Iron Saturation Effects Research Articles

Hybrid Analytical Model of Permanent Magnet Linear Motor Considering Iron Saturation and End Effect

Hybrid Analytical Model of Permanent Magnet Linear Motor Considering Iron Saturation and End Effect

Modified Induction Machine Equivalent Circuit Including Solid Shaft Eddy Currents

The shaft eddy currents cause a significant saturation in two-pole induction machines (IMs) as they generate an opposing field and repulse the main flux, thus tightening the flux path. This results in inaccurate performance estimations with the magnetizing inductance measured in no-load conditions when the machine is loaded. This article presents a modified IM equivalent circuit considering the rotor back iron saturation effects caused by the solid shaft eddy currents using experimental measurements and recursive parameter estimation techniques. The classical equivalent circuit (CEC) parameters are determined with the standard test techniques followed by the parameter estimation of the newly introduced modified equivalent circuit (MEC) parameters. The proposed modified equivalent circuit is benchmarked with CEC and finite element analysis (FEA) simulations with and without considering eddy effects. The proposed MEC model and the FEA that consider eddy effects performed better than the other models and yielded a negligibly small error over a wide range of loading conditions. Compared to the FEA, the proposed MEC estimates the IM performance much faster, which makes it more appealing for IM performance estimations.

Nonlinear Analytical Model of Linear Switched Reluctance Motor With Segmented Secondary Considering Iron Saturation and End Effect

Nonlinear Analytical Model of Linear Switched Reluctance Motor With Segmented Secondary Considering Iron Saturation and End Effect

A Modified Dynamic Model of Single-Sided Linear Induction Motors Considering Longitudinal and Transversal Effects

This paper proposes a modified dynamic equivalent circuit model for a linear induction motor considering both longitudinal end effect and transverse edge effect. The dynamic end effect (speed-dependent end effect) is based on conventional Duncan’s approach. The transverse edge effect is investigated by using three correction factors applied to the secondary resistance and magnetizing inductance. Moreover, the iron saturation effect, the skin effect, and the air-gap leakage effect are incorporated into the proposed model by using the field-analysis method. A new topology of the steady-state and space-vector model of linear induction, regarding all mentioned phenomena, is presented. The parameters of this model are calculated using both field analysis and the finite-element method. The steady-state performance of the model is first validated using the finite-element method. Additionally, the dynamic performance of the proposed model is studied. The results prove that the proposed equivalent circuit model can precisely predict the dynamic and steady-state performances of the linear induction.

Comprehensive Analysis and Design of a Pulsating Signal Injection-Based Position Observer for Sensorless Synchronous Motor Drives

The work focuses on a new mathematical formulation for the transfer function (TF) of a pulsating injection-based position observer, as the key point for its correct design. The proposed analysis exploits the modulation/demodulation control theory to derive the TF of the whole estimator in the Laplace domain. Magnetic iron saturation effects and cross saturation between the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$dq$ </tex-math></inline-formula> -axes are considered in the observer design. To test the effectiveness of the new TF representation of the observer, it is used to synthesize two different regulators, namely by the direct synthesis and the internal model principle. An extensive experimental stage is included pointing to fully verify the accuracy of the proposed model and the theoretical considerations. A comparison with the existing mathematical model of the observer is also reported to show the improvement achievable in the position estimation by the proposed observer synthesis.

Cogging Torque Minimization in Transverse Flux Permanent Magnet Generators using Two-step Axial Permanent Magnet Segmentation for Direct Drive Wind Turbine Application

Transverse flux permanent magnet machines (TFPMs) are categorized as synchronous machines that benefit from having high value of torque density and capablity of accommodating high pole numbers. These characteristics make TFPMs suitable candidates for low-speed applications where high torque density value is requred such as direct drive wind turbine application. Despite the aforementioned advantages, TFPMs suffer from intrinsically high cogging torque value which is an important concern for wind turbine application. This paper focuses on axial PM segmentation technique to minimized cogging torque of TFPM topologies. Concept of the proposed method is discussed using analytical equations and optimum segmentaion angle is formulized. Non-linear magnetic equivalent circuit (MEC) is adopted where the PM segmentation, armature reaction, rotor transition and iron saturation effect are carefully modeled. The results of the MEC simulation are compared with the finite element method (FEM) results in terms of accuracy and computational time. The results from the analysis indicate that the proposed MEC method is almost ten times faster than FEM with reasonable level of precision. Taguchi method is adopted as a fast-response optimization method to improve the generator torque characteristics. The results show that the cogging torque has reduced by 97% with respect to the initial design while the average torque has only dropped by 8% which is an acceptable side effect due to the significant improvement in machine cogging torque.

First Field Measurements of the 15 T Nb3Sn Dipole Demonstrator MDPCT1

Within the US Magnet Development Program (MDP), a 15 T Nb3Sn dipole was developed to demonstrate a possible magnet design for a post-LHC proton-proton Collider. The magnet design is based on 60 mm aperture 4-layer shell-type coils, graded between the inner and outer layers to maximize magnet performance. Magnet coils are surrounded by vertically split thick iron laminations, connected by aluminum I-clamps, and a thick stainless-steel skin. The magnet coils were preloaded to achieve 14 T in the first test. The magnet was tested at the Vertical Magnet Test Facility (VMTF) at Fermilab. This paper reports the first results of magnetic measurements of the 15 T Nb3Sn dipole demonstrator, including dipole strength, geometrical harmonics, coil magnetization and iron saturation effects. At the maximum quench current of 9742 A we obtained a dipole strength of 14.13 T.

Finite Element Design of Rotor Permanent Magnet Flux Switching Machine with Arbitrary Slot, Pole and Phase Combinations

A two-dimensional finite element approach for designing RPMFS (Rotor Permanent Magnet Flux Switching) machines is presented in this paper. The proposed method enables fast, accurate and computationally efficient assessment of different RPMFS machine designs with an arbitrary number of rotor poles, stator slots and stator phases. The appropriate stator winding layout is assembled for any feasible slot, pole and phase combination by employing the winding distribution table, which contributes to automating the design process. Based on the proposed method, a program is developed using the Octave FEMM (Finite Element Method Magnetics) toolbox. The program is suited for the use in the design stage, where it is necessary to determine various machine parameters for given core dimensions, terminal voltage constraints and adopted value of current density in the conductors, while taking iron saturation effects into account. Verification was carried out by simulating torque and EMF waveforms for several RPMFS machine designs.

Magnetic Measurements on the Prototype Magnets of the High-Order Correctors for HL-LHC

The National Institute for Nuclear Physics (INFN) is developing, at the Laboratory of Accelerators and Applied Superconductivity (LASA Milan, Italy), five families of corrector magnets, from skew quadrupole up to dodecapole order, which will be installed in the interaction regions of the High-Luminosity Large Hadron Collider (LHC). These magnets are based on a superferric design, which allows a relatively simple, compact and easy-to-construct magnets. This activity takes place within the framework of a collaboration agreement between CERN and INFN. The magnets have been designed and prototype units have been built and tested for the sextupole, octupole, and decapole orders. Magnetic measurements have been performed in order to characterize the field quality, and to validate the design and construction. This paper presents the instruments and the approach for the magnetic measurements on the prototype magnets. Moreover, the results of measurements at cryogenic temperature, up to the nominal field level, are reported. The magnetic field quality, in terms of transfer function and field multipoles, is analysed as function of the excitation level. The iron saturation effects, which are a major concern of the selected design, are compared with the 3-D magnetic calculations and discussed in view of the construction of the series magnets to be integrated in the corrector package assembly.

Magnetic Analysis of the MQXF Quadrupole for the High-Luminosity LHC

The high-luminosity upgrade of the Large Hadron Collider (HL-LHC) requires new high-field and large-aperture quadrupole magnets for the low-beta inner triplets (MQXF). The U.S. HiLumi-LHC Accelerator Upgrade and CERN are jointly developing a 150-mm aperture Nb 3 Sn magnet. Due to the large beam size and orbit displacement in the final focusing triplet, MQXF has challenging field quality targets at collision energy. Magnetic measurements have been performed both at ambient and cryogenic temperatures in the four short models that were built and tested. This paper presents the magnetic analysis, comparing field measurements with the expectations and the field quality requirements. The analysis is focused on the geometrical harmonics and iron saturation effect, including three-dimensional effects and transfer function repeatability. Persistent currents and dynamic effects are also discussed.

Field Measurement to Evaluate Iron Saturation and Coil End Effects in a Modified Model Magnet of Beam Separation Dipole for the HL-LHC Upgrade

A beam separation dipole magnet for the high luminosity large hadron collider upgrade is developed. The development of the 2-m-long model magnet (MBXFS1) was initiated so as to evaluate the design and performance of the beam separation dipole magnet. In the first cold test in 2016, the quench performance was not satisfactory because the coil prestress at the pole was completely released during excitation. After reassembly to improve the quench performance, the excitation test of the modified model magnet (MBXFS1b) was performed at 1.9 K in 2017 at KEK. Due to the large coil aperture and limited outer diameter of the iron yoke, the control of iron saturation effects on the field quality has been a design issue. Regarding the magnetic performance, field saturation effects on the transfer function and the multipole field variation along the excitation, and coil end effects to the straight section need to be evaluated by the field measurement. In this paper, field measurement results will be presented and the comparison with the three-dimensional field calculation will be discussed.

Field Quality of MBH 11-T Dipoles for HL-LHC and Impact on Beam Dynamic Aperture

For the high-luminosity upgrade of the Large Hadron Collider (HL-LHC), the development of the 11-T Nb $_3$ Sn dipole (MBH) is progressing. At present, one double-aperture and five single-aperture short-model magnets have been built and tested. Magnetic measurements have been performed both at ambient and cryogenic temperatures. In addition, a double-aperture short model and the first full-length collared-coil assemblies have been produced and measured at ambient temperature. In this paper, the measurement results collected so far are presented and discussed. The geometrical field multipoles, the iron saturation effects, as well as the effects of persistent currents are summarized. Experimental data are compared with the magnetic calculations using the CERN field computation program ROXIE and discussed in view of the construction of the final magnets. In addition, based on the measured field errors, beam dynamics simulations have been carried out by taking into consideration different scenarios with and without MBH magnets installed in the accelerator.

Magnetic Analysis of the Nb3Sn Low-Beta Quadrupole for the High-Luminosity LHC

Author(s): Bermudez, SI; Ambrosio, G; Chlachidze, G; Ferracin, P; Holik, E; Di Marco, J; Todesco, E; Sabbi, GL; Vallone, G; Wang, X | Abstract: As part of the Large Hadron Collider Luminosity upgrade (HiLumi-LHC) program, the US LARP collaboration and CERN are working together to design and build 150-mm aperture Nb3Sn quadrupoles for the LHC interaction regions. A first series of 1.5-m-long coils were fabricated, assembled, and tested in the first short model. This paper presents the magnetic analysis, comparing magnetic field measurements with the expectations and the field quality requirements. The analysis is focused on the geometrical harmonics, iron saturation effect, and cold-warm correlation. Three-dimensional effects such as the variability of the field harmonics along the magnet axis and the contribution of the coil ends are also discussed. Moreover, we present the influence of the conductor magnetization and the dynamic effects.

Magnetic Measurements and Analysis of the First 11-T Nb3Sn Dipole Models Developed at CERN for HL-LHC

The high-luminosity upgrade for the LHC (HL-LHC) envisages the replacement of some 15-m-long NbTi dipoles in the dispersion suppressor area by shorter Nb3Sn magnets with a nominal field of 11 T. The new magnets must be compatible with the lattice and other main systems of the LHC. The shorter length of new units will allow the installation of collimators. The successful use of the Nb3Sn technology requires an intense R&D program, and therefore, a CERN–Fermilab joint development program was established. This paper describes the magnetic measurement procedure and presents the analysis of the magnetic measurements on the first 2-m-long single-aperture demonstrators built and tested at CERN. The geometrical field multipoles, the iron saturation effects, and the effects of persistent currents are presented. The experimental data are compared with the magnetic calculations using the CERN field computation program ROXIE and are discussed in view of the requirements for machine operation.

Magnetic Measurements and Analysis of the First 11-T Nb3Sn 2-in-1 Model for HL-LHC

In the framework of the High-Luminosity upgrade of the Large Hadron Collider, the design and development of new magnets, relying on Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn superconducting cables, is progressing. In particular, a double-aperture dipole, with a bore diameter of 60 mm and a central field of 11 T, is required for the replacement of some Nb-Ti dipoles in the dispersion suppressor areas. The new magnets must comply with the specifications of the machine in terms of reliability and field quality. An intense short-model campaign was launched in order to validate the design choices. Various single-aperture models have been built and tested. Recently, the first 2-in-1 model has been produced by assembling the collared coils already tested in the single-aperture configuration. This paper presents the analysis of the magnetic measurements on the first 2-m-long, double-aperture demonstrator built and tested at CERN. The geometrical field multipoles, the iron saturation effects, the magnetic cross-talk as well as the effects of persistent currents are presented. The experimental data are compared with the magnetic calculations using the CERN field computation program ROXIE and are discussed in view of the construction of the full-length magnets.

Design Optimization of the New D1 Dipole for HL-LHC Upgrade

The High-Luminosity Large Hadron Collider upgrade (LHC) project aims to increase the peak luminosity of the LHC to 5 ×1034 cm - 2s - 1, and a total integrated luminosity of 3000 fb - 1 from 2020 to 2030 by upgrading the low-beta insertion system for the ATLAS and CMS experiments. The aperture of the insertion magnets including the focusing/defocusing quadrupoles and separation dipoles will be doubled to achieve a smaller β*. This paper presents the latest design updates of the separation dipole D1 magnet, including the study of the different cable types to vary the main field; the modifications of the iron shape for the new design options to minimize the iron saturation effect on field quality; and the optimization of the coil ends to reduce the peak field and higher order harmonic field integrals in the ends.

Field Quality Measurements in a Single-Aperture 11 T $ \hbox{Nb}_{3}\hbox{Sn}$ Demonstrator Dipole for LHC Upgrades

The upgrade of the Large Hadron Collider (LHC) collimation system foresees additional collimators in the LHC dispersion suppressor areas. The longitudinal space for the collimators could be provided by replacing some NbTi LHC main dipoles with shorter 11 T Nb3Sn dipoles. To demonstrate this possibility, Fermilab and CERN have started a joint program to develop a Nb3Sn dipole prototype suitable for installation in the LHC. The first step of this program is the development of a 2-m-long, 60-mm-bore, single-aperture demonstrator dipole with the nominal field of 11 T at the LHC operational current of 11.85 kA. This paper presents the results of magnetic measurements of the single-aperture Nb3Sn demonstrator dipole including geometrical harmonics, coil magnetization, and iron saturation effects. The experimental data are compared with the magnetic calculations.

Design of a Large Single-Aperture Dipole Magnet for HL-LHC Upgrade

An upgrade of the low-beta insertion system for the ATLAS and Compact Muon Solenoid experiments is proposed in the high luminosity Large Hadron Collider upgrade project. It includes final beam focusing quadrupoles, beam separation and recombination dipoles, and larger aperture matching section quadrupoles. KEK is in charge of the conceptual design of the large aperture separation dipole D1. The latest design parameters are a main field of ~ 5 T at 1.9 K with Nb-Ti superconducting technology, a coil aperture of 160 mm, and a cos-theta one-layer coil with Large Hadron Collider dipole cable. Because the new D1 is expected to be operated in a very high radiation environment, radiation resistance and a cooling scheme are being carefully considered. The collaring-yoke structure is adopted to provide the mechanical support for the single-layer Nb-Ti coil. We summarize the design study of this magnet, including i) the very large iron saturation effect on field quality due to the large aperture and limited size of the iron yoke, ii) the stray field at the outer surface of the iron cryostat, and iii) the stress management from room temperature assembly to final operation.

Development of the 15 T $\hbox{Nb}_{3}\hbox{Sn}$ Dipole HD2

The superconducting magnet program at Lawrence Berkeley National Laboratory (LBNL) is continuing the development of HD2, a 1 m long dipole generating a dipole field of 15 T in a 36 mm clear bore. With tilted (flared) ends to avoid obstructing the beam path, HD2 represents a step towards the development of high field and cost effective accelerator quality magnets. The design has been optimized to minimize geometric harmonics and to address iron saturation and conductor magnetization effects. The support structure is based on an external aluminum shell, pre-tensioned with pressurized bladders and interference keys. Aluminum axial rods and stainless steel end plates provide longitudinal support to the coil ends during magnet excitation. This paper reports on field quality optimization and magnet parameters. The design and fabrication of the coil and structure components, and results from coil winding, reaction, and potting are also presented.

Test Results of a 2 Tesla Superconducting Transmission Line Magnet Obtained With 102 Sensors Array of Hall Station

A prototype of a 2 Tesla superconducting transmission line magnet for future hadron colliders was designed, built and tested at Fermilab. This combined function magnet with a 4%/cm gradient and a 1.96 Tesla dipole field has a room temperature iron yoke with two horizontally separated air gaps for beam pipes. The magnetic field in both gaps is generated by a single-turn superconducting transmission line of 90 kA nominal current placed in the center of the iron yoke. The magnetic measurements were made simultaneously in both air gaps using a Hall Probe Station with 102 Hall sensors. The main parameters of Hall Station are briefly described. The magnetic design, pole tip and field quality optimization are presented. The iron saturation effects and their reduction with pole holes are also discussed. The results of magnetic measurements are compared with calculations, design parameters and the quality of magnetic field is discussed