JPH0564015B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a rotor of a rotating field type rotating electric machine such as a two-pole turbine generator, which has economically improved resistance to negative phase power transmission.

[Technical background of the invention and its problems]

In order to deal with three-phase unbalanced loads and unbalanced load accidents in electric power systems, rotating electric machines such as turbine generators and phase adjusters are required to have the ability to withstand unbalanced loads.

During unbalanced load operation, a negative sequence current component flows through the stator windings of the rotating electric machine, and an eddy current flows along the surface of the cylindrical rotor. If there is a place with high electrical resistance on the path through which this eddy current flows, a large amount of joule heat is generated in that place, causing local overheating, resulting in a decrease in material strength and an increase in residual stress. There is a risk of damage to the rotor shaft.

In particular, in cylindrical rotors such as large-capacity two-pole turbine generators, in order to eliminate the circumferential anisotropy of bending stiffness, narrow grooves in the longitudinal vertical direction, that is, cross slots provided in the magnetic poles, are inserted into the outer periphery of the magnetic poles. There is a risk that the eddy current will become a hindrance to the eddy current that attempts to flow in the axial direction on the surface, and that the eddy current will concentrate on the core surface between the magnetic pole at the end of the cross slot and the coil slot closest to it, causing this portion to overheat due to joule heat.

Conventionally, in order to reduce the resistance to the eddy current, a damper bar made of electrically conductive material of the same thickness and extending over the entire length of the coil slots is installed in contact with the lower surface of the wedge of all the coil slots, or in addition to this. A structure is used in which a longitudinal damper slot is provided in the magnetic pole part, and a damper bar is installed over the entire length of the iron core in the longitudinal direction.

In this prior art, the damper bars in the coil slots have the same thickness in all coil slots, so in a two-pole rotor with cross slots, the temperature at the cross slot ends is still the highest, while the temperature on the core surface between adjacent coil slots is the same. As the temperature decreases, there is a temperature margin greater than necessary between adjacent coil slots, resulting in the problem of using more material than necessary.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a rotor for a rotating electrical machine that improves negative phase tolerance while saving materials.

[Summary of the invention]

In the present invention, there is one magnetic pole each of N and S poles, a plurality of cross slots are provided in the magnetic pole part in a direction perpendicular to the longitudinal direction and spaced apart in the longitudinal direction, and a plurality of cross slots are provided in the magnetic pole part in a direction perpendicular to the longitudinal direction, and a plurality of cross slots are provided in the magnetic pole part in a direction spaced apart in the circumferential direction. It has a cylindrical rotor core with multiple coil slots in the longitudinal direction, and contains field coil conductors, insulators, etc. laminated in the radial direction within the coil slots to hold them against centrifugal force. In the rotor of a rotating electrical machine equipped with a wedge, a thick damper bar is provided on the underside of the wedge in a given coil slot, extending over the entire length of the coil slot in the longitudinal direction, to increase the negative phase resistance, and other coil slots are provided with thinner damper bars. Alternatively, the material is saved by not providing a damper bar.

[Embodiments of the invention]

Example 1 A first example of the example will be described below with reference to FIGS. 1 and 2.

There is a circumferential iron core 2 in the center of the rotor shaft 1, and this iron core 2 is provided with one N magnetic pole and one S magnetic pole 4. A plurality of cross slots 10 are provided in the direction, and a plurality of coil slots 3 are provided in the longitudinal direction and spaced apart in the circumferential direction between the magnetic poles 4, 4. The coil slot 3 consists of a shallow coil slot 3A closest to the magnetic pole and a deep intermediate coil slot 3B. The intermediate coil slot 3B houses a slot insulator 5, a multi-turn field coil conductor 6 laminated in the radial direction, a turn insulator (not shown), and a clipage block 7, and is used to hold these items against centrifugal force. A wedge 9 has been inserted. On the other hand, in the coil slot 3A closest to the magnetic pole, a damper bar 8 is inserted between the clippage block 7 and the wedge 9 in addition to the above-mentioned stored items. This damper bar 8 is wedge 9
The wedge 9 is in contact with the lower surface of the coil slot 3A and extends over the entire length of the coil slot 3A in the longitudinal direction, and the wedge 9 is divided into a plurality of pieces in the longitudinal direction. In the coil slot 3A closest to the magnetic pole, the number of turns of the field coil conductor 6 is reduced by an amount corresponding to the shallower slot and the thickness of the damper bar 8. 11 is the cross slot end.

Next, the effect will be explained.

When the three-phase unbalanced load increases or an unbalanced accident occurs in the power system, the negative sequence current component in the stator winding (not shown) of the rotating electric machine increases. A voltage is induced on the surface of the rotor by the magnetic field generated by this negative phase current, and an eddy current is accordingly generated on the rotor surface. These eddy currents flow laterally at the longitudinal ends of the rotor, and flow primarily longitudinally at other parts. Between the cross slot end 11 and the coil slot 3A closest to the magnetic pole, the eddy current flows detouring not only to the surface of the iron core 2 and the wedge 9 but also to the damper bar 8. On the other hand, the eddy current flows only on the surface of the iron core 2 and the wedge 9 between adjacent coil slots, that is, between 3A and 3B or between 3B and 3B. The amount of the eddy current is much larger between the cross slot end 11 and the coil slot 3A closest to the magnetic pole than between adjacent coil slots, that is, between 3A and 3B or between 3B and 3B. Therefore, the temperature increase due to the eddy current is still the highest near the cross slot end 11, but the temperature decreases due to the eddy current flowing through the damper bar 8, and the temperature rise is the highest between the adjacent coil slots. Since there is no damper bar in the coil slot 3B, the temperature rises, and the temperature difference at each part of the surface of the iron core 2 is significantly reduced compared to the conventional case.

Therefore, by inserting the damper bar 8 only in the coil slot 3A closest to the magnetic pole, the temperature rise near the cross slot end 11 due to the eddy current flowing on the rotor surface due to the reverse phase current is suppressed as before, and the reverse phase withstand capability is maintained. By making the thickness of the damper bar 8 thicker than before, the reverse phase resistance can be further improved, and by eliminating the damper bar in the other intermediate coil slot 3B, the material can be saved without unnecessary temperature rise suppression. It can be used as a rotor of an economized rotating electric machine.

Embodiment 2 Next, a second embodiment will be described using FIGS. 1 and 2. This is the middle coil slot 3B
A damper bar (not shown) is also inserted into the lower surface of the wedge 9, and this damper bar (not shown) is thinner than the damper bar 8 used in the coil slot 3A closest to the magnetic pole.

If this is done, the amount of material used will increase by the amount of the damper bar provided in the intermediate coil slot 3B, but since it is thin, the same effects as in the first embodiment can be obtained.

Embodiment 3 Next, a third embodiment will be described with reference to FIG.

This means that the wedge 9A that engages with the coil slot 3A closest to the magnetic pole is thinner than the wedge 9B that engages with the other intermediate coil slot 3B, so that the stress that each wedge 9A and 9B receive from centrifugal force is made to be the same. A thicker damper bar 8A is inserted into the coil slot 3A closest to the magnetic pole, and a thinner damper bar 8B is inserted into the intermediate coil slot 3B to compensate for the thinner damper bar. Others are Example 1
It is as follows.

In this way, the coil slot 3A closest to the magnetic pole is shallower than the other intermediate coil slot 3B, and the number of turns of the field coil conductor 6 is smaller. Since it is smaller, it is rational and material-saving to make it thinner to equalize the stress. In other respects, the same effects as in Example 1 can be obtained.

Incidentally, the damper bar 8B in the middle coil slot 3B may be omitted.

Embodiment 4 Next, a fourth embodiment will be described with reference to FIG.

The coil slot 3A closest to the magnetic pole is numbered 1, and each coil slot 3 is numbered in order from the first slot to the outside of the magnetic pole 4, and the wedges 9C of the odd-numbered coil slots #1, #3, #5, etc. The thickness of the damper bar 8A that is in contact with the lower surface of the thin wedge 9C is made thicker by the thickness of the thin wedge 9C, and the thickness of the damper bar 8A that is in contact with the lower surface of the thin wedge 9C is made thicker by the thickness of the thin wedge 9C. is even #2,
If the material of the thicker wedge 9D of the coil slot #4 is made of aluminum, the material of the thinner wedge 9C is selected to be a high-strength aluminum alloy. and,
For each coil slot 3, the sum of the thicknesses of the wedges 9C, 9D and the damper bars 8A, 8B is kept constant.

By doing this, the coil slot 3 of the iron core 2
Since the electrical resistance of the part having the group can be reduced by the thickness of the damper bar 8A of the odd-numbered coil slot, the cross slot end 1
If the distance between 1 and the coil slot 3A closest to the magnetic pole is not too narrow, the temperature rise of each part of the rotor surface due to the reverse phase current can be made uniform, and the thin wedge 9C, which is susceptible to stress, is made of high-strength material. As a result, both the wedges 9C and 9D maintain the conventional strength margin, resulting in a highly reliable rotor.

Example 5 Next, a fifth example will be described with reference to FIG.

This is the thin damper bar 8B of the fourth embodiment shown in FIG. 4 made infinitely thinner, that is, the damper bar is eliminated.

In this way, the effect similar to that of the fourth embodiment can be obtained, and the cost can be increased by eliminating the damper bars of the even-numbered coil slots.

〔Effect of the invention〕

As explained above, according to the present invention, a thick damper bar extending over the entire longitudinal length of the coil slot is provided on the lower surface of the wedge of a predetermined coil slot in order to increase the negative phase withstand capability, and a thin damper bar is provided in the other coil slots. By providing a bar or not providing a damper bar, it is possible to save materials and provide a highly reliable rotor of a rotating electrical machine with improved resistance to negative sequence current.

[Brief explanation of the drawing]

FIG. 1 is an elevational view showing a first embodiment of a rotor for a rotating electrical machine according to the present invention, FIG. 2 is an enlarged cross-sectional view of essential parts taken along line M-M in FIG. 1, and FIGS. FIG. 5 is a sectional view showing the main parts of the third to fifth embodiments, respectively. 1... Rotor shaft, 2... Iron core, 3... Coil slot, 3A... Coil slot closest to the magnetic pole,
3B...middle coil slot, 4...magnetic pole, 5
...Slot insulation, 6...Field coil conductor, 7...
...Clippage block, 8...Damper bar, 8
A... Thick damper bar, 8B... Thin damper bar, 9... Wedge, 9A... Wedge that engages with the coil slot closest to the magnetic pole, 9B... Wedge that engages with the middle coil slot, 9C... Odd numbered Wedge engaged with coil slot, 9D...Wedge engaged with even numbered coil slot, 10...Cross slot, 11...Cross slot end.

Claims (1)

[Claims] 1. It has one magnetic pole each of N and S poles, and the magnetic pole part has a plurality of cross slots spaced apart in the longitudinal direction and provided in a direction perpendicular to the longitudinal direction, and the magnetic poles are spaced apart in the circumferential direction. It has a cylindrical rotor core with multiple coil slots in the longitudinal direction, and the field coil conductors, insulators, etc. stacked in the radial direction are housed in the coil slots, and these are held against centrifugal force. In the rotor of a rotating electrical machine, which has a wedge for the purpose of increasing the negative phase resistance, a thick damper bar is installed on the underside of the wedge in a given coil slot, extending over the entire length of the coil slot in the longitudinal direction, and other coil slots are equipped with thin damper bars. 1. A rotor for a rotating electric machine, characterized in that the rotor is provided with a damper bar or is not provided with a damper bar. 2. A rotor for a rotating electric machine according to claim 1, wherein the predetermined coil slot is the coil slot closest to the magnetic pole. 3. The predetermined coil slot is the one closest to the magnetic pole, this coil slot is shallower than the other coil slots, and the wedge that engages with that coil slot is thinner than the wedge that engages with other intermediate coil slots. A rotor for a rotating electric machine according to claim 1. 4. The prescribed coil slots are the coil slots closest to the magnetic pole and the odd-numbered coil slots counting from that coil slot to the outside of the magnetic pole, and the wedges for the coil slots at those locations are made thinner by the thickness of the damper bar. A rotor for a rotating electric machine according to claim 1, characterized in that a material having higher strength than a wedge is used.