Hello together,

I'm trying to build a model of a resolver by using the transformer block.
It consists of one excitation coil (L1) and two receiving coils (L2,L3) that are aligned 90° degree to each other.
Depending on the angle of the excitation coil the coupling inductance of the receiving coils vary so that there is an output of
a sinus and cosinus voltage.

My intention was to set a time-variant coupling inductance (M) for the transfomer (Modelica.Electrical.Analog.Basic.Transformer) like the following expression:

M = abs(sin(2*PI*f*time))*sqrt(L1*L2)

When trying to simulate the following error is shown:
The variability of the definition equation: ... is higher than the declared variability of the variables.

I considered that the maximum value of the coupling inductance (M) does not exceed the value 1 so that I guess I made another mistake.

I would be happy if you can give me some advises about using time-variant variables within function blocks like those.

Kind regards,
Matthias