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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2023

Design, Modeling, and Testing of a Novel Inductor for Electric Vehicles: Iron Nitride Soft Magnetic Composites

New technology for electric vehicles (EVs) must meet the requirements of higher energy usage, lower costs, and more sustainable source materials. One promising material for EV power system components is iron nitride (IN) soft magnetic composites (SMCs) because of their competitive magnetic properties and high abundance of the source materials. As part of an ongoing program at Sandia National Laboratories, this project focused on using computer modeling to optimize the prototyping process for an iron nitride SMC toroidal inductor to reach a target inductance of 600 μH. Four inductors with different combinations of wiring (26 AWG and 20 AWG) and vol% loading of iron nitride (65 vol% and 50 vol%) were fabricated at Cal Poly and characterized using an LCR meter. These inductors were also modeled using COMSOL Multiphysics™ with the Magnetic Fields module. The inductance data from the experiment and the model show that the 65 vol% IN prototypes and models agree with about 8% difference, while the 50 vol% IN samples show about a 9% difference between the prototype and the model. These results suggest that the model can predict inductance with both accuracy and precision with low confidence for the given sample size of four. An additional parameter of AC resistance is studied but the AC resistance results from the inductors and from the model generally do not agree closely, suggesting that the current model used in the project does not fully capture the mechanisms behind AC resistance of the inductor. With the focus of the project on inductance, the percent difference results of less than 9% across the four inductors that were tested increases confidence in the model’s predictive capabilities for inductance only. Using the inductance results from both the model and experiment, the final suggested inductor design is a 65 vol% core with 150 windings of 20 AWG wire that is 8 cm across and 1.5 cm tall to reach the inductance goal of 600 μH based on analysis using the optimized COMSOLTM model.

33 ADVANCED PROPULSION SYSTEMS↗
NASA NTRS2017

Coupling Inductor Based Hybrid Millimeter-Wave Switch

A switch comprising a plurality of inductors and a plurality of shunt transistors is described. Each inductor can be electrically coupled between adjacent shunt transistors to form a distributed switch structure. At least two inductors in the plurality of inductors can be inductively coupled with each other. The plurality of inductors can correspond to portions of a coupling inductor, wherein the coupling inductor can have an irregular octagonal shape.

Shu, Ran↗
DOE OSTI2024

The Integrated Reference Region Analysis for Parallel DFIGs’ Interfacing Inductors

Although the traditional design of doubly-fed induction generators (DFIGs)’ interfacing inductors consider the peak ripple of the grid-side converter (GSC)’s output current, it does not consider the inductors’ impact on DFIGs’ smallsignal stability. Located in series between the GSC and the stator, the inappropriate selection of the interfacing inductor can easily result to system instability. Therefore, this paper first proposes the integrated reference region analysis for small wind farm's interfacing inductors to improve the traditional design method. Firstly, a new detailed parallel DFIGs’ smallsignal model that considers output currents’ coupling is built in d-q coordinate system with state-space approach. The model focuses on representing the operating states of parallel DFIGs in wind farm. Secondly, the linearized state-space matrix of parallel DFIGs is decomposed into nominal-value matrix and location matrix. Considering the traditional design requirements, the integrated reference region for interfacing inductor is proposed through spectral radius and bialternate matrix sum (BMS). Furthermore, it can provide better guidance for parameter selecting and stabilization method researches. Finally, the simulation and experimental results show that the proposed integrated reference region for parallel DFIGs’ interfacing inductors is accurate and instructive.

47 OTHER INSTRUMENTATION↗
DOE OSTI2020

Four-phase interleaved TCM DC-DC buck converter with matrix inductor in battery charging application

In this paper, a 1-kW DC-DC buck converter with a four-phase interleaved matrix inductor is proposed for battery charging applications. It is well-known that the DC bias on the inductor will cause high core loss as it changes the B–H characteristic. Typically, the transient conduction mode employed in high voltage applications for zero-voltageswitching of devices would cause higher inductor current ripple. The conventional approach to reduce the effect of DC bias and inductor current ripple is employing multi-phases. However, the cost and size of the converter will increase significantly. This paper proposes the matrix inductor which has a small volume and reduces the effect of the DC bias by flux sharing and flux cancellation at the same time, results in low inductor core loss. With the interleaved operations the output current ripple can be lower which is suitable for battery charging application. Besides, the comparison of the synchronous and interleaved operation is presented. A 1-kW prototype is built and the experimental results show that the peak efficiency is 99.1% and 99.2% for synchronous and interleaved control, respectively. Additionally, the output current ripple of the interleaved operation is reduced by 85% in comparison with the synchronous operation.

14 SOLAR ENERGY↗
NASA NTRS1996

Low Temperature Performance of a Boost Converter with MPP and HTS Inductors

Low temperature performance of a 150 W, 50 kHz, 24/48 V boost PWM dc-to-dc converter is reported. The efficiency of the converter using a molypermalloy powder (MPP) core based inductor went up from 94% at room temperature (23 C) to 95.9% at liquid nitrogen temperature (-196 C). A BSCCO based high temperature superconducting (HTS) inductor with a transition temperature of approximately -158 C was compared to a MPP core based inductor in terms of the power converter performance at liquid nitrogen temperature. The use of the HTS inductor in the converter tested yielded no significant performance improvement over the same converter with the MPP inductor. The experimental results are discussed along with the HTS inductor characteristics.

Ray, Biswajit↗
DOE OSTI2021

Fully integrated multi-phase buck converter with coupled air core inductors

A multi-phase buck switching converter having grouped pairs of phases, each phase using two magnetically coupled air-core inductors. For each group, a first driver circuit controlling switching of a first power transistor switching circuit coupled to a first air-core inductor output for driving an output load at the first phase. A second driver circuit controlling switching of a second power transistor switching circuit coupled to a second air-core inductor output for driving said output load at the second phase. The first and second phases are spaced 180° apart. The coupled air-core inductors per group of such orientation, separation distance and mutual inductance polarity relative to each other such that magnetic coupling between the two or more inductors at each phase results in a net increase in effective inductance per unit volume. Each air-core inductor is a metal slab of defined length, height and thickness formed using back-end-of-line semiconductor manufacturing process.

Zhang, Xin↗
DOE OSTI2021

Medium Voltage Converter Inductor Insulation Design Considering Grid Requirements

Medium voltage (MV) SiC devices facilitate direct (without 50-/60-Hz transformer) connection of the power electronics converter to the MV grid using simple topology. Compared to the insulation design of MV inductors that have been widely used in the power system, the insulation design of the MV converter filter inductors has new challenges. Particularly, the grid impact on insulation requirements on converter filter inductors is rarely discussed. This article introduces the insulation design of a grid-side filter inductor for a 13.8-kV power conditioning system converter. The grid insulation requirements, including the short-duration power frequency overvoltage and the lightning impulse voltage, are considered in the design. To meet the requirements, the layer-to-layer insulation, winding-to-core/ground insulation, the air gap discharge between the winding and the core, the local electric field, as well as the interturn transient voltage distribution are considered. Furthermore, the designed inductors are validated by the 46 kV (>1 min) dc hi-pot test, 12-kV ac partial discharge test, one-hour single-phase converter full rating test, as well as three-phase converter full rating test.

42 ENGINEERING↗
DOE OSTI2020

An Inductor Current Estimation Approach for DC/DC Converters Based on Bisection Method

The trends toward higher power density and efficiency for the DC/DC converters has posed more strict requirements for inductors. The inductor current in turn affect the operating characteristics of the converters significantly and thus needs to be accurately estimated. In this paper, a new bisection-method-based inductor current estimation approach considering the variation of inductance is proposed. The proposed approach can be adapted and applied for various DC/DC converters, including the widely used buck and boost converters and etc. Comparing to the conventional estimation method using constant inductance, the proposed method can obtain more precise estimations of both the inductor current waveform and the power loss. Experimental results on a buck converter with a ferrite-core inductor are presented to validate the effectiveness of the proposed approach.

Zhao, Zhe↗
NASA NTRS2000

High-Q X-Band and K-Band Micromachined Spiral Inductors for Use in Si-Based ICs

A micromachined structure with reduced parasitics is proposed to enhance the resonant frequency and the quality factor (Q) of a spiral inductor. Inductors with various etch depths have been fabricated on a high resistivity Si substrate. Two-port S-parameters measurement is taken to characterize the performance of the inductors. With an etch depth of 20 micron, a fabricated 1.8 nH spiral inductor achieves a maximum resonant frequency of 25.6 GHz and a maximum Q of 20.2 at 14.5 GHz. This technology is compatible with SiGe/Si HBT technology, and the spiral inductors are especially suitable for Si-based monolithic microwave integrated circuit (MMIC) applications.

Lu, Liang-Hung↗
NASA NTRS2005

Design Considerations for High Temperature Power Inductors

A uniform B-field approximation model is used to develop design formulas for single-layer wound, toroidal core, ac power inductors that must handle a specified current. Such a geometry is well suited for high temperature, high frequency inductors, where removal of heat from the core becomes critical. Explicit expressions are derived for core radii, core and winding volumes, winding turns and core permeability as functions of a dimensional scaling ratio (S). A limit on the maximum allowed core B-field leads to the result that the minimum core volume is proportional to the permeability, which has a lower bound. Plots versus S are provided for a specific case, to show that good designs can be picked in the overlap regions around the minima in mass and overall size, where the mass and size are relatively flat. Data to 250 C are presented for an MPP core based inductor to show that a quasi-linear, high temperature inductor can be constructed with available materials. A similar development is applied to a toroidal air-core geometry, showing that for the same ratings, such an inductor is considerably bigger and more massive, at least in the single-layer version.

Niedra, Janis M.↗
NASA NTRS2020

Core Losses in Co-Rich Inductors with Tunable Permeability

High frequency, low loss power systems enable electrified aircraft propulsion. Filter inductors that reduce noise in high current systems can account for 50% of the motor drive mass. Efficient inductor cores with tunable permeability reduce system mass by producing less heat, that removes heat sink mass. Requirements for filter inductors vary based on the chosen topology, but all inductor cores must operate below saturation levels. As the saturation flux density is limited (less than ~2 T), high differential current applications require cores with low relative permeabilities. The large induced anisotropies possible in Co-rich metal amorphous nanocomposite materials enables gapless inductors with relative permeabilities down to ~20. These materials have fine grain size ~8nm with a faulted, close packed structure. The impact of different processing methods on core losses are presented along with comparison to other low permeability soft magnetic materials.

Leary, Alex↗
DOE OSTI2024

Geometrically stable nanohenry inductor

Systems, methods, and devices are provided for producing and using a low-value inductor which is stable at high frequencies, the inductor including a plurality of radial spokes extending between two concentric rings. The inductance of the inductor is controlled by the number and dimensions of the plurality of spokes, as well as the materials of the inductor. In some cases, the inductor is used as a low value inductance standard for directly measuring a low value electrical inductance.

Kautz, David↗
DOE OSTI2021

Medium Voltage Converter Inductor Insulation Design Considering Grid Insulation Requirements

Medium voltage SiC devices facilitate direct (without 50/60 Hz transformer) connection of the power electronics converter to the medium voltage grid using simple topology. Compared to the insulation design of medium voltage inductors that have been widely used in the power system, the insulation design of directly connected medium voltage converter filter inductors has more challenges. Although some works has been done discussing that, the grid insulation requirements on converter filter inductors are rarely discussed. This paper introduces the insulation design of a grid-side filter inductor for a 13.8 kV power conditioning system converter. The grid insulation requirements, including the short-duration power frequency overvoltage and the lightning impulse voltage, are considered in the design. To meet the requirements, the layer-to-layer insulation, winding-to-core/ground insulation, the air gap discharge between the winding and the core, as well as the local electrical field have been taken into consideration. Experimental tests are provided to validate the design.

Li, Haiguo↗
NASA NTRS1985

Designing high frequency ac inductors using ferrite and Molypermalloy Powder Cores (MPP)

The major considerations in the design of high frequency ac inductors are reviewed. Two methods for designing the inductor: the area product method and the core geometry method, are presented. The two major effects of the inductor air gap, fringing flux power loss and increase of inductance, are discussed. Equations for the inductor design and a step-by-step design procedure are given. The use of a lumped air gap or a distributed air gap are discussed and a comparison of the losses resulting from these gaps, together with experimental results are presented.

Mclyman, W. T.↗
DOE OSTI2020

Enhanced Inductance and Winding Loss Model for Coupled Inductors

An enhanced model for coupled inductors with significant fringing effect is developed in the form of equivalent circuit. The equivalent circuit is derived from a physical model that captures the flux paths through a leakage inductor and two mutual inductors on the primary and secondary side. A mutual winding resistor is added in parallel with the mutual inductor to model the winding loss affected by the fringing flux that penetrates the winding. The equivalent circuit is verified by finite-element simulation (FES) and successfully predicts the open-circuit winding loss and winding loss variation with phase-shift impact.

Xue, Lincoln↗
DOE OSTI2021

Smart controller with phantom inductor current sensing for switched mode power supplies

Voltage on the output terminal of an inductor is obtained as a first input signal to a control block (CB); the inductor has an input terminal connected to a power switch and driver block at a switching node. A sense input voltage is obtained on an output terminal of a sensing circuit that is not directly connected to the switching node, as a second input signal to the CB. A voltage is generated on a first output terminal of the CB and is selected such that the CB can use its first and second input signals to infer the current through the inductor. A pulse width modulation (PWM) signal is generated on a second output terminal of the CB, based on the inferred current through the inductor; the second output signal from the CB is provided to a PWM input terminal of the power switch and driver block.

Zhang, Xin↗
DOE OSTI2023

Functionally graded thermal vias for inductor winding heat flow control

Embodiments of the disclosure relate to apparatuses for enhanced thermal management of an inductor assembly using functionally-graded thermal vias for heat flow control in the windings of the inductor. In one embodiment, a PCB for an inductor assembly includes a top surface and a bottom surface. Two or more electrically-conductive layers are embedded within the PCB and stacked vertically between the top surface and the bottom surface. The two or more electrically-conductive layers are electrically connected to form an inductor winding. A plurality of thermal vias thermally connects each of the two or more electrically-conductive layers to a cold plate thermally connected to the bottom surface. A number of thermal vias thermally connecting each electrically-conductive layer to the cold plate is directly proportional to a predetermined rate of heat dissipation from the electrically-conductive layer.

Dede, Ercan↗
DOE OSTI2026

A Dual-Active-Bridge Converter Employing a Variable Inductor Without an Auxiliary Circuit

This paper proposes a dual active bridge (DAB) converter employing a variable inductor (VI) without an auxiliary circuit. Unlike conventional VI-based designs that require an external DC bias circuit, the proposed DAB utilizes the input DC current itself as the bias source, enabling automatic inductance variation with load conditions. The inductance naturally increases at low power and decreases at high power, effectively extending the zero voltage switching (ZVS) range and reducing circulating current, respectively. The VI was experimentally implemented and characterized to obtain its inductance-current profile, which was then integrated into a PLECS model of the DAB converter for circuit and thermal simulations. Simulation results confirm that the proposed auxiliary-free VI-DAB converter achieves a wider ZVS range and lower circulating current compared with a conventional fixed-inductor DAB converter. By realizing a variable inductor without any auxiliary bias circuitry, the proposed approach maintains soft switching and reduces reactive current losses across a wide load range, leading to improved efficiency and simplified implementation.

Jo, Cheolhui [ORNL] (ORCID:0000000322692434)↗