Motor control system utilizing a shutter wheel tachometer

Claim 2

An electric tachometer for providing an indication of the combined rotational speed of two members, comprising: an annular AC inductive coil; first and second members disposed in a confronting spaced apart relationship interior to said inductive coil whereby, said inductive coil is located in proximity to the outer peripheral edges of both of said members, said members having electrically conductive sections of such a configuration that a varying eddy current loading effect is provided on said inductive coil as said members are rotated relative to each other; and detection means including a source of alternating current connected with said inductive coil for detecting the variations in the inductance of said coil which accompany relative rotation of the two members.

Claim 3

An electric tachometer for providing an indication of the combined rotational speed of two disc members, comprising: first and second disc members, each of said disc members provided with electrically conductive toothlike members spaced on its circumference; said disc members being disposed in a confronting spaced apart relationship; an RF inductive coil; said RF coil being disposed in proximity with and circumferentially encircling said first and said second disc members whereby, the instantaneous inductance of said RF coil is determined by the instantaneous relative positions of said disc members in accordance with the eddy current loading effect of said conductive toothlike members on said RF coil; a source of RF signals; means connecting said source of RF signals with said RF coil; and detection means connected with said RF coil for detecting the resultant amplitude modulation of the RF signal impressed across said RF coil which is correlated with the combined rotational speed of said disc members.

Claim 4

An electric tachometer for providing an indication of the combined rotational speed of two disc members, comprising: first and second disc members, each of said disc members provided with electrically conductive toothlike members spaced on its circumference; said disc members being disposed in a confronting spaced apart relationship; an RF inductive coil; said RF coil being disposed in proximity with and circumferentially encircling said first and said second disc members whereby, the instantaneous inductance of said RF coil is determined by the instantaneous relative positions of said disc members in accordance with the eddy current loading effect of said conductive toothlike members on said RF coil; a source of RF signals; means connecting said source of RF signals with said RF coil; and detection means connected with said RF coil for detecting the resultant amplitude modulation of the RF signal impressed across said RF coil which is correlated with the combined rotational speed of said disc members.

Claim 5

A control system for controlling the output frequency of a variable output frequency switching circuit coupled to an induction motor comprising: a first rotatable disc member adapted to be mechanically connected to the rotor of an induction motor, said first disc member provided with electrically conductive toothlike members spaced on its circumference; a second rotatable disc member adapted to be driven by a control device, said second disc member provided with electrically conductive toothlike members spaced on its circumference; an annular coil winding; means positioning said coil winding around the outer peripheral edges of said discs, the inductance of said coil winding varying as a function of the relative speed of rotation of said discs due to eddy currents induced in said discs; and a control circuit including a source of alternating current coupled to said coil winding operative to provide an output signal as a function of the varying inductance of said coil winding caused by relative rotation of said discs, said output signal adapted to be coupled to said switching circuit to control its output frequency.

Claim 6

A control system for controlling the output frequency of a variable output frequency switching circuit coupled to an induction motor comprising: a first rotatable disc member adapted to be mechanically connected to the rotor of an induction motor, said first disc member provided with electrically conductive toothlike members spaced on its circumference; a second rotatable disc member adapted to be driven by a control device, said second disc member provided with electrically conductive toothlike members spaced on its circumference; an annular coil winding; means positioning said coil winding around the outer peripheral edges of said discs, the inductance of said coil winding varying as a function of the relative speed of rotation of said discs due to eddy currents induced in said discs; and a control circuit including a source of alternating current coupled to said coil winding operative to provide an output signal as a function of the varying inductance of said coil winding caused by relative rotation of said discs, said output signal adapted to be coupled to said switching circuit to control its output frequency.

Claim 7

An AC induction motor slip frequency control system for controlling the output frequency of an inverter coupled to an induction motor, comprising: an AC induction motor; an inverter connected with said induction motor to provide power to energize said motor during operating intervals, said inverter being capable of providing power at a controlled frequency; a first rotatable member, said first rotatable member being connected with said induction motor''s rotor and being provided with electrically conductive toothlike members spaced on its circumference; a slip frequency control motor; a second rotatable member, said second rotatable member being connecteD with said slip frequency control motor and being provided with electrically conductive toothlike members spaced on its circumference; an RF inductive coil, said RF coil being disposed in proximity with and circumferentially encircling both said first rotatable member and said second rotatable member whereby, the instantaneous inductance of said RF coil is determined by the instantaneous relative positions of said rotatable members in accordance with the eddy current loading effect of said toothlike members on said RF coil; a source of RF signals; means connecting said source of RF signals across said RF coil whereby, the RF signal impressed upon said RF coil is amplitude modulated in accordance with the combined rotational speed of said rotatable members; and detection means connected with said RF coil for detecting the resultant amplitude modulation of the RF signal, said detection means providing an output signal which is adapted to control the output frequency of said inverter.

Claim 8

An AC induction motor slip frequency control system for controlling the output frequency of an inverter coupled to an induction motor, comprising: an AC induction motor; an inverter connected with said induction motor to provide power to energize said motor during operating intervals, said inverter being capable of providing power at a controlled frequency; a first rotatable member, said first rotatable member being connected with said induction motor''s rotor and being provided with electrically conductive toothlike members spaced on its circumference; a slip frequency control motor; a second rotatable member, said second rotatable member being connecteD with said slip frequency control motor and being provided with electrically conductive toothlike members spaced on its circumference; an RF inductive coil, said RF coil being disposed in proximity with and circumferentially encircling both said first rotatable member and said second rotatable member whereby, the instantaneous inductance of said RF coil is determined by the instantaneous relative positions of said rotatable members in accordance with the eddy current loading effect of said toothlike members on said RF coil; a source of RF signals; means connecting said source of RF signals across said RF coil whereby, the RF signal impressed upon said RF coil is amplitude modulated in accordance with the combined rotational speed of said rotatable members; and detection means connected with said RF coil for detecting the resultant amplitude modulation of the RF signal, said detection means providing an output signal which is adapted to control the output frequency of said inverter.