Asynchronous motor with features creating magnetic field disturbance

An asynchronous motor comprising:

• a stator including a plurality of windings and being configured to generate a rotating magnetic field when a current is provided to the plurality of windings;
• a rotor positioned within the stator and configured to rotate relative thereto responsive to the rotating magnetic field;
• and
• a component separate from the stator and the rotor and positioned within the rotating magnetic field, the component being configured to alter a magnetic reluctance of the rotor so as create a disturbance in the rotating magnetic field;
• wherein the component comprises:
• a body;
• and
• a plurality of projections extending out from the body, the plurality of projections being spaced apart such that a plurality of slots are formed between the plurality of projections.

An asynchronous motor comprising:

• a stator including a plurality of windings and being configured to generate a rotating magnetic field when a current is provided to the plurality of windings;
• a rotor positioned within the stator and configured to rotate relative thereto responsive to the rotating magnetic field;
• a component separate from the stator and the rotor and positioned within the rotating magnetic field, the component being configured to alter a magnetic reluctance of the rotor so as create a disturbance in the rotating magnetic field;
• and
• a motor drive to control current and voltage provided to the stator, the motor drive including a processor programmed to:
• measure a stator phase current spectrum of the stator;
• apply a fast Fourier transform to the stator phase current spectrum to translate the stator phase current spectrum from a time domain to a frequency domain;
• and
• determine a speed of the rotor based on observed frequencies within the stator phase current spectrum, with the determination being based on an applied stator frequency in the stator phase current spectrum and a stator phase current spectrum peak;
• wherein the disturbance in the rotating magnetic field created by the component introduces a stator current spectral component into the stator phase current spectrum, with the stator current spectral component introduced by the component comprising the stator phase current spectrum peak used to determine the speed of the rotor;
• and
• wherein the processor is further programmed to introduce at least one of a variable load and a variable eccentricity to the asynchronous motor to introduce a stator current spectral component into the stator phase current spectrum, with the stator current spectral component introduced into the stator phase current spectrum by the at least one of the variable load and the variable eccentricity being at a same frequency as the stator current spectral component introduced by the component.

An asynchronous motor comprising:

• a stator including a plurality of windings and being configured to generate a rotating magnetic field when a current is provided to the plurality of windings;
• a rotor positioned within the stator and including a rotor core and a plurality of rotor bar conductors, the rotor configured to rotate relative to the stator responsive to the rotating magnetic field;
• a component positioned adjacent to the rotor and configured to alter a reluctance of the asynchronous motor so as to generate a disturbance in the rotating magnetic field, wherein the disturbance in the rotating magnetic field generated by the component introduces a current signal into a stator phase current spectrum of the stator;
• and
• a motor drive to control current and voltage provided to the stator, the motor drive including a processor programmed to:
• measure the stator phase current spectrum of the stator;
• apply a fast Fourier transform to the stator phase current spectrum to translate the stator phase current spectrum from a time domain to a frequency domain;
• and
• determine a speed of the rotor based on an applied stator frequency in the stator phase current spectrum and a stator phase current spectrum peak, the stator phase current spectrum peak corresponding to the current signal introduced by the component;
• wherein the processor is further programmed to vary at least one of a load and an eccentricity of the asynchronous motor to introduce a current signal into the stator phase current spectrum to increase an amplitude of the stator current spectral component introduced by the component.

An x-ray tube comprising:

• a housing enclosing a vacuum chamber;
• a cathode positioned within the vacuum chamber and configured to emit electrons;
• an anode positioned within the vacuum chamber to receive the electrons emitted from the cathode and configured to generate a beam of x-rays from the electrons;
• and
• an induction motor configured to rotate the anode, the induction motor comprising:
• a stator including a plurality of windings and being configured to generate a rotating magnetic field when a current is provided to the plurality of windings;
• a rotor positioned within the stator and configured to rotate relative thereto responsive to the rotating magnetic field, thereby causing the anode to rotate;
• and
• a component positioned on one end of the rotor and being configured to alter a reluctance of the rotor, thereby creating a disturbance in the rotating magnetic field, and
• a motor drive to control current and voltage provided to the induction motor, the motor drive including a processor programmed to:
• measure a stator phase current spectrum of the stator;
• apply a fast Fourier transform to the stator phase current spectrum to translate the stator phase current spectrum from a time domain to a frequency domain;
• and
• determine a speed of the rotor based on observed frequencies within the stator phase current spectrum;
• wherein the component is configured to create a disturbance in the rotating magnetic field so as to introduce a stator current spectral component in the stator phase current spectrum that is detectable by the processor, such that the stator current spectral component provides for the determination of the speed of the rotor;
• and
• wherein the processor is further programmed to vary at least one of a load and an eccentricity of the asynchronous motor to introduce a stator current spectral component into the stator phase current spectrum, with the stator current spectral component introduced by the variation of the at least one of the load and the eccentricity increasing an amplitude of the stator current spectral component introduced by the component.