Encoder system and method for determining absolute rotor position by taking a mid value of the multiple coil output sinusoidal signals

摘要

A method and system for determining absolute rotor position with a Variable Reluctance (VR) motor. An inductance sensor is compatible with the VR motor and is adapted to generate a plurality of variable inductance values corresponding to the position of the rotor. The inductance values may be plotted during calibration as phase-separated pseudo-sinusoidal waveforms with a resultant inductance/position profile having near-linear regions with determinable slopes and offsets. Excitation electronics converts variable inductance values to corresponding digital values which are suitable for computer processing. A micro computer is adapted to determine which of the digital values is a mid-value and to convert the mid-value to high resolution motor rotor angular units in accordance with the calibration-determined slopes and offsets.