Composite ventilation stator end leakage flux shielding structure

Abstract

The present invention relates to the field of steam turbine generators. Specifically, disclosed is a composite ventilation stator end leakage flux shielding structure. The structure consists of a pres

Description

[0001] The present disclosure relates to the field of turbo-generators, and in particular to a composite ventilating leakage flux shielding structure of a stator end. BACKGROUND

[0002] The design of large turbo-generators is limited by many factors, so the cooling demands can be satisfied using high parameters, high air gap magnetic density and high specific electric load. For full-speed generators, the pitch of stator coils is large, the number of coils in each phase is large, the size of the stator end is long, and there is a large rotating leakage magnetic field at the end. A leakage magnetic field rotating with the rotor is also formed at the rotor end, and the stator leakage magnetic field and the rotor leakage magnetic field are synthesized into the end leakage magnetic field. The end leakage magnetic field, which is mainly based on the stator leakage magnetic field, is complicated in distribution and affected by many factors, such as specific electric load, short circuit ratio, end structure, material and size. The stator end leakage flux passes along a path with the minimum magnetic resistance, so the stator and rotor leakage flux is concentrated at an inner ring of the stator pressing ring, pressing fingers and tooth heads of iron core at the edge section, leading to the increase of additional loss and temperature rise in these parts. When the generator is in over-voltage operation, especially when the generator is in leading power factor operation, the synthetic flux of stator and rotor is added, and the end leakage flux is increased, which makes the temperature of these structures exceed an allowable limit, seriously endangering the operation of the generator, and even burning down the end structure of the generator, resulting in a major shutdown accident. Therefore, there are usually strict restrictions on the leading power factor operation and over-voltage operation state of generators in the operation conditions of generator sets.

[0003] However, due to the operation demands of grids, some generators are often required to operate at the leading power factor to stabilize the grid voltage, and large generators are required to have a certain ability to operate at the leading power factor. For a direct-current extra high voltage power transmission and transformation system, a synchronous phase modifier is required to be provided, which is specially used for leading or lagging power factor operation, so as to adjust the reactive power of the grid, improve the quality of the grid and strengthen the response ability of the grid to sudden short circuit accidents. Therefore, in the design of large generators and synchronous phase modifiers, necessary measures must be taken on the stator end structure of the generator to meet the operation requirements. For example, the copper shield, aluminum pressing ring and magnetic shunting structure at the generator end are the measures taken in the past to strengthen the leading power factor operation ability of the generator, and certain results have achieved.

[0004] However, there are some shortcomings in the application of the copper shield, aluminum pressing ring and magnetic shunting structure in the past, i.e., the application of the copper shield and aluminum pressing ring is limited by self-heating, and an external pressing plate of the magnetic shunting structure is affected by leakage flux, resulting in excessive temperature and increased end leakage reactance, and the stator tooth head is not effectively shielded, which is prone to overheating, burning loss, and loosening. The operation of the generator is limited by the problems of overheating, burning loss and loosening at the dovetail part of the locating rib on the back of the iron core. The operation temperature of the previous single-layer copper shield is subjected to finite element simulation. As can be seen from the simulation nephogram, the concentrated heating spot of the previous single-layer copper shield is at the end tip of the inner edge arc region, and the finite element analysis results show that the high point temperature has far exceeded the allowable value of the structural temperature. In order to ensure the ability of large generators and synchronous phase modifiers to cope with extreme working conditions, the temperature of key structure of the stator end is reduced to guarantee reliable operation of generators or synchronous phase modifiers. Some improved stator end shielding structures have been applied in recent years, i.e., the patent End Loss Reduction Ventilation Device of High-capacity Synchronous Phase Modifier (202011369810.6). However, this structure does not change leakage flux heating distribution of a copper shield at a concentrated heating spot in an inner edge arc region, and still has the characteristics of concentrated heating like the traditional structure. As the heating is reduced to a limited extent only using a method of improving ventilation, the local overheating problem cannot be completely eliminated. The main structure of the device different from the previous one is that an auxiliary shielding layer composed of double-layer fan-shaped plates is added at an outer edge of the copper shield. Because the double-layer circular rings composed of the fan-shaped shielding plates cannot form an annular conductive structure, the shielding efficiency is greatly reduced, and moreover, a rectangular groove exists at a joint of the fan-shaped shielding plate and the single-layer shielding layer and an insulating structure is provided between the fan-shaped shielding plate and the single-layer shielding layer, a shielding dead zone is formed in this region, which forms a leakage flux 2 concentration channel, and another overheating spot is generated due to the fact that the pressing ring structure at the corresponding position is harmed by the leakage flux. As can be seen from the finite element simulation nephogram, the structure has not effectively alleviated the overheating spot problem at the inner edge region of the traditional structure, and has also caused a new overheating spot on the pressing ring structure. In the patents Combined Stator End Leakage Flux Barrier Structure (201610739054.9), Laminated Leakage Flux Barrier Structure (201620944415.9), Stator End Leakage Flux Barrier Structure (201610739051.5), Tooth Head Leakage Flux Barrier Structure (201620944544.8), Copper Shield Structure of Stator Core End of Turbo-generator (201921269420.4), and Iron Core Back Leakage Flux Barrier Structure capable of being Assembled in Segmentation" (201620946243.9), these stator end shielding structure are greatly improved compared with the past structures, but the temperature rise at the stator end of the generator and the improvement of hot spot temperature are not obvious, and there are also some limitations and shortcomings. For example, the structural schemes are all around the aspects of increasing the size and range of shielding or increasing the number of shielding layers to reduce the harm of leakage flux, and adding ventilation ducts to enhance the cooling effect and avoid overheating of copper shield, and the hot spot temperature problem of the copper shield is not solved. This is because the shielding current has the characteristics of skin effect and edge effect, the loss of the copper shield is always concentrated on the outer surface of the inner edge of the copper shield, and the excessive heating density causes local overheating region in this part. The prior art cannot effectively and reliably solve this problem, for example, increasing the thickness of copper shield or increasing the number of layers is affected by the skin effect, so the shielding current cannot enter the increased thickness, and the method of increasing the number of layers cannot be realized due to the limitation of mechanical stiffness and strength, this is because the best material for the copper shield is pure copper, power frequency penetration depth of which is about 12 mm. If the effect that the outer copper shield bears 50% or less shielding is to be achieved, the thickness of the outer copper shield must be equal to or less than 3 mm. For large turbo-generators, if the thickness of the outer copper shield is equal to or less than 3 mm, the stiffness and strength requirements of the own structure cannot be satisfied, there will be the problems and hidden dangers such as resonance and fatigue cracks, making this scheme unable to be effectively implemented and unable to achieve the purpose of reducing the hot spot temperature. The measures of increasing the cooling and ventilation speed and ventilation volume are limited by the internal structure of the generator and the air volume distribution, and the increase of the heat dissipation surface in the overheating region is limited by the structure, manufacturing technology and cost. As can be seen from the 3 finite element simulation nephogram of operation temperature, these structures cannot alleviate the overheating spot problem at the inner edge region of the traditional structure. As also can be seen from the nephogram, the provided inner shielding has no effect on heat dissipation due to the characteristics of skin effect and edge effect. Moreover, in the patent Flux Shieldfor Electric Motor (201480053345 .1), the essence is still the traditional ring-plate structure, the only change is in the position and other aspects, and thus it is also impossible to change the leakage flux heating distribution of the copper shield at a concentrated heating spot of the inner edge arc region, and there is still the problem of concentrated heating in the traditional structure. Further, in some of these stator end shielding structures appeared in recent years, there is also the problem that the service life of the shielding structure is reduced caused by a situation that an air guide insulating structure is close to the local overheating region of the copper shield, and there are shortcomings such as great difficulty in manufacturing and assembly, high cost and the like. SUMMARY

[0005] An objective of the present disclosure is to provide a composite ventilating leakage flux shielding structure of a stator end, which can effectively change the distribution of a shielding current in a copper shielding structure, eliminate the problem of excessive concentration of the shielding current, evenly spread the shielding current to a wider region, and eliminate the local overheating phenomenon of the copper shield under the condition of ensuring the effective shielding effect. A formed cooling air path is isolated from a rotor ventilation air path, thus preventing the adverse influence on the ventilation smoothness or the air intake temperature. The structure is concise and reliable, low in cost, simple in manufacturing process, and has no need of expensive special fixture and large numerical control equipment for machining. The operation reliability of the generator is improved.

[0006] The technical solution of the present disclosure is as follows: a composite ventilating leakage flux shielding structure of a stator end is composed of a pressing ring, a copper shield with an inner edge arc region provided with radial grooves, an interlayer ventilation duct, fan-shaped caps, a first ventilation duct, a second ventilation duct, an isolation air guide cover, and a pressing finger radial ventilation duct. The interlayer ventilation duct is provided between the pressing ring and the copper shield, an inner hole surface of the pressing ring is covered with the fan-shaped caps, and the number of the fan-shaped caps is the same as that of the radial grooves. A spacing gap is formed between adjacent fan-shaped caps, and the spacing gaps and the radial grooves are staggered at equal intervals in a tangential direction. The third ventilation duct is formed between the fan-shaped caps and the inner hole surface of the pressing ring, the 4 first ventilation duct is formed between the fan-shaped caps and the copper shield, a region, which is provided with the radial grooves, of the copper shield is covered with a head end of the isolation air guide cover, the second ventilation duct is formed between the copper shield and an inner surface of the isolation air guide cover, and the pressing finger radial ventilation duct is covered with a tail end of the isolation air guide cover, making the second ventilation duct, the third ventilation duct and the first ventilation duct jointly form a composite ventilation duct with the pressing finger radial ventilation duct.

[0007] In the above composite ventilating leakage flux shielding structure of a stator end, the radial groove has a width of 3 mm.

[0008] In the above composite ventilating leakage flux shielding structure of a stator end, a calculated air speed in each of the interlayer ventilation duct, the first ventilation duct, the second ventilation duct, the isolation air guide cover and the pressing finger radial ventilation duct is 20 m / s.

[0009] In the above composite ventilating leakage flux shielding structure of a stator end, the spacing gap has a width of 5 mm.

[0010] In the above composite ventilating leakage flux shielding structure of a stator end, the copper shield and fan-shaped cap are made of pure copper plates.

[0011] In the above composite ventilating leakage flux shielding structure of a stator end, the isolation air guide cover is made of an epoxy glass cloth laminate, and is of a three-dimensional annular structure.

[0012] In the above composite ventilating leakage flux shielding structure of a stator end, a fixing bolt of the isolation air guide cover is made of a diamagnetic stainless-steel material.

[0013] In the above composite ventilating leakage flux shielding structure of a stator end, a joint of the isolation air guide cover and the copper shield is lined with a heat-resistant rubber sheath.

[0014] Compared with the prior art, the present disclosure has beneficial effects as follows:

[0015] As the copper shield is of a disc-shaped annular copper plate structure, and an inner edge arc region is provided with radial grooves, an edge structure of a circular hole, which is originally located in a shielding current concentration region, is changed from a continuous structure to a discontinuous comb-like structure, and the distribution of magnetic lines and the distribution of shielding current have also changed. Firstly, the radial grooves cut the shielding current originally distributed in a plane into a narrow small ring current, which reduces the current intensity, eddy current loss and heat generation, thus reducing the hot spot temperature. Meanwhile, the discontinuous comb-like structure adds a groove edge on the basis of the original inner hole edge structure, which greatly increases the total length of the overall edge structure, 5 reduces the heat generation per unit edge length, and further reduces the hot spot temperature. The radial groove increases the heat dissipation surface area and forms a ventilation cooling channel to further improve heat exchange efficiency of ventilation and cooling and further reduce the hot spot temperature, thus making temperature rise of the copper shield tend to be balanced and eliminating the overheating spot of the copper shield. As the inner hole surface of the pressing ring is covered with the fan-shaped cap, the fan-shaped cap plays a role in shielding on the surface of the pressing ring to isolate and shield the leakage flux passing through the radial groove. The number of the fan-shaped caps is the same as that of the radial grooves, a spacing gap is formed between adjacent fan-shaped caps, and the spacing gaps and the radial grooves are staggered at equal intervals in a tangential direction, such that there is a fan-shaped cap behind each radial groove to play a role in shielding on a boss surface. Due to the spacing gap between the adjacent fan-shaped caps, the shielding current density of the fan-shaped caps can be controlled by adjusting the number and the gap of the fan-shaped caps, thus achieving the purpose of balancing eddy current loss distribution. Therefore, the fan-shaped caps and the grooved copper shield have a double shielding effect, and magnetic lines are balanced and superimposed with each other. The number of grooves in the copper shield is determined according to finite element analysis, which can make the eddy current loss of the fan-shaped cap equal to the eddy current loss generated by the grooved copper shield, thus eliminating the uneven eddy current density. The shielding protection on the pressing ring and an iron core is better than that of the traditional structure, the deterioration of the shielding effect caused by simple grooving and the concentrated heating at the groove end are avoided, the shielding eddy current concentration region is spread to a wider region, and the eddy current density is reduced. Because the third ventilation duct is formed between the fan-shaped cap and the inner hole surface of the pressing ring, the first ventilation duct is formed between the fan-shaped cap and the copper shield, a region, which is provided the radial grooves, of the copper shield is covered with a head end of the isolation air guide cover, a second ventilation duct is formed between the copper shield and the inner surface of the isolation air guide cover, and the pressing finger radial ventilation duct is covered with the tail end of the isolation air guide cover, the second ventilation duct, the third ventilation duct and the first ventilation duct jointly form a composite ventilation duct with the pressing finger radial ventilation duct. The cooling and heat dissipation surface area in the eddy current concentration region is increased, the hot spot temperature is reduced, an independent cooling path can be formed under the action of a fan inside the generator, thus cooling the heating components such as the pressing ring, the copper shield and the fan-shaped cap better, and reducing the temperature rise. However, the cooling and 6 ventilation structure of the traditional structure is related to a stator air-gap air path, which is influenced by the rotor ventilation, such that the ventilation smoothness and the air intake temperature are adversely affected. The composite ventilation duct of the interlayer ventilation duct, the first ventilation duct, the second ventilation duct, the third ventilation duct and the pressing finger radial ventilation duct provided by the present disclosure is not related to the stator air-gap air path and the rotor ventilation, so that the influence of the rotor ventilation can be avoided. On the premise of ensuring the proper shielding protection efficiency, the shielding current is evenly spread to increase the heat dissipation surface area and form a smooth cooling air path, the heat dissipation effect is improved, the temperature rise is reduced, the concentrated heating problem that harms the reliability of the generator is eliminated, and the local overheating phenomenon of the copper shield is eliminated. The structure is concise and reliable, low in cost, simple in manufacturing process, and has no need of expensive special fixture and large numerical control equipment for machining. The operation reliability of the generator is improved.

[0016] The radial groove has a width of 3 mm, which can play a role in cutting partial shielding ring current and is convenient for machining. The calculated wind speed in the interlayer ventilation duct, the first ventilation duct, the second ventilation duct, the isolation air guide cover and the pressing finger radial ventilation duct is 20 m / s, thus both the ventilation and cooling air volume requirements and ventilation and heat exchange requirements can be satisfied. The spacing gap has a width of 5 mm, which can reduce the requirement of assembly accuracy and facilitate the manufacturing and assembly. The thickness of each of the copper shield and the fan-shaped cap is calculated and selected according to a power frequency penetration depth, which can reduce the manufacturing cost on the premise of meeting the shielding requirements, and the use of pure copper plate can reduce the shielding loss and facilitate the manufacturing and machining. The isolation air guide cover is made of epoxy glass cloth laminate, which can satisfy the requirements of structural stiffness and strength and avoid eddy current loss. The fixing bolt of the isolation air guide cover is made of a diamagnetic stainless-steel material, so as to avoid heating due to the influence of an end electromagnetic field. The joint of the isolation air guide cover and the copper shield is lined with a heat-resistant rubber sheath to avoid wear and air leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is a schematic diagram of the present disclosure;

[0018] FIG. 2 is a right view of FIG. 1;

[0019] FIG. 3 is a schematic diagram of the dispersion principle of shielding eddy current;

[0020] FIG. 4 is a schematic diagram of a flow direction of a composite air path.

[0021] In the drawings: 1-pressing ring; 2-radial groove; 3-copper shield; 4-interlayer ventilation duct; 5-fan-shaped cap; 6-first ventilation duct; 7-second ventilation duct; 8-isolation air guide cover; 9-pressing ring radial ventilation duct; 10-spacing gap; 11-third ventilation duct; 13-tail end. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] In the description of the present disclosure, it needs to be understood that the orientation or positional relationship indicated by terms "first", "second", "third" is based on the orientation or positional relationship shown in the drawings only for convenience of description of the present disclosure and simplification of description rather than indicating or implying that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and thus are not to be construed as limiting the present disclosure. In addition, in the following description, the description of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present disclosure.

[0023] The present disclosure is further described in detail below with reference to the accompanying drawings. The embodiments below are illustrative of the present disclosure, and the present disclosure is not limited thereto.

[0024] On the whole, as shown in FIG. 1 and FIG. 2, a composite ventilating leakage flux shielding structure of a stator end is composed of a pressing ring 1, a copper shield 3 with an inner edge arc region provided with radial grooves 2, an interlayer ventilation duct 4, fan-shaped caps 5, a first ventilation duct 6, a second ventilation duct 7, an isolation air guide cover 8, and a pressing finger radial ventilation duct 9. The interlayer ventilation duct 4 is provided between the pressing ring 1 and the copper shield 3, an inner hole surface of the pressing ring 1 is covered with the fan-shaped caps 5, and the number of the fan-shaped caps 5 is the same as that of the radial grooves 2. A spacing gap 10 is formed between adjacent fan-shaped caps 5, and the spacing gaps 10 and the radial grooves 2 are staggered at equal intervals in a tangential direction. The third ventilation duct 11 is formed between the fan-shaped caps 5 and the inner hole surface of the pressing ring 1, the first ventilation duct 6 is formed between the fan-shaped caps 5 and the copper shield 3, a region, which is provided with the radial grooves 2, of the copper shield 3 is covered with a head end 12 of the isolation air guide cover 8, the second ventilation duct 7 is formed between the copper shield 3 and an inner surface of the isolation air guide cover 8, and the pressing finger radial ventilation duct 9 is covered with a tail end 13 of the isolation air guide 8 cover 8, making the second ventilation duct 7, the third ventilation duct 11 and the first ventilation duct 6 jointly form a composite ventilation duct with the pressing finger radial ventilation duct 9. The copper shield 3 is of a disc-shaped annular copper plate structure, the thickness of which is calculated and selected according to a power frequency penetration depth, the outer surface of the pressing ring 1 is covered with the copper shield 3, and there is a ventilation gap between the copper shield 3 and the pressing ring 1. The number of the radial grooves 2 can be determined according to leakage flux finite element analysis or by tests, and the highest temperature of the copper shield 3 is equal to that of the fan-shaped cap 5. As the copper shield 3 is of a disc-shaped annular copper plate structure, an inner edge arc region of which is provided with the radial grooves 2 to change an edge structure of a circular hole, which is originally located in a shielding current concentration region, from a continuous structure to a discontinuous comb-like structure, and thus the distribution of magnetic lines and the distribution of shielding current have also changed.

[0025] Specifically, the radial grooves 2 cut the shielding current originally distributed in a plane into a narrow small ring current, which reduces the current intensity, eddy current loss and heat generation, thus reducing the hot spot temperature. Meanwhile, the discontinuous comb-like structure adds a groove edge on the basis of the original inner hole edge structure, which greatly increases the total length of the overall edge structure, reduces the heat generation per unit edge length, and further reduces the hot spot temperature. The radial groove 2 increases the heat dissipation surface area and forms a ventilation cooling channel to further improve heat exchange efficiency of ventilation and cooling and further reduce the hot spot temperature, thus making temperature rise of the copper shield 3 tend to be balanced and eliminating the overheating spot of the copper shield 3.

[0026] As shown in FIG. 3, as the inner hole surface of the pressing ring 1 is covered with the fan-shaped cap 5, the fan-shaped cap 5 plays a role in shielding on the surface of the pressing ring 1 to isolate and shield the leakage flux passing through the radial groove 2. The number of the fan-shaped caps 5 is the same as that of the radial grooves 2, a spacing gap is formed between adjacent fan-shaped caps 5, and the spacing gaps and the radial grooves 2 are staggered at equal intervals in a tangential direction, such that there is a fan-shaped cap 5 behind each radial groove 2 to play a role in shielding on a boss surface, the principle of which is that reverse magnetic flux generated by the shielding current is superimposed with the leakage flux, such that the leakage flux penetrating through the copper plate is greatly reduced, the leakage flux penetrating from the radial groove 2 faces the fan-shaped cap 5, the reverse magnetic flux generated by the shielding current induced in the fan-shaped cap 5 is also superimposed with 9 these leakage fluxes, which greatly weakens the leakage flux penetrating through the fan-shaped cap 5, while a leakage flux path running through the radial groove 2 and an isolation groove is lengthened due to staggered arrangement, so the magnetic resistance of the path is increased and the leakage flux passing through the path is also greatly weakened. Therefore, the fan-shaped cap 5 and the grooved copper shield 3 have a double shielding effect, and the shielding protection on the pressing ring and an iron core is better than that of the traditional structure. The shielding eddy current concentration region is spread to a wider region, and the eddy current density is reduced. Due to the spacing gap between the adjacent fan-shaped caps, the shielding current density of the fan-shaped caps 5 can be controlled by adjusting the number and the gap of the fan-shaped caps 5, thus achieving the purpose of balancing eddy current loss distribution. Therefore, the fan-shaped cap 5 and the grooved copper shield 3 have a double shielding effect, the number of the grooves can be determined according to the finite element analysis, which makes the eddy current loss of the fan-shaped cap 5 equal to that generated by the grooved copper shield 3. The magnetic lines are balanced and superimposed with each other to eliminate the uneven eddy current density, the shielding protection on the pressing ring and an iron core is better than that of the traditional structure, the deterioration of the shielding effect caused by simple grooving and the concentrated heating at the groove end are avoided, the shielding eddy current concentration region is spread to a wider region, and the eddy current density is reduced.

[0027] As shown in FIG. 4, the third ventilation duct 11 is formed between the fan-shaped caps 5 and the inner hole surface of the pressing ring 1, the first ventilation duct 6 is formed between the fan-shaped caps 5 and the copper shield 3, a region, which is provided with the radial grooves 2, of the copper shield 3 is covered with a head end 12 of the isolation air guide cover 8, the second ventilation duct 7 is formed between the copper shield 3 and an inner surface of the isolation air guide cover 8, and the pressing finger radial ventilation duct 9 is covered with a tail end 13 of the isolation air guide cover 8, making the second ventilation duct 7, the third ventilation duct 11 and the first ventilation duct 6 jointly form a composite ventilation duct with the pressing finger radial ventilation duct 9. The cooling and heat dissipation surface area in the eddy current concentration region is increased to reduce the hot spot temperature. An independent cooling path can be formed under the action of a fan inside the generator to cool the heating components such as the pressing ring 1, the copper shield 3 and the fan-shaped cap 5 better and reduce the temperature rise. However, the cooling and ventilation structure of the traditional structure is related to a stator air-gap air path, which is influenced by the rotor ventilation, such that the ventilation smoothness and the air inlet temperature are adversely affected. The composite ventilation duct of the interlayer ventilation duct 4, the first ventilation 10 duct 6, the second ventilation duct 7, the third ventilation duct 11 and the pressing finger radial ventilation duct 9 is not related to the stator air-gap air path and the rotor ventilation, so the influence of the rotor ventilation can be avoided.

[0028] On the premise of ensuring the proper shielding protection efficiency, the shielding current is evenly spread to increase the heat dissipation surface area and form a smooth cooling air path, the heat dissipation effect is improved, the temperature rise is reduced, the concentrated heating problem that harms the reliability of the generator is eliminated, and the local overheating phenomenon of the copper shield is eliminated.

[0029] The radial groove 2 has a width of 3 mm, which can play a role in cutting partial shielding ring current and is convenient for machining. The calculated wind speed in the interlayer ventilation duct 4, the first ventilation duct 6, the second ventilation duct 7, the isolation air guide cover 8 and the pressing finger radial ventilation duct 9 is 20 m / s, thus both the ventilation and cooling air volume requirements and ventilation and heat exchange requirements can be satisfied. The spacing gap has a width of 5 mm, which can reduce the requirement of assembly accuracy and facilitate the manufacturing and assembly. The thickness of each of the copper shield 3 and the fan-shaped cap 5 is calculated and selected according to a power frequency penetration depth, which can reduce the manufacturing cost on the premise of meeting the shielding requirements, and the use of pure copper plate can reduce the shielding loss and facilitate the manufacturing and machining. The isolation air guide cover 8 is of a three-dimensional annular structure and is made of epoxy glass cloth laminate, which can satisfy the requirements of structural stiffness and strength and avoid eddy current loss. The fixing bolt of the isolation air guide cover is made of a diamagnetic stainless-steel material, so as to avoid heating due to the influence of an end electromagnetic field. A region, which is provided with the radial roove, of the copper shield 3 is covered with the head end 12 of the isolation air guide cover 8, the pressing finger radial ventilation duct 9 is covered with the tail end 13 of the solation air guide cover 8, and the joint of the head end 12 of the isolation air guide cover 8 and the copper shield 3 is lined with a heat-resistant rubber sheath to prevent the isolation air guide cover 8 and the copper shield 3 from wearing and air leakage.

[0030] The above embodiments are only used to illustrate the technical solution of the present disclosure rather than limiting. Although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that it is still possible to modify the technical solution described in the foregoing embodiments, or to replace part or all of technical features with equivalents. However, these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the 11 scope of the technical solutions of various embodiments of the present disclosure.

Claims

1. A composite ventilating leakage flux shielding structure of a stator end, composed of a pressing ring (1), a copper shield (3), fan-shaped caps (5), an isolation air guide cove (8), and a pressing finger radial ventilation duct (9), wherein an inner edge arc region of the copper shield (3) is provided with radial grooves (2), an interlayer ventilation duct (4) is provided between the pressing ring (1) and the copper shield (3), an inner hole surface of the pressing ring (1) is covered with the fan-shaped caps (5), and the number of the fan-shaped caps (5) is the same as that of the radial grooves (2); a spacing gap (10) is formed between adjacent fan-shaped caps (5), the spacing gaps (10) and the radial grooves (2) are staggered at equal intervals in a tangential direction; a third ventilation duct (11) is formed between the fan-shaped caps (5) and the inner hole surface of the pressing ring (1), a first ventilation duct (6) is formed between the fan-shaped caps (5) and the copper shield (3), a region, which is provided with the radial grooves (2), of the copper shield (3) is covered with a head end of the isolation air guide cover (8), a second ventilation duct (7) is formed between the copper shield (3) and an inner surface of the isolation air guide cover (8), and the pressing finger radial ventilation duct (9) is covered with a tail end (13) of the isolation air guide cover (8), making the second ventilation duct (7), the third ventilation duct (11) and the first ventilation duct (6) jointly form a composite ventilation duct with the pressing finger radial ventilation duct (9).

2. The composite ventilating leakage flux shielding structure of a stator end according to claim 1, wherein the radial groove (2) has a width of 3 mm.

3. The composite ventilating leakage flux shielding structure of a stator end according to claim 1, wherein a calculated air speed in each of the interlayer ventilation duct (4), the first ventilation duct (6), the second ventilation duct (7), the isolation air guide cover (8) and the pressing finger radial ventilation duct (9) is 20 m / s.

4. The composite ventilating leakage flux shielding structure of a stator end according to claim 1, wherein the spacing gap has a width of 5 mm.

5. The composite ventilating leakage flux shielding structure of a stator end according to claim 1, wherein the copper shield (3) and fan-shaped cap (5) are made of pure copper plates.

6. The composite ventilating leakage flux shielding structure of a stator end according to 13claim 1, wherein the isolation air guide cover (8) is made of an epoxy glass cloth laminate, and is of a three-dimensional annular structure.

7. The composite ventilating leakage flux shielding structure of a stator end according to claim 1, wherein a fixing bolt of the isolation air guide cover (8) is made of a diamagnetic stainless-steel material.

8. The composite ventilating leakage flux shielding structure of a stator end according to claim 1, wherein a joint of the isolation air guide cover (8) and the copper shield (3) is lined with a heat-resistant rubber sheath.INTERNATIONAL SEARCH REPORT International application No. PCT / CN2023 / I26324A. CLASSIFICATION OF SUBJECT MATTER H02K ll / 01(2016.01)i; H02K l / 12(2006.01)i; H02K l / 20(2006.01)i; H02K9 / 02(2006.01)i According to International Patent Classification (IPC) or to both national classification and IPC B. FIELDS SEARCHED Minimum documentation searched (classification system followed by classification symbols) IPC: H02K Documentation searched other than minimum documentation to the extent that such documents are included in the fields searched Electronic data base consulted during the international search (name of data base and, where practicable, search terms used) CNTXT; ENTXT; ENTXTC: DWPI; WPABS; CNKI: IEEE: SeSM fi, Wff, M BR, iviP, generator, stator, magnetic, flux, shield+, copper, ventilate, cool+, air C. DOCUMENTS CONSIDERED TO BE RELEVANT Category* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. PX CN 116155036 A (HARBIN ELECTRIC MACHINERY CO., LTD.) 23 May 2023 (2023-05-23) claims 1-8, description, paragraphs 22-29, and figures 1-4 1-8 A A CN 106130257 A (HARBIN ELECTRIC MACHINERY CO., LTD.) 16 November 2016 (2016-11-16) description, paragraphs 6-12, and figures 1-4 CN 104319946 A (BEIJING JIAOTONG UNIVERSITY) 28 January 2015 (2015-01-28) entire document 1-8 1-8 A CN 106208442 A (HARBIN ELECTRIC MACHINERY CO., LTD.) 07 December 2016 (2016-12-07) entire document 1-8 A CN 210167879 U (DONGFANG ELECTRIC MACHINERY CO., LTD.) 20 March 2020 (2020-03-20) entire document 1-8 | | Further documents are listed in the continuation of Box C. | J | See patent family annex. * Special categories of cited documents: “T” later document published after the international filing date or priority “A” document defining the general state of the art which is not considered date and not in conflict with the application but cited to understand the to be of particular- relevance principle or theory underlying the invention “D” document cited by the applicant in the international application -‘X” document of particular relevance; the claimed invention cannot be “E" earlier application or patent but published on or after the international considered novel or cannot be considered to involve an inventive step filing date when the document is taken alone “L" document which may throw doubts on priority claim(s) or which is “Y” document of particular relevance; the claimed invention cannot be cited to establish the publication date of another citation or other considered to involve an inventive step when the document is special reason (as specified) combined with one or more other such documents, such combination “O” document referring to an oral disclosure, use, exhibition or other being obvious to a person skilled in the ait means document member of the same patent family “P” document published prior to the international filing date but later than the priority date claimed Date of the actual completion of the international search 18 December 2023 Date of mailing of the international search report 26 December 2023 Name and mailing address of the ISA / CN China National Intellectual Property Administration (ISA / CN) China No. 6, Xitucheng Road, Jimenqiao, Haidian District, Beijing 100088 Authorized officer Telephone No.INTERNATIONAL SEARCH REPORT International application No. PCT / CN2023 / I26324 C. DOCUMENTS CONSIDERED TO BE RELEVANTCategory* Citation of document, with indication, where appropriate, of the relevant passages Relevant to claim No. A CN 213585299 U (HARBIN UNIVERSITY OF SCIENCE AND TECHNOLOGY) 29 June 2021 (2021-06-29) 1-8 entire document A JP 2006320100 A (MITSUBISHI ELECTRIC CORP.) 24 November 2006 (2006-11-24) entire document 1-8 A JP 2008054405 A (HITACHI, LTD.) 06 March 2008 (2008-03-06) entire document 1-8 A W (FU, Ziqing). "QFSN-300-2Sfift® WKSMOCK W (non-official translation: Experiment and Study on Copper Shielding Effect of Stator End of QFSN-300-2 Turbogenerator)" ^^7^1 (Dongfang Electric Review), No. 3, 30 September 1987 (1987-09-30), 16-20 ISSN: 1001-9006, entire document 1-8INTERNATIONAL SEARCH REPORT Information on patent family members International application No. PCT / CN2023 / I26324Patent family member(s)Publication date (day / month / year)Patent document cited in search reportPublication date (day / month / year)CN 116155036 A 23 May 2023 None CN 106130257 A 16 November 2016 None CN 104319946 A 28 January 2015 None — — — --------------------------- CN 106208442 A 07 December 2016 None — — — -------------------------- — CN 210167879 u 20 March 2020 None — — — — — CN 213585299 u 29 June 2021 None JP 2006320100 A 24 November 2006 JP 4468856 B2 26 May 2010 JP 2008054405 A 06 March 2008 JP 4876780 B2 15 February 2012

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