EPE Association: EPE 2025 - DS1o: Magnetic Components

EPE 2025 - DS1o: Magnetic Components - Inductors and Transformers
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2025 - Conference > EPE 2025 - Topic 08: Components linked to Power Electronics > EPE 2025 - DS1o: Magnetic Components - Inductors and Transformers

   [return to parent folder]

   2D FEM Modeling Comparison of Multi-Winding Magnetic Couplers for Power Electronics Applications
By Floran CASSIN, Adrien MERCIER, Éric LABOURÉ, Jeanne-Marie DALBAVIE, Patrice GOMEZ [View]
[Download]

Abstract: Multiple-Active Bridge (MAB) converters, an extension of Dual-Active Bridge (DAB) converters, have emerged as a promising approach for multi-source, multi-load energy exchanges. A critical factor in their performance is the design of the multi-windings magnetic coupler, which determines the equivalent inductances and consequently the power flow between ports. This paper presents 2D FEM modeling techniques for multi-windings magnetic couplers, comparing various geometries models to balance precision and speed. The air gap-free FEM geometry reduces simulation time while maintaining accuracy, whereas the two stretched models involve a trade-off between precision on electrical model parameters.

   Development of Medium-Frequency Molded Transformer for SST with Simultaneous Insulation and Forced Air-Cooling capabilities
By Ritsuki YONETOMI, Keisuke KUSAKA [View]
[Download]

Abstract: This paper proposes a new plastic mold structure for medium-frequency molded transformers used in solid-state transformers (SSTs), aiming to enhance both the cooling performance of windings and insulation capabilities. In medium-frequency transformers for 6.6-kV SST, high-voltage insulation performance is required between the primary and secondary windings. Therefore, insulation should be provided by molding around the windings. In contrast, an effective cooling method for windings is necessary because copper losses in the windings also increase as the operating frequency rises.In this paper, temperature rise in the windings, which is a problem in medium-frequency molded transformers, is addressed by applying plastic molding only to the high electric field generating part in a structure that allows efficient cooling. Experimental results show that the developed transformer, which has a power density of 12.6 kW/L, continuously transmit 37.5 kW with a maximum transmission efficiency of 99.2\%. In addition, partial discharge tests of the developed transformer show that it has sufficient insulation performance for SST with a 6.6-kV input.

   Innovative Flyback Transformer Design : Enhancing Efficiency and Reducing Harmonic Current
By Wai Keung MO, Kasper M PAASCH, Thomas EBEL [View]
[Download]

Abstract: A novel flyback transformer design reduces harmonics and improves efficiency. It use two auxiliary windings and a curved air gap. Simulations and experiments show significant improvements compared to traditional designs. Future research will focus on optimizing the design for various applications and power levels.

   Integrating PV Systems with Non-Standard Grid Voltages: The Need for Low-Induction Transformers
By José Antonio BADRI, Jordi-Roger RIBA, Antoni GARCIA, Santi TRUJILLO, Albert MARZÀBAL [View]
[Download]

Abstract: Installing grid-connected photovoltaic (PV) systems is challenging in regions with non-standard grid voltages, as PV inverters are designed for standard levels. To overcome this limitation, transformers can be used, but their inrush current often trips inverter protection. This paper explores this issue, emphasizing the need for specially designed low-induction transformers.

   Mission-Profile Based Reliability Framework for Medium-Frequency Transformers
By Ahmed MELIGY, Rafael COELHO-MEDEIROS, Ilknur COLAK, Seddik BACHA [View]
[Download]

Abstract: This paper presents a theoretical framework for assessing the reliability of medium frequency transformers by dividing their structure into dielectric regions and forecasting its lifetime based on mission profiles. The framework incorporates both random failure and wear-out analysis to provide reliability estimates, highlighting specific failure mechanisms associated with high-frequency switching and insulation stresses. A case study of a 200 kW, 15 kHz dual active bridge converter is presented to demonstrate the proposed methodology. The derived lifetime distribution can support the design of the medium-frequency transformer and help evaluate the related risk of unreliability.

   Overview, Comparison and Extension of Concepts for Current-Controlled, Adjustable Inductances
By Guido SCHIERLE, Jonas PFEIFFER, Klaus F. HOFFMANN [View]
[Download]

Abstract: Magnetic components are an important part of many DC/DC converters. The use of active premagnetization makes them adjustable, which means an additional degree of freedom in the design of the respective converter topology. However, when selecting the most suitable premagnetization method for the specific application, various impact factors should be taken into account to ensure an optimal design.This paper presents, analyzes and discusses impact factors such as the adjustability range of the inductance value, the magnetic feedback as well as the behaviour of the auxiliary circuit for different premagnetization methods and different inductor design approaches. The measurement verification was carried out using a buck converter.

   Reconfigurable single-layer air coil inductor with bistable compliant windings
By Norbert SELIGER, Nico LEIRICH [View]
[Download]

Abstract: We present an air coil with bistable compliant single layer windings. Due to stable elastic snapping deformation of wire segments, the self-inductance of the air coil can be precisely varied in multiple steps. A numerical and analytical design methodology is proposed and successfully validated by magneto-quasi-static field simulations and experiments on prototypes.

EPE 2025 - DS1o: Magnetic Components - Inductors and Transformers
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2025 - Conference > EPE 2025 - Topic 08: Components linked to Power Electronics > EPE 2025 - DS1o: Magnetic Components - Inductors and Transformers
	[return to parent folder]

	2D FEM Modeling Comparison of Multi-Winding Magnetic Couplers for Power Electronics Applications By Floran CASSIN, Adrien MERCIER, Éric LABOURÉ, Jeanne-Marie DALBAVIE, Patrice GOMEZ	[View] [Download]
Abstract: Multiple-Active Bridge (MAB) converters, an extension of Dual-Active Bridge (DAB) converters, have emerged as a promising approach for multi-source, multi-load energy exchanges. A critical factor in their performance is the design of the multi-windings magnetic coupler, which determines the equivalent inductances and consequently the power flow between ports. This paper presents 2D FEM modeling techniques for multi-windings magnetic couplers, comparing various geometries models to balance precision and speed. The air gap-free FEM geometry reduces simulation time while maintaining accuracy, whereas the two stretched models involve a trade-off between precision on electrical model parameters.

	Development of Medium-Frequency Molded Transformer for SST with Simultaneous Insulation and Forced Air-Cooling capabilities By Ritsuki YONETOMI, Keisuke KUSAKA	[View] [Download]
Abstract: This paper proposes a new plastic mold structure for medium-frequency molded transformers used in solid-state transformers (SSTs), aiming to enhance both the cooling performance of windings and insulation capabilities. In medium-frequency transformers for 6.6-kV SST, high-voltage insulation performance is required between the primary and secondary windings. Therefore, insulation should be provided by molding around the windings. In contrast, an effective cooling method for windings is necessary because copper losses in the windings also increase as the operating frequency rises.In this paper, temperature rise in the windings, which is a problem in medium-frequency molded transformers, is addressed by applying plastic molding only to the high electric field generating part in a structure that allows efficient cooling. Experimental results show that the developed transformer, which has a power density of 12.6 kW/L, continuously transmit 37.5 kW with a maximum transmission efficiency of 99.2\%. In addition, partial discharge tests of the developed transformer show that it has sufficient insulation performance for SST with a 6.6-kV input.

	Innovative Flyback Transformer Design : Enhancing Efficiency and Reducing Harmonic Current By Wai Keung MO, Kasper M PAASCH, Thomas EBEL	[View] [Download]
Abstract: A novel flyback transformer design reduces harmonics and improves efficiency. It use two auxiliary windings and a curved air gap. Simulations and experiments show significant improvements compared to traditional designs. Future research will focus on optimizing the design for various applications and power levels.

	Integrating PV Systems with Non-Standard Grid Voltages: The Need for Low-Induction Transformers By José Antonio BADRI, Jordi-Roger RIBA, Antoni GARCIA, Santi TRUJILLO, Albert MARZÀBAL	[View] [Download]
Abstract: Installing grid-connected photovoltaic (PV) systems is challenging in regions with non-standard grid voltages, as PV inverters are designed for standard levels. To overcome this limitation, transformers can be used, but their inrush current often trips inverter protection. This paper explores this issue, emphasizing the need for specially designed low-induction transformers.

	Mission-Profile Based Reliability Framework for Medium-Frequency Transformers By Ahmed MELIGY, Rafael COELHO-MEDEIROS, Ilknur COLAK, Seddik BACHA	[View] [Download]
Abstract: This paper presents a theoretical framework for assessing the reliability of medium frequency transformers by dividing their structure into dielectric regions and forecasting its lifetime based on mission profiles. The framework incorporates both random failure and wear-out analysis to provide reliability estimates, highlighting specific failure mechanisms associated with high-frequency switching and insulation stresses. A case study of a 200 kW, 15 kHz dual active bridge converter is presented to demonstrate the proposed methodology. The derived lifetime distribution can support the design of the medium-frequency transformer and help evaluate the related risk of unreliability.

	Overview, Comparison and Extension of Concepts for Current-Controlled, Adjustable Inductances By Guido SCHIERLE, Jonas PFEIFFER, Klaus F. HOFFMANN	[View] [Download]
Abstract: Magnetic components are an important part of many DC/DC converters. The use of active premagnetization makes them adjustable, which means an additional degree of freedom in the design of the respective converter topology. However, when selecting the most suitable premagnetization method for the specific application, various impact factors should be taken into account to ensure an optimal design.This paper presents, analyzes and discusses impact factors such as the adjustability range of the inductance value, the magnetic feedback as well as the behaviour of the auxiliary circuit for different premagnetization methods and different inductor design approaches. The measurement verification was carried out using a buck converter.

	Reconfigurable single-layer air coil inductor with bistable compliant windings By Norbert SELIGER, Nico LEIRICH	[View] [Download]
Abstract: We present an air coil with bistable compliant single layer windings. Due to stable elastic snapping deformation of wire segments, the self-inductance of the air coil can be precisely varied in multiple steps. A numerical and analytical design methodology is proposed and successfully validated by magneto-quasi-static field simulations and experiments on prototypes.