JPS6412170B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rotor for a rotating electric machine, and particularly to a rotor for a rotating electric machine suitable for application to a cylindrical rotor of a turbine generator.

Generally, in a turbine generator, an unbalanced current flows through the windings when an accident occurs in the system or when the load is not balanced in three phases. The unbalanced component contained in this current is generally called an anti-sequence current and creates a magnetic field that is not synchronized with the rotor speed, inducing current in the rotor conductors and causing rotor heating. Therefore, a dedicated damper winding is provided near the rotor surface to allow this induced current to flow.

FIG. 1 shows the conductor structure of this type of rotor which has been generally employed in the past. In the figure, reference numeral 1 indicates a magnetic pole, and reference numeral 2 indicates a circumferential groove for rigidity balance formed on the surface of the magnetic pole 1. A field coil 3 is inserted into a number of grooves formed in the rotor and held by a wedge 4. A damper bar 5 is provided between the wedge 4 and the field coil 3, and a damper ring 6 formed integrally with the damper bar 5 communicates between the damper bars. A retaining ring 7 is provided at the end of the rotor to prevent the field coil 3 and damper ring 6 from being damaged by centrifugal force during rotation. Reference numeral 8 indicates a tooth, and reference numeral 9 indicates an end ring. In a rotor having such a structure, an induced current flows on the rotor surface along a complicated path as shown by the arrow, but most of this current flows from the damper bar 5 through the damper ring 6.

FIG. 2 shows the entire damper bar and damper ring. This damper winding does not have a damper bar at the magnetic pole portion, and is usually made of a thin conductor such as copper. The induced current tends to flow along the field winding as shown by the arrow in the figure. That is, the induced current flows into the damper ring 6 from a large number of damper bars, changes its direction in the circumferential direction, flows through the damper ring, and flows to the other damper bar in a state symmetrical about the center of the magnetic pole.

When such a structure is adopted, as shown in the cross section in Figure 3, the distribution of induced current will have a phenomenon in which the magnitude and phase of the induced current differ depending on the axial position, as indicated by symbols A, B, and C. . Therefore, an electromagnetic excitation force having a different magnitude and phase is generated in the damper ring 6 depending on the axial position, which tends to cause electromagnetic vibration as shown by the dotted line in FIG. 3. Since this vibration acts to cause the damper ring 6 to wave, the damper ring 6 becomes mechanically fatigued, and if such vibration occurs repeatedly during long-term operation, this damper ring will eventually be damaged. This phenomenon was one of the major causes of lower reliability. This trend is becoming stronger as electric and magnetic loading increases with the increase in single-term capacity.

An object of the present invention is to provide a rotor for a rotating electrical machine that is configured to suppress abnormal vibrations of a damper ring.

According to the present invention, the above object is achieved by adopting a structure in which the damper ring near the magnetic pole is divided in the axial direction to limit the flow of induced current.

Hereinafter, the present invention will be explained in detail together with embodiments shown in the drawings.

FIG. 4 shows an embodiment of the present invention, in which the same parts as in FIGS. 1 to 3 are designated by the same reference numerals. In this embodiment, the damper ring 6
A plurality of slits 10 are bored along the circumferential direction and at positions facing the magnetic pole portion in the axial direction. These slits 10, which are illustrated as three slits in the figure, are configured such that the circumferential distance is long on the outer end side in the axial direction of the damper ring, and the circumferential distance is sequentially shorter on the inner end side.

Since this embodiment employs the above-described structure, the path through which the induced current flows is limited by the slit 10, so the damper ring 6 is inserted into the slit of the damper ring as shown in cross section in FIG. It shows a form in which only the parts divided by 10 vibrate independently. This condition is shown in dotted lines in FIG. Therefore, the entire damper ring 6 does not vibrate as a unit as in the conventional case, and the vibration of the damper ring is significantly suppressed.

FIG. 6 explains another embodiment of the present invention. In this embodiment, the above embodiment in which circumferential slits are provided only in the damper ring is further developed, and the slits 10 are arranged in the direction of the damper bar. It was formed by extending it. Therefore, the damper bar and the damper ring are one continuous damper coil 11.
Most of each damper coil 11 has a configuration corresponding to that of the field coil. Even if such a structure is adopted, the fourth
The same effects as the embodiment shown in the figures can be obtained, and there is also the advantage that assembly work is simplified.

By the way, the above embodiments are all embodiments for the d-axis damper winding, but if a q-axis damper coil is required for design reasons, the damper coil 11 can be replaced with the above-mentioned damper coil as shown in FIG. Of course, it may be formed in the same manner as .

As is clear from the above description, according to the present invention, the damper ring near the magnetic pole is divided in the axial direction,
Since the structure that limits the flow of induced current is adopted, it is possible to obtain a rotor of a rotating electric machine configured to suppress abnormal vibrations of the damper ring.

[Brief explanation of drawings]

Figures 1 to 3 explain the conventional structure.
Fig. 1 is a perspective view of the rotor, Fig. 2 is a perspective view of the damper ring, Fig. 3 is an enlarged sectional view taken along the line - - in Fig. 2, and Fig. 4 and subsequent figures illustrate embodiments of the present invention. FIG. 4 is a perspective view illustrating an embodiment of the present invention, FIG. 5 is an enlarged sectional view taken along the - line in FIG.
7 and 7 are perspective views illustrating different embodiments of the present invention. 1... Magnetic pole, 2... Cross slot, 3... Field coil, 4... Wedge, 5... Damper bar,
6...Damper ring, 7...Retaining ring, 10...Slit.

Claims (1)

[Scope of Claims] 1. A rotor having a groove bored in the outer axial direction of the rotor so as to constitute magnetic poles in the radial direction of the rotor, and a field coil inserted into the groove, and a field coil inserted into the groove. In a rotor of a rotating electric machine, the rotor includes a damper bar inserted into a predetermined groove, and a damper ring having a sufficient width to electrically connect the ends of the damper bars to each other, , characterized in that a plurality of slits are provided along the circumferential direction and at positions facing the magnetic pole portion in the axial direction, the slits becoming sequentially shorter from the outer end to the inner end in the axial direction. The rotor of a rotating electric machine.