JP7358271B2 - Electric motor system and discharge detection method - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electric motor systems, and more particularly to the detection of electric discharges.

In order to curb global warming, _CO2 emission regulations are being tightened all over the world, and electrification of power systems is being actively promoted as an alternative to engines that use fossil fuels. On the other hand, the power density of electric motor systems (here, a group of equipment including rotating machines, power converters, batteries, etc.) is required to be more than twice that of the current level, and technology to support higher voltages is required. It has been demanded.

On the other hand, there is a need to reduce the cost of insulation systems, and to achieve this, it is necessary to eliminate excess margins in insulation properties. In order to eliminate excess margin, it is necessary for the diagnostic system to be able to detect when an abnormality occurs.

Patent Document 1 describes, "a first ozone detection section that detects the ozone concentration of air flowing into the coil of a rotating electric machine; and a second ozone detection section that detects the ozone concentration of the air around the coil or the air flowing out from the periphery of the coil. a detection unit; and a partial discharge monitoring unit that monitors the occurrence of partial discharge based on the difference value between the first ozone concentration detected by the first ozone detection unit and the second ozone concentration detected by the second ozone detection unit. A partial discharge monitoring device for rotating electric machines has been proposed.

Patent Document 2 states, ``A switching element module having a cooling function includes an outer conductor tube, an inner conductor tube that is at least partially located inside the outer conductor tube and transmits electric power together with the outer conductor tube, 1 switching element and a second switching element, the inner conductor tube has a protruding portion protruding from the opening of the outer conductor tube, and the first switching element is provided on an outer surface of the outer conductor tube. , the second switching element is provided on the outer surface of the protruding portion, and the refrigerant flows inside the inner conductor tube, outside the protrusion portion, and outside the outer conductor tube.''

Japanese Patent Application Publication No. 2018-200179 Japanese Patent Application Publication No. 2014-135410

In Patent Document 1, the ozone absorbing material constituting the first ozone detection section and the second ozone detection section is taken out and collected outside during regular inspections of a rotating electric machine at a predetermined period, and is degassed with nitrogen gas. The accumulated ozone concentration is measured and the measurement results are output to the discharge deterioration monitoring section. In other words, it is possible to collect and diagnose the ozone absorbent and detect the ozone concentration, but the system is complicated as it consists of a collection section and an analysis section, and the collection section may not be attached depending on the structure of the rotating machine. There is sex.

Patent Document 2 targets a power conversion device for transportation equipment, and suppresses surge voltage by increasing the capacitance of a conductor and reducing inductance in a cooled switching element module, thereby reducing partial discharge. suppress the occurrence of Essentially, the design suppresses the occurrence of discharge, but it does not have a function to detect when discharge occurs due to a sudden abnormality.

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a motor system and a discharge detection method that can detect discharge without using a complicated device.

In order to achieve the above object, the electric motor system of the present invention is a closed electric motor system having a power supply section , and includes a power conversion device including a switching element, a substrate, a cooling path, and a capacitor. A discharge detection material that is colored or changes color when it reacts with ozone gas generated when discharge occurs is disposed at or near the charging section of the power converter, and the color change of the discharge detection material is detected by the electric motor system. It is characterized by being monitored by a built-in camera.

The electric motor system includes a power converter including a switching element, a substrate, a cooling path, and a capacitor, and a discharge detection material is disposed at or near the energizing section of the power converter. It has a rotating electric machine that includes a coil, a stator core, and an insulation, and a discharge detection material is placed at or near the energizing part of the rotating electric machine.

The discharge detection material is characterized by being one of potassium iodide, semiconductor thin film, HVA (hydroxy-methoxyphenylacetic acid), HPPA (hydroxyphenylpropionic acid), and acetamidophenol, which are materials that react with ozone gas. Other aspects of the present invention will be explained in the embodiments described below.

According to the present invention, discharge can be detected without using a complicated device.

FIG. 3 is a diagram showing discharge detection for the power conversion device according to the first embodiment. FIG. 7 is another diagram illustrating discharge detection for a bus bar in the power conversion device according to the second embodiment. FIG. 7 is another diagram illustrating discharge detection for a bus bar in the power conversion device according to the third embodiment. It is a figure which shows the discharge detection with respect to the rotating electric machine based on 4th Embodiment. FIG. 7 is another diagram showing discharge detection for the rotating electrical machine according to the fifth embodiment. FIG. 7 is another diagram showing discharge detection for the rotating electrical machine according to the sixth embodiment. 1 is a diagram showing an overview of an electric motor system.

An object of an embodiment of the present invention is to provide an electric motor system that is an electrical device mainly having a energizing section of 300 V or more, and in which a discharge detection material is disposed near the energizing section. Particularly, the target is the part where electric discharge is likely to occur, for example, in the case of a rotating machine, it is the coil end part. For power converters, bus bars, wire bonding, etc. are applicable.

The following embodiments mainly relate to partial discharge detection of a motor system at a rated voltage of 300 to 3000V. However, partial discharge detection can be applied to all devices that can generate partial discharge.

<First embodiment>
FIG. 1 is a diagram illustrating discharge detection for a power conversion device according to a first embodiment. In a power conversion device with a rated voltage of 300 V or higher, which is composed of a switching element 13 as a power module, a substrate, a cooling fin 15 (cooling path), a capacitor 16, a bus bar 11, etc., a discharge detection mechanism or A discharge detection material 1 is provided. Note that the power module refers to a combination of multiple power semiconductors.

As shown in FIG. 1, the capacitor 16 and the switching element 13 are connected by a bus bar 11. In this case, the discharge detection material 1 (shaded portion) is placed, for example, on the surface of the bus bar 11 where discharge is likely to occur, on the lead wire connecting the bus bar 11 and the switching element 13, or the like. The discharge detection material 1 may be applied or sprayed onto the bus bar 11 or the like.

In the power conversion device, in order to reduce the inductance of the bus bars 11 by canceling the reciprocating current, the insulation distance between the bus bars 11 is shortened and the surface area of the bus bars 11 is widened. Therefore, the larger the area, the more likely insulation defects will occur due to foreign matter adhesion, peeling, voids, cracks, etc., and high insulation properties will be required.

For example, a material that reacts with ozone gas is used as the discharge detection material. This method indirectly detects discharge by detecting ozone gas produced when discharge occurs. Examples of materials that can be used to detect ozone gas include potassium iodide, semiconductor thin films, HVA (hydroxy-methoxyphenylacetic acid), HPPA (hydroxyphenylpropionic acid), and acetamidophenol, but these materials do not react with ozone gas. If any, it is not limited to the above.

For example, ozone detection using potassium iodide is explained using the following chemical formula. As shown in the chemical formula below, iodine is generated by the reaction of ozone, iodide ions, and water. It is possible to detect the generation of ozone by coloring with iodine.
O ₃ +2I ^- +H ₂ O⇒I ₂ +O ₂ +2OH ^-
It is preferable to coat the bus bar 11 and the like with a resin (for example, epoxy resin) containing potassium iodide. In reality, moisture in the air reacts with ozone, causing the resin part to change color.

Examples of semiconductor thin films include germanium thin films on glass. Germanium thin film changes color when it reacts with ozone gas.
As described above, highly versatile partial discharge detection becomes possible in the power conversion device.

<Second embodiment>
FIG. 2 is another diagram showing discharge detection for the bus bar 11 of the power conversion device according to the second embodiment. Refer to FIG. 1 as appropriate. In a power conversion device, an insulating material 113 is sometimes sandwiched between bus bars 110 between the capacitor 16 and the switching element 13 to shorten the insulation distance. This is generally called a laminate bus bar, etc., but the electrical stress in the laminate bus bar is higher than in other parts, and if foreign matter is attached, partial discharge is likely to occur.

Therefore, it is effective to detect the discharge that occurs between the opposing bus bars 111 and 112 by disposing the discharge detection material 1 on the contact surface with the insulating material 113 of the laminate bus bar. , highly versatile partial discharge detection becomes possible.

<Third embodiment>
FIG. 3 is another diagram showing discharge detection for the bus bar 11 of the power conversion device according to the third embodiment. Refer to FIG. 1 as appropriate. In a high-voltage multilevel inverter, a plurality of switching elements 13 are arranged in series to divide the voltage, and a potential difference occurs between the switching elements 13.

Therefore, electrical stress increases between the bus bar 11 between the switching elements 13 and the adjacent bus bar (not shown). A discharge detection material 1 is placed on the surface of the bus bar 11 in order to quickly detect partial discharge in the relevant portion in the event of an abnormality.
As described above, highly versatile partial discharge detection becomes possible in the power conversion device.

<Fourth embodiment>
FIG. 4 is a diagram showing discharge detection for a rotating electrical machine according to a fourth embodiment. Rotating electrical machines refer to machines that have rotating parts, such as generators and electric motors.
In FIG. 4 a schematic diagram of a stator to be energized is shown. The stator is composed of a stator core 23, a coil, insulating paper, etc., and both ends where the coil does not fit into the core are called coil ends 21. A slot liner 24 is provided within the stator slot to electrically isolate the coils from the stator core.

Since discharge is likely to occur at the coil end 21, the discharge detection material 1 is provided at the coil end 21. However, this embodiment is applicable not only to the stator but also to the coil end of a secondary exciter where the rotor is also energized.

As the discharge detection material, a material that reacts with ozone gas can be used as in the first embodiment. The above enables highly versatile partial discharge detection in rotating electrical machines.

<Fifth embodiment>
FIG. 5 is another diagram showing discharge detection for the rotating electric machine according to the fifth embodiment. FIG. 5 shows a schematic diagram of a stator to which electricity is applied. As described above, the stator is composed of the stator core 23, a coil, insulating paper, etc., and both ends where the coil does not fit into the core are called coil ends 21.

In a rotating machine driven by a power conversion device such as an inverter, a surge voltage is applied to the lead portion of the coil end 21, increasing electrical stress. The discharge detection material 1 is placed on the surface of the lead wire 25 in order to quickly detect partial discharge in the relevant portion in the event of an abnormality or the like. The above enables highly versatile partial discharge detection in rotating electrical machines.

<Sixth embodiment>
FIG. 6 is another diagram showing discharge detection for the rotating electric machine according to the sixth embodiment. Refer to FIG. 5 as appropriate. FIG. 6 shows a schematic diagram of a stator to which electricity is applied. The stator is composed of a stator core 23, coils, insulating paper, etc., and insulating paper may be provided between different phases (for example, U-phase coil end 21U, W-phase coil end 21W). Teflon (registered trademark), aramid paper, or the like is applied to this insulating paper.

Electrical stress increases between different phases. An insulating material 2 coated with a discharge detection material 1 is used in order to quickly detect partial discharge in the relevant part in the event of an abnormality. Specifically, the discharge detection material 1 is applied to the surface of the insulating paper between the different phases.
The above enables highly versatile partial discharge detection in rotating electrical machines.

<Seventh embodiment>
In the seventh embodiment, a semiconductor thin film is used as the discharge detection material 1. Semiconductor thin films are oxidized by ozone gas, increasing their resistance. By detecting the increase in resistance, ozone gas can be detected. The semiconductor thin film of the seventh embodiment is applicable to both power converters and rotating electric machines.

In this case, a resistance detection mechanism is required. Since it is difficult to arrange the detection mechanism in the energizing section, in this case, it is placed in a part near the energizing section where no voltage is applied.

This embodiment can be arranged in the structures of the first to fifth embodiments described so far. For example, in the case of a rotating electrical machine, this corresponds to the vicinity of the coil end 21 (see FIG. 4) at the end of the core. In a power conversion device, it is placed in a laminate insulating material around a bus bar or in an insulating casing of a switching element.
The above enables highly versatile partial discharge detection in rotating electric machines and power converters.

<Eighth embodiment>
In the eighth embodiment, a luminescent material is used as the discharge detection material 1. This detects light generated by discharge. The eighth embodiment is applicable to both a power conversion device and a rotating electric machine.

As the luminous material, silicon, silicate aluminate mixed system, alkaline earth aluminate system, strontium aluminate (SrAl ₂ O ₄ ), europium, etc. are applicable, but as long as it can store light, it is limited to the above. It is not something that will be done.

When using a phosphorescent material, the following methods are available to confirm discharge detection. For equipment that has a high degree of continuous operation and has a sealed housing, it is conceivable to have a built-in camera for constant monitoring. Alternatively, instead of including a camera inside, a glass window may be provided in the casing so that confirmation can be made with the camera or visually.

For equipment that does not have high continuous operability, it is possible to check this through periodic inspections. In this case, pre-operate at a voltage higher than the rated voltage and apply a load higher than normal. Immediately after that, it is possible to visually confirm the glowing part and detect discharge.

However, the method for checking discharge detection in the luminescent material is not limited to the above, and the process is not limited as long as it is a method that can check discharge light.
The above enables highly versatile partial discharge detection in rotating electric machines and power converters.

In the first to sixth embodiments, when observing the color change of the discharge detection material 1, there are the following methods for checking discharge detection, as in the eighth embodiment.

For equipment that has a high degree of continuous operation and has a sealed housing, it is conceivable to have a built-in camera for constant monitoring. Alternatively, instead of including a camera inside, a glass window may be provided in the casing so that confirmation can be made with the camera or visually. For equipment that does not have high continuous operability, it is possible to check this through periodic inspections. It is possible to visually confirm the color change area and detect discharge.

That is, in a motor system having a voltage application section, a discharge detection method can be applied in which the discharge detection material 1 is arranged at or near the power application section and a change in the discharge detection material 1 is detected.

An example of the electric motor system 200 shown in the first to eighth embodiments is shown.
FIG. 7 is a diagram showing an overview of the electric motor system 200.
The electric motor system 200 includes an inverter 201 (power converter), an electric motor 202, and the like. It is converted into AC power by an inverter 201, and this three-phase AC power is supplied to an electric motor 202. The inverter 201 is composed of legs 203 (203U, 203V, 203W) composed of a plurality of semiconductor elements, and both ends of the legs 203 are connected to a capacitor 301. The upper arm of the leg 203U is composed of a switching element 204UH and a diode element 205UH for free circulation. Further, the lower arm of the leg 203U is composed of a switching element 204UL and a diode element 205UL for free circulation. Similarly, the upper arm of the leg 203V is composed of a switching element 204VH and a freewheeling diode element 205VH. Further, the lower arm of the leg 203V is composed of a switching element 204VL and a diode element 205VL for free circulation. Further, the upper arm of the leg 203W is composed of a switching element 204WH and a diode element 205WH for free circulation. Further, the lower arm of the leg 203W is composed of a switching element 204WL and a diode element 205WL for free circulation. Switching signals to switching elements 204UH, 204UL, 204VH, 204VL, 204WH, and 204WL are controlled by inverter gate control section 302, which is a lower control section.

As described above, in order to improve the output density of each device in an electric motor system, it is necessary to provide an insulation diagnostic system that can contribute to higher voltage.
In this embodiment, by having an inexpensive and highly versatile diagnostic function (detection function), it is possible to optimize the margin related to insulation reliability and optimize the device size.

In this embodiment, an electric motor system is proposed in which a discharge detection material is disposed near the energizing part in an electric device having an energizing part. Specifically, a description has been given of a rotating electrical machine in which a discharge detection material is disposed near a charging section, with a coil being electrically charged. Furthermore, a power converter including a switching element, a substrate, a reactor, a cooling path, and a capacitor, and a power converter in which a discharge detection material is disposed near a power applying part has been described. Although this embodiment does not provide a particularly applicable voltage range, it is particularly effective in a voltage range where there is no effective electrical discharge detection method in the rated voltage range of 300V to 3000V. Ozone absorbers, phosphorescent materials, glass materials, etc. are applied to the discharge detection materials described above.

In order to improve the output density, the electric motor system of this embodiment has a discharge detection mechanism (discharge detection material) inside each device, so that even if an abnormality such as partial discharge occurs, complete circuit breakdown will occur. It is possible to prevent system outages before they occur. In addition, the discharge detection mechanism makes it possible to optimize margin design regarding insulation reliability, contributing to system miniaturization, and making it possible to prevent mechanical failures due to enlargement. .

1 Discharge detection material 2 Insulating material 11 Bus bar 13 Switching element 15 Cooling fin 16 Capacitor 21 Coil end 23 Stator core 24 Slot liner 25 Lead wire 110, 111, 112 Bus bar 113 Insulating material 200 Motor system 201 Inverter 202 Motor 203 Leg 301 Capacitor

Claims (6)

In an electric motor system having a sealed energizing section,
It has a power conversion device that includes a switching element, a substrate, a cooling path, and a capacitor, and when the power supply part of the power conversion device or its vicinity reacts with ozone gas generated when discharge occurs, coloring or A motor system characterized in that a color-changing discharge detection material is disposed, and a color change of the discharge detection material is monitored by a camera built into the motor system. The electric motor system according to claim 1,
An electric motor system characterized in that a rated voltage of 300V or more and 3000V or less is applied. The electric motor system according to claim 1 or 2 ,
An electric motor system characterized in that the discharge detection material is any one of potassium iodide, a semiconductor thin film, HVA (hydroxy-methoxyphenylacetic acid), HPPA (hydroxyphenylpropionic acid), and acetamidophenol. The electric motor system according to claim 1 ,
A motor system characterized in that the discharge detection material is disposed on a surface of an insulator provided between a reciprocating bus bar between a capacitor and a switching element of the power converter. The electric motor system according to claim 1 ,
An electric motor system characterized in that the discharge detection material is disposed on a surface of a charging section provided between switching elements of the multi-level power converter. In an electric motor system having a sealed energizing section,
It has a power conversion device that includes a switching element, a substrate, a cooling path, and a capacitor, and when the power supply part of the power conversion device or its vicinity reacts with ozone gas generated when discharge occurs, coloring or A discharge detection method in which a discharge detection material that changes color is arranged, a color change of the discharge detection material is monitored by a camera built in the motor system, and a color change of the discharge detection material is detected.

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