EPE Association: EPE 2016 - DS3a: Passive Components

EPE 2016 - DS3a: Passive Components
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 01: Devices, Packaging and System Integration > EPE 2016 - DS3a: Passive Components

   [return to parent folder]

   A phase shifted full bridge converter with novel control over the leakage inductance
By Muhammad Abu BAKAR [View]
[Download]

Abstract: The electronics industry is progressing towards the high density board solutions due to the requirement of compact and intelligent electronic systems. In order to meet the industry demands, the power system is required to be of high power density. This article proposes one of the solution to improve the power density for the medium power applications. In phase shifted full bridge converter, the intrinsic leakage inductance of the main transformer is not high enough to obtain the zero voltage switching of the power switches for the entire operating conditions. An additional shim inductor is usually connected in series with the primary winding of the main transformer to increase the collective leakage inductance. This additional shim inductor degrades the power density of the converter. This paper proposes a method to embed and control the resonance inductance inside the main transformer. In addition to the increased inter-winding spacing, this paper proposes a practical approach to integrate the ferrite rods inside the main transformer for further increase in the leakage inductance. A power transformer is constructed and investigated by using the modelled equations to estimate the leakage inductance. A prototype phase shifted full bridge converter is also developed to investigate the performance of the proposed transformer. The converter is designed for the switching frequency of 400kHz, and tested up to 600watts output power at the input voltage of 200Vdc. The performance of the proposed converter is also compared with the converter of using an external inductor. The investigations show that, in addition to the improved power density, the converter with the proposed transformer is more efficient than the converter with the traditional transformer.

   Analytical Calculation of the Current Depending Inductance of a Stepped Air Gap Inductor
By Erika STENGLEIN [View]
[Download]

Abstract: Magnetic devices are essential components in the field of power electronics. Exploiting the non-linear behavior of inductors and transformers offers the great merit of increasing the performance of switch mode power supplies. For instance, the light-load efficiency of a buck voltage regulator can be improved by using a non-linear inductor with stepped air gap. Moreover, non-linear chokes can be used for passive power factor correction or are employed in solar PV systems. For an optimal design, however, a controlled decrease in inductance at a larger current is required. Such a characteristic is displayed by inductors with stepped air gaps. To optimize the gap geometry, the knowledge of the exact behavior of the non-linear choke is crucial. As simulation tools require rather long computation times in order to calculate the non-linear characteristic, the authors chose a different approach. This paper demonstrates the analytical calculation of the current depending inductance of pot cores with stepped air gap. By solving a boundary value problem the magnetic vector potential inside the winding area is obtained assuming linear core material. Subsequently, the non-linearity of the core material is incorporated by decomposing the original non-linear problem into linear subproblems. Following this, the solution of the original problem is composed by using the solutions of the linear subproblems. Once the magnetic vector potential as a function of inductor current has been determined, the current depending inductance can be calculated. Results derived from both simulations with COMSOL Multiphysics and measurements show good agreement with the theoretical predictions.

   DC Link RMS Current Estimation in Systems with Several Converters Connected to a Shared DC Link with Distributed Capacitors
By Tobias KRONE [View]
[Download]

Abstract: This paper presents a new approach for DC link RMS current estimation in systems with several converters and connected DC links. The proposed calculation method in frequency domain enables accurate and fast estimations for an optimized design of the DC link components considering effects of interconnection parasitics and PWM interleaving.

   Efficiency Impact of Air-Cored Inductors in Multi-MHz Power Converters
By Christoph RINDFLEISCH [View]
[Download]

Abstract: The efficiency impact of air-cored inductors used close to and beyond its cut-off frequency in multi-MHz converters is investigated. A method is presented to determine the converter switching frequency that causes the lowest losses in a given inductor. Influential parameters are analysed to optimize an inductor for a predefined switching frequency.

   Iron loss comparison of standard SiFe and nanocrystalline materials for power transformers in a dual active bridge converter
By Tobias KAUDER [View]
[Download]

Abstract: This paper presents an analysis of different structured ferromagnetic materials for medium frequency applications. Metrological characteristics are performed at standardized instruments made by Brockhaus, i.e., Epstein frames and ring coil testing module. The final application is a transformer core used in a galvanically isolated phase-shifted dc-dc converter. The efficiency of a dual-active-bridge (DAB3) DC-DC converter is influenced, among others, by the iron losses of the medium frequency transformer. The iron losses of grain-oriented SiFe, non-oriented SiFe and nanocrystalline materials are measured at medium frequencies up to several kilohertz under sinusoidal excitation. The IEM-5-Parameter iron loss formula, which is based on semi-physical parameters, is used to evaluate the material characteristics. In addition, the excitation signal is adapted to the DAB3 application. The signal is examined by using a fast Fourier transform. The semi-physical iron loss separation model is adapted to consider the occurring harmonics in polarization.

   Material savings using coupled inductors in hard switched power-electronic building blocks: Modeling and experimental validation
By Patrick DECK [View]
[Download]

Abstract: A full-bridge power-electronic building block using an inverse coupled inductor (CI) is presented whichcould substitute standard hard switched inverter legs. In contrast to commercial CPU supplies using CIs,the system is operated at full duty cycle range 0...1 at elevated power levels and shows experimentallyproven material savings. The mathematical modeling leads to a volume comparison between singleinductors (SIs) and coupled inductors using E-cores. An outlook is given on CIs based on tape-woundcores.

   New Low µ Nanocrystalline Cores: an Efficient Way Decreasing Volume and Mass
By Bashar GONY [View]
[Download]

Abstract: In this paper, we present a new generation of Nanocrystalline magnetic cores (kµ) with lowpermeability. They allow magnetic core volume (resp. core mass) to be reduced by up to 5.5 times(resp. by up to 3 times) compared to Ferrite magnetic core. Moreover, no air gap is needed in suchcore to get low µ, so no electromagnetic perturbation will be emitted by the core. Exhibiting also highcut-off frequency, low magnetic losses, low magnetostriction or high B-H linearity, the kµ magneticcores appear as a new and efficient product for passive component integration or embeddedelectronics.

   Optimization of integrated magnetic planar transformer
By Ahmat Taha MAHAMAT [View]
[Download]

Abstract: Two designs of integrated magnetic planar transformer called Face to Face transformer are studied: The first one consists in depositing the copper windings on the magnetic material, the second consists in micromachining the magnetic layer before depositing the conductive layer in order to bury copper windings inside the magnetic material.

   Planar transformer equivalent thermal resistance variation with ambient temperature and power losses
By Reda BAKRI [View]
[Download]

Abstract: In this paper, the thermal resistance of planar magnetic components in natural convection is studied in order to obtain analytical formula taking into account effects of ambient temperature as well as power dissipated inside the component. The analytical model is deduced from Computational Fluid Dynamic simulations and is validated with thermal measurements on a transformer prototype.

   Prediction of the Leakage Inductance in High Frequency Transformers
By Hans ROSSMANITH [View]
[Download]

Abstract: In this paper, approximation formulas for the calculation of the leakage inductance of transformers with two winding layers or two stacked bobbins are reviewed and verified by simulation results and experiments. The accuracy of the approximation is examined for practical applications, e.g. if the available winding area is defined by a coil former. Finally, the influence of an air gap in the center leg is investigated.

EPE 2016 - DS3a: Passive Components
You are here: EPE Documents > 01 - EPE & EPE ECCE Conference Proceedings > EPE 2016 ECCE Europe - Conference > EPE 2016 - Topic 01: Devices, Packaging and System Integration > EPE 2016 - DS3a: Passive Components
	[return to parent folder]

	A phase shifted full bridge converter with novel control over the leakage inductance By Muhammad Abu BAKAR	[View] [Download]
Abstract: The electronics industry is progressing towards the high density board solutions due to the requirement of compact and intelligent electronic systems. In order to meet the industry demands, the power system is required to be of high power density. This article proposes one of the solution to improve the power density for the medium power applications. In phase shifted full bridge converter, the intrinsic leakage inductance of the main transformer is not high enough to obtain the zero voltage switching of the power switches for the entire operating conditions. An additional shim inductor is usually connected in series with the primary winding of the main transformer to increase the collective leakage inductance. This additional shim inductor degrades the power density of the converter. This paper proposes a method to embed and control the resonance inductance inside the main transformer. In addition to the increased inter-winding spacing, this paper proposes a practical approach to integrate the ferrite rods inside the main transformer for further increase in the leakage inductance. A power transformer is constructed and investigated by using the modelled equations to estimate the leakage inductance. A prototype phase shifted full bridge converter is also developed to investigate the performance of the proposed transformer. The converter is designed for the switching frequency of 400kHz, and tested up to 600watts output power at the input voltage of 200Vdc. The performance of the proposed converter is also compared with the converter of using an external inductor. The investigations show that, in addition to the improved power density, the converter with the proposed transformer is more efficient than the converter with the traditional transformer.

	Analytical Calculation of the Current Depending Inductance of a Stepped Air Gap Inductor By Erika STENGLEIN	[View] [Download]
Abstract: Magnetic devices are essential components in the field of power electronics. Exploiting the non-linear behavior of inductors and transformers offers the great merit of increasing the performance of switch mode power supplies. For instance, the light-load efficiency of a buck voltage regulator can be improved by using a non-linear inductor with stepped air gap. Moreover, non-linear chokes can be used for passive power factor correction or are employed in solar PV systems. For an optimal design, however, a controlled decrease in inductance at a larger current is required. Such a characteristic is displayed by inductors with stepped air gaps. To optimize the gap geometry, the knowledge of the exact behavior of the non-linear choke is crucial. As simulation tools require rather long computation times in order to calculate the non-linear characteristic, the authors chose a different approach. This paper demonstrates the analytical calculation of the current depending inductance of pot cores with stepped air gap. By solving a boundary value problem the magnetic vector potential inside the winding area is obtained assuming linear core material. Subsequently, the non-linearity of the core material is incorporated by decomposing the original non-linear problem into linear subproblems. Following this, the solution of the original problem is composed by using the solutions of the linear subproblems. Once the magnetic vector potential as a function of inductor current has been determined, the current depending inductance can be calculated. Results derived from both simulations with COMSOL Multiphysics and measurements show good agreement with the theoretical predictions.

	DC Link RMS Current Estimation in Systems with Several Converters Connected to a Shared DC Link with Distributed Capacitors By Tobias KRONE	[View] [Download]
Abstract: This paper presents a new approach for DC link RMS current estimation in systems with several converters and connected DC links. The proposed calculation method in frequency domain enables accurate and fast estimations for an optimized design of the DC link components considering effects of interconnection parasitics and PWM interleaving.

	Efficiency Impact of Air-Cored Inductors in Multi-MHz Power Converters By Christoph RINDFLEISCH	[View] [Download]
Abstract: The efficiency impact of air-cored inductors used close to and beyond its cut-off frequency in multi-MHz converters is investigated. A method is presented to determine the converter switching frequency that causes the lowest losses in a given inductor. Influential parameters are analysed to optimize an inductor for a predefined switching frequency.

	Iron loss comparison of standard SiFe and nanocrystalline materials for power transformers in a dual active bridge converter By Tobias KAUDER	[View] [Download]
Abstract: This paper presents an analysis of different structured ferromagnetic materials for medium frequency applications. Metrological characteristics are performed at standardized instruments made by Brockhaus, i.e., Epstein frames and ring coil testing module. The final application is a transformer core used in a galvanically isolated phase-shifted dc-dc converter. The efficiency of a dual-active-bridge (DAB3) DC-DC converter is influenced, among others, by the iron losses of the medium frequency transformer. The iron losses of grain-oriented SiFe, non-oriented SiFe and nanocrystalline materials are measured at medium frequencies up to several kilohertz under sinusoidal excitation. The IEM-5-Parameter iron loss formula, which is based on semi-physical parameters, is used to evaluate the material characteristics. In addition, the excitation signal is adapted to the DAB3 application. The signal is examined by using a fast Fourier transform. The semi-physical iron loss separation model is adapted to consider the occurring harmonics in polarization.

	Material savings using coupled inductors in hard switched power-electronic building blocks: Modeling and experimental validation By Patrick DECK	[View] [Download]
Abstract: A full-bridge power-electronic building block using an inverse coupled inductor (CI) is presented whichcould substitute standard hard switched inverter legs. In contrast to commercial CPU supplies using CIs,the system is operated at full duty cycle range 0...1 at elevated power levels and shows experimentallyproven material savings. The mathematical modeling leads to a volume comparison between singleinductors (SIs) and coupled inductors using E-cores. An outlook is given on CIs based on tape-woundcores.

	New Low µ Nanocrystalline Cores: an Efficient Way Decreasing Volume and Mass By Bashar GONY	[View] [Download]
Abstract: In this paper, we present a new generation of Nanocrystalline magnetic cores (kµ) with lowpermeability. They allow magnetic core volume (resp. core mass) to be reduced by up to 5.5 times(resp. by up to 3 times) compared to Ferrite magnetic core. Moreover, no air gap is needed in suchcore to get low µ, so no electromagnetic perturbation will be emitted by the core. Exhibiting also highcut-off frequency, low magnetic losses, low magnetostriction or high B-H linearity, the kµ magneticcores appear as a new and efficient product for passive component integration or embeddedelectronics.

	Optimization of integrated magnetic planar transformer By Ahmat Taha MAHAMAT	[View] [Download]
Abstract: Two designs of integrated magnetic planar transformer called Face to Face transformer are studied: The first one consists in depositing the copper windings on the magnetic material, the second consists in micromachining the magnetic layer before depositing the conductive layer in order to bury copper windings inside the magnetic material.

	Planar transformer equivalent thermal resistance variation with ambient temperature and power losses By Reda BAKRI	[View] [Download]
Abstract: In this paper, the thermal resistance of planar magnetic components in natural convection is studied in order to obtain analytical formula taking into account effects of ambient temperature as well as power dissipated inside the component. The analytical model is deduced from Computational Fluid Dynamic simulations and is validated with thermal measurements on a transformer prototype.

	Prediction of the Leakage Inductance in High Frequency Transformers By Hans ROSSMANITH	[View] [Download]
Abstract: In this paper, approximation formulas for the calculation of the leakage inductance of transformers with two winding layers or two stacked bobbins are reviewed and verified by simulation results and experiments. The accuracy of the approximation is examined for practical applications, e.g. if the available winding area is defined by a coil former. Finally, the influence of an air gap in the center leg is investigated.