Inductive angular position sensor
AssigneeSemiconductor Components Industries, LLC
InventorJacques Jean Bertin
Life of this patent
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Abstract
An inductive sensor may track an angle of a movable element. In some cases, it is desirable to operate the inductive sensor using battery power so that turns are tracked properly even when power is lost. The disclosed inductive sensor includes circuitry to conserve power, such as a non-resonant driver that allows for fast measurements without wasting energy and a difference encoder that can estimate the angle within a range without the need for digitization and complicated processing.
Claims25
An inductive sensor comprising:
- an exciter coil;
- a non-resonant driver coupled to the exciter coil, the non-resonant driver configured to switch the exciter coil alternately between a positive terminal and a negative terminal of a voltage source to generate an excitation current in the exciter coil, the excitation current having a triangular-shaped amplitude;
- a plurality of receiver coils;
- a rotor coil mechanically coupled to a movable element, the rotor coil configured to couple a magnetic field generated by the excitation current to the plurality of receiver coils according to an angle-dependent inductive coupling between the rotor coil and the plurality of receiver coils, the magnetic field generating a plurality of coil voltages at the plurality of receiver coils;
- and
- a difference encoder configured to compare the plurality of coil voltages to determine an angle measurement of the movable element.
A method for measuring an angle, the method comprising:
- moving a rotor coil of a transducer to the angle;
- switching, using a non-resonant driver, an exciter coil of the transducer alternately between a positive terminal and a negative terminal of a voltage source during a measurement period to generate an excitation current having a non-sinusoidal amplitude;
- generating a plurality of coil voltages at a plurality of receiver coils based on an angle-dependent inductive coupling between the rotor coil an each of the plurality of receiver coils;
- and
- comparing, using a difference encoder, the plurality of coil voltages to measure the angle.
A system for measuring angular movement, comprising:
- a controller;
- a communication channel;
- and
- an inductive sensor configured to capture angle measurements in a low-power mode using a battery power while not powered by a power supply, the inductive sensor in the low-power mode configured to:
- switch an exciter coil alternately between a positive terminal and negative terminal of a voltage source to generate an excitation current in the exciter coil;
- receive a plurality of coil voltages corresponding to a position of a rotor coil at a plurality of receiver coils;
- and
- compare the plurality of coil voltages to determine a plurality of comparisons;
- and
- determine an angle state of a state machine based on the plurality of comparisons, the angle state corresponding to an angle measurement of a movable element mechanically coupled to the rotor coil.
Dependencies are inferred from the claim text.