The broad application of electronic device in the power systems requires a practical model to characterize hysteresis loops of electrical steel excited with harmonic components. However, the existing dynamic models may not appropriate for application because of their complexities and neglects of the minor loops caused by harmonics. This paper proposes a new algorithm that updates model parameters with magnetization history to modify Tellinen Model. The improved model can describe the static hysteresis loops containing minor loops and predict return-point memory effect. Also, combining with the Thin Sheet Model, a new dynamic model is built to characterize dynamic loops with harmonic components. The new model only requires quasi-static major hysteresis loops and dynamic major hysteresis loops under sinusoidal excitation to identify parameters. A comparison between measured loops and calculated results under both sinusoidal and harmonic excitations shows good agreement and validates the accuracy of the proposed model.

Accurate measurement of magnetic fields holds immense significance across various disciplines, such as IC circuit measurement, geological exploration, and aerospace. The sensitivity and noise parameters of magnetic field sensors play a vital role in detecting minute fluctuations in magnetic fields. However, the current detection capability of tunneling magnetoresistance (TMR) is insufficient to meet the requirements for weak magnetic field measurement. This study investigates the impact of structural and fabrication parameters on the performance of TMR sensors. We fabricated series-connected TMR sensors with varying long-axis lengths of the elliptical cross-section and adjusted their performance by modifying annealing magnetic fields and magnetic field bias along the easy axis. The results demonstrate that TMR sensitivity decreases with increasing long-axis length, increases initially and then decreases with an annealing magnetic field, and decreases with a higher bias magnetic field along the easy axis. The voltage noise level of TMR sensors decreases as the long-axis length increases. Notably, the detection capability of TMR sensors exhibits a non-monotonic dependence on long-axis length. Moreover, we optimized the hysteresis of TMR sensors by applying a magnetic field bias along the easy axis. When the bias along the easy axis reached 16 Oe or −40 Oe, the hysteresis level was reduced to below 0.5 Oe. After encapsulating the TMR devices into a full Wheatstone bridge structure, we achieved a detection capability of 17 nT/$\sqrt{\mathrm{Hz}}$@1Hz. This study highlights that the detection capability of TMR devices is jointly influenced by fabrication parameters. By optimizing parameter configuration, this work provides theoretical guidance for further enhancing the performance of TMR devices in magnetic field measurements.

In this article, a model that describes the anisotropic behavior and core loss of electrical steel sheets over a wide range of rotational excitation is developed. Based on the definition of the effective field, the macroscopic anisotropy field is deduced from a weighted average of the magnetocrystalline energy of a single crystal. An anisotropic vector hysteresis model is then proposed by applying the effective field to the energy-based model. Experimental measurements are used to fit and validate the model. Either alternating or rotational measurements with a maximum magnetic flux density 1.55 T under 10 Hz are employed to fit the model parameters and the remaining set of measurements is used for validating the model accuracy. The results show that the model can naturally account for the drop in the rotational losses at high flux densities regardless of whether it is identified from alternating or rotational measurement data. The generality of the model is demonstrated through continuous angle results and modeling of another material.

Single sheet tester (SST) is a traditional method for measuring magnetic properties of silicon steel. In order to make the measurement more accurate, this paper presents an improved SST with double yokes and double sheets. The electromagnetic simulation demonstrates that the magnetic field strength H between the two sheets that are in symmetric magnetic path approximately equal to H of two sheets, proving that the improved SST has higher test accuracy than the traditional double-yoked SST. A novel control method is proposed for the measurement system to make sure the symmetry of magnetic path. In this experiment, the magnetic field strength H and the magnetic flux density B of the tested samples are measured by an induction coil method, and the maximum working frequency of this apparatus can be up to 20 kHz.

Measuring weak magnetic fields proposes significant challenges to the sensing capabilities of magnetic field sensors. The magnetic field detection capacity of tunnel magnetoresistance (TMR) sensors is often insufficient for such applications, necessitating targeted optimization strategies to improve their performance in weak-field measurements. Utilizing magnetic flux concentrators (MFCs) offers an effective approach to enhance TMR sensitivity. In this study, the finite element method was employed to analyze the effects of different MFC geometric structures on the uniformity of the magnetic field in the air gap and the magnetic circuit gain (MCG). It was determined that the MCG of the MFC is not directly related to the absolute values of its parameters but rather to their ratios. Simulation analyses evaluated the impact of these parameter ratios on both the MCG and its spatial distribution uniformity, leading to the formulation of MFC design optimization principles. Building on these simulation-derived principles, several MFCs were fabricated using the 1J85 material, and an experimental platform was established to validate the simulation findings. The fabricated MFCs achieved an MCG of 7.325 times. Based on the previously developed TMR devices, a detection sensitivity of 2.46 nT/$\sqrt{\mathrm{Hz}}$ @1Hz was obtained. By optimizing parameter configurations, this work provides theoretical guidance for further enhancing the performance of TMR sensors in magnetic field measurements.