Method and apparatus for determining the speed of rotation of an AC motor
First Claim
1. A method for determining the speed of rotation of a rotor in a motor having a stator with main and auxiliary windings, the method comprising the steps of:
- magnetizing a portion of the rotor by supplying a test current pulse of limited duration to the main winding;
receiving a feedback signal corresponding to an EMF signal induced in the auxiliary winding by the magnetized portion of the rotor;
determining the speed of rotation of the rotor based on said feedback signal.
3 Assignments
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Accused Products
Abstract
A speed control apparatus for determining and controlling the speed of rotation of a rotor in an AC motor. The motor includes a stator having main and auxiliary windings. Main and auxiliary winding controllers control the operational input signals supplied to the main and auxiliary windings by a signal generator. A pulse generator is connected to the main winding for providing a test pulse during a speed measurement operation. The test pulse magnetizes a portion of the rotor which induces a feedback EMF signal in the auxiliary winding. A feedback sensor circuit receives the feedback signal and forwards it to a microprocessor. The microprocessor calculates the rotational speed of the rotor based on the feedback signal.
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Citations
39 Claims
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1. A method for determining the speed of rotation of a rotor in a motor having a stator with main and auxiliary windings, the method comprising the steps of:
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magnetizing a portion of the rotor by supplying a test current pulse of limited duration to the main winding; receiving a feedback signal corresponding to an EMF signal induced in the auxiliary winding by the magnetized portion of the rotor; determining the speed of rotation of the rotor based on said feedback signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A speed control apparatus for determining the speed of rotation of a rotor in a motor having a stator with main and auxiliary windings, the speed control apparatus comprising:
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pulse generator means connected to the main winding for providing an input pulse of limited duration to the main winding to magnetize a portion of said rotor; feedback means connected to the auxiliary winding for receiving a feedback signal from the auxiliary winding corresponding to an EMF signal induced in the auxiliary winding in response to said main winding input pulse magnetizing the rotor; and processor means operably connected to said feedback means for determining the speed of rotation of the rotor based on said feedback signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An AC motor comprising:
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a rotor configured to rotate at a rotational speed; a stator having main and auxiliary windings; signal generator means for generating motor input signals for said main and auxiliary windings, said auxiliary winding motor input signal being phase offset from said main winding motor input signal producing a rotating magnetic field which causes an EMF in said rotor causing said rotor to rotate; pulse generator means operably connected to said main winding for providing an input pulse of limited duration to said main winding to magnetize a portion of said rotor; feedback means operably connected to said auxiliary winding for receiving a feedback signal from said auxiliary winding corresponding to an EMF signal induced in the auxiliary winding in response to said main winding input pulse magnetizing the rotor; and processor means operably connected to said feedback means for determining the speed of rotation of the rotor based on said feedback signal. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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26. An x-ray system comprising:
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a rotating anode x-ray tube having an anode inside a vacuum sealed glass tube; an x-ray generator means for providing power to said x-ray tube for an x-ray exposure operation; a motor having a stator outside said glass tube and a rotor inside said glass tube, said rotor being operably connected to said anode and said stator having a main winding and an auxiliary winding; signal generator means for generating motor input signals for said main and auxiliary windings, said auxiliary winding motor input signal being phase offset from said main winding motor input signal producing a rotating magnetic field which causes an EMF in said rotor causing said rotor to rotate; pulse generator means operably connected to said main winding for providing an input pulse of limited duration to said main winding to magnetize a portion of said rotor; feedback means operably connected to said auxiliary winding for receiving a feedback signal from said auxiliary winding corresponding to an EMF signal induced in the auxiliary winding in response to said main winding input pulse magnetizing the rotor; and processor means operably connected to said feedback means for determining a speed of rotation of said rotor based on said feedback signal. - View Dependent Claims (27, 28, 29, 30, 31)
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32. A method for performing an x-ray exposure using an x-ray system including a rotating anode x-ray tube having a rotating anode connected to a motor having a rotor and a stator, the anode being connected to the rotor and being configured to rotate with the rotor and the stator having a main and an auxiliary winding the method comprising the steps of:
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measuring the speed of rotation of the rotating anode by magnetizing a portion of the rotor by applying a test pulse to the main winding, receiving a feedback signal corresponding to an EMF signal induced in the auxiliary winding by the magnetized portion of the rotor, and determining the speed of rotation of the rotor based on said feedback signal; comparing the measured speed of rotation of the anode to a predetermined desired speed of rotation; increasing the speed of rotation of the rotor if the measured speed of rotation of the anode is less than the desired speed of rotation and reexecuting the measuring and comparing steps; decreasing the speed of rotation of the rotor if the measured speed of rotation of the anode is greater than the desired speed of rotation and reexecuting the measuring and comparing steps; and allowing x-ray exposure if the measured speed of rotation of the anode is equal to the desired speed of rotation. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39)
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Specification