Design Methodology and Optimization of a Medium-Frequency Transformer for High-Power DC–DC Applications

Abstract

The medium-frequency power transformer (MFPT) is one of the key elements of an isolated, bi-directional DC-DC converters in applications such as future all-DC offshore wind farms, traction and solid state transformers. This paper describes a design methodology taking into account the loss calculation, isolation requirements and thermal management. Incorporating this design methodology, an optimization process with a wide range of parameter variations is applied on a design example to find the highest power density while the efficiency, isolation, thermal and leakage inductance requirements are all met.

100 kW, 10 kHz Medium-Frequency Transformer Design Optimization and Experimental Verification

“…Several examples of computer based design optimization can be found in the literature resulting in next MFT prototypes: litz wire/metglas/25 kW/2 kHz [22], litz wire/nanocrystalline and ferrite/166 kW/20 kHz [23], litz wire/nanocrystalline and ferrite/50 kW/5 kHz [24]. They are mostly based on selection and appropriate application of the earlier mentioned and often quite old models thus limiting the quality of the overall optimization process and its results.…”

Electric Field Simulations and Analysis for High Voltage High Power Medium Frequency Transformer

“…The case study is performed based on a 35 kW MFT used in a 10 kV EPT. The maximum working voltage of this EPT is 10 kV, thus, the target insulation voltage for this MFT is 10 kV, and safety factor [7] should be considered when determining the insulation distance. The structure of the core type MFT is shown in Figure 2a.…”

“…Previous works regarding MFT can be found in literatures [6][7][8][9][10][11]. Literature [6] presents an improved thermal model for multi-layer winding consisting of litz-wire and the analytical calculation of maximum electric field strength in the core window area.…”

“…Literature [6] presents an improved thermal model for multi-layer winding consisting of litz-wire and the analytical calculation of maximum electric field strength in the core window area. Literature [7] proposes a design methodology of medium-frequency power transformer that accounts for a tuned leakage inductance of the transformer, core and winding losses mitigation, thermal management, and high isolation requirements. In literature [8], two optimized transformer concepts, differing in their core material and cooling strategies, are constructed, aiming for different power density/efficiency goals, and the author proposes that the research on the effectiveness of the utilized isolation strategies concerning long term operation and different operation conditions should be addressed in order to make the high power EPT, and desirable efficiency can be achieved.…”

Geometry optimization and characterization of three-phase medium frequency transformer for 10kVA Isolated DC-DC converter

“…For high power energy conversion application, design methods of single-phase transformers operating at medium or high frequencies are introduced [15][16][17]. More recently, in [18], estimations of core losses with non-sinusoidal excitation in medium/high frequency transformer are introduced.…”