Method and apparatus to tune rotor's torsional natural frequency by geometry of rotor winding slot

• US 6,833,640 B2
• Filed: 12/07/2000
• Issued: 12/21/2004
• Est. Priority Date: 12/07/2000
• Status: Expired due to Fees

• Current Assignee: Siemens Energy Incorporated (Siemens AG)
• Original Assignee: Siemens Westinghouse Power Corporation
• Inventors: Light, Kevin M., Rico, Raul, Chianese, Richard B., Ross, Christopher W.
• Primary Examiner(s): Mullins, Burton S.
• Application Number:
  US09/731,501
• Publication Number:
  US 20020070622A1
• Time in Patent Office: 1,475 Days
• Field of Search: 310/261, 310/51, 310/210, 310/214
• US Class Current: 310/51
• CPC Class Codes: H02K 1/26 Rotor cores with slots for windings

Abstract

A method and apparatus for tuning the torsional natural frequency of a rotor is disclosed. At least one tuning slot is formed within the winding slots defined by radially projecting winding teeth. The tuning slot extends radially inward from the bottom of the winding slot a distance to tune the rotor to a desired torsional natural frequency. This tuning slot can be positioned preferably at the quadrature axis.

Claims

1. A method for tuning the torsional natural frequency of a turbine generator rotor comprising the step of forming within winding slots defined by radially projecting winding teeth at least one tuning slot that extends radially inwardly from the bottom of the winding slot, or from the bottom of a cooling channel under the winding slot, a distance to tune the rotor to a desired torsional natural frequency;

wherein the at least one tuning slot comprises a set of tuning slots numbering substantially fewer than the winding slots and positioned at a location that minimizes impact to the electromagnetic characteristics of the rotor cross-section.

2. A method for tuning the torsional natural frequency of a generator rotor having opposing poles and a quadrature axis, comprising the step, of forming within the winding slots defined by radially projecting winding teeth that are positioned substantially at the quadrature axis, at least one tuning slot that extends radially inwardly from the bottom of the winding slot, or from the bottom of a cooling channel under the winding slot, a distance to tune the rotor to a desired torsional natural frequency;

wherein the at least one tuning slot comprises a set of tuning slots numbering fewer than the winding slots and positioned at a location that minimizes impact to the electromagnetic characteristics of the rotor cross-section.

3. A turbine generator rotor comprising:

a rotor shaft;

a cylindrically configured rotor body formed as part of the shaft and having a plurality of radially projecting winding teeth defining winding slots for receiving winding wire therein, said rotor body having two or more poles and a quadrature axis, said winding slots having a bottom spaced radially inward and optionally including a cooling channel; and

at least one tuning slot positioned at the quadrature axis and extending radially inward from the bottom of the winding slot or the bottom of the cooling slot a distance that tunes the rotor to a desired torsional natural frequency, wherein said at least one tuning slot has a width substantially smaller than either the winding slot or the cooling channel;

wherein the at least one tuning slot comprises a set of tuning slots numbering substantially fewer than the winding slots and positioned at a location that minimizes impact to the electromagnetic characteristics of the rotor cross-section.

4. A generator rotor comprising:

a rotor shaft;

a cylindrically configured rotor body formed as part of the shaft, said rotor body having a plurality of radially projecting winding teeth defining winding slots for receiving winding wire therein, said rotor body having two poles and a quadrature axis, said winding slots having a lowest surface formed by either the bottom of the winding slot or the bottom of a cooling channel located radially inward from the winding slot; and

at least one tuning slot extending radially inward from the lowest surface of the winding slot a distance that tunes the rotor to a desired torsional natural frequency, wherein said winding slots positioned near said poles are devoid of any tuning slot so that fewer that all of said winding slots incorporate a tuning slot.

5. A rotor according to claim 4, wherein said at least one tuning slot has a width smaller than the diameter of any winding wire received within the winding slot to prevent winding wire from passing into the tuning slot.

6. A rotor according to claim 4, wherein the at least one tuning slot is positioned at a location that minimizes impact to the electromagnetic characteristics of the rotor cross-section.