About Amal's research on Integrated Transformers for Efficient Power Conversion:

This project aims to extend the efficiency and isolation of transformer-based power conversion to widespread applications. Through the integration of thin-film magnetic cores, transformers can be taken from macroscopic, lumped element use to being implemented on-chip and incorporated into both AC-to-DC and DC-to-DC power conversion. While the most significant source of loss for transformer designs arises from coupling loss, we have previously demonstrated transformers with an unprecedented value of greater than 97% coupling efficiency. Additional factors limiting the efficiency of specifically magnetic transformers consist of material losses, including hysteresis loss, eddy current loss, and ferromagnetic resonance loss. Hysteresis loss is proportional to the area inside the B-H loop and equates to energy lost per cycle, potentially leading to significant losses at higher frequencies. To limit hysteresis loss, materials with low coercivities are desired, reducing the overall area of the B-H loop and the energy lost per cycle. As a field is applied to magnetize the material, small currents arise in the cross-section to produce an opposing field. These eddy currents thereby decrease the effect of the applied field. Eddy currents can be minimized in two ways, through the use of more resistive materials as well as laminations, which break apart the thickness of the cores and reduce the currents in the cross-section. As with the first two loss mechanisms, ferromagnetic resonance loss also increases with frequency when the imaginary part of the permeability rises to the same order of magnitude as the real part. Magnetic materials with a high ferromagnetic resonance frequency (FMR) are desired to mitigate the FMR losses. In order to address these material losses, magnetic nanoparticles will be synthesized to produce the desired properties tuned for the most efficient magnetic cores.