magnetic field strength is measured with the axis of the search coil of the magnetic field sensor aligned with the axis of the winding wound around the teeth. The edge, in other words, the influence of the magnetic field produced by the portion of the winding wound around the tooth that is located radially outwardly away from the axis can be suppressed to a low level. As a result, it is possible to more accurately diagnose the presence or absence of short-circuiting of the windings.

According to a preferred embodiment of the winding short-circuit diagnosis method according to the present invention, short-circuiting of the windings in a stator or rotor of a rotating machine in which concentrated winding is applied to a plurality of teeth arranged at approximately equal intervals in the circumferential direction is detected. A winding short circuit diagnostic method for diagnosing is configured. The winding short circuit diagnosis method includes (a) applying an alternating voltage between terminals of a winding wound for each tooth, and (b) detecting a magnetic field generated in the winding wound for each tooth in response to the application of the alternating voltage. is measured at predetermined intervals along the extending direction of the teeth, and (c) the alternating voltage or the alternating current flowing through the winding due to the alternating voltage, and the measured magnetic field strength, (d) determining a magnetic field orientation for each of the stored predetermined intervals based on the alternating voltage or alternating current and the strength of the magnetic field; (e) determining all of the determined magnetic field orientations in the first In the case of the first pattern, which is the direction, it is determined that no short circuit has occurred in the winding, and the direction of the determined magnetic field is changed from the first direction to the second direction opposite to the first direction. After the change, in the case of the second pattern changing from the second direction to the first direction, it is determined that a short circuit has occurred between the windings adjacent in the extending direction of the teeth, and stored in the determination memory. In the case of the third pattern in which the direction of the magnetic field changes from the first direction or the second direction to the second direction or the first direction and then remains in the second direction or the first direction, and all the directions of the magnetic field are In the case of the fourth pattern in the second direction, it is determined that a short circuit has occurred between the winding layers.

Here, the "strength of the magnetic field" in the present invention corresponds to the magnitude of the magnetic flux density generated in the winding wound for each tooth, or the voltage proportional to the magnitude of the magnetic flux density.

As a result of intensive research on short-circuiting of the windings in the stator or rotor of a rotating machine in which the teeth are subjected to concentrated winding, the present inventor found that the strength of the magnetic field obtained at predetermined intervals along the extending direction of the teeth. It was found that the pattern of changes in the strength and direction of the magnetic field differs depending on the mode of winding short circuit. Based on such research results, in the present invention, in the case of the first pattern, it is determined that no short-circuit has occurred in the winding, and in the case of the second pattern, It is determined that a short circuit has occurred between the windings, and in the case of the third pattern and the fourth pattern, it is determined that a short circuit has occurred between the layers of the windings. can be specified. As a result, it is possible to feed back short-circuit state information to the design stage, and to take countermeasures regarding the winding method of the windings, the structure of the teeth for winding the windings, and the like. As a result, the rate of occurrence of short circuits in rotating machines such as electric motors and generators can be reduced, which can contribute to quality improvement.

According to a further aspect of the turn short circuit diagnosis method according to the present invention, step (e) is the case of the third pattern, and the magnetic field from the first direction or the second direction to the second direction or the first direction If the change in the direction of occurs at the end of the tooth in the extending direction, the strength of the magnetic field in the second direction is compared with a threshold, and if the strength of the magnetic field is greater than or equal to the threshold, and/ Alternatively, the absolute value of the rate of change in the strength of the magnetic field when the direction of the magnetic field changes from the first direction or the second direction to the second direction or the first direction is compared with the reference rate of change, and the absolute value of the rate of change If the value is equal to or greater than the reference rate of change, it is determined that a short circuit has occurred between the windings adjacent in the longitudinal direction of the tooth, and if the strength of the magnetic field is less than the threshold and/or the rate of change If the absolute value is less than the reference rate of change, determining that a short circuit has occurred between layers of the winding.

According to this embodiment, a short circuit in the windings that occurs at the end of the tooth in the extending direction and at the measurement start position or the measurement end position of the magnetic field may be a short circuit between the windings adjacent in the tooth extending direction. , a short circuit between the layers of the winding. Even if there is a short circuit between windings adjacent to each other in the extending direction of the tooth, if the winding short circuit occurs at the end of the extending direction of the tooth and at the magnetic field measurement start position or the measurement end position. by comparing the strength of the magnetic field in the second direction with a preset threshold, since the direction of the magnetic field remains changed from the first direction or the second direction to the second direction or the first direction, and / Or by comparing the absolute value of the change rate of the strength of the magnetic field when the direction of the magnetic field changes from the first direction or the second direction to the second direction or the first direction with a preset reference change rate It is then determined whether the short circuit that has occurred is a short circuit between adjacent windings in the extending direction of the tooth or a short circuit between winding layers. Here, under the same conditions, the magnetic field strength of the short circuit between the layers of the winding is weaker than the short circuit between the windings adjacent in the extension direction of the teeth, or the magnetic field strength Since the absolute value of the rate of change is small, the strength of the magnetic field when a short circuit occurs between the layers of the winding, or the absolute value of the rate of change in the strength of the magnetic field and the windings adjacent in the extending direction of the teeth By setting the threshold value or reference rate of change to an appropriate value between the strength of the magnetic field when a short circuit occurs between them, or the absolute value of the rate of change in the strength of the magnetic field, the extending direction of the teeth It is possible to distinguish between a short circuit between adjacent windings and a short circuit between winding layers.

Advantageous Effects of Invention According to the present invention, it is possible to identify the mode of short-circuiting of windings in a stator or rotor of a rotating machine in which concentrated winding is applied to teeth.

1 is a configuration diagram showing an outline of the configuration of a winding short-circuit diagnostic device 1 according to an embodiment of the present invention; FIG. FIG. 3 is an explanatory view showing a state of the electric motor 2 with the rotor 32 removed, viewed from one side in the axial direction; 2 is an explanatory diagram showing the outline of the configuration of a stator 22; FIG. FIG. 11 is a perspective explanatory view showing the positional relationship between a U-phase winding 24U and a search coil 62 installed on the U-phase winding 24U; FIG. 10 is an explanatory diagram showing the positional relationship between a U-phase winding 24U and a search coil 62 installed on the U-phase winding 24U as viewed in a cross section taken along a plane orthogonal to axes CL1 and CL2. FIG. 10 is an explanatory diagram showing how the magnetic field is measured while moving the search coil 62 installed on the U-phase winding 24U at predetermined intervals d along the extending direction of the teeth 22b. FIG. 4 is an explanatory diagram schematically showing a state of a magnetic field generated around a U-phase winding 24U when an AC voltage is applied between terminals of the U-phase winding 24U; FIG. 10 is an explanatory diagram schematically showing a state of a magnetic field generated around the U-phase winding 24U when a short circuit S occurs in a part of the U-phase winding 24U; FIG. 10 is an explanatory diagram showing the state of the alternating current and the output voltage Vs when the phase difference is within a predetermined range; FIG. 10 is an explanatory diagram showing the state of the alternating current and the output voltage Vs when the phase difference is outside the predetermined range; It is an experimental result which shows the measurement result of the output voltage Vs in solenoid coil SLC1. It is an experimental result which shows the measurement result of the output voltage Vs in solenoid coil SLC2. It is an experimental result which shows the measurement result of the output voltage Vs in solenoid coil SLC3. It is an experimental result which shows the measurement result of the output voltage Vs in solenoid coil SLC4. It is an experimental result which shows the measurement result of the output voltage Vs in solenoid coil SLC5. It is an experimental result which shows the measurement result of the output voltage Vs in solenoid coil SLC6. It is an experimental result which shows the measurement result of the output voltage Vs in solenoid coil SLC7. It is an experimental result which shows the measurement result of the output voltage Vs in solenoid coil SLC8. It is an explanatory view showing solenoid coil SLC1 typically. It is explanatory drawing which shows solenoid coil SLC2 typically. It is explanatory drawing which shows solenoid coil SLC3 typically. It is explanatory drawing which shows solenoid coil SLC4 typically. It is explanatory drawing which shows solenoid coil SLC5 typically. It is explanatory drawing which shows solenoid coil SLC6 typically. It is explanatory drawing which shows solenoid coil SLC7 typically. It is explanatory drawing which shows solenoid coil SLC8 typically. FIG. 11 is an explanatory diagram showing how an output voltage Vs is measured using a magnetic field sensor 106 of a modified example;

BEST MODE FOR CARRYING OUT THE INVENTION Next, the best mode for carrying out the present invention will be described using examples.

As shown in FIG. 1, the winding short-circuit diagnosis device 1 according to the embodiment of the present invention is configured to detect any of three-phase windings 24U, 24V, and 24W described later of an electric motor 2 (see FIG. 2) as a rotating machine. A voltage oscillator 4 that applies an AC voltage between terminals; a magnetic field sensor 6 that measures the magnetic field generated in the three-phase windings 24U, 24V, and 24W by the application of the AC voltage by the voltage oscillator 4; An A/D converter 8 electrically connected to the oscillator 4 and the magnetic field sensor 6 by signal lines L1 and L2, and a diagnostic unit 10 electrically connected to the A/D converter 8 by a signal line L3. , and a display device 12 electrically connected to the diagnostic unit 10 by a signal line L4.

The electric motor 2 is configured as a general-purpose three-phase induction motor, and mainly includes a stator 22 and a rotor 32, as shown in FIG.

The stator 22 is configured by laminating thin electromagnetic steel plates (ferromagnetic materials), and as shown in FIG. and a plurality of teeth 22b extending toward the center of.

For example, 18 teeth 22b are provided at equal intervals in the circumferential direction on the inner peripheral surface of the yoke 22a. As shown in FIG. 2, three-phase windings 24U, 24V, and 24W are applied directly to each tooth 22b via an insulator (not shown) (so-called concentrated winding system). That is, 6 of the 18 teeth 22b are wound with the U-phase winding 24U, the other 6 are wound with the V-phase winding 24V, and the remaining 6 are wound with the W-phase winding 24W. there is The ends of the three-phase windings 24U, 24V, and 24W form connection terminals 26 that are drawn out of the electric motor 2 as lead wires and connected to a commercial AC power supply. Here, the stator 22 having the teeth 22b on which the three-phase windings 24U, 24V, and 24W are wound by a concentrated winding method corresponds to the "concentrated winding on a plurality of teeth arranged at substantially equal intervals in the circumferential direction" in the present invention. It is an example of an implementation configuration corresponding to the "rotating machine stator".

Voltage oscillating unit 4 operates between U-phase winding 24U and V-phase winding 24V among three-phase windings 24U, 24V, and 24W (hereinafter referred to as “between the UV phases”), or between V-phase windings 24V and W AC voltage can be applied between the phase windings 24W (hereinafter referred to as "V-W phases") or between the W-phase windings 24W and U-phase windings 24U (hereinafter referred to as "W-U phases"). It is configured as a function generator capable of changing the frequency of the AC voltage to be applied. The AC voltage applied between the UV phase, the VW phase, and the WU phase by the voltage oscillator 4 or the AC current ACI flowing by the AC voltage is A/D converted as shown in FIG. After being digitized by the unit 8, it is transmitted to the diagnostic unit 10 via the signal line L3.

In this embodiment, the AC voltage applied between the UV phase, the VW phase, and the WU phase by the voltage oscillator 4 is 200 volts or less, and the frequency is 60 Hz (or 200 Hz) was set to 1 kHz. For example, by setting the AC voltage to 50 volts or less, it is possible to downsize the power supply and to finish the electronic circuit of the voltage oscillator 4 at a low cost. As a result, it is possible to reduce the size and cost of the winding short-circuit diagnosis device 1 itself. Also, by setting the frequency to 1 kHz, which is higher than the commercial AC power frequency of 60 Hz (or 50 Hz), it becomes easier to identify that a short circuit has occurred in the three-phase windings 24U, 24V, and 24W. The details of the reason will be described later.

The magnetic field sensor 6 includes a search coil 62 and an amplifier 64 that amplifies the magnitude of the output voltage Vs output from the search coil 62, as shown in FIG. The search coil 62 has a structure in which a coil is wound from several turns to several tens of turns, thereby outputting an output voltage Vs proportional to the magnitude of the magnetic flux density. The output voltage Vs, which is an analog signal output from the search coil 62 and amplified by the amplifier 64, is digitized by the A/D conversion section 8 and then transmitted to the diagnosis section 10 via the signal line L3.

The diagnostic unit 10 is configured as a microprocessor centering on a CPU 70 (not shown), and in addition to the CPU 70, a ROM 72 (not shown) for storing processing programs, a RAM 74 for temporarily storing data, and a signal line L3 are connected. and an output port to which the signal line L4 is connected. The diagnosis unit 10 receives the output voltage Vs, the AC voltage, and the AC current ACI from the A/D conversion unit 8. From the diagnosis unit 10, short-circuit diagnosis results for each of the three-phase windings 24U, 24V, and 24W are provided. is output to the display device 12 via the signal line L4.

Next, the operation of short-circuit diagnosis of the three-phase windings 24U, 24V, and 24W of the electric motor 2 by the winding short-circuit diagnosis device 1 according to the embodiment of the present invention configured as described above will be described. Here, the short-circuit diagnosis of the three-phase windings 24U, 24V, and 24W is performed with the rotor 32 removed from the electric motor 2, that is, with only the concentrated winding stator 22 (see FIG. 2). The diagnosis is performed for each tooth 22b around which one of the three-phase windings 24U, 24V, and 24W is wound. A case of diagnosing a short circuit in the winding 24U will be described as an example.

First, as shown in FIG. 2, in the stator 22 with the rotor 32 removed from the electric motor 2, the magnetic field sensor 6 is installed on any one tooth 22b around which the U-phase winding 24U is wound. Here, as shown in FIGS. 2, 4 and 5, the magnetic field sensor 6 is arranged such that the axis CL1 of the search coil 62 is aligned with the axis CL2 of the U-phase winding 24U wound around the teeth 22b (the axis CL2 of the teeth 22b). , and the distance of the axis CL1 from the surface of the U-phase winding 24U is a predetermined distance h (for example, 5 mm) (see FIG. 5), and the electric motor 2 (stator 22, When viewed from one side of the rotor 32) in the axial direction (when viewed from the direction perpendicular to the paper surface of FIG. 2), the positional relationship (see FIG. 2) is such that the axis CL1 and the axis CL2 overlap. Installed. At this time, as shown in FIG. 6, the magnetic field sensor 6 is positioned on the U-phase winding 24U in which the search coil 62 is wound around the base of the tooth 22b (the connection end of the tooth 22b to the yoke 22a), that is, the measurement It is installed so that it comes to position _t0 .

Then, in the installation state, an alternating voltage (200 V or less) with a frequency of 1 kHz is applied between the voltage oscillator 4 and the terminals of the U-phase winding 24U, more specifically, between the UV phases (or between the W and U phases). to flow an alternating current ACI. Here, the AC current ACI that flows through the U-phase winding 24U due to the AC voltage is digitized by the A/D conversion unit 8, and then linked to the measured measurement position _t0 and stored in the RAM 74 of the diagnosis unit 10. temporarily stored in

When an AC voltage is applied between terminals of U-phase winding 24U (between UV phases or between WU phases), a magnetic field is generated around U-phase winding 24U. As a result, the strength of the magnetic field is output from the search coil 62 as an output voltage Vs proportional to the magnitude of the magnetic flux density. The output voltage Vs output from the search coil 62 is amplified by the amplifier 64 and digitized by the A/D converter 8, and then linked to the measurement position _t0 at which the output voltage Vs was measured to be sent to the diagnostic unit. 10 is temporarily stored in the RAM 74 . The RAM 74, which stores the alternating current ACI flowing through the U-phase winding 24U due to the alternating voltage and the output voltage Vs in association with the measurement position _t0 , is an example of an implementation configuration corresponding to the "memory" in the present invention. is.

Here, when the U-phase winding 24U is not short-circuited, that is, when the U-phase winding 24U is in a normal state and an AC voltage is applied between the terminals of the U-phase winding 24U, the solid line in FIG. As indicated by the arrow, an alternating current ACI flows through the U-phase winding 24U, and the alternating current ACI generates a magnetic field of strength _H0 around the U-phase winding 24U. However, if a short circuit S occurs in part of the U-phase winding 24U, a new closed loop 24Us is generated by the short circuit S in the U-phase winding 24U, as shown in FIG. Since the resistance of the short circuit S is almost zero, the alternating current ACI flows through the short circuit S and does not flow through the closed loop 24Us.

On the other hand, in the closed loop _24Us , an induced electromotive force is generated by the passage of the magnetic field generated around the U-phase winding 24U by the alternating current ACI, and the current IS flows due to the induced electromotive force (see FIG. 8). ). As a result, as shown in FIG. 8, there is a magnetic field around the closed loop 24Us with a strength H _S due to the current I _S and a direction opposite to the direction of the magnetic field generated around the U-phase winding 24U by the alternating current ACI. A magnetic field is generated. That is, the output voltage Vs output from the search coil 62 is composed of the magnetic field intensity H ₀ generated around the U-phase winding 24U by the alternating current ACI and the magnetic field intensity _{H S generated} around the closed loop 24Us by the current IS. The size is proportional to the difference between

Since the induced electromotive force can be expressed as a function of the frequency of the AC voltage applied between the terminals of the U-phase winding 24U, the frequency of the AC voltage applied between the terminals of the U-phase winding 24U can be increased. can intentionally increase the strength of the magnetic field H _S generated around the closed loop 24Us. This facilitates identification of whether or not a short circuit has occurred in U-phase winding 24U.

In other words, as the frequency of the AC voltage applied between the terminals of U-phase winding 24U increases, the measured magnetic flux density decreases due to the influence of the inductance component of U-phase winding 24U. , the rate of decrease in the magnetic flux density measured at the location where the short circuit S occurs tends to be greater than the rate of decrease in the magnetic flux density measured at the location where the short circuit S does not occur. As the frequency of the AC voltage applied between the terminals of the winding 24U increases, the value of the magnetic flux density measured at the location where the short circuit S occurs and the normal location where the short circuit S does not occur A large difference can be generated between the value of the magnetic flux density measured at , and it becomes easy to identify whether or not a short circuit has occurred in the U-phase winding 24U.

Here, in FIG. 8, the U-phase winding 24U is short-circuited between adjacent windings in the direction of the axis CL2 of the U-phase winding 24U (the direction of the axis CL2 of the teeth 22b or the extension direction of the teeth 22b). However, even if the U-phase winding 24U is short-circuited between winding layers, a new closed loop is similarly generated by the short-circuit S in the U-phase winding 24U. An induced electromotive force is generated, and a magnetic field is generated in a direction opposite to the direction of the magnetic field generated around U-phase winding 24U by AC current ACI.

Note that when a short circuit occurs between adjacent windings in the direction of the axis CL2 of the U-phase winding 24U (the direction of the axis CL2 of the teeth 22b or the direction in which the teeth 22b extend), the U-phase winding 24U The value of the current IS flowing through the closed loop _24Us also becomes larger than when a short circuit occurs between the winding layers (see the following equations (1) and (2)). Therefore, when a short circuit occurs between adjacent windings in the direction of the axis CL2 of the U-phase winding 24U (the direction of the axis CL2 of the teeth 22b or the extending direction of the teeth 22b), the U-phase winding 24U The absolute value of the strength H _S of the magnetic field generated around the closed loop 24Us and the rate of change of the magnetic field are larger than when a short circuit occurs between the winding layers.

(Number 1)
Is=1/√(R ² +n ² ·ω ² ·L ² )·dφ/dt (1)
Is=1/√(R ² +N ² ·ω ² ·L ² )·dφ/dt (2)

Here, the expression (1) expresses the current Is Equation (2) is an equation for determining the current Is when a short circuit occurs between the winding layers of the U-phase winding 24U, where N>n. Here, R is the resistance of the short-circuit S portion, ω is the angular frequency, L is the inductance component of the short-circuit S portion, φ is the magnetic flux passing through the short-circuit S portion, t is time, and n and N are the short-circuit S is the number of turns of

When the output voltage Vs is temporarily stored in the RAM 74 together with the measurement position _t0 , the CPU 70 of the diagnostic unit 10 subsequently detects the magnetic field sensor 6 ( Determine the orientation of the magnetic field measured by the search coil 62). Specifically, the phase difference between the alternating current ACI and the output voltage Vs is compared, and the direction of the magnetic field is determined based on the phase difference. As shown in FIG. 9, if the phase difference between the AC current ACI and the output voltage Vs is within a predetermined range, it is determined that the direction of the magnetic field is in the positive direction. If the phase difference with respect to the voltage Vs is outside the predetermined range, it is determined to be in the negative direction. Here, the positive direction of the magnetic field is defined as the direction of the magnetic field measured by the magnetic field sensor 6 (search coil 62) being the same as the direction of the magnetic field generated around the U-phase winding 24U. , that the direction of the magnetic field is negative is defined as that the direction of the magnetic field measured by the magnetic field sensor 6 (search coil 62) is opposite to the direction of the magnetic field generated around the U-phase winding 24U. . Here, the CPU 70 of the diagnostic unit 10, which compares the phase difference between the AC current ACI and the output voltage Vs and determines the direction of the magnetic field based on the phase difference, is an example of implementation configuration corresponding to the "processor" in the present invention. be. The embodiment in which the direction of the magnetic field is in the positive direction corresponds to the "first direction" in the present invention, and the embodiment in which the direction of the magnetic field is in the negative direction corresponds to the "second direction" in the present invention. be.

The reason why the direction of the magnetic field measured by the magnetic field sensor 6 (search coil 62) is determined in this way is to more accurately diagnose whether or not a short circuit has occurred in the U-phase winding 24U. That is, in the concentrated winding, even if a minor short circuit such as a short circuit occurs due to the configuration in which the tooth 22b is made of a ferromagnetic material, the direction of the magnetic field generated by other portions where no short circuit occurs is opposite to the direction of the magnetic field. Since a strong magnetic field is generated, the difference between the case where a short circuit occurs and the case where a short circuit does not occur may be unclear only with the strength of the magnetic field (magnitude of the output voltage Vs). It may be difficult to determine the occurrence of a short circuit, but by considering the direction of the magnetic field, the difference between when a short circuit has occurred and when it has not occurred becomes clear, so the occurrence of a short circuit can be reliably diagnosed.

Then, a process of adding a positive value related to the determined direction of the magnetic field to the stored output voltage Vs is executed. That is, the process of replacing the output voltage Vs (with no positive/negative information added) previously stored in the RAM 74 with the output voltage Vs with positive/negative information added is executed. When the process of storing the output voltage Vs added with positive/negative information at the measurement position _t0 in the RAM ₇₄ is completed in this way, the magnetic field sensor ₆ is moved so that the search coil 62 comes to the measurement position t1. In addition to measuring the output voltage Vs, the direction of the magnetic field is determined based on the relationship between the output voltage Vs and the alternating current ACI, and the output voltage Vs previously stored in the RAM 74 (with no positive/negative information added) is A process of replacing with an output voltage Vs to which positive/negative information is added is executed.

Such processing is repeatedly performed while moving by a predetermined interval d to the measurement position _tL . That is, the position of the search coil 62 is moved from the root of the tooth 22b (the connection end of the tooth 22b to the yoke 22a) toward the tip of the tooth 22b (the end near the center of the stator 22) along the axis CL2 of the tooth 22b. The above-described processing (processing from measuring the output voltage Vs without positive/negative information to replacing it with the output voltage Vs with positive/negative information) is executed while moving by a predetermined interval d along the extending direction of the do. The predetermined interval d can be set, for example, to a value substantially equal to the center-to-center distance of the coils forming the three-phase windings 24U, 24V, and 24W.

Then, a process of determining a change mode of the output voltage Vs for each measurement position t _i (i=0 to L) to which positive/negative information is added is executed. Specifically, the first pattern in which the output voltage Vs is all positive, or the second pattern in which the output voltage Vs changes from positive to negative and then changes from negative to positive again is determined. It is determined whether it is a third pattern in which the output voltage Vs remains negative or positive while changing from positive or negative to negative or positive, or a fourth pattern in which the output voltage Vs remains negative.

In the case of the first pattern, it is determined that the U-phase winding 24U is not short-circuited, and the determination result is transmitted to the display device 12 . In the case of the second pattern, a process of comparing the absolute value of the output voltage Vs to which negative information is added and the threshold value Vsref1 is executed. Here, the threshold Vsref1 is set when a short circuit occurs between adjacent windings in the direction of the axis CL2 of the U-phase winding 24U (the direction of the axis CL2 of the teeth 22b or the extension direction of the teeth 22b). It is a value set to determine the location of the short circuit, and in the present embodiment, it is obtained in advance by experiments or the like and stored in the ROM 72 . The threshold Vsref1 is an example of implementation configuration corresponding to the "second threshold" in the present invention.

As a result of comparing the absolute value of the output voltage Vs to which negative information is added and the threshold Vsref1, if there is an output voltage Vs determined to be equal to or greater than the threshold Vsref1, it is first determined to be equal to or greater than the threshold Vsref1. At the measurement position t _i (i=0 to L) of the output voltage Vs, the winding adjacent in the direction of the axis CL2 of the U-phase winding 24U (the direction of the axis CL2 of the teeth 22b or the extension direction of the teeth 22b) It determines that a short circuit has occurred between them, and transmits the determination result to the display device 12 .

Further, when it is determined that the change mode of the output voltage Vs is the third pattern, the measurement position t _i (i=0 to L) of the output voltage Vs changed from positive or negative to negative or positive is the tooth It is determined whether or not the end of 22b (extending end of tooth 22 or end of tooth 22 on the connection side to stator 22), that is, measurement position _t0 or measurement position _tL . When the measurement position t _i (i=0 to L) of the output voltage Vs changed from positive or negative to negative or positive is not the measurement position t ₀ , t _L , the output voltage Vs changes from positive to negative If there is, it is determined that a short circuit has occurred between the layers of the U-phase winding 24U at the measurement position t _i (i=0 to L) of the output voltage Vs to which negative information is first added, and the output voltage Vs is changed from negative to positive, the U-phase _winding It determines that a short circuit has occurred between the layers of the line 24U, and transmits the determination result to the display device 12 .

On the other hand, when the measurement positions t _i (i=0 to L) of the output voltage Vs changed from positive or negative to negative or positive are the measurement positions t ₀ and t _L , the output voltage to which negative information is added Whether or not the absolute value of Vs is equal to or greater than the threshold value Vsref2, or the difference between the peak value of the output voltage Vs to which positive information is added and the peak value of the output voltage Vs to which negative information is added is determined as a positive value. measurement position t i (i=0 to L) of the peak value of the output voltage Vs to which information is added and measurement position t _i (i=0 to L) of the peak value of the output voltage Vs to which negative information is added _; It is determined whether or not the absolute value of the change rate CR calculated by dividing by the difference is greater than or equal to the reference change rate BCR. Here, the threshold Vsref2 and the reference rate of change BCR are determined when a short circuit occurs between windings adjacent to the U-phase winding 24U in the direction of the axis CL2 (the direction of the axis CL2 of the teeth 22b or the extending direction of the teeth 22b). or the U-phase winding 24U is short-circuited between layers. It was configured as follows. The threshold Vsref2 is an example of implementation configuration corresponding to the "threshold" in the present invention.

If the absolute value of the output voltage Vs to which negative information is added is equal to or greater than the threshold value Vsref2, or if the absolute value of the change rate CR is equal to or greater than the reference change rate BCR, then at the measurement positions t ₀ and t _L , the U-phase winding 24U (the direction of the axis CL2 of the teeth 22b or the extending direction of the teeth 22b). On the other hand, if the absolute value of the output voltage Vs to which negative information is added is less than the threshold value Vsref2, or if the absolute value of the change rate CR is less than the reference change rate BCR, then at the measurement positions t ₀ and t _L , the U-phase winding It determines that a short circuit has occurred between the layers of the line 24U, and transmits the determination result to the display device 12 .

Furthermore, when it is determined that the change mode of the output voltage Vs is the fourth pattern, it is determined that a short circuit has occurred between the layers of the U-phase winding 24U, and the determination result is transmitted to the display device 12. . Generated in the U-phase winding 24U based on the change mode (first, second, third and fourth patterns) of the output voltage Vs for each measurement position t _i (i=0 to L) to which positive/negative information is added , i.e., whether a short circuit occurs between windings adjacent to each other in the direction of the axis CL2 of the U-phase winding 24U, or whether a short circuit occurs between layers of the winding concerned. The CPU 70 is an example of implementation structure corresponding to the "processor" in the present invention.

Next, FIG. 11 to FIG. 11 show experimental results of diagnosing the occurrence of short circuits in the above-described first, second, third and fourth patterns using the winding short circuit diagnostic device 1 of the present invention according to the present embodiment. 26 for explanation. In the experiment, a solenoid coil was used in which two layers of winding were wound in a range of 50 mm in the center in the longitudinal direction of a rectangular parallelepiped iron material having a length of 60 mm, leaving only 5 mm at both ends in the longitudinal direction. The magnetic field sensor 6 is installed so that the search coil 62 is arranged at one end (hereinafter referred to as the “measurement start point”), and the magnetic field sensor 6 is 2 mm (the length of the winding) in the axial direction of the solenoid coil (the longitudinal direction of the rectangular parallelepiped). Center-to-center distance), the magnetic field was measured by changing the measurement point to the other end of the solenoid coil in the longitudinal direction (hereinafter referred to as "measurement end point").

In this experiment, the solenoid coil SLC1 (FIGS. 11 and 19) having a two-layer winding structure without a short circuit, and the solenoid coil at a point 30 mm from the measurement start point (measurement position t ₃₀ , FIGS. A solenoid coil SLC2 with a two-layer winding structure in which a short circuit is generated between windings adjacent to each other in the longitudinal direction, and a winding adjacent to the solenoid coil in the longitudinal direction at the measurement start point (measurement position t ₀ , FIGS. 13 and 21) A two-layer winding structure solenoid coil SLC3 in which a short circuit is generated between the lines, and a short circuit is generated between windings adjacent in the longitudinal direction of the solenoid coil at the measurement end point (measurement position t ₅₀ , FIGS. 14 and 22). A solenoid coil SLC4 with a two-layer winding structure, a solenoid coil SLC5 with a two-layer winding structure in which a short circuit is generated between the winding layers at a point 37 mm from the measurement start point (FIGS. 15 and 23), and a measurement end point ( 16, 17, 24 and 25), two-layer winding structure solenoid coils SLC6 and SCL7 (the solenoid coil SCL6 and the solenoid coil SCL7 have the same short-circuited portion, in which a short circuit is generated between the winding layers). 18 and 26), and a solenoid coil SLC8 with a three-layer winding structure in which a short circuit is generated between winding layers at the measurement start point (measurement position t ₀ , FIGS. 18 and 26). and An alternating current ACI of about 70 mA was passed between the terminals of the solenoid coil (the frequency at this time was 1 kHz).

In the solenoid coil SLC1 (see FIG. 19), as shown in FIG. 11, the output voltage Vs is a positive value over the entire range from the measurement position _t0 (measurement start point) to the measurement position _t50 (measurement end point). Indicated. As a result, it was confirmed that if the change mode of the output voltage Vs was the first pattern, it could be determined that a short circuit did not occur in the windings.

In the solenoid coil SLC2 (see FIG. 20), as shown in FIG. 12, the output voltage Vs becomes negative from the measurement position t ₂₈ (28 mm from the measurement start point), and the measurement position t ₃₄ (34 mm from the measurement start point) becomes negative. ), the output voltage Vs becomes positive again. As a result, it was confirmed that if the change mode of the output voltage Vs was the second pattern, it could be determined that a short circuit had occurred between the windings adjacent in the longitudinal direction of the windings. It was also confirmed that the occurrence of a short circuit could be identified at the measurement position t30 ( ₃₀ mm from the measurement start point) where the absolute value of the output voltage Vs was equal to or greater than the threshold Vsref1.

In the solenoid coil SLC3 (see FIG. 21), as shown in FIG. 13, the output voltage Vs is negative at the measurement position t ₀ (measurement start point), and at the measurement position t ₄ (a point 4 mm from the measurement start point). , the output voltage Vs turns positive and remains positive until the measurement position _t50 (measurement end point). Here, the absolute value of the output voltage Vs at the measurement position t ₀ (measurement start point) is equal to or greater than the threshold Vsref2 (chain line in FIG. 13). In addition, the absolute value of the slope of the straight line connecting the positive peak value and the negative peak value of the output voltage Vs (the two-dot chain line in FIG. 13) (change rate CR of the output voltage Vs) is the reference change rate BCR (see FIG. 13). 13 solid line). As a result, when the change mode of the output voltage Vs is the third pattern, the short circuit occurs at the end of the tooth 22b (the extended end of the tooth 22b or the end of the tooth 22b connected to the stator 22). , the absolute value of the output voltage Vs is equal to or greater than the threshold value Vsref2, or if the change rate CR of the output voltage Vs is equal to or greater than the reference change rate BCR, the winding adjacent to the tooth 22b in the longitudinal direction It has been confirmed that it can be determined that a short circuit has occurred between the lines. It was also confirmed that the occurrence of a short circuit can be identified at the measurement position t ₀ (measurement start point) where the absolute value of the output voltage Vs is equal to or greater than the threshold Vsref1 (broken line in FIG. 13).

In the solenoid coil SLC4 (see FIG. 22), as shown in FIG. 14, the output voltage Vs turns negative at the measurement position t48 (a point ₄₈ mm from the measurement start point) and reaches the measurement position _t50 (measurement end point). Until then, the output voltage Vs remains negative. Note that the absolute value of the output voltage Vs at the measurement position t ₅₀ (measurement end point) is equal to or greater than the threshold Vsref2 (one-dot chain line in FIG. 14). In addition, the absolute value of the slope of the straight line connecting the positive peak value and the negative peak value of the output voltage Vs (the two-dot chain line in FIG. 14) (change rate CR of the output voltage Vs) is the reference change rate BCR (see FIG. 14). 14 solid line). As a result, when the change mode of the output voltage Vs is the third pattern, the short circuit occurs at the end of the tooth 22b (the extended end of the tooth 22b or the end of the tooth 22b connected to the stator 22). , the absolute value of the output voltage Vs is equal to or greater than the threshold value Vsref2, or if the change rate CR of the output voltage Vs is equal to or greater than the reference change rate BCR, the tooth 22b is adjacent to the tooth 22b in the longitudinal direction. It was confirmed that it was possible to determine that a short circuit had occurred between the windings. It was also confirmed that the occurrence of a short circuit can be identified at the measurement position _t50 (measurement end point) where the absolute value of the output voltage Vs is equal to or greater than the threshold Vsref1 (broken line in FIG. 14).

In the solenoid coil SLC5 (see FIG. 23), as shown in FIG. 15, the output voltage Vs turns negative at the measurement position t38 ( ₃₈ mm from the measurement start point) and reaches the measurement position _t50 (measurement end point). Until then, the output voltage Vs remains negative. As a result, even if the change mode of the output voltage Vs is the third pattern, and the short circuit occurs at a position other than the end of the tooth 22b, that is, other than the measurement positions t ₀ and t ₅₀ (measurement end point). It has been confirmed that if there is, it can be determined that a short circuit has occurred between the winding layers. It was also confirmed that it was possible to identify the occurrence of a short circuit at the measurement position t38 ( ₃₈ mm from the measurement start point) where the output voltage Vs changed from positive to negative.

In the solenoid coil SLC6 (see FIG. 24), as shown in FIG. 16, the output voltage Vs turns negative at the measurement position t50 ( ₅₀ mm from the measurement start point). Note that the absolute value of the output voltage Vs is less than the threshold Vsref2 (chain line in FIG. 16) at the measurement position _t50 (measurement end point). In addition, the absolute value of the slope of the straight line connecting the positive peak value and the negative peak value of the output voltage Vs (the two-dot chain line in FIG. 16) (change rate CR of the output voltage Vs) is the reference change rate BCR (see FIG. 16). 16 solid line). As a result, when the change mode of the output voltage Vs is the third pattern, the short circuit occurs at the end of the tooth 22b (the extended end of the tooth 22b or the end of the tooth 22b connected to the stator 22). , if the absolute value of the output voltage Vs is less than the threshold value Vsref2, or if the change rate CR of the output voltage Vs is less than the reference change rate BCR, then a short circuit occurs between the winding layers. It was confirmed that it is possible to determine that It was also confirmed that it was possible to identify the occurrence of a short circuit at the measurement position _t50 (measurement end point) at which the output voltage Vs changed from positive to negative.

As shown in FIG. 25, the solenoid coil SLC7 basically causes a short circuit at the same place as the solenoid coil SLC6, but the measurement start point and the measurement end point are opposite to those of the solenoid coil SLC6. . That is, in the solenoid coil SLC7, the measurement start point is the measurement position _t50 , and the measurement end point is the measurement position ₀ . In the solenoid coil SLC7, as shown in FIG. 17, the output voltage Vs is negative at the measurement position _t50 (measurement start point), and thereafter, the output voltage Vs is negative at the measurement position _t48 (2 mm from the measurement start point). After turning positive, the output voltage Vs remains positive until the measurement position t ₀ (measurement end point). Here, the absolute value of the output voltage Vs at the measurement position t ₅₀ (measurement start point) is less than the threshold Vsref2 (one-dot chain line in FIG. 17). In addition, the absolute value of the slope of the straight line connecting the positive peak value and the negative peak value of the output voltage Vs (the two-dot chain line in FIG. 17) (change rate CR of the output voltage Vs) is the reference change rate BCR (see FIG. 17). 17 solid line). As a result, when the change mode of the output voltage Vs is the third pattern, the short circuit occurs at the end of the tooth 22b (the extended end of the tooth 22b or the end of the tooth 22b connected to the stator 22). , if the absolute value of the output voltage Vs is less than the threshold value Vsref2, or if the change rate CR of the output voltage Vs is less than the reference change rate BCR, then a short circuit occurs between the winding layers. It was confirmed that it was possible to determine that It was also confirmed that it was possible to identify the occurrence of a short circuit at the measurement position _t50 (measurement start point) where the output voltage Vs changed from positive to negative.

As shown in FIG. 26, unlike the solenoid coils SLC1-7, the solenoid coil SLC8 has a three-layer winding structure (the solenoid coils SLC1-7 have a two-layer winding structure). In the solenoid coil SLC8 (see FIG. 26), as shown in FIG. 18, the output voltage Vs has a negative value over the entire range from the measurement position _t0 (measurement start point) to the measurement position _t50 (measurement end point). Indicated. As a result, it was confirmed that if the change mode of the output voltage Vs is the fourth pattern, it can be determined that a short circuit has occurred between the winding layers. In this case, it is not possible to identify the location of the short circuit.

According to the winding short-circuit diagnosis device 1 of the present invention according to the present embodiment described above, the magnetic fields generated in the three-phase windings 24U, 24V, and 24W wound for each tooth 22b are directed in the extension direction of the tooth 22b. Along with measuring every predetermined interval d along, comparing the phase difference between the alternating current ACI flowing in the three-phase windings 24U, 24V, and 24W and the output voltage Vs at each measurement position t _i (i = 0 to L) The direction of the magnetic field measured by the magnetic field sensor 6 (search coil 62) is determined, and the three-phase winding 24U is selected depending on which pattern 1 to 4 the variation of the output voltage Vs considering the direction of the magnetic field corresponds to. , 24V and 24W in the extending direction of the tooth 22b, or between adjacent windings in the direction in which the tooth 22b extends. It is possible to specify in what manner the three-phase windings 24U, 24V, and 24W are short-circuited. As a result, it is possible to obtain information on the manner in which short circuits tend to occur, and by feeding this information back to the design stage, it is possible to take measures such as how to wind the windings and the structure of the teeth for winding the windings. can apply. As a result, the rate of occurrence of short circuits in rotating machines such as the electric motor 2 and the generator can be reduced, which can contribute to quality improvement.

In this embodiment, the magnetic field sensor 6 having one search coil 62 wound with several turns to several tens of turns is moved from the measurement position _t0 to the measurement position _tL along the extending direction of the axis CL2. While measuring the magnetic field (output voltage Vs) at each measurement position t _i (i=0 to L), the configuration is not limited to this. For example, as shown in the magnetic field sensor ₁₀₆ of the modified example illustrated in FIG. (i=0 to L), and the magnetic field (output voltage Vs) at each measurement position t _i (i=0 to L) is measured at once. According to this configuration, the time for moving the search coil 62 can be omitted, so that the measurement time can be shortened and the measurement can be simplified.

In the present embodiment, the phase difference between the AC current ACI and the output voltage Vs is compared and the direction of the magnetic field is determined based on the phase difference, but the present invention is not limited to this. For example, in determining the direction of the magnetic field, the phase difference between the AC voltage and the output voltage Vs may be compared, and the direction of the magnetic field may be determined based on the phase difference.

In the present embodiment, the strength of the magnetic field is measured from the root portion of the tooth 22b (the connection end portion of the tooth 22b to the yoke 22a) toward the tip portion of the tooth 22b (the end portion near the center of the stator 22). In addition, the configuration is such that processing for determining the direction of the magnetic field is performed, but the present invention is not limited to this. For example, contrary to the present embodiment, the magnetic field is generated from the tip of the tooth 22b (the end near the center of the stator 22) toward the root of the tooth 22b (the connection end of the tooth 22b to the yoke 22a). The configuration may be such that the intensity is measured and the process of determining the direction of the magnetic field is performed.

In the present embodiment, the change mode of the output voltage Vs is the third pattern, and the short circuit occurs at the end of the tooth 22b (the extended end of the tooth 22 or the connecting portion of the tooth 22 to the stator 22). end), whether or not the absolute value of the output voltage Vs to which negative information is added is equal to or greater than the threshold value Vsref2, and whether the absolute value of the change rate CR of the output voltage Vs is the reference change. Although it is configured to determine both whether or not the ratio is equal to or greater than the ratio BCR, the present invention is not limited to this. For example, whether or not the absolute value of the output voltage Vs to which negative information is added is equal to or greater than the threshold value Vsref2, or whether or not the absolute value of the change rate CR of the output voltage Vs is equal to or greater than the reference change rate BCR. It is good also as a structure which judges only one. Further, it is determined whether or not the absolute value of the output voltage Vs to which the negative information is added is equal to or greater than the threshold Vsref2, and whether or not the absolute value of the change rate CR of the output voltage Vs is equal to or greater than the reference change rate BCR. When both determinations are made, only when both are "possible", a short circuit occurs between the windings adjacent in the direction of the axis CL2 of the U-phase winding 24U (the direction of the axis CL2 of the teeth 22b or the extending direction of the teeth 22b). has occurred, and if both are "no", it may be determined that a short circuit has occurred between the layers of the U-phase winding 24U.

In the present embodiment, the frequency of the AC voltage applied between the UV phase, the VW phase, and the WU phase by the voltage oscillator 4 is set to 1 kHz, but the frequency is not limited to this. The frequency of the AC voltage applied between the UV phase, the VW phase, and the WU phase by the voltage oscillator 4 can be any value as long as the frequency is higher than the commercial AC power frequency of 60 Hz (or 50 Hz). can be

In the present embodiment, the AC voltage applied between the UV phase, the VW phase, and the WU phase by the voltage oscillator 4 is set to 200 volts or less, but the present invention is not limited to this.

In the present embodiment, the predetermined interval d, which is the interval at which the search coil 62 is moved, is set to a value approximately equal to the center-to-center distance of the coils forming the three-phase windings 24U, 24V, and 24W. is not limited to

In the present embodiment, the stator 22 having teeth 22b around which the three-phase windings 24U, 24V, and 24W are directly wound is configured to diagnose a short circuit of the three-phase windings 24U, 24V, and 24W. is not limited to For example, the rotor 32 having slots around which the three-phase windings 24U, 24V, and 24W are directly wound may be configured to diagnose short-circuiting of the three-phase windings 24U, 24V, and 24W. In this case, the stator 22 may be removed from the electric motor 2 and only the rotor 32 may be used to diagnose short-circuiting of the three-phase windings 24U, 24V, and 24W.

This embodiment shows an example of a form for carrying out the present invention. Therefore, the present invention is not limited to the configuration of this embodiment. In addition, the corresponding relationship between each component of this embodiment and each component of the present invention is shown below.

1 Winding short-circuit diagnostic device (winding short-circuit diagnostic device)
2 Electric motor (rotating machine)
4 Voltage oscillator (voltage oscillator)
6 magnetic field sensor (magnetic field sensor)
8 A/D converter 10 diagnostic unit 22 stator (stator)
22a Yoke 22b Teeth (teeth)
24U U-phase winding (winding)
24Us closed loop 24V V-phase winding (winding)
24W W-phase winding (winding)
26 connection terminal 32 rotor (rotor)
62 search coil (search coil)
64 amplifier 70 CPU (processor)
72 ROMs
74 RAM (memory)
106 magnetic field sensor (magnetic field sensor)
ACI alternating current (alternating current)
L1 signal line L2 signal line L3 signal line L4 signal line Vs output voltage (output voltage)
CL1 axis CL2 axis H ₀ magnetic field strength H _s magnetic field strength I _s current S Short circuit t ₀ measurement position t _L measurement position t _i measurement position d predetermined interval h predetermined distance Vsref1 threshold (second threshold)
Vsref2 threshold (threshold)
SLC1 solenoid coil SLC2 solenoid coil SLC3 solenoid coil SLC4 solenoid coil SLC5 solenoid coil SLC6 solenoid coil SLC7 solenoid coil SLC8 solenoid coil

Claims (10)

A winding short-circuit diagnosis device for diagnosing a winding short circuit in a stator or rotor of a rotating machine in which concentrated winding is applied to a plurality of teeth arranged at approximately equal intervals in the circumferential direction,
a voltage oscillator configured to apply an alternating voltage between terminals of the winding;
a magnetic field sensor that measures the strength of the magnetic field generated in the winding wound for each tooth in response to the application of the AC voltage at predetermined intervals along the extending direction of the tooth;
a memory for storing the alternating voltage or the alternating current flowing in the winding caused by the alternating voltage and the strength of the magnetic field;
The direction of the magnetic field stored in the memory is determined for each measurement position based on the alternating voltage or the alternating current and the intensity of the magnetic field, and all of the determined directions of the magnetic field are in the first direction. In the case of pattern 1, it is determined that a short circuit has not occurred in the winding, and after the direction of the magnetic field changes from the first direction to the second direction opposite to the first direction, In the case of the second pattern changing from the second direction to the first direction, it is determined that a short circuit has occurred between the windings adjacent to the extending direction of the teeth, and the direction of the magnetic field is changed to the first direction. In the case of a third pattern in which the second direction or the first direction remains after changing from the one direction or the second direction to the second direction or the first direction, and all the directions of the magnetic fields are in the first direction a processor that determines that a short circuit has occurred between layers of the winding in the case of a fourth pattern that is two directions;
A winding short circuit diagnostic device comprising: The processor determines that, in the case of the third pattern, a change in the orientation of the magnetic field from the first direction or the second direction to the second direction or the first direction is the extension direction of the teeth. If so, comparing the strength of the magnetic field in the second direction with a threshold, and if the strength of the magnetic field is greater than or equal to the threshold and/or the orientation of the magnetic field is in the first direction. comparing the absolute value of the rate of change in the strength of the magnetic field when changing from the one direction or the second direction to the second direction or the first direction with a reference rate of change, wherein the absolute value of the rate of change is If it is equal to or greater than the reference rate of change, it is determined that a short circuit has occurred between the windings adjacent in the longitudinal direction of the teeth, and if the strength of the magnetic field is less than the threshold value and/or the change 2. The winding short circuit diagnosis device according to claim 1, wherein when the absolute value of the ratio is less than the reference change ratio, it is determined that a short circuit has occurred between layers of the winding. The memory can store the strength of the magnetic field in association with the measurement position,
When the processor determines that a short circuit has occurred between layers of the winding, the processor determines that the short circuit has occurred in the winding at the measurement position where the direction of the magnetic field first becomes the second direction. The winding short-circuit diagnosis device according to claim 1 or 2. The memory can store the strength of the magnetic field in association with the measurement position,
When the processor determines that a short circuit has occurred between the windings adjacent to each other in the longitudinal direction of the tooth, the processor compares the strength of the magnetic field in the second direction with a second threshold, and first 4. The winding according to any one of claims 1 to 3, wherein it is determined that a short circuit has occurred in the winding at the measurement position linked to the strength of the magnetic field determined to be two or more thresholds. Line short circuit diagnostic device. The winding short-circuit diagnosis device according to any one of claims 1 to 4, wherein the voltage oscillator applies an AC voltage having a frequency higher than a commercial frequency between terminals of the winding. The winding short-circuit diagnostic device according to any one of claims 1 to 5, wherein the voltage oscillator applies an AC voltage of 200 volts or less between terminals of the winding. The magnetic field sensor has a search coil for measuring the strength of the magnetic field, and when measuring the strength of the magnetic field, the axial direction of the search coil is the axial direction of the winding wound on the tooth. The winding short-circuit diagnosis device according to any one of claims 1 to 6, which is arranged so as to be parallel to the . The magnetic field sensor has a search coil for measuring the strength of the magnetic field, and when measuring the strength of the magnetic field, a virtual The winding short-circuit diagnostic device according to any one of claims 1 to 7, wherein an axis of the search coil on a projection plane is arranged to overlap an axis of the winding wound around the tooth. A winding short-circuit diagnosis method for diagnosing a short circuit of the winding in a stator or rotor of a rotating machine in which concentrated winding is applied to a plurality of teeth arranged at substantially equal intervals in the circumferential direction,
(a) applying an alternating voltage between terminals of the winding wound for each tooth;
(b) measuring the strength of the magnetic field generated in the winding wound for each tooth in response to the application of the AC voltage at predetermined intervals along the extending direction of the tooth;
(c) storing the alternating voltage or the alternating current flowing through the winding due to the alternating voltage and the measured magnetic field strength;
(d) determining the orientation of the magnetic field at each of the predetermined intervals stored based on the alternating voltage or current and the strength of the magnetic field;
(e) In the case of a first pattern in which all of the determined directions of the magnetic field are in the first direction, it is determined that no short-circuit has occurred in the winding, and the determined direction of the magnetic field is the first direction. In the case of a second pattern that changes from one direction to a second direction opposite to the first direction and then changes from the second direction to the first direction, the teeth are adjacent to the extending direction of the teeth. It is determined that a short circuit has occurred between the windings, and after the direction of the determined magnetic field changes from the first direction to the second direction, a third pattern in which the direction remains in the second direction or in the case of a fourth pattern in which all directions of the magnetic field are in the second direction, it is determined that a short circuit has occurred between layers of the winding.
The step (e) is for the third pattern, wherein a change in orientation of the magnetic field from the first direction or the second direction to the second direction or the first direction causes the extension of the teeth. if it occurs at the end of the outgoing direction, comparing the strength of the magnetic field in the second direction with a threshold, and if the strength of the magnetic field is greater than or equal to the threshold and/or the orientation of the magnetic field; comparing the absolute value of the rate of change in the strength of the magnetic field when changing from the first direction or the second direction to the second direction or the first direction with a reference rate of change, and the absolute value of the rate of change If the value is equal to or greater than the reference rate of change, it is determined that a short circuit has occurred between the windings adjacent to each other in the longitudinal direction of the teeth, and if the strength of the magnetic field is less than the threshold, and/or 10. The winding short circuit diagnosis method according to claim 9, further comprising determining that a short circuit has occurred between layers of the winding when the absolute value of the rate of change is less than the reference rate of change.

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