EA015583B1 - Stator for an electric machine - Google Patents

Abstract

The invention relates to a stator for a turbogenerator provided with the affective gas cooling of the coil and teeth thereof. A core (2) with a winding (3) is arranged in the stator body (1). The core consists of the packages of steel plates (5) and ventilating channels (7). Said ventilating channels are formed by ventilating spreaders (8) and are closed on the side of the bore of the stator core. A high-pressure chamber (9) located in the space between the body and the core is provided with air ducts (10) which are disposed on the external surface of the core along the total length thereof in each second intertooth interval. Said air ducts are connected to the ventilating channels on one side and to a low-pressure chamber, which is situated in the space of the face parts of the stator winding, on the other side. The ventilating spreaders are placed in the tooth area in such a way that the cooling gas flow is shifted in an axial direction towards the adjacent ventilating channel via through holes (6). Said ventilating spreaders are arranged in a heelpiece area in such a way that the cooling gas flow in the even ventilating channels passes from the high-pressure chamber to the tooth area and in the uneven ventilating channels said flow passes from the tooth area to the air ducts.

Description

The invention relates to electrical engineering, in particular to gas-cooled electric machines, for example, turbogenerators.

Known design and gas cooling system of the stator of an electric machine, described in the invention The ventilation system of an electric machine (RF patent No. 2220491, Н02К 9/00, Н02К 1/20, publ. 12/27/2003). In the design of the electric machine under consideration, grooves are placed under the grooved wedges connecting the radial channels of adjacent teeth and forming a single radial tangential ventilation channel with the inlet and outlet of the cooling gas from the outer surface of the stator core.

In the design under consideration, all ventilation ducts are closed on the side of the bore of the stator core, i.e. separated from the air gap between the stator and the rotor.

This design has the following disadvantages:

a forced increase in the height of the groove without increasing the net volume occupied by the winding;

high aerodynamic drag of the radial tangential ventilation channel due to the limited section of the groove section of the channel;

increasing the temperature of the cooling gas in the area of the radial tangential channel from the entrance to the outer surface of the stator core to the channel placed under the groove wedge due to the heat influx along the steel of the core in the tangential direction from another part of this channel that removes the heated gas from the core.

The closest in technical essence to the claimed invention is the design described in the invention Stator of an electric machine (RF patent No. 2047257, Н02К 1/20, Н02К 9/02, publ. 10/27/1995). In this invention, the stator of an electric machine with a gas multi-jet ventilation system has a housing divided into alternating compartments (chambers) of high and low gas pressure. The stator core consists of burst packages separated by radial ventilation ducts. The ventilation ducts are formed by means of ventilation struts installed between the packages in the yoke and core teeth zones. Radial channels communicate with the compartments (cameras) of the housing. At least in the middle part of the core, the ventilation struts in the yoke zone are installed with the cooling gas flow displaced in the tangential direction by a multiple of the step along the compartments (chambers) of the stator housing, and in the teeth, the ventilation struts are installed with the axial flow displaced to the adjacent channel using through slotted holes distributed along the height of the teeth.

In the first case, direct ventilation spacers are installed in the teeth and inclined in the yoke of the stator core, and the inclination of the spacers in adjacent ventilation ducts is made in opposite directions.

In the second case, the ventilation struts have straight sections in the teeth and in the yoke through one ventilation channel along the length of the core and straight sections in the teeth and sloping in the yoke in the remaining ventilation channels.

In the third case, the ventilation struts are made straight in the teeth and in the yoke, and the ventilation channels are equipped with partitions located on the outer circumference of the core with a step equal to the width of the compartments (chambers) of the housing, and the partitions of adjacent channels are offset by the said step.

In the ventilation ducts in the tooth zones of high gas pressure, removable plugs are installed between the ventilation struts.

Between compartments (chambers) of high pressure of the stator housing and between compartments (chambers) of low pressure, tangential bypass channels are made.

This design and cooling system have the following disadvantages.

1. The entry into the ventilation ducts, communicating with the low-pressure compartments, of heated gas from the gap between the stator and the rotor leads to a significant increase and uneven distribution of the temperature of the winding and stator steel along the length of the core.

2. There is no gas circulation between the winding and the ventilation struts in the area of the teeth of the ventilation ducts in communication with the high pressure compartments and separated from the gas in the gap between the stator and the rotor by removable plugs installed between the ventilation struts.

3. The design is complicated by the separation of the stator housing into axial compartments alternating in a tangential direction and by connecting the compartments of various pressures using bypass channels.

The problem solved by the invention is to improve the cooling of the windings and teeth along the entire length and circumference of the stator core due to the intensification of heat transfer.

The specified technical result is achieved in that the stator of an electric machine with a gas ventilation system comprises a housing, a core, air ducts, a low pressure chamber and a high pressure chamber. The low-pressure chamber is located in the area of the frontal parts of the stator winding, and the high-pressure chamber is located in the space between the housing and the core. A winding is laid in the grooves of the core, and the core consists of burst packages and ventilation ducts in communication with the high and low pressure chambers. Ventilation ducts formed by ventilation

- 1 015583 spacers that are attached to the burnt packages in the tooth zone and the core yoke zone. All ventilation ducts are closed on the side of the bore of the stator core. Air ducts are placed in the high-pressure chamber on the outer surface of the core along its entire length in increments of one tooth division, which, on the one hand, communicate with the low-pressure chamber, and on the other hand, with the ventilation ducts of the core. In the tooth zone of the core, ventilation spacers are installed to provide a displacement of the cooling gas flow in the axial direction through the through holes made in the burst package along the height of the tooth into the adjacent ventilation channel. In the core yoke zone, ventilation struts are installed to ensure that the flow of cooling gas from the high pressure chamber passes through the even ventilation channels to the tooth zone and the cooling gas flows from the tooth zone to the air ducts through the odd ventilation channels.

It is advisable to install four ventilation spacers in each tooth. The first two ventilation spacers are installed radially at a distance from the bore of the stator core and symmetrically with respect to the axis of symmetry of the tooth with the formation of three radial channels for the passage of cooling gas. At a distance from the first two ventilation spacers, two other ventilation spacers are installed so as to separate part of the openings. The ends of the said struts, facing the first two ventilation struts, are brought together on the axis of symmetry of the tooth, and their opposite ends are installed at a distance from the base of the tooth and are apart in opposite directions from the axis of symmetry of the tooth.

The proposed installation of ventilation spacers in the tooth allows you to get a uniform distribution of the flow of cooling gas over the cross section of each axial hole in the tooth.

In the first embodiment, ventilation struts are installed in the yoke zone obliquely to the radial axes of the grooves and are connected in pairs on one side to the side walls of each duct. On the other hand, the opposite ends of each pair of ventilation spacers are installed to allow passage at the bottom of the grooves for part of the flow of cooling gas supplied from the high-pressure chamber. In the even ventilation ducts, the inclination of the ventilation struts is made towards each other, and in the odd ventilation ducts - in the direction from each other.

In this embodiment, the location of the ventilation struts in the yoke zone, in addition to the passage of cooling gas from the pressure chamber through the ventilation channels to the tooth zone in the even ventilation channels and the passage of cooling gas from the tooth zone to the air ducts in the odd ventilation channels, provides an additional passage of part of the cooling gas flow at the bottom of the grooves, bypassing the tooth zone. This makes it possible to divert part of the losses emanating from the yoke steel by the cooling gas, and makes it possible to reduce the heating of the cooling gas in the tooth zone and lower the temperature of the winding and teeth.

In the second embodiment, partitions are additionally installed in the yoke zone, and ventilation spacers are located radially opposite the side walls of the air ducts at a distance from the partitions to ensure the passage of the cooling gas flow. Partitions are attached to the side walls of each duct. In even ventilation ducts, using the partitions, the passage for cooling gas to each duct is closed, and in the odd ventilation channels, the passage for cooling gas between adjacent ducts is closed.

With this arrangement of ventilation spacers, the entire flow of cooling gas is directed to the tooth zone. Due to this, there is an increase in the speeds of the cooling gas in the ventilation ducts, heat transfer coefficients from the surfaces of the teeth and axial holes made in the teeth, and a decrease in the temperature of the winding and teeth.

New in the claimed design is:

closing of all ventilation channels from the side of the stator core bore;

the location of the low-pressure chamber in the space of the frontal parts of the stator winding, and not in the space between the housing and the stator core;

placement of air ducts in the high-pressure chamber on the outer surface of the core along its entire length in increments of one tooth division;

the communication of the ducts on the one hand with the low-pressure chamber, and on the other hand with the ventilation channels of the core;

installation of ventilation struts in the yoke zone with the passage of the cooling gas flow in the even ventilation ducts from the high pressure chamber to the tooth zone, and in the odd ventilation ducts from the tooth zone to the air ducts.

The proposed design of the stator core in comparison with the prototype allows to obtain a uniform distribution of the temperature of the winding and the teeth along the length and circumference of the core, to increase the cooling rate and reduce the temperature of the winding and the teeth of the stator core.

- 2 015583

A sign is the installation of ventilation spacers in the yoke zone with the passage of the cooling gas flow in the even ventilation ducts from the high pressure chamber to the tooth zone, and in the odd ventilation ducts from the tooth zone to the air ducts, it is not revealed in the prior art, from which it can be concluded that the proposed as an invention, the technical solution meets the condition of patentability inventive step.

The drawings show examples of specific performance of the proposed stator.

In FIG. 1 shows a longitudinal section through the stator core;

In FIG. 2 shows the installation of ventilation spacers in the prong of the stator core;

In FIG. Figure 3 shows a cross section of the stator along adjacent ventilation channels (a - even channels, b - odd channels), if the ventilation struts in the yoke zone are installed obliquely;

In FIG. 4 shows a cross section of the stator along adjacent ventilation ducts (a - even channels, b - odd channels), if the ventilation struts in the yoke zone are installed radially and the channels are equipped with additional partitions.

The stator of the electric machine contains a housing 1, a core 2, in the grooves of which a winding 3 is laid, fixed by grooved wedges 4. The core 2 consists of burnt packages 5, in the tooth zone of which there are axial through holes 6 located along the axis of symmetry of the teeth, and ventilation ducts 7 formed by ventilation struts 8. In the space between the housing 1 and the core 2, which is the high-pressure chamber 9, there are air ducts 10 that occupy part of the height of the high-pressure chamber 9. Ducts 10 are connected They are connected with the entrance windows to the surface of the core 2 and communicate with the low-pressure chamber (not shown in the drawing) located in the area of the frontal parts of the winding 3. The ducts 10 have a length equal to the length of the core 2, and their side walls forming the entrance windows are placed along the axes symmetry of adjacent teeth of the core 2 through one tooth division.

The ventilation channels 7 communicate with the high pressure chamber 9 and through the ducts 10 with the low pressure chamber (not shown). The ventilation ducts 7 are closed from the side of the core bore 2 by tangential distance struts 11 installed in the teeth between the groove wedges 4 that secure the winding 3.

In each tooth shown in FIG. 2, four ventilation struts 8 are installed, the first two ventilation struts 8 are located at a distance from the tangential distance strut 11, have a length close to half the height of the tooth, are installed symmetrically about its axis, forming three radial channels for gas passage. The ends of two other ventilation struts 8 are brought together on the axis of symmetry of the tooth, moved to the base of the tooth from the ends of the first two ventilation struts 8, separating part of the holes 6. The opposite ends of the ventilation struts 8 are moved left and right from the axis of symmetry near the base of the tooth. The ventilation spacers 8 provide a displacement of the flow of cooling gas in the axial direction to the adjacent channel through the through holes 6.

In the yoke zone in the first embodiment shown in FIG. 3, the ventilation struts 8 are mounted obliquely to the radial axes of the grooves. The ventilation spacers 8 are connected to the side walls of the ducts 10, forming their opposite ends at the bottom of the grooves, the axes of which are installed ducts 10, gas passages. In even ventilation ducts 7, the inclination of the ventilation struts 8 connected to each duct 10 is made towards each other. In the odd ventilation ducts 7, the inclination of the ventilation struts 8 is made in the direction from each other.

In the second embodiment shown in FIG. 4, additionally installed U-shaped partitions 12, which are attached to the side walls of the air ducts 10. Each partition 12 in the even ventilation ducts 7 closes the passage for the flow of cooling gas into the ducts 10, and in the odd ventilation ducts 7 closes the passage for the cooling flow gas into the high-pressure chamber 9. Ventilation struts 8 are installed radially at a certain distance from the partitions 12 and from the bottom of the grooves.

When the electric machine is operating, the flow of cooling gas from the high-pressure chamber 9 passes between the air ducts 10 into the even ventilation channels 7 of the yoke zone, formed by ventilation spacers 8 between the burnt packages 5 of the core 2. In the yoke zone, the cooling gas moves through the even ventilation channels 7 in the direction of the tooth zone. In the tooth zone, from the even ventilation channels 7, through the axial through-holes 6, the cooling gas enters adjacent (odd) ventilation channels 7. Next, the cooling gas moves from the tooth zone through the odd ventilation channels 7 to the yoke zone and then through the air ducts 10 enters the low pressure chamber (not shown in the drawings) located in the area of the frontal parts of the winding 3 of the core 2.

A feature of the first design option is as follows. Part of the flow of cooling gas in the even ventilation ducts 7 is directed from the yoke zone through passages formed along the axes of the air ducts 10 near the bottom of the grooves with inclined ventilation struts 8, bypassing the tooth

- 3 015583 zone, into the air ducts 10. In the odd ventilation ducts, part of the cooling gas stream from the high pressure chamber 9 moves along the yoke and, through the passages formed along the axes between the air ducts 10 near the bottom of the groove, by the inclined ventilation struts 8, is connected to the gas stream following from the tooth zone, and is sent to the ducts 10.

Claims (4)

1. The stator of an electric machine with a gas ventilation system, comprising a housing, air ducts, a low pressure chamber and a high pressure chamber located in the space between the housing and the core with windings laid in the grooves, the core consisting of burst bags and communicating with the high and low pressure chambers ventilation ducts formed by ventilation struts attached to the burnt packages in the tooth zone and the yoke zone, and in the tooth zone ventilation struts are installed to ensure displacement of the cooling gas flow in the axial direction to the adjacent ventilation channel through openings distributed along the height of the teeth, characterized in that all ventilation channels are closed on the side of the bore of the stator core, air ducts are placed in the high pressure chamber on the outer surface of the core along its length in increments of one tooth division, with the air ducts on the one hand communicating with the ventilation channels, on the other hand communicating with the low-pressure chamber located in space wallpaper and continuing stator windings, and a yoke mounted ventilation zone spacers ensuring the cooling gas flow passage in a ventilation duct even from the high pressure chamber to the perforated zone and into the ventilation ducts of odd tooth zone into the duct. 2. The stator according to claim 1, characterized in that each tooth has four ventilation spacers, the first two ventilation spacers installed radially at a distance from the bore of the stator core and symmetrically with respect to the axis of symmetry of the tooth with the formation of three radial channels for the passage of cooling gas, and two other ventilation spacers are installed at a distance from the first two ventilation spacers to separate part of the openings, the ends of which facing the first two ventilation spacers are brought together and the axis of symmetry of the tooth, and the opposite ends are installed at a distance from the base of the tooth and are apart in opposite directions from the axis of symmetry of the tooth. 3. The stator according to claim 2, characterized in that in the yoke zone the ventilation struts are connected on one side to the side walls of the ducts and, on the other hand, mounted obliquely to the radial axes of the grooves with the formation of gas passages at the bottom of the grooves, and in even ventilation ducts the inclination of the ventilation struts attached to the side walls of each duct is made towards each other, and in the odd ventilation ducts - towards each other. 4. The stator according to claim 2, characterized in that in the yoke zone partitions are installed in the ventilation ducts, and the ventilation struts are installed radially opposite the side walls of the air ducts at a distance from the partitions, and in the even ventilation ducts of the partition the gas passage is closed into each duct, and in odd ventilation ducts - between adjacent ducts.