ROTATIONAL SENSING WITH INDUCTIVE SENSOR AND ROTATING AXIAL TARGET SURFACE

摘要

A rotational sensing system is adaptable to sensing motor rotation based on eddy current sensing. An axial target surface (20) is incorporated with the motor rotor (15), and includes one or more conductive target segment(s) (21A, 21B, 23A, 23B). An inductive sensor (30) is mounted adjacent the axial target surface (20), and includes one or more inductive sense coil(s) (31 A, 31B, 33A, 33B), such that rotor rotation rotates the target segment(s) (21 A, 21B, 23A, 23B) laterally under the sense coil(s) (31 A, 31B, 33A, 33B). An inductance-to -digital converter (IDC) (50) drives sensor excitation current to project a magnetic sensing field toward the rotating axial target surface (20). Sensor response is characterized by successive sensor phase cycles that cycle between L_MIN in which a sense coil is aligned with a target segment, and L_MAX in which the sense coil is misaligned. The number of sensor phase cycles in a rotor rotation cycle corresponds to the number of target segments (21A, 21B, 23A, 23B). The IDC (50) converts sensor response measurements from successive sensor phase cycles into rotational data.