Sahil Kumar Bhagat et al. Int. Journal of Engineering Research and Applications www.ijera.com ISSN: 2248-9622, Vol. 6, Issue 3, (Part - 2) March 2016, pp.05- 08 www.ijera.com 5|Page Design and Simulation of a Fractal Micro-Transformer Sahil Kumar Bhagat 1 , Navdeep Batish 2 Dept of Electrical Engineering, Sri Sai College of Engineering & Technology, Pathankot, Punjab-15001, India ABSTRACT Due to advancement in smart technologies, the issues like renewable energy integrations into the existing power systems, reduced weight and size of power equipments is required. In this regard, this work is focused on the study and design of fractal type micro-transformer for day-to-day applications. An air core transformer is designed using finite element modeling. The obtained results showed far better implementation parameters in comparison to the macro transformers. Keywords - Finite element modeling, micro-transformer, 2D simulation, energy conversion, magnetic field. I. INTRODUCTION Coils and transformers are basic components in electronic devices. Integrating transformers in electronic ICs is usually done with planar structures but the resulting efficiency is low. A lot of work has been done recently in order to overcome this drawback. Some processes have been studied both by realizing a thick integrated magnetic circuit and by realizing high thickness coils by copper electro- deposition [1–3]. Both techniques have shown good results. In coming decades, new generations of electronic products such as mobile phones, notebooks, and e-paper will be developed with the primary goals of mobilization and miniaturization. New CMOS fabrication technology will be applied to fabricate the miniaturized IC of electronic products on silicon substrates, including on-chip micro- transformers. Several issues of on-chip micro- transformers have been investigated for many years [4]. Some researches focused on the material of the magnetic core and the geometry of the transformer [5]. Some papers discussed the parasitic effect of the conductive substrates. Transformer losses become dramatic at high frequencies and limit the performance of the transformers. Previous studies have discussed in detail the causes of transformer losses such as parasitic capacitance, ohmic loss, and substrate loss [6] [7]. Core loss from the solid magnetic core significantly affected the performance of the transformers. Transformers with magnetic core exhibit relatively high loss and compromised isolation at high frequencies due to degradation in magnetic core performances with the increase of frequency. Several ferrite core magnetic transformers have been reported by researchers. But it was estimated that the efficiency, operating frequency, and current limitation are the main challenges because of the magnetic saturation and eddy current losses in the ferrite magnetic core material at high frequencies. However, it is observed that the performance of the air core transformer is better than the magnetic core counterpart at high frequencies due to no lossy core material involved in air core transformers. The solutions for the solid magnetic core loss were proposed. II. MATHEMATICAL ANALYSIS The device presented in this paper is a two-winding transformer, with bonding wires as coils completed on the metallization layer, and a toroidal ferrite as a magnetic core. The low-frequency self-inductance of each winding L is estimated by the reluctance formula as [8]. 2 0 1 c c n A L l    where 7 0 4 10      H/m is the free-space permeability, μ 1 is the core relative permeability, A c is the cross-sectional area of the core, l c is the mean magnetic path length, and n is the number of turns of the coil considered. The low frequency series resistance of the winding R can be expressed as R = n(R b + R m ), where R b is the bonding wire resistance, and R m is the printed circuit board (PCB) metal conductor resistance [9] [10]. Since in a real transformer not all flux produced by the primary winding is coupled to the secondary one, the mutual inductance L 12 is defined by: 1 2 2 22 12 1 11 n L n n L         12 11 22 . L k L L  where k is the coupling coefficient which measures the magnetic coupling between the coils, and L 11 and L 22 are the self-inductances evaluated by (1) of primary and secondary windings, respectively. For the transformer we can define the turns ratio RESEARCH ARTICLE OPEN ACCESS