A low cost position sensor for linear variable reluctance motor

This paper presents a novel position sensing system for a linear switched reluctance motor. By measuring the inductance variation on the fixed tooth track using two coiled devices aligned 90 degrees out of phase, the position and direction information of the moving platform can be obtained. To increase the resolution 16 times its original tooth pitch resolution, signal alignment and nonsinusoidal waveform interpolation techniques are employed. The proposed sensing system is designed, fabricated and implemented on a linear variable reluctance motion platform. Preliminary results show that the proposed sensing system can produce reliable position information with high accuracy and repeatability, and at high pulse output rate. This position information is useful for both accurate phase commutation and servo position feedback.