## Data Acquisition and Model Construction
### Quest for Magnetic Component Size Reduction  
Single winding inductors are made out of two main parts, the magnetic core and the winding. In power electronics, for high switching frequency operation, the magnetic cores are mostly realized in ferrite materials while the windings are mostly made out of copper wires. Under operation, both parts are producing losses, which have been widely investigated and modelled in the literature [9; 10; 11; 12; 13]. Among them, the impact of the ripple current, its frequency, its shape and its magnitude have drawn a significant interest [14]. Nonetheless, it remains today difficult to forecast properly what the losses are in magnetic devices, especially the ones induced by the high-frequency part of the applied signals. In most design procedures, the switching frequency and the ripple current are selected first to keep reasonable AC losses. Then, the value for the inductor is derived from converter specifications. Prototypes are then manufactured and characterized, based on allowed volume and total losses. Nonetheless, using \"reasonable\" to qualify inductor losses is never satisfactory for an engineer. In the proposed approach, we are considering only off-the-shelf magnetic components, pre-designed, optimized and manufactured in volume. Manufacturers are producing component series in which power electronics engineers can select the component they prefer. However, several important data are missing in most manufacturer datasheets, making difficult the selection of the best device. In particular, component loss abacus or equivalent models are missing. In this part, we are considering building a set of data and models, from existing inductor series. These data will be later on used in converters' design optimization. The characterization and modelling work has been carried out on three series of inductors from Coilcraft manufacturers. Their datasheets are recalled in [15; 16; 17]. Somerelevant parameters are summarized in Table 1 below. These three series were chosen for their advanced features such as low ESR, high-frequency working capacity, low volume and their wide range of use. A wide range of inductance values can be seen in each series. They are also declared by the manufacturer as using their most advanced technology. The three series pictured in Figure 2 are mapping a wide range of high-frequency inductor values and current saturation as illustrated in the plot in Figure 3. With this set of components, the power electronics designer has in its hands many options to design power converters in the range of a few tens of volts and amps, leading to converters from tens to hundreds of watts. Maximum energy density can be derived with Equations (1) and (2). In the selected series, the volume energy density ranges from 0.2 kJ/L up to 0.35 kJ/L. \[Ev=L\times I_{sat}2/V\ \ \ [\mathrm{J/L}] \tag{1}\]  
\[Ev=L\times I_{sat}2/W\ \ \ [\mathrm{J/kg}] \tag{2}\]  
Looking at plots Figure 3, one can see that, globally, the maximum stored energy (in mJ) is quite stable within a component series respectively 80, 180 and 500 mJ for series MSS1210, MSS1260 and XGL6060. This points out that each device is individually designed and optimized in a similar way for given material and technology. Also, it confirms that energy density is quite dependent on the component volume of a given material and technology. In other words, for a given series, defined by a volume, a material and a technology, the value of the inductor is inversely proportional to the square of the saturation current. Regarding the energy density itself, one can see that the two series exhibits similar densities while the bigger series exhibits a fairly higher energy density. This might come from a different material or technology or a different proportion between copper and core material.