Method and apparatus for improving performance of AC machines
AssigneeThe University of Texas at Austin
InventorsHerbert H. Woodson, John S. Hsu
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Abstract
A method and apparatus for improving the performance of polyphase AC machines. The polyphase AC machines are excited both with a fundamental frequency and with an odd harmonic of the fundamental frequency. The odd harmonic flux wave is phase controlled so as to interact with otherwise waste harmonic flux waves generated by the rotor. The interaction of the harmonic flux waves enhances the pull-out torque, power factor, and efficiency of the polyphase AC machine.
Claims20
A method of enhancing the torque in a synchronous machine having a stator and rotor, windings placed thereon, and an air gap formed therebetween, the method comprising the steps of:
- generating a fundamental flux wave in the air gap of said machine by delivering a fundamental excitation signal to said stator winding;
- generating an odd harmonic flux wave in said air gap of said machine by delivering an odd harmonic excitation signal to said stator winding, said odd harmonic flux wave rotating about said air gap in substantial unison with said fundamental flux wave;
- generating rotor flux in the air gap of said machine by delivering an excitation signal to said rotor windings;
- generating rotor space harmonics in said air gap of said machine by interaction between said fundamental flux wave and said rotor flux, said rotor space harmonics rotating in said air gap in substantial unison with said rotor and said odd harmonic flux wave;
- and
- controlling the phase angle of said odd harmonic flux wave relative to said rotor space harmonics.
A method of enhancing the torque in a synchronous machine having a stator and rotor, windings placed thereon, and an air gap formed therebetween, comprising the steps:
- generating a fundamental flux wave rotating in the air gap of said machine at a first preselected speed by delivering a fundamental excitation signal to said stator winding
- generating an odd harmonic flux wave rotating in the air gap of said machine substantially at said first preselected speed by delivering an odd harmonic excitation signal to said stator winding;
- generating rotor flux in the air gap of said machine by delivering an excitation signal to said rotor windings;
- generating rotor space harmonics is said air gap of said machine by interaction between said fundamental flux wave and said rotor flux, said rotor space harmonics rotating in said air gap substantial at said first preselected speed with said rotor;
- and
- controlling the phase angle between said odd harmonic flux wave and said rotor space harmonics so that said odd harmonic flux wave lags said rotor space harmonics.
A method of enhancing the torque in a synchronous machine having a stator and rotor, windings placed thereon, and an air gap formed therebetween, comprising the steps:
- generating a fundamental flux wave in the air gap of said machine by delivering a fundamental excitation signal to said stator winding
- generating an odd harmonic flux wave in said air gap of said machine by delivering an odd harmonic excitation signal to said stator winding, said odd harmonic flux wave rotating about said air gap in substantial synchronism with said fundamental flux wave;
- generating rotor flux in the air gap of said machine by delivering an excitation signal to said rotor windings;
- generating rotor space harmonics is said air gap of said machine by interaction between said fundamental flux wave and said rotor flux, said rotor space harmonics rotating in said air gap in substantial synchronism with said rotor and said odd harmonic flux wave;
- and
- controlling the phase angle between said odd harmonic flux wave and said rotor space harmonics so that said odd harmonic flux wave leads said rotor space harmonics.
An apparatus for enhancing the torque in a synchronous machine having a rotor and a stator, and an air gap formed therebetween, comprising:
- a stator winding;
- means for delivering a fundamental excitation signal to said stator winding so that a fundamental flux wave is generated in the air gap of said machine;
- means for delivering an odd harmonic excitation signal to said stator winding so that an odd harmonic flux wave is generated in said air gap of said machine, rotating about said air gap in substantial unison with said fundamental flux wave;
- a rotor winding;
- means for controllably generating rotor flux in the air gap of said machine be delivering an excitation signal to said rotor winding, said fundamental flux wave interacting with said rotor flux to produce rotor flux harmonics in the air gap of said machine, rotating in substantial unison with said rotor;
- and
- means for controlling the phase angle of said odd harmonic flux wave relative to said rotor space harmonics.
Dependencies are inferred from the claim text.