Device for driving a rotary-anode X-ray tube
AssigneeU.S. Philips Corporation
InventorGerd Vogler
Life of this patent
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Abstract
The invention relates to a drive system for a rotary-anode X-ray tube which comprises an asynchronous motor. The current through the stator windings is generated by two pulse-width modulators to which sinusoidal signals which are phase-shifted 90.degree. with respect to one another are supplied by a sine and a cosine memory. The amplitude thereof is controlled in dependence on the amplitude of the current through the relevant stator winding.
Claims5
In a device for driving a rotary-anode X-ray tube comprising an asynchronous motor having stator windings each supplied with an alternating current of predetermined frequency via a respective switching amplifier, the improvement comprising:
- (a) a pulse width modulator for controlling a respective switching amplifier, the pulse-width modulator producing an output signal having a high pulse frequency in comparison with the motor speed,
- (b) an alternating voltage generator for each stator winding, the various alternating voltage generators generating output phase-shifted sinusoidal alternating voltages,
- (c) a current measuring member for each stator winding for measuring the current through the stator windings, an output signal of said current measuring member being compared with a reference value signal in a comparison circuit,
- (d) means connecting the output of an alternating voltage generator to an input of the pulse-width modulator, at least the switching amplifier, the current measuring member and the comparison circuit forming a control loop for reducing the difference signal between the reference value signal and the output signal of the current measuring member.
Dependencies are inferred from the claim text.