INDUCTIVE POSITION SENSOR FOR DC COMMUTATORLESS MOTOR ROTOR Russian patent published in 2001 - IPC

FIELD: DC motor control gear members and positioning-system angle sensors. SUBSTANCE: carrier coupled with motor rotor that mounts alternating poles of magnetically soft ferromagnetic and diamagnetic of high electric conductivity is used as inductor. Parallel resonance-tuned circuit fed from harmonic oscillator functions as sensing element. Displacement of inductor poles relative to coils of resonance-tuned circuit causes variations in circuit tuning frequency. Amplitude-modulated sine-wave signal is built up across output of sensing element due to appropriate selection of initial adjustment for resonance-tuned circuit. Harmonic oscillator frequency and circuit resonance-tuning frequency are relatively offset so that oscillator frequency coincides with linear section of resonance characteristic of circuit adjacent to its passband boundary. Its width is chosen to reduce requirements to difference in initial parameters of inductances of mentioned circuit and to dispense with its tuning. Operating frequency of mentioned oscillator is chosen to ensure that increment in inductance as result of ferromagnetic action were of same value as its reduction due to effect of diamagnetic conducting material. Differential processing of signals arriving from opposite sides of sensing element through detectors at adders shapes sine-wave error signal across their output that shows angular discrepancy between rotor and stator axes of motor. EFFECT: enhanced precision of producing continuous data on angular error between stator and rotor of motor with controlled mechanical characteristic. 2 cl, 5 dwg