Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1993-11-29
1997-09-09
Stephan, Steven L.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 68R, 310 68B, H02K 709
Patent
active
056660138
ABSTRACT:
By using a hysteresis amplifier for driving an electromagnet, a highly accurate electromagnetic bearing may be produced without the need for independent position detectors to maintain the levitated position of a rotor constant. In one embodiment, the electromagnetic bearing includes multiple electromagnets for levitating a rotor in a predetermined position. Multiple hysteresis amplifiers each supply a switching signal for driving each of the electromagnets. The switching frequency of the switching signals changes in accordance with the inductance of the electromagnets, which varies in accordance with the relative position of the electromagnets. A phase comparator detects the phase difference between the switching waveforms of each hysteresis amplifier. A loop filter supplies a target current value converted from an output of the phase comparator to the hysteresis amplifiers. By controlling the input signals to the respective hysteresis amplifiers to maintain the frequency of the switching signal output of the respective hysteresis amplifiers constant, the position of the rotor is also maintained constant. Accordingly, a magnetic bearing may precisely control the levitated position of a rotor without the use of position detectors.
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Enad Elvin G.
Seiko Seiki Kabushiki Kaisha
Stephan Steven L.
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