Conference Agenda

The surface charging effect causes an inverted potential gradient at the triple junction of solar cells, which may easily trigger the primary discharge and threaten the safe operation of the spacecraft. In this study, based on the current balance equation, the PIC (particle-in-cell) method is used to simulate the surface charging effect of low-orbit spacecraft solar cells under three operating conditions: shadow, illumination, and polar, and the surface potential distribution under different operating voltages is obtained. The electric field distortion distribution at the triple junction is also obtained by the finite element method. This study can provide important theoretical guidance and technical support for evaluating the primary discharge risk of spacecraft solar cells.

Magnetic shielding devices (MSDs) can provide high shielding factors (SFs) and low magnetic noise (MN) environments for fundamental physics research, ultra-weak mind-brain magnetic high-resolution imaging, and material magnetic field analysis. To further suppress and calculate MN, we propose a permalloy-nanocrystalline (P-N) composite shielding structure and establish a quantitative calculation model for MN. Validation experiments conducted on the P-N composite MSD show an average error of 5.32% between theoretical and calculated values within the 3-100 Hz range, confirming the accuracy of the proposed calculation method. Compared to the permalloy MSD, the P-N composite MSD achieves a 29.6% reduction in MN.This research not only establishes a theoretical foundation for the design of low magnetic noise magnetic shielding devices but also offers innovative approaches and technical support for optimizing the application of ultra-weak magnetic field measurement systems.

Nanocrystalline magnetic shielding provides a near-zero magnetic field environment for spin-exchange relaxation-free (SERF) atomic magnetometers, enabling precise measurements of magnetocardiography (MCG) and magnetoencephalography (MEG). Accurate analysis of magnetic noise and its suppression of nanocrystalline magnetic shielding is critical to achieving ultra-high sensitivity in SERF magnetometers. In this study, a magnetic noise model for nanocrystalline spindle-shaped magnetic shielding cylinder (SMSC) considering anisotropy is proposed. Moreover, to more effectively demagnetize the nanocrystalline SMSC to achieve magnetic noise suppression, a segmented dynamic demagnetization model considering anisotropy is proposed.

Magnetic Flux Leakage (MFL) and Alternating Current Field Measurement (ACFM) are widely employed techniques for detecting defects in steel. However, their detection performance is often influenced by the orientation of the cracks, which is difficult to predict in real-world inspection scenarios. To overcome this challenge, we propose a novel fusion gradient imaging method. This approach involves scanning the defect along two orthogonal directions, combining the results, and computing the gradient to generate a fused magnetic map that is independent of crack orientation. Through both simulations and experiments on cracks with various orientations, we demonstrate that the proposed method effectively determines the position and orientation of surface cracks. The fusion gradient imaging technique ensures accurate and reliable crack detection, representing a significant advancement in electromagnetic non-destructive testing for surface crack inspection.

Air-core Rogowski coils (RCs) have been massively adopted in switchgears in smart distributions owing to various advantages, for instance non-magnetic saturation, non-contact measurement, light weight as well as low cost. Nevertheless, the measuring accuracy of the RC based current transformer (CT) at harmonics in general suffers from the skin effect, proximity effect, and crosstalk effect. In this paper, a rectangular RC (RRC) is designed and the degradation on the measuring accuracy caused by diverse effects is further analyzed. Initially, to consider the impact of the skin effect of a single-phase rectangular busbar, the analytical solutions for the computations of the distribution of the magnetic field and of the induced voltage are derived. Subsequently, for a three-phase rectangular busbar system the combined influence of skin effect, proximity effect, and crosstalk effect are assessed by using finite element method (FEM). The nonlinearity of the RRC at harmonics are then evaluated by considering the amplitude of the excitation and the central distance between two adjacent busbars. The results can be employed for the optimal design of the linearity for the RRC based CT.

Among the means of sensor-based position detection in electric machines, eddy current absolute position sensors have inherent advantages over magnetic encoders and resolvers in terms of size, cost, and robustness. To address the complexity of existing FEA based design methods, this paper proposed a general analytical model for sinusoidal-coil eddy current position sensors, clarifying the quantitative relationship between the output voltage and design parameters. The accuracy of the analytical model is validated through both FEA and experimental tests.

A whisker sensor based on magnetostrictive material is being investigated by using the finite element software LS-DYNA. The sensor’s behavior is based on the interaction between external force loadings and electromagnetic response. The material model includes different nonlinear B-H curves which depend on external stresses allowing the sensor to detect the effect of displacement. The numerical tool relies on intrinsic coupling between LSDYNA’s mechanical and electromagnetic (EM) solvers. During the simulation, geometry, mesh positions and material properties are given to the EM solver which uses this information to compute and update electromagnetic quantities (permeability, magnetic flux density, etc.). The EM solver returns electromagnetic forces to the mechanical solver that will subsequently apply as loading.

The previous work on the demagnetization fault detection of permanent synchronous magnet motor (PMSM) focuses on giving information of the fault’s existence or severity. However, the magnetic flux density distribution is rarely considered which provides the detailed model of the machine. As the sensor configuration affects the accuracy of the reconstructed field, in this paper, a greedy algorithm associated with a reduced order model based on POD is firstly proposed to solve the sensor placement problem while the sensors’ positions are confined on the surface of the stator for the ease of installation. And then the gappy proper orthogonal decomposition (Gappy-POD) is used to reconstruct the magnetic field when limited measurement points are available. An example of 2D surface-mounted PMSM with local demagnetization is presented. The results show that the Gappy-POD can reconstruct the magnetic field accurately with limited data and comparing to the randomly selected sensors, the sensor configuration determined by the proposed greedy algorithm provides better reconstruction performance.

Silicon steel in high-performance electrical equipment usually works at high saturation points (above 2 T) and high frequencies (above1000Hz). However, the existing measurement methods based on steady-state excitation are currently difficult to generate sufficient excitation magnetic fields to accurately measure the characteristics of silicon steel under high saturation states and high frequencies. Therefore, this paper proposes the Pulsed Magnetic Field (PMF) method to solve the problem. During the measurement process, a hysteresis loop correction technique is proposed to correct the hysteresis loop. It is found that the excitation magnetic field generated by the pulsed large current can reach above 200,000 A/m and can achieve a high saturation state above 2.3 T. By adjusting the capacitance value, the iron losses within the frequency range of 136 Hz to 1,000 Hz can be measured and the measurement error of iron loss is 3.2%. Depending on the circuit parameters, maximum frequency and induction during measurement can be configured. The PMF method fills the gap in the high-frequency and high saturated state testing area of the existing methods.

The precise measurement of permanent magnet (PM) materials' performance is crucial for related electrical equipment design. Currently, high-coercivity PM materials' demagnetization curves are mainly measured by pulse magnetic field (PMF) method. However with PM materials' development, their coercivity rises and requires more discharge energy. The large discharge energy affects coil's force and temperature, influencing its lifespan. To address these, an improved PMF method with a field shaper is proposed. The field shaper concentrates the magnetic field in the sample area, reducing discharge energy and keeping the sample's field strength. A new pickup coil is also proposed to calculate H, J and B via two built-in coils. The experimental results demonstrate that this method can enhance the magnetic field intensity by 34% under the same discharge voltage, thereby expanding the testing range of the device and enabling precise measurement of the demagnetization curve of the sample.

The Rogowski coil is a well-known transducer device use for its linear or large bandwidth characteristic, but it’s quiet a challenge

to wind a perfect Rogowski coil to minimize the current measurement error. In this paper, we will discuss the influence of different

winding and positioning defaults such as coil and turn tilt, turn density, and conductor positioning on current measurement. Using

Sobol’s method combined with Monte Carlo method, the aim of this study is to put the light on the manufacturing defaults that

have the worst influence on the actual current measurement accuracy

A characterization method for predicting the transfer curves of magnetic tunnel junction under applied field with different directions is proposed. By combining the Stoner-Wohlfarth model with the energy-based model, the coherent rotation and wall displacement process of domains in free layer are accounted simultaneously. The comparison between measured and calculated resistance shows that the model can accurately predict the magnetic properties of free layer and the transfer curves of magnetic tunnel junction.

This digest introduces an enhanced Jiles Atherton(J-A) model with angle-dependent parameters to achieve high-precision magnetization computations for permalloy alloys under conditions of anisotropic magnetic permeability. The conventional J-A model typically employs a uniaxial approach, fitting magnetization curves or hysteresis loops only along the easy magnetization axis. However, permalloy exhibits pronounced magnetic anisotropy, and in practical applications, magnetization or demagnetization may occur in any arbitrary direction. Therefore, the fitting of single axis leads to significant errors in magnetization predictions. To resolve this issue, the hysteresis and magnetization curves of permalloy sheets at various directions were measured and a nonlinear mathematical model for angles and JA parameters is established. The angle-dependent parameter J-A(ADP·J-A) model perform the magnetic field calculation using the magnetization parameters corresponding to the specific direction.