WO2002039128A1

WO2002039128A1 - Method and apparatus of nondestructive insulation test for small electric machine

Info

Publication number: WO2002039128A1
Application number: PCT/JP2001/009785
Authority: WO
Inventors: Masahiro Tsubokawa
Original assignee: Matsushita Electric Industrial Co., Ltd.
Priority date: 2000-11-10
Filing date: 2001-11-08
Publication date: 2002-05-16
Also published as: CN1216296C; KR20050087887A; CN1473273A; JP2002148300A; KR20040008114A; KR100705121B1

Abstract

A nondestructive insulation test method for a small electric machine having a coil, comprising a step for bringing about a depressurized atmosphere in a container (2) containing the small electric machine (1) and applying a high frequency voltage to the coil of the small electric machine (1), and a step for detecting for generation of corona discharge from the small electric machine, wherein a decision is made whether the small electric machine is acceptable or not by a corona pulse increasing upon application of a high frequency voltage of 600-1100V between a winding coil and a laminate core.

Description

Specification

Non-destructive insulation test method and apparatus for small electric machines

The present invention relates to a test method and an apparatus for detecting a defect in an insulating state between a winding part such as a small motor and a laminate core in a non-destructive state and detecting the defect with very high sensitivity. Background art

Generally, when a small motor is used, the insulation between the winding and the laminated core is broken, and the main cause of the life is that the winding magnet wire and insulators (film, resin, etc.) Magnet wire and laminated cores due to cracks, scratches, pinholes, etc. caused by impact, mechanical pressure, friction, etc. given by any machine or jig during the wire process or assembling process as a motor Contacts or abnormally closes, causing dielectric breakdown (so-called ground short-circuit) due to electrical, thermal, mechanical, or chemical factors during use, causing abnormal current such as short-circuit current to flow and heating and burning the winding This is what you'll want to do.

Conventionally, methods for inspecting the insulation state include an AC withstand voltage test, an insulation resistance test, a partial discharge measurement test, a surge test, a reduced pressure surge test, a pinhole test, and a visual sensory test. Hereinafter, these methods will be described.

In the AC withstanding voltage test and insulation resistance test, the magnet wire coil damage is quite large, and it is impossible to detect unless the laminate core is directly in contact with or close to the laminate core.

The partial discharge measurement test is a measurement of the partial discharge. When the magnet wire contacts the laminating core, it can be detected with extremely high sensitivity. This determines whether a partial discharge occurs between the coil and the laminated core through the insulating film of the magnet wire, so it is not possible to detect the phenomenon that a healthy magnet wire is slightly separated from the laminated core It is. Also, in a partial discharge measurement test under a reduced pressure atmosphere, only the partial discharge generation start voltage changes, and its detection ability does not change. The surge test is effective in detecting layer shorts caused by coil flaws adjacent to the coil and coil, in addition to the coil flaws being in contact with the laminated core, but has limited detection of coil flaws.

The pressure-reduction surge test has a very high detection power for detecting a lay short caused by adjacent coil scratches between coils and detecting coil scratches, but a phenomenon in which a sound magnet wire comes into contact with or approaches a laminate core. Is undetectable.

The pinhole test involves completely immersing the sample in a saline solution + phenolphthalene solution. Although coil wounds are detected, this test is a destructive test and cannot be 100% tested.

The visual sensory inspection is performed during the winding process and the motor assembly process, but it is an inspection of the surface only, and there are many places that cannot be seen. Effect cannot be expected.

The conventional test method for inspecting the insulation state as described above uses the high sensitivity, mass production process, and the phenomenon that the magnet wire abnormally approaches the laminate core and causes the dielectric breakdown during operation in the near future. However, it is not satisfactory to perform a 100% inspection, and there are the following problems (a) and (b).

(a) It is difficult to automatically detect a defective phenomenon in which a healthy magnet wire is abnormally close to the laminated core (within 1 mm). To detect the defect electrically, a discharge phenomenon must be applied to the defect. High voltage (300 000 V or more) is required for commercial power, which causes corona discharge from the entire small electric machine (especially through insulating paper), burying information. .

(b) Applying a high voltage results in a destructive test, which makes it impossible to perform 100% inspection.

In other words, the conventional test method is to detect a state of poor quality (when there is a coil flaw in the magnet wire or when the magnet wire comes into direct contact with the laminate core), and a healthy magnet wire and the laminate core approach abnormally. It is not possible to detect the condition.

The present invention solves the above-mentioned conventional problems, and a non-destructive inspection is performed to detect a defective portion where a sound winding coil has abnormally approached (within 1 mm) the laminating core. It is an object of the present invention to provide an insulation test method and apparatus capable of 100% inspection in a mass production process. Disclosure of the invention

In order to solve this problem, the present invention provides a non-destructive insulation test method for a small electric machine having a coil, wherein a pressure inside a container storing the small electric machine is set to a reduced pressure atmosphere, and a high frequency voltage is applied to a coil of the small electric machine. And a step of detecting whether or not corona discharge is generated from the small electric machine. The method comprises the steps of: applying a high-frequency voltage between the winding coil and the laminated core; The pass / fail judgment is made based on the corona pulse which increases when 0 to 110 V is applied.

This enables non-destructive inspection of all defective parts in which a healthy winding coil has approached the laminated core abnormally (within 1 mm) in the mass production process.

The present invention provides a first step of storing a small electric machine having a coil in a container, a second step of reducing the pressure in the container, a third step of applying a high-frequency voltage to the coil, and the small electric machine. A non-destructive insulation test method for a small electric machine having a coil, characterized by comprising a fourth step of determining whether or not a corona discharge has occurred from the coil. It has the effect of being able to

The present invention also provides a non-destructive insulation test apparatus for a small electric machine having a coil, a container for accommodating the small electric machine, a decompression device for evacuating the inside of the container to a reduced pressure atmosphere, and applying a high-frequency voltage to the coil. A non-destructive insulation test device comprising: a high-frequency power source to be applied; and a high-frequency corona measuring device that detects whether corona discharge is generated from the small electric machine. It has the effect that corona discharge can be generated by voltage. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 shows a non-destructive insulation test apparatus of the present invention. FIG. 2 shows a circuit configuration of the present invention.

FIG. 3 shows the corona generation starting voltage in the test mode (good) according to one embodiment of the present invention.

FIG. 4 shows the start of corona generation at a failure phenomenon portion of the test motor according to one embodiment of the present invention.

FIG. 5 shows a corona pulse generation frequency according to an embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the non-destructive insulation test method of the present invention. In Fig. 1, 1 is a test mode (small electric machine), 2 is a decompression tank (vessel), 3 is a high-frequency corona measuring device, 4 is a vacuum gauge, 5 is a valve, 6 is a vacuum pump, 7 is a pushing, 8 is Yuichi Minaru.

Under the atmospheric pressure, the test mode 1 is stored in the decompression tank 2, the test mode 1 is relayed to the terminal 8, passes through the pushing 7, and is connected to the lead wire of the motor winding coil.

The decompression device is composed of a vacuum pump 6, a valve 5, and a vacuum gauge 4.The degree of decompression in the decompression tank 2 is controlled by the vacuum gauge 4 and reduced to a predetermined degree by the vacuum pump 6 via the valve 5. Is done. The optimal degree of decompression of the decompression tank 2 is 65 to 20 O T O r rr by experiments, and decompression management should be performed according to the type of the DUT (test sample 1).

In general, when focusing on the decompression corona, 1 to 5 Torr is the most sensitive according to Paschen's law. However, since corona discharge is too active in this region, there is a lot of meaningless noise-like corona, so it should be detected originally. The corona discharge information from a failure phenomenon that has a distance of 1 mm or less between one magnet wire of the motor winding to be tested and the laminator core is buried, which significantly lowers the SN ratio.

The high-frequency voltage generated by the high-frequency power supply in the high-frequency corona measuring device 3 is guided by a high-voltage cable, applied to the coil of the motor 1 through the lead wire, and gradually increases the applied voltage. Corona discharge occurs between the wire and the laminate core. Corona discharges generated in the windings (magnet wires) of small electric machines can be broadly divided into (1) discharges generated through insulators (film, resin, etc.) between the magnet wires and the laminated core, ( 2) There is a discharge generated between the magnet wire and the laminating core through the air insulation.

Phenomenon (1) is a phenomenon in which the dielectric constant of the insulator is higher than that of (2) and the corona generation starting voltage is low, and the phenomenon occurs early. It was difficult. However, phenomenon (2) has a high probability of failure in the future due to electrical, mechanical, thermal, and scientific factors, and must be determined and detected in advance. A high-frequency power supply (1 to 40 kHz) should be used for this task. This is because the impedance (Z) of a small electric machine having a coil is (1 / coC). By increasing the power supply frequency (ω), the impedance is reduced and the amount of charge flowing in the winding is reduced. By increasing the voltage, it became possible to generate corona discharge at a low voltage at the defective part.

Furthermore, as a method for determining the corona discharge in (1) and (2), the corona pulse frequency in (2) was found to increase near 1.5 MHz by experiments, and a single-pass filter (500 kHz) and a high-pass filter were used. Judgment and detection can be realized by means for forming a band-pass filter using a combination of filters (2 MHz). Fig. 3 shows the relationship between the voltage at which corona discharge occurs from the entire test motor and the degree of vacuum, and Fig. 4 shows the distance between one magnet wire of the test motor winding and the laminated core of 0.3 mm. The relationship between the corona generation starting voltage and the degree of vacuum at the failure reproduction location is shown. As shown in Fig. 3 and Fig. 4, the meaningless corona discharge generated from the whole motor under test (especially the corona discharge generated through the slot insulating paper) and the significant corona discharge generated at the defective part are shown. Need to be distinguished.

This method is illustrated in FIG. The voltage generated by the high-frequency power supply 50 (high-frequency power supply whose sinusoidal signal whose frequency can be varied from 1 to 50 KHz is boosted up to MAX 3000 V (0-P) by a transformer) is used for the test mode. Apply to the winding and stay overnight. At that time, high frequency components are superimposed on the power supply due to corona discharge generated from the test mode. Among these discharge pulses, a corona pulse having a low frequency is detected by the detection circuit 52. Corona frequency that is meaningless among the detected corona pulses and the motor under test In order to distinguish the corona frequency of a faulty part having a distance of 1 mm or less from one winding magnet wire to the laminated core, a mouth-pass filter (500 KHz) and a high-pass filter Yuichi (2. 5 MHz) and a band pass filter 52 formed by the band pass filter 52.

Since the corona pulse is an electrically very small signal, the signal is amplified by the AMP54. A corona pulse generated for a negative voltage applied from the high-frequency power supply 50 is also effective. Since the pulse is also a negative pulse, the pulse is changed to a positive pulse throughout the absolute value circuit 55.

Thereafter, the corona pulse is counted by the pulse counter 56, the number of pulses is calculated by the integrating circuit 57, the discharge amount is calculated by the integrating circuit 57, and the peak level of the corona pulse is detected by the peak detector 58. The detection was made possible by judging it as defective. Fig. 5 shows the results of a comparative measurement of a non-defective product in the test mode and a product with a defective phenomenon using the above method.

Compared to the non-defective test motor, the pulse increased from about 150 V, the pulse increased from 75 V in the test motor with the failure phenomenon. With the test motor having this relationship, testing at 900 V makes it possible to judge good and defective products. Industrial applicability

As described above, according to the first and second aspects of the present invention, all of the defective portions in which a healthy winding coil has abnormally approached (within l mm) the laminate core are subjected to non-destructive inspection in the mass production process. The advantageous effect of being able to provide an insulation test method that enables inspection can be obtained.

Claims

Claims A first step of storing a small electric machine having a coil in a container, a second step of reducing the pressure in the container, a third step of applying a high-frequency voltage to the coil, A non-destructive insulation test method for a small electric machine having a coil, comprising a fourth step of determining whether or not corona discharge has occurred.

The small electric machine according to claim 1, wherein the pressure in the vessel is reduced to 65 to 250 Torr in the second step, and a high-frequency voltage of 1 to 40 kHz is applied in the second step. Destructive insulation test method.

In a non-destructive insulation test apparatus for a small electric machine having a coil, a container for accommodating the small electric machine, a decompression device for evacuating the inside of the container to a reduced pressure atmosphere, a high frequency power supply for applying a high frequency voltage to the coil, A non-destructive insulation test device comprising a high-frequency corona measuring device for determining whether corona discharge is generated from a small electric machine.