Analysis of the Influence of Current and Turn Ratio on the Performance of Micro Transformers

Integrated planar transformers are essential in many electronic devices, especially when size, efficiency, and reliable power transfer are important. However, managing their heat remains a significant challenge because Joule losses in the windings can affect both the performance and lifespan. In this study, we investigated the effects of electric current density and number of turns in the secondary winding on the heat management of a planar microtransformer with a stacked design. We built a 3D multiphysics model in COMSOL Multiphysics using the finite- element method. This model simultaneously solves Maxwell’s equations and the heat transfer equation at the same time, which helps us observe the temperature patterns and heat flow inside the transformer. We first performed a mesh sensitivity analysis to ensure the accuracy of our simulations. The results show that the primary cause of heating is the primary current, which increases the resistive losses in the copper windings. In addition, the number of turns in the secondary winding changes the way heat spreads, affecting the current density and heat movement within the component. These simulations provide a clear picture of how electrical and thermal factors work together in planar microtransformers. They also highlight the importance of carefully adjusting the winding layout and operating conditions to maintain the temperature and improve the reliability of the device.