SaM - Variable Transformers

So in general there are many different devices which are based on variable transformer that can be used to measure the position, the displacement or the angle.

• The philosophy behind is always the same:
  • We have a fixed primary, and the moveable secondary circuit.
  • The sensing is based on the variation of the mutual induction.
  • Moving the second circuit we create a measurable change of the mutual induction.

Rember that the formula we have defined for transformers is: A transformer with mutual inductance $M$ and two currents $i_1$ and $i_2$ flowing trough its two “branches”, then we will have the two voltage drops equal to (in the frequency domain):\begin{align}&V_1 = j\kern2px \omega \kern1px M \kern1px i_2\\&V_2 = j\kern2px \omega \kern1px M \kern1px i_1\end{align}