Electricity: motive power systems – Induction motor systems – Primary circuit control
Patent
1991-08-02
1993-05-18
Shoop, Jr., William M.
Electricity: motive power systems
Induction motor systems
Primary circuit control
388809, 388811, 378131, 318778, H01J 3510, H02P 912
Patent
active
052124371
ABSTRACT:
An x-ray tube (10) of a CT scanner has a rotating anode and rotor combination which is propelled by AC currents applied to run and phase windings (42, 46) by a starter (22). A monitor (24) includes Hall effect current detectors (40, 44) which detect the actual current flowing through the run and phase windings. The detected analog current values, voltage values, and the like are multiplexed (132) and digitized in a preselected order by an analog to digital converter (60) and stored in that order in a FIFO memory (62). A microprocessor (64) performs a Fourier transform (94, 96) to convert the digital run and phase signals into frequency spectra. The run and phase frequency spectra are compared (100, 102, 104, 106) with frequency spectra indicative of rotor speed, bearing wear, anode vibration, failure of the anode to rotate, and other conditions, analyzed for symmetry or other characteristics, or the like (FIG. 5 ) to generate digital run and phase reference signals. An error amplifier (54) controls a pulse width modulator ( 56) or other power amplifier controls in accordance with a deviation between analog reference signals converted from the digital signals by a reference digital to analog converter (66) and the actually sensed run and phase signals (40, 44) to adjust the starter. A direct coupled driver (122) adjusts DC offsets in the drive currents to maintain balance and drive efficiency.
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Dupuis Walter A.
Hescht Donald A.
Resnick Theodore A.
Szabo William E.
Cabeca John W.
Picker International Inc.
Shoop Jr. William M.
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