A 3-D vector magnetization model with interaction field

This paper presents a vector model of magnetization based on the three-dimensional (3-D) Stoner-Wohlfarth elemental operator. To account for the magnetic interactions between particles, a phenomenological mean-field approximation is employed. The paper also illustrates the numerical simulation results of the magnetization in 3-D. This model will be useful to simulate the magnetization process of complicated topology flux electromagnetic devices. © 2005 IEEE

A general electromagnetic field-circuit coupling method based on time-stepping finite element analysis for performance analysis of pulse-width modulated switching converters considering hysteresis effects

Considering the special characteristics existing in the pulse-width modulated (PWM) switching converter, a general method for the time-stepping finite element analysis based electromagnetic field coupling with its feeding circuit used in the analysis of PWM switching converter considering hysteresis effects is introduced in this paper. Comparing with the electromagnetic field-circuit indirect coupling method (ICM), the proposed method has overcome the drawback that the ICM cannot take the hysteresis effects into account. Compared with the electromagnetic field-circuit direct coupling method (DCM), the proposed method has the similar accuracy but higher efficiency. Furthermore, like the ICM, the proposed method also divides the system with higher state dimensions produced by the DCM into two subsystems with lower state dimensions; this may reduce the algorithm convergence problem which often happens in high dimensional systems. © 2008 American Institute of Physics

Measurement and modeling of core losses of soft magnetic composites under 3-D magnetic excitations in rotating motors

Soft magnetic composite (SMC) materials are especially suitable for construction of low-cost high-performance motors with three-dimensional (3-D) magnetic fields. The 3-D finite-element analysis (FEA) conducted in the design of a claw pole transverse flux motor (CPTFM) with an SMC core reveals very complicated B (flux density) loci in the core when the motor rotates. In order to understand and account for the effects of the patterns of B loci on motor parameters and performance such as core losses, a 3-D magnetic property testing system was built for magnetic measurement on a cubic SMC sample. 3-D rotational core loss models in SMC materials and rotating motors are developed. © 2005 IEEE

Improved measurement with 2-D rotating fluxes considering the effect of internal field

This paper analyzes the effect of the internal field on the measurement with two-dimensional (2-D) rotating fluxes. It is demonstrated that due to the effect of the internal field, the misalignment of H sensing coils, causing the asymmetry of H loci and the discrepancy of the rotational core losses between two opposite rotating directions cannot be corrected completely. A numerical averaging method is employed to eliminate the angular error. Finally, the B and H loci and rotational core losses of a soft magnetic composite (SMC) material were measured under circular rotating magnetic flux density vectors, and the results were corrected by the proposed averaging method. © 2005 IEEE

Magnetic flux penetration in polycrystalline SmFeO0.75F0.2As

The recently discovered Fe-As superconducting materials which show high potential ability to carry current due to their low anisotropy have attracted a great number of attentions to understand their superconductivity mechanism and explore their applications. This paper presents a method to synthesis SmFeO0.75F0.20As polycrystalline by hot press in detail. The magnetization at different temperatures and applied fields obtained by a superconducting quantum interference device are also discussed. In addition, the local magnetization process is presented by magneto-optical imaging technique at the conditions of zero-field-cooling and field-cooling. It is found that the collective magnetization process of the newly discovered Fe-As superconductors is very similar to that of high-Tc cuprates. For instance, the Fe-As superconductors and high-Tc cuprates have the same magnetization features due to strong pining and intergrain weak link. The global supercurrent is significantly lower than local grain supercurrent due to the weak line between the grains

Enhancing resilience by reducing critical load loss via an emergent trading framework considering possible resources isolation under typhoon

Leveraging distributed resources to enhance distribution network (DN) resilience is an effective measure in response to natural disasters. However, the willingness and economy of distributed resources are typically ignored. To address this issue, this paper proposes an emergent trading framework that uses parking lots (PLs) as resources to provide power support to critical loads (CLs) in a blackout due to typhoons. In this trading framework, an evolutionary Stackelberg game-based trading model is established to consider maximizing all stakeholders' economic benefits, considering possible resources isolation under typical fault scenarios caused by typhoons, and a benefit allocation mechanism is proposed for all stakeholders to motivate all stakeholders to participate in the trading. This framework allows that critical loads could reduce their load loss, parking lots could receive adequate compensation to stimulate them to participate in the trading, and distribution utility could ensure its economic benefits. Furthermore, an iterative evolutionary-Stackelberg solution set-up is applied to obtain the equilibria of the proposed framework. Simulation results on the modified IEEE 69-bus test system and IEEE 123-bus test system reveal the validity of the proposed method

Flux distribution at the cross section of stacked nanostructured magnetic ribbon

Conventional magnetization methods only measure the average magnetic properties over the whole sample. The information is insufficient to understand the local character. This paper presents the visualized magnetization process and its profiles in detail at the cross section of the FINEMET ribbon using advanced magnetooptical imaging technique. External magnetic fields were applied parallel to the surface of the ribbon. A magnetization curve was plotted by interpreting the profile of intensity of magnetooptical images. The profile indicates that the flux densities are higher at the cross section of the ribbons compared with those at the gaps between the ribbons. The flux lines mainly transmit inside the FINEMET ribbons though there are some stray fields between the ribbons. © 2009 IEEE

Robust optimization in HTS cable based on design for six sigma

The nonuniform ac current distribution among the multilayer conductors in a high-temperature superconducting (HTS) cable reduces the current capacity and increases the ac loss. Various numerical simulation techniques and optimization methods have been applied in structural optimization of HTS cables. While the existence of fluctuation in design variables or operation conditions has a great influence on the cable quality, in order to eliminate the effects of parameter perturbations in design and to improve the design efficiency, a robust optimization method based on design for six sigma (DFSS) is presented in this paper. The optimization results show that the proposed optimization procedure can not only achieve a uniform current distribution, but also improve significantly the reliability and robustness of the HTS cable quality, comparing with those by using the particle swarm optimization. © 2008 IEEE

Measurement of soft magnetic composite material using an improved 3-D tester with flexible excitation coils and novel sensing coils

In this paper, accurate measurement of three dimensional (3-D) magnetic properties of soft magnetic composite (SMC) material is carried out by using an improved 3-D tester with adjustable excitation coils and novel sensing coils attached upon the surface of the SMC specimen. Comparing with the conventional 3-D tester operating at 50 Hz, the improved 3-D tester enables measurements over wide frequency range from 2 Hz to 1000 Hz. The relationships between the B vector and H vector are measured under both alternating and rotating flux conditions, and the core loss features are analyzed. These experimental results are crucial for designing new SMC electrical machines, which are expected to operate at 200 Hz or above. © 2006 IEEE

Study on rotational hysteresis and core loss under three-dimensional magnetization

In this paper, magnetic properties of soft magnetic composite (SMC) materials under alternating and various rotational magnetizations have been properly measured, modeled, and analyzed at typical frequencies of 5, 50, and 500 Hz. The relationship between the magnetic flux density vector B and magnetic field strength vector H has been systemically studied when the B loci are well controlled to be circles and ellipses in three orthogonal planes of the three-dimensional (3-D) tester. The core loss features against magnetic flux densities with alternating and rotational magnetizations are also compared and analyzed. It is found that the rotational core losses are nearly twice of the alternating core losses at the same magnitude of flux density. Experimental results show that SMC materials have good 3-D features, and great potential for application in rotational magnetic flux machines. © 2011 IEEE