Our main purpose is create the transfer function of a transformer. And we want that for resonance frequency higher than 1 MHz for our LLC transformer in LED project.  https://www.omicron-lab.com/fileadmin/assets/Bode_100/ApplicationNotes/Transformer_modelling/App_Note_Transformer_modelling_V_2_0.pdf We apply the this document's processes for this goal. We have already calculated and measured R1, Ll1, Lmag1, Gain, R2, Ll2, C12, C1, C2, Lc1, Lc2 but we seen that our C1 and C2 capacitance values become negative. In which situation capacitances values become negative and why it happens?

Therefore without these calculations  , when I measure the transformer capacitance from LCR meter  , the result is also negative. What is the reason of that? Thanks,

Our main purpose is create the transfer function of a transformer, and we want that for a resonance frequency higher than 1 MHz for our LLC transformer in an LED project. 

https://www.omicron-lab.com/fileadmin/assets/Bode_100/ApplicationNotes/Transformer_modelling/App_Note_Transformer_modelling_V_2_0.pdf

We apply this document's processes for this goal. We have already calculated and measured R1, Ll1, Lmag1, Gain, R2, Ll2, C12, C1, C2, Lc1, and Lc2, but we have seen that our C1 and C2 capacitance values are negative.

In which situation can capacitance values become negative and why does this happens?

Without these calculations, when I measure the transformer capacitance from an LCR meter, the result is also negative. What is the reason for that?