Loss measurement of magnetic components under real application conditions

Kleeb, Thiemo; Dombert, Benjamin; Araújo, Samuel; Zacharias, Peter

doi:10.1109/epe.2013.6631895

Cited by 19 publications

(9 citation statements)

References 9 publications

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“…For the measurement of the total losses, a calorimetric setup, depicted in Fig. 25(a), is used [40], [41]. It consists of an inner calorimeter chamber and an outer reference chamber, which is used to ensure steady ambient conditions during the experiment.…”

Section: Experimental Verificationmentioning

confidence: 99%

“…The calorimeter chamber accommodates the DUT and a heating device, i.e., a resistor, an attached heat sink, and fans, to ensure a homogeneous temperature inside the chamber. The employed setup enables measurements at a defined ambient temperature without the need for pre-calibrations [40], [41]. The accuracy of the calorimeter has been assessed by means of reference loss measurements conducted with a 1 kΩ power film resistor (RCH series by Vishay [42] Fig.…”

Section: Experimental Verificationmentioning

confidence: 99%

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Minimum Loss Operation and Optimal Design of High-Frequency Inductors for Defined Core and Litz Wire

Papamanolis

Guillod

Krismer

et al. 2020

IEEE Open J. Power Electron.

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This paper studies the loss-optimal design of a power inductor employed in a 2 kW, 400 V input DC-DC converter. The design of an inductor is subject to a large number of design parameters and the implications of the different design parameters on the losses are often not clearly traceable in a full optimization, e.g., different current ripple amplitudes can lead to designs with similar losses, as larger ripple amplitudes lead to increased AC core and winding losses but lower DC losses in the winding due to lower inductance values and/or numbers of turns. In an effort to achieve a comprehensible description of the implications of the key design parameters (switching frequency, current ripple, number of turns) on the losses, the remaining parameters, e.g., core (E55/28/21 N87) and type of conductor (litz wire), are considered to be given. In a first step, the investigation is based on a simplified analytical model, which is refined in a step-by-step manner, e.g., to consider core saturation. In a second step, the implications of further critical aspects on the losses, e.g., temperatures of core and coil, are examined using a comprehensive semi-numerical model. Surprisingly, the evaluation of the losses calculated in the fr domain reveals that nearly minimum inductor losses are obtained for a current ripple that is inversely proportional to the frequency, i.e., for a constant inductance, within a wide frequency range, from 200 kHz to 1 MHz. Furthermore, the investigation reveals a decrease of the losses for increasing frequencies up to 375 kHz, e.g., from 4.32 W at 80 kHz (r = 110 %) to 2.37 W at 375 kHz (r = 18 %). The detailed analysis related to these results enables the compilation of a simple two-equations guide for the design of an inductor that achieves close to minimum losses. In a next step, interesting trade-offs are identified based on a study of the design space diversity, e.g., with respect to low cost and increased partial-load efficiency. The findings of this work are experimentally verified, i.e., the losses of three different inductors are measured with an accurate calorimetric method and at four different frequencies, ranging from 150 kHz to 700 kHz.

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Section: Experimental Verificationmentioning

confidence: 99%

Section: Experimental Verificationmentioning

confidence: 99%

Minimum Loss Operation and Optimal Design of High-Frequency Inductors for Defined Core and Litz Wire

Papamanolis

Guillod

Krismer

et al. 2020

IEEE Open J. Power Electron.

View full text Add to dashboard Cite

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“…The measurement of inductor losses under real operating conditions is a difficult task, especially when a high accuracy is desired. Therefore, several calorimetric measurement methods have been developed in literature [45]- [47]. Thereby, steady state measurement methods [30], [46] and transient measurement methods [45] are used.…”

Section: B Calorimetric Efficiency Measurementmentioning

confidence: 99%

99.1% Efficient 10 kV SiC-Based Medium-Voltage ZVS Bidirectional Single-Phase PFC AC/DC Stage

Rothmund

Guillod

Bortis

et al. 2019

IEEE J. Emerg. Sel. Topics Power Electron.

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Due to their extremely high energy demand, data centers are directly supplied from a medium voltage (MV) grid. However, a significant part of this energy is dissipated in the power supply chain, since the MV is reduced step-by-step through multiple power conversion stages down to the chip voltage level. In order to increase the efficiency of the power supply chain, the number of conversion stages must be substantially reduced. In this context, Solid-State Transformers (SSTs) are considered as a possible solution as they could directly interface the MV AC grid to a 400 V DC bus, whereby server racks with a power consumption of several tens of kilowatts could be directly supplied from an individual SST. With a focus on the lowest system complexity, the SST ideally should be built as simple two-stage system consisting of an MV AC/DC PFC rectifier stage followed by an isolated DC/DC converter. Accordingly, this paper focuses on the design and realization of a 25 kW, 3.8 kV single-phase AC to 7 kV DC PFC rectifier unit based on 10 kV SiC MOSFETs. By simply adding an LC-circuit between the switch nodes of the well-known full-bridge-based PWM AC/DC rectifier, the integrated Triangular Current Mode (iTCM) concept is implemented, which only internally superimposes a large triangular current ripple on the AC mains current and therefore enables zero voltage switching (ZVS) over the entire AC mains period. Special attention is paid to the realization of the MV inductors and their electrical insulation, the AC-input LCL-filter to limit EMI emissions, and the challenges arising due to cable resonances when connecting the SST to the MV grid via a MV cable. Despite the large insulation distances required for MV, the realized 25 kW MV PFC rectifier achieves an unprecedented power density of 3.28 kW/L (54 W/in 3 ) and a full-load efficiency of 99.1 %, determined using a calorimetric measurement setup, which is discussed in detail in the Appendix.

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“…(Corresponding author: Armin Jafari, e-mail: armin.jafari@epfl.ch). Calorimetric methods have been used to directly determine losses from generated heat in power converters [8], [11], pulsed-power generators [12], motors and drives [13], [14], semiconductor devices and passive components [7], [15].…”

Section: Introductionmentioning

confidence: 99%

High-Accuracy Calibration-Free Calorimeter for the Measurement of Low Power Losses

Jafari

Heijnemans

Soleimanzadeh

et al. 2021

IEEE Trans. Power Electron.

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Wide-band-gap technologies enable ultra-high efficiencies in high-frequency power conversion. However, inadequate accuracies in electrical measurements could lead to spurious efficiency measurements, even above 100%. Furthermore, bandwidth limitations, particularly for current probing, delay mismatches between current and voltage probes, loading effects and electromagnetic interferences make electrical techniques inappropriate for measuring extremely-low losses in switches with high dv/dt and di/dt values and magnetic components with high-frequency excitations. Calorimetric methods overcome this issue by a direct loss measurement through the generated heat. Nevertheless, limited ranges and accuracies of existing systems hinder their application in sensitive measurements. Moreover, time-consuming calibrations with extensive data processing impede rapid design assessments. In this work, we propose a closed-type double-chamber calorimeter based on a real-time calibration between two identical chambers, to eliminate extra compensation for ambient variations or changes within the system itself. By streaming the same coolant in both chambers, our system removes the need for flow measurements, enabling extremely low flow rates which improves sensitivity and reduces complexity and system cost. The system provides adjustable cooling and can measure losses down to 500 mW, enabling the evaluation of highperformance power converters and their components with no dependencies on the geometries of the evaluated devices or systems.

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Loss measurement of magnetic components under real application conditions

Cited by 19 publications

References 9 publications

Minimum Loss Operation and Optimal Design of High-Frequency Inductors for Defined Core and Litz Wire

Minimum Loss Operation and Optimal Design of High-Frequency Inductors for Defined Core and Litz Wire

99.1% Efficient 10 kV SiC-Based Medium-Voltage ZVS Bidirectional Single-Phase PFC AC/DC Stage

High-Accuracy Calibration-Free Calorimeter for the Measurement of Low Power Losses

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