Nanocrystalline and Silicon Steel Medium-Frequency Transformers Applied to DC-DC Converters: Analysis and Experimental Comparison

Abstract

High performance, highly efficient DC-DC converters play a key role in improving the penetration of renewable energy sources in the context of smart grids in applications such as solid-state transformers, built-in power drives in electric vehicles and interfacing photovoltaic and wind-power systems. Advanced medium-frequency transformers (MFTs) are fundamental to enhance DC-DC converters and determining its behavior, therefore MFT design procedures have become increasingly important in this context. This paper investigates which type of core material, between nanocrystalline and silicon steel, has the best properties for designing MFTs for distinct applications. Unlike to other proposals, in this work, two 1 kVA-120 V/240 V-1 kHz lab MFT prototypes, with a different type of core material, are developed for the purpose of comparing its physical characteristics, behavior, and performance under real-life conditions. A final section, the experimental results show that the nanocrystalline MFT has greater power density and efficiency. The results of this work introduce nanocrystalline MFTs as an option in a wider range of applications in niches in which other materials are currently used.

Performance Comparison of Ferrite and Nanocrystalline Cores for Medium-Frequency Transformer of Dual Active Bridge DC-DC Converter

“…Silicon steels and nanocrystalline materials were compared for the construction of 1-kVA 120 V/240 V transformers operating under at 1 kHz [21], in which reported the silicon steel transformer was reported to exhibit much Several studies have focused on the design and performance evaluation of the transformer of the DAB DC-DC converter. Silicon steels and nanocrystalline materials were compared for the construction of 1-kVA 120 V/240 V transformers operating under at 1 kHz [21], in which reported the silicon steel transformer was reported to exhibit much lower efficiency and power density than the nanocrystalline core. Nonetheless, the advantage of the nanocrystalline materials over the silicon steels cannot be justified in this work, since the silicon steel transformer was tested under a reduced power rating.…”

An Experimental Comparison of the Effects of Nanocrystalline Core Geometry on the Performance and Dispersion Inductance of the MFTs Applied in DC-DC Converters

“…Each proposal in Table 10 includes an experimental prototype. In [20] and [22], an MFT with the toroidal core is presented, tested at 5 and 1 kHz, respectively. Both MFTs have an efficiency above 99%, at 1 kVA but the difference between them is the power density, which was 83.3% higher in the MFT at 5 kHz.…”

Effective Permeability of Multi Air Gap Ferrite Core 3-Phase Medium Frequency Transformer in Isolated DC-DC Converters

“…The performance factor, which is defined as a product of the frequency and flux density at a specified core loss density, is used to compare different types of core materials [26,27]. The amorphous and especially nanocrystalline materials are preferred in the low and medium frequencies due to the high flux density [28,29]. On the other hand, the main advantage of ferrite cores is their low power loss, which makes them an attractive material for the construction of medium and high frequency transformers [30,31].…”