JP2002507109A - Ventilation system for exciting winding of large salient pole machine - Google Patents

Abstract

(57) [Summary] In addition to the magnetic pole gap (1), in the winding layer (4) of the exciting winding (21), for better cooling of the exciting winding of a large salient pole electric machine especially for hydraulic power. A cooling medium passage (2) is formed for guiding the cooling medium radially outward.

Description

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to a ventilation system of a star excitation system of a salient pole electric machine for forcibly cooling an excitation winding by a gaseous cooling medium. Such salient pole electric machines are generally used as generators, particularly as hydroelectric generators.

FIG. 16 shows the basics of a salient pole electric machine. A winding 31 on a cylindrical inner surface of the stator core 30;
For example, a coil inserted in a groove is arranged around an excitation system that rotates around a rotor shaft 32. This excitation system protrudes from the rotor shaft 32 in a star shape,
It consists of salient poles that are magnetized in the radial direction and alternately show opposite polarities. In the illustrated example, four pairs of such magnetic poles, that is, eight salient poles are respectively formed in a fan shape in the winding head space 33.
And are separated from one another in the tangential direction by a pole gap 1 which is connected to each other via this winding head space. The magnetization of each salient pole is controlled by an excitation winding 21, usually a flat strip copper conductor or similar strip conductor, which is arranged around a pole axis 20 and forms individual winding layers, each separated by an insulating layer. Will be In order to guide the generated magnetic field, the pole axis has in each case a pole piece 10 arranged in the winding head space 33 against the head of the excitation winding. The other end of each magnetic pole shaft 20 is transferred to the rotor yoke 12.

In such a configuration, for example, a large salient pole electric machine required for output in the MW region forms a rotor shaft 32 as a hollow shaft, and supplies a cooling medium through the cavity 34. It allows to be introduced into the pole gap and to be discharged from the winding head space via the corresponding outlet of the stator core.

[0004] Losses occurring in the excitation windings have to be released to limit the temperature and require intensive cooling of the excitation system. Such cooling is achieved by a cooling gas flow guided through the cylindrical interior space of the stator core, for which two methods are customary.

[0005] The first method uses the rotation of the rotor itself as a pressure source for the ventilation system without additional ventilation. This prior art is represented by DE-A-195 15 260.

In this case, the gaseous cooling medium exits from the slit of the rotor yoke and flows radially into the magnetic pole gap. The heat flow from the flat strip copper conductor (winding layer) to the pole axis is reduced due to the large thermal resistance caused by the electrical insulation between the excitation winding and the pole axis. A major part of the heat flow is thus provided to the cooling air in the pole axis and winding head space on the side opposite to the pole axis of the excitation winding.

The speed in the head space of the end face of the excitation winding, which is effective for cooling, is substantially higher than in the pole gap. The cooling is therefore also stronger in this part and the conductor temperature is accordingly lower.

In order to increase the cooling area, the flat strip-shaped copper conductor is provided with a cooling rib on a surface opposite to the magnetic pole axis. The rib extends axially in the pole gap and circumferentially in the end face region. The cooling ribs arranged axially in the pole gap are oriented at right angles to the radial direction of the cooling medium flow, so that a lateral flow of the ribs takes place in this case. The heat transfer of such a rib configuration is not very strong. This is an essential drawback of this ventilation system with regard to the cooling of the excitation windings.

A second method is to use two mainly ventilators axially displaced from the magnetic poles as pressure sources, thereby forcing the cooling medium to flow axially through the magnetic pole gap. The cooling of the excitation winding is effected in this case by flowing the cooling medium in the axial direction and then radially through the stator cooling passages. In order to enhance the cooling of the exciting winding, a back ventilation means can be provided between the exciting winding and the magnetic pole axis. This results in additional heat dissipation from the region between the excitation winding and the pole axis. A conventional example of such a means for back cooling is shown in EP-A-0415057. The disadvantage of this cooling method is that it is structurally and technically expensive.

[0010] In a large non-salient pole electric machine used as a turbo generator, an exciting winding is accommodated in a groove. A radial slit is provided in the center of the conductor within the groove area to ensure strong cooling. A gaseous cooling medium flows through the slit, cooling the excitation winding. Such a configuration of a conductor for a non-salient pole electric machine is disclosed in International Patent Application No. 92/2014.
It is the subject of No. 0. This cooling method is not suitable for salient pole electric machines.

An object of the present invention is to provide a high-efficiency cooling technique for enlarging the cooling area of an exciting winding of a large salient-pole electric machine by a structurally simple means and achieving a high heat transfer coefficient. It is to present a typical solution.

According to the present invention, the object is to provide an opening in the winding layer, whereby the cooling medium flows radially outward as in the magnetic pole gap, and the cooling medium flows in the direction opposite to the magnetic pole axis. The problem is solved by forming a cooling medium passage leading along the side of the exciting winding through the inside of the winding. The cooling medium passage leads directly to the winding head space or to a part of the pole gap that transitions into the winding head space. This window-shaped opening in the winding layer of the excitation winding significantly increases the cooling surface, especially in the region of its head.

Although the cross section of the opening can take any contour, the cooling medium flows through the cross section of the opening in a substantially radial direction at substantially the same flow velocity as in the pole gap.

The cooling medium passage can then be straight, but can also be bent. The cooling medium is then directed radially outwards, as in the pole gap, and thus results in a parallel connection of additional cooling medium flows. This parallel cooling medium passage is made in the winding layer without the window-like opening made in the winding layer, for example a flat strip copper conductor, being covered by the insulating layer arranged between the winding layers. The openings are overlapped with one another, in which case the insulation can only enter the window-like openings slightly. The edges of this window-like opening must not have sharp corners in order to avoid flashes between winding layers, ie coil shorts.

Usually, the cooling medium passage starts from an inlet opening formed by a window provided in the lowermost winding layer of the exciting winding, and the corner of the inlet opening is rounded or obliquely dropped.

This cooling medium flow is unimpeded by the structural details as it exits the head or top winding layer and the pole pieces.

These and other exemplary embodiments of the present invention are described in claim 2 and the following.

The solution according to the invention significantly enhances the cooling of the excitation winding. The resulting development reserve can be directed to various aspects, such as lowering the temperature of the excitation winding or improving electromagnetic utilization. The exciting winding of a large salient pole machine can thus be realized with a saving of material and space. This opens the way for improved efficiency, especially by reducing ventilation losses through enhanced cooling.

An advantage of the present invention is that the present invention can be applied to both new installation and modification of an existing electric machine.

The present invention and advantageous examples thereof will be described below with reference to the drawings. In each of the drawings, parts having the same functions are denoted by the same reference numerals.

FIG. 1 shows the flow of the cooling medium in the region of the magnetic pole gap 1 and one or a plurality of flat copper conductors 4 forming the winding layer of the exciting winding 21, in the area of the tip 3. 2 shows a flow of a cooling medium through a so-called parallel cooling medium passage 2. The winding layers are insulated from each other by an insulating layer 5. In the space 13 between the rotor yoke 12 and the excitation winding 21, this arrangement is such that, without additional guides, one is due to the pole gap 1 and the other to the outer tip of the flat copper conductor 4. The flow is forcibly divided by the parallel cooling medium passages 2 in the section 3.

In the space 13 between the rotor yoke 12 and the excitation winding 21, an additional guiding device for dividing and guiding the flow of the cooling medium can be arranged.

FIG. 2 shows one embodiment of the rectangular opening 14 at the tip 3 outside the flat strip copper conductor 4 and the insulating layer 5. It should be noted that the top view of the winding head according to FIG. 15 shows that the cooling medium passage by the opening 14 has a circular or any other cross-sectional shape and that a portion 35 of the winding head that extends radially beyond the pole piece 10. Indicates that it can communicate with the winding head space. Furthermore, the cooling medium passage extends substantially radially along the outer surface 36 of the excitation winding opposite the pole axis and facing the pole gap 1, i.e., the surface portion 36 between the two salient poles. On the other hand, it is not necessary to provide a cooling medium passage and an opening between the pole piece and the outer side surface 37 defined by the exciting winding in the axial direction.

FIG. 3 shows that when the flat copper conductors 4 separated by the insulating layer 5 overlap each other, the opening is formed at the magnetic pole gap 1 at the tip 3 outside the winding layer 4 and the insulating layer 5.
This shows how the cooling medium passage 2 to the region or the winding head space is formed. All the openings of the flat strip copper conductor 4 and the insulating layer 5 have the same shape here, and the insulating layer 5
Extends slightly up to the edge of the opening or substantially so as to have little effect on the flow.

FIG. 4 shows a configuration similar to FIG. In order to improve the heat transfer in the region of the pole gap 1 and the winding head space, a cooling surface 15 is additionally provided at the outer tip 3 of the flat copper conductor 4, for example, outwardly continuous or interrupted. An axial or radial or base cut-out or needle-shaped cooling rib 15 is arranged on itself.

FIG. 5 schematically shows a cross section of a part of the exciting winding in which the thickness of the winding layer is reduced at the outer end portion 3 of the flat copper conductor 4. The insulating layer 5 is disposed only in a range where the thickness of the winding layer is not reduced. They can also cover a slightly reduced thickness range. The magnetic pole gap 1 and the cooling medium passage 2
An open connection (punching) occurs between the two. This configuration eliminates the need to cut off the edge of the opening of the flat strip copper conductor 4, and reduces the magnetic pole gap 1 and the parallel cooling medium passage 2.
The advantage is that the exchange of flows between and takes place.

The cross-sectional view of FIG. 6 shows that the magnetic pole gap 1 is provided with a throttle 16 that extends long with respect to the salient pole electric machine cooled by the cooling medium guided through the slit 11 of the rotor yoke 12. ing. The apertures 16 are arranged in an axial direction substantially parallel to the rotor axis. Thereby, the speed of the cooling medium in the magnetic pole gap 1 and the cooling medium passage 2 can be increased.

FIG. 7 shows a schematic cross section of an embodiment of a salient pole electric machine provided with an additional cooling rib provided on the outer end portion 3 of the flat strip copper conductor 4 and a guide device 17. In this case,
The cooling medium flows out through the slits 11 of the rotor yoke 12. This guide device 1
Numeral 7 extends in the axial direction over most of the axial length of the salient pole in the magnetic pole gap 1. Each guide device 17 includes a fixed portion 23 and one or more guide blades 22. The guide vanes 22 obliquely protrude from the fixed portion 23 in a radial flow (the attachment angle α is preferably smaller than 90 °), and extend straight or curved. The dimension of the guide vanes 22 in the direction parallel to the rotor axis may substantially match the dimension of the slit 11 in this axial direction. It is also desirable that the number of guide vanes is not greater than the number of slits. For a radially flowing cooling medium, the pole gap provides a much larger flow cross section than the cross section occupied by the guide device.

In order to improve the flow of the cooling medium, the guide vanes 22 have an additional restriction in the axial direction and are arranged obliquely with respect to the tangential direction with respect to the rotor axis. The arrangement of the guide device 17 in the pole gap 1 results in a high flow velocity in the region of the guide device 17, which flow has an axial component especially at the cooling surface of the excitation winding in the pole gap.

FIG. 8 schematically shows another embodiment of a salient pole electric machine in which a cooling medium flow flows out of a slit 11 of a rotor yoke 12, in which an outflow nozzle 19 facing an exciting winding is provided. A hollow aperture 18 is provided. The hollow throttle 18 is disposed in the magnetic pole gap 1 over most of the magnetic pole length in the axial direction. The hollow diaphragm 18 is connected to the exciting winding 2
Since it is open towards the space 13 between 1 and the rotor yoke 12, the cooling medium flows directly into the hollow throttle 18 from the slit 11 of the rotor yoke 12. The axial length of the hollow throttle 18 is preferably relatively large or substantially equal to the axial length of the slit 11 of the rotor yoke 12, and the number thereof is the same as that of the slit 11 of the rotor yoke 12. It should be no more than the number. The nozzle-shaped outlet 19 can be straight or curved, but the flow has an axial component, since an additional change of direction takes place. An additional guiding device can be arranged inside the hollow throttle 18.

In FIG. 9, the winding head is covered with the pole piece 10 including its side edges, that is,
The length of the pole piece 10 protruding from the pole axis 20 is equal to the width of the flat copper conductor 4. In this embodiment, the upper or upper strip-shaped copper conductor 9 is punched outward to form an opening 8.
have.

At the base of the excitation winding, as shown in FIG.
6 are formed. The corners of the inlet 46 are rounded to avoid inflow losses.

As in the case of FIG. 5, in the schematic representation of the other embodiment according to FIG. 11, the outer tip 3 of the winding layer is in each case the winding between the pole axis 20 and the outer tip 3. It has a smaller thickness (radial dimension) than the wire layer. In that case, the insulating layer extends only over this intermediate range. That is, the insulating layer extends completely or almost only slightly at the tip 3 having the reduced thickness. In particular, the opening forming the cooling medium passage is at the tip 3 with this reduced thickness in the winding layer. In the middle between the reduced thickness winding layers, a punched opening connecting the coolant passage to the pole gap is provided. Such an opening into the pole gap can contribute to effective cooling of the excitation winding. Therefore, unlike FIG. 5, in FIG. 11, a window-shaped opening 14 completely surrounded by the material of the winding layer is formed in each case to form the cooling medium passage 2. Are indicated by broken lines.
Rather, the winding layer itself may also have a stamped opening that connects the coolant passage 2 or opening 14 completely to the pole gap 1 at the leading end of the winding layer. The ends 3 of the winding layers then act as additional cooling ribs for each winding layer at this point. Each of these openings may be provided in the outermost coolant passage in each individual winding layer, but it is preferred that the individual openings and / or the individual winding layers have such openings.

Further, as shown by broken lines in FIG. 11, the openings 14 of the individual winding layers do not necessarily have to have the same size, and the edges of these openings do not necessarily have to be in line with each other. . This is more clearly illustrated in FIG. 12, where the cross-section of the opening 14 is alternately sized differently.

The embodiment of FIG. 13 comprises a stop 16 arranged in the pole gap between two adjacent salient poles, as in the embodiment of FIG. The aperture 16 of FIG. 13 has, however, a side surface 26 which supports the excitation windings of two adjacent salient poles. The support side surface 26 extends over substantially the entire length of the leading end of the winding layer, that is, over substantially the entire axial length of two adjacent excitation windings. The aperture may be made solid, for example, of a lightweight metal, or have a cavity to reduce its mass. A cooling medium may likewise be able to flow through this cavity for better cooling. FIG. 13 shows a further cooling in the throttle, more precisely in the area adjacent to the support outer surface 26, for connecting the circumference of the pole base to the winding head to improve cooling of the winding layer for improved cooling. Medium passage 25
Is shown.

Further, one or a plurality of elastic spacers 2
4 to compensate for manufacturing tolerances of the excitation winding and the diaphragm.

Such a diaphragm, which covers the entire distance between two adjacent excitation windings and thus the pole gap 1, supports the pole windings with one another, so that a deformation of the excitation system is avoided. At the same time, this leads to an optimal division and guidance of the cooling medium flow.

[0038] The best mechanical retention is that only the appropriate inlet passages reaching the coolant passage 2 and the coolant passage 25 are opened, and almost the entire pole gap between the excitation windings is filled with filler up to the rotor yoke. It can be realized by filling. However, since the passage of the cooling medium through the hollow rotor shaft and the appropriate outflow slits of this rotor shaft presupposes a large overall structure, injecting filler into such a large pole gap is a manufacturing technique. It is difficult to implement in an efficient manner. Therefore, it is preferable to use a pre-manufactured diaphragm, possibly together with the elastic spacer 24 described above, and to fix it to the excitation winding with, for example, a casting. Another example of mechanical retention is that, as shown in FIG. 14, the pole piece 10 covers the outer tip 3 and furthermore the outer tip of the winding layer is held so that the pole piece embraces the stop 16. It is realized by exceeding. The embraced portion and the support side of the diaphragm 16 then form a practically mating and holding structure. The cooling medium passages 2 and the other cooling medium passages 25 formed by the openings in the winding layer then pass through the outlet opening of the pole piece or, as shown in FIG. Guided around.

The features recited in the subclaims and the description of the individual figures can in each case be combined in an advantageous manner with other alternative embodiments.

[Brief description of the drawings]

1 shows a schematic cross section of a sector A of FIG.

FIG. 2 shows a top view of an outer end portion of a winding layer and a window-like opening forming a coolant flow path.

FIG. 3 shows a schematic cross section of a plurality of winding layers between which an insulating layer and a penetrating cooling medium passage are formed.

FIG. 4 shows a cross section of a winding layer having a cooling surface at the outer tip.

FIG. 5 shows a cross section similar to FIG. 3 with a small thickness outer tip of the winding layer.

FIG. 6 shows a section similar to FIG. 1 with a stop in the pole gap.

FIG. 7 shows a section similar to FIG. 1 with a guide device in the pole gap.

FIG. 8 shows a section similar to FIG. 6 with a hollow stop.

FIG. 9 shows a cross section of a winding head.

FIG. 10 shows a cross section of the base of the excitation winding.

FIG. 11 shows a cross section similar to FIG. 3 with a lateral passage in the cooling medium passage.

FIG. 12 shows a cross section similar to FIG. 4 with a winding layer with openings having different cross sections in alternating order.

FIG. 13 shows a section similar to FIG. 6 with a stop supported by an adjacent excitation winding.

FIG. 14 shows a cross section similar to FIG. 6 with the stop held by the pole pieces.

FIG. 15 shows a top view of a salient pole with a pole piece and an underlying excitation winding.

FIG. 16 shows a schematic diagram of a salient pole electric machine.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 magnetic pole gap 2 cooling medium passage 3 leading end of winding layer 4 winding layer (flat copper conductor) 5 insulating layer 6 inlet of cooling medium passage 7 lower winding layer 9 upper winding layer 10 pole piece 11 Slit 12 Rotor yoke 13 Space between magnetic pole gap and exciting winding 14 Opening 15 Cooling rib 16 Restrictor 17 Guide device 18 Hollow restrictor 19 Outflow nozzle 20 Magnetic pole shaft 21 Exciting winding 22 Guide vane 23 Guide device Fixed part 24 Spacer 25 Coolant passage in guide device 26 Outer surface of throttle 30 Stator core 31 Stator winding 32 Rotor shaft 33 Inner surface of stator core 34 Cavity of rotor shaft 35 Radius of exciting winding head Part beyond the pole piece in the direction 36 outer surface of the exciting winding on the side opposite to the magnetic pole axis 37 outer surface restricted in the axial direction of the exciting winding

──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H603 AA12 BB02 BB12 CA02 CA04 CB02 CB03 CB23 CC03 CC11 CC17 CD02 CE02 CE13 FA01 5H609 BB04 PP06 PP07 PP08 PP09 PP10 QQ02 QQ03 QQ13 QQ14 RR36 RR43

Claims (18)

[Claims] 1. A salient pole (34) extending in a star shape radially outward from a rotor shaft.
), And each of these salient poles transitions to one winding head space (1).
) And tangentially separated from each other by a magnetic pole axis (20) and arranged around this magnetic pole axis (20), and a plurality of winding layers (7, 9) and between these winding layers Excitation winding (21) with disposed insulating layer (5), in particular having at least one strip-shaped copper conductor (4) and pole piece (10) disposed at the head of the excitation winding The opening (14) provided in the winding layer (4, 5, 7, 9) extends along the side surface (36) opposite to the magnetic pole axis of each exciting winding and directly or at least has a magnetic pole. A ventilation system for exciting windings of a salient pole electric machine, wherein a cooling medium passage (2) communicating with a head space of a winding through a gap (1) is formed. 2. A space (13) between the exciting winding (21) and the rotor yoke (12) formed by the base of the salient poles has an additional guiding device (17, 22, 18,...). 1
The ventilation system according to claim 1, wherein 9) is installed. 3. An outer surface of the excitation winding (21) is provided with a cooling surface, for example a cooling rib (15) which is continuous or interrupted outwardly, twisted or needle-shaped at its axial or radial direction or at its base. The ventilation system according to claim 1, wherein the ventilation system is arranged. 4. A cooling medium passage according to claim 1, wherein the cooling medium passage is formed only along an outer surface of the exciting winding facing the magnetic pole gap. Ventilation system. 5. The ventilation system according to claim 1, wherein the cooling medium passage is connected to the magnetic pole gap via a plurality of lateral punches. 6. An outer end of each winding layer having a thickness smaller than that of the winding layer between the pole axis and the outer end, and an insulating layer. 6. Ventilation system according to claim 1, wherein 5) extends at most only slightly to the outer tip (3). 7. A pole piece (10) almost completely covers the head of the excitation winding, and a cooling medium passage is laterally formed on the outer surface of the excitation winding via an opening (14) in the pole gap (1).
The ventilation system according to one of claims 1 to 6, characterized in that it communicates with a ventilation system. 8. The cooling medium passage according to claim 1, wherein the cooling medium passage starts from an opening having a rounded or beveled edge in the lower winding layer. A ventilation system according to one of the preceding claims. 9. The copper strip conductors (4), which are stacked one upon the other during stratification, have openings (14) having different cross sections in alternating order.
9. The ventilation system according to one of claims 1 to 8. 10. An elongated stop (16) whose longitudinal direction is aligned substantially parallel to the rotor axis is arranged in the pole gap (1).
A ventilation system according to item 1. 11. A guide device (17) having a fixed part (23) and a guide vane (22) is arranged in the pole gap (1), and the guide vane (22) is in particular parallel to the rotor axis. Slit (11) for introducing the cooling medium in the radial direction into the magnetic pole gap (1) in different directions
11. Ventilation system according to one of the preceding claims, having approximately the same dimensions as. 12. At the pole gap (1), at least one elongated hollow throttle (18) having an outlet nozzle towards the excitation winding (21) extends in the direction of the rotor axis, said hollow throttle being 2. The method according to claim 1, wherein the opening is open to a space between the exciting winding and a rotor yoke arranged at the lower end of the pole axis. The ventilation system according to one of the eleventh to eleventh aspects. 13. A pole gap (1) between two adjacent excitation windings (21).
13. Ventilation system according to one of the preceding claims, characterized in that it comprises a throttle (16) with a side surface supported by the two excitation windings (21). 14. Ventilation system according to claim 13, wherein the supported sides of the throttles (16) are each formed by at least one elastic spacer. 15. The ventilation system according to claim 13, wherein the throttle is supported by the exciting winding over substantially the entire axial length of the salient pole. 16. The cooling medium passage according to claim 1, wherein the further cooling medium passages extend radially through the throttle and into the region of the respective outer surface supported.
16. The ventilation system according to one of 3 to 15. 17. Ventilation system according to one of claims 13 to 16, characterized in that the pole piece (10) overlies the stop (16). 18. Ventilation system according to claim 1, wherein all cooling medium passages are fluidly connected to the cavity of the rotor shaft.