The use of planar transformers throughout the industry is growing fast due to their advantages as low profile, higher efficiency, manufacturing repeatability and reduced electromagnetic interferences. One of the characteristics of planar transformers is the possibility of obtaining a very good coupling between windings, but the drawback is the increment of the parasitic capacitance. Consequently, obtaining the value before manufacturing the transformer is crucial for avoiding potential problems.
EXAMPLE OF HOW FRENETIC AI HANDLES THIS PARASITIC CAPACITANCE
In this app note we are going to prove the effectiveness of Frenetic AI calculating the parasitic capacitance comparing Frenetic estimation with the theoretically calculated using different models and real measurements. As an example, we will use a 2 layers PCB on primary and two layers PCB on secondary transformer.Laboratory measurements:
The values needed are obtained, with a measurement from the equipment Bode 100 and processing this data with the equations that follow.
The theoretical models from (Ziwei Ouyang, Ole C.Thomsen, Majid Pahlevaninezhad, Djilali Hamza, Amish Servansing) are used for a theoretical estimation of the parasitic capacitance
Frenetic AI found variables that were not considered in other models that affect in the calculation of the capacitance, and use them to obtain a solution really close to the reality and also in a short time.
In planar technology the PCB windings implementation causes higher parasitic capacitance than other technologies. The capacitance affects to the resonance frequency and operation of the transformer, limiting the operating region of the transformer, therefore, obtaining a very accurate estimation will avoid future problems.