Version 1.0, August 31, 2001, Copyright, Hugh Jack 1993-2001
· This is effectively a transformer with a moving inner core. The moving core changes the inductance, and this can be converted to a position.
· In these devices there are three sets of windings. The first set of windings is in the center, and is powered by an AC source. The other two coils are at the opposite sides of the main coils. As the core is moved forward/back the magnetic coupling will change.
· If the core shown is in the center, the output will be 0Vac, as it shifts to the left there will be more coupling between the center and left coil, and the signal magnitude will be larger than the right hand coil. This difference can be converted to a calculated difference.
· This sensor is used for linear position sensing to high accuracies such as,
· The signals from the LVDT can be conditioned with the circuit below.
· Near the center of the movement range the voltage is linearly proportional to core movement.