Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-03-28
2002-05-28
Nguyen, Tran (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S091000, C310S269000
Reexamination Certificate
active
06396188
ABSTRACT:
BACKGROUND
The invention relates generally to salient pole synchronous machines and more particularly to rotors of salient pole synchronous machines.
A conventional large salient pole synchronous machine
10
including a stator
12
and a rotor
14
is shown in
FIG. 1
, and a sectional view of a portion of the rotor is shown in FIG.
2
. Examples of conventional salient pole synchronous rotors are shown, for example, in MICHAEL LIWSCHITZ-GARIK & CLYDE C. WHIPPLE, ALTERNATING-CURRENT MACHINES (2d ed. 1961) and RALPH R. LAWRENCE, PRINCIPLES OF ALTERNATING-CURRENT MACHINERY (Henry E. Richards reviser, 4
th
ed. 1953). In these rotors, end plates
28
typically comprise copper sheets that are shaped to match the profiles of poles
22
. Each end plate extends about half-way down the pole and is clamped between supports
32
and
34
which typically comprise shortened steel laminations that permit bending of the end plates and thus allow axial movement of rotor bars
30
(situated in bar holes
26
and electrically coupled to the end plates to form a rotor cage) to accommodate thermal expansion and contraction.
When such machines are driven by electronic converters, considerable harmonic current results in the rotor bars and rotor core and leads to increased heat burdens. During normal operation, because the rotor bar cage is interrupted in the span regions between the poles, rotor bars near pole ends
29
carry more current than the other bars and are more prone to failure. Additionally, harmonic flux penetrates into the rotor core
16
, rotor key slots
20
, pole keys
24
, shaft
18
, and rotor windings
17
and creates destructive currents there.
BRIEF SUMMARY
It would therefore be desirable to provide a salient pole synchronous machine rotor with reduced concentration of currents in rotor bars situated near the pole ends. It would additionally be desirable to reduce induction of destructive currents in the rotor core, key slots, pole keys, shaft and windings.
Briefly, in accordance with one embodiment of the present invention, a salient pole synchronous machine rotor comprises a rotor shaft, a plurality of salient poles concentric to the rotor shaft, and end plates facing opposing ends of the salient poles with each end plate extending continuously around the rotor shaft.
REFERENCES:
patent: 3831268 (1974-08-01), Boyd et al.
patent: 4161669 (1979-07-01), Aimar
patent: 5053666 (1991-10-01), Kliman et al.
patent: 5436519 (1995-07-01), Takahashi et al.
patent: 5463262 (1995-10-01), Uchida
patent: 5739615 (1998-04-01), McClelland
M. Liwschitz-Garik, Et Al, Alternating-Current Machines (2nd Ed 1961) 1 Page.
Ralph R. Lawrence “Principles of Alternating-Current Machinery” (Henry E. Richards Reviser, 4th Ed. 1953), p. 333.
Kliman Gerald Burt
Shah Manoj Ramprasad
Agosti Ann M.
Breedlove Jill M.
General Electric Company
Nguyen Tran
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