DocumentCode :
1309937
Title :
Harmonic field analysis for slip-ring motors including general rotor asymmetry
Author :
Smith, Alexander C.
Author_Institution :
Imperial Coll. of Sci., Technol., & Med., London, UK
Volume :
26
Issue :
5
fYear :
1990
Firstpage :
857
Lastpage :
865
Abstract :
A field analysis is presented for slip-ring induction motors with general external impedance asymmetry. The method is based upon a rotating-field theory approach including spatial MMF (magnetomotive force) harmonics. It is shown that a series of nonmains frequency voltages are induced in the stator winding for both balanced and unbalanced rotors. The method is also used to derive the harmonic equivalent circuit for a balanced three-phase slip-ring motor with a skewed rotor. The analysis is verified by comparing predicted torque and current characteristics with measured values obtained from a machine with a balanced rotor and with a rotor connected to asymmetrical external resistances. The influence of MMF harmonics on the phase equivalent circuit and the motor performance is demonstrated. Operation with an unbalanced rotor results in a loss of steady torque and the introduction of large oscillating torques
Keywords :
equivalent circuits; harmonics; induction motors; machine theory; rotors; slip (asynchronous machines); stators; asymmetrical external resistances; current; equivalent circuit; general external impedance asymmetry; general rotor asymmetry; harmonic field analysis; machine theory; nonmains frequency voltages; performance; rotating-field theory; slip-ring induction motors; spatial MMF; stator winding; three-phase; torque; Current measurement; Equivalent circuits; Frequency; Harmonic analysis; Impedance; Induction motors; Magnetic analysis; Rotors; Stator windings; Voltage;
fLanguage :
English
Journal_Title :
Industry Applications, IEEE Transactions on
Publisher :
ieee
ISSN :
0093-9994
Type :
jour
DOI :
10.1109/28.60051
Filename :
60051
Link To Document :
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