Rongge Yan

Optimization of hysteresis parameters for the Jiles-Atherton model using a genetic algorithm

A dynamic model with hysteretic nonlinearity for magnetostrictive actuators has been established, combined with the Jiles-Atherton model. The hysteresis parameters for the model have been optimized using the genetic algorithm (GA). Simulation and experimental results demonstrated the effectiveness of the model and parameter identification approach.

Design and Realization of a Novel Compact Fluxgate Current Sensor

A new closed-loop magnetic current sensor is presented in this paper. The sensor consists of two toroidal magnetic cores. One core works in fluxgate principle for the measurement of dc and low-frequency ac, and the other one is used as a current transformer for higher frequency application. Based on the simulation results, a prototype was designed, and the test results have a good agreement with the simulation results. The closed-loop configuration with a magnetic core and a feedback winding in the sensor improved the sensitivity of the sensor, eliminated the offset and drift related to temperature, and greatly reduced the error caused by magnetic hysteresis phenomenon. It can measure currents up to 20 A, with an accuracy of 0.5%, and a 50 kHz small signal bandwidth.

A Magneto-Mechanical Strongly Coupled Model for Giant Magnetostrictive Force Sensor

In this paper, the modeling of force sensors built with rare-earth iron giant magnetostrictive materials is studied. For such a purpose, a magneto-mechanical strongly coupled FE model is proposed. Using the proposed model, the input-output characteristic of a force sensor built with giant magnetostrictive material (Tb-Dy-Fe alloy) is calculated. The obtained results are compared with the measured ones to examine the validity of the proposed magneto-mechanical strongly coupled model and the FE implementation. Satisfactory agreements are achieved. This indicates that the proposed FE model can be used in the design and optimization of giant magnetostrictive force sensors

A numerical model of displacement for giant magnetostrictive actuator

A numerical model of displacement for a giant magnetostrictive actuator was founded. According to the model and the measured magnetic characteristic of giant magnetostrictive material, the relation between input current and output displacement for the actuator was calculated by means of the finite element method. A comparison between the calculating result and experimental one for the actuator was carried out and it was found that they were in agreement well. This demonstrates that the numerical model can be used for the design of giant magnetostrictive actuators.

Numerical computation for a new way to reduce vibration and noise due to magnetostriction and magnetic forces of transformer cores

Magnetostriction (MS) caused by the global magnetization of limbs and yokes and magnetic forces are the undisputed causes of the vibration and noise in power transformer cores. This paper presents a novel way to reduce the vibration and noise, in which nanocrystalline soft magnetic composite (NSMC) material with high permeability is used to fill the step-lap joint gaps of the power transformer magnetic cores. In order to numerically predict the effectiveness of the proposed method, a 3-D magneto-mechanical strong coupled model including MS and magnetic anisotropy of steel sheet was founded. Then, the numerical model was applied to analyze the step-lap joint region of the corner of magnetic cores. The analysis results illustrated that the deformation and noise of core with NSMC are lower than with the traditional epoxy damping material. Moreover, the validity of the proposed new way was verified by the simplified step-lap joint cores, which were achieved based on Epstein Frames.

Dynamic Response of Pressure Sensor With Magnetic Liquids

This paper presents our study on differential pressure sensors realized with magnetic liquids. We illustrate our work using a ¿U¿ tube type magnetic liquid sensor model and the corresponding experimental setup. Three major efforts are: developing the mathematical model describing the dynamic characteristic of the sensor based on the first law of thermodynamics, conducting FE simulation of electromagnetic field with magnetic liquids, and performing experimental implementation and examination using a non-magnetic based differential pressure sensor purchased. Experimental observation indicates a good agreement between the step-response and random response given by the developed magnetic liquids based sensor and the purchased non-magnetic liquids based sensor.

Electromagnetic Vibration of Motor Core Including Magnetostriction Under Different Rotation Speeds

The vibration of permanent magnet synchronous motor (PMSM) cores is related to the rotation speed. This paper presents a generalized magnetoelastic 3-D finite-element model, which can be used to calculate the magnetic field and structural vibration of laminated cores, including magnetostrictive effect. Magnetostriction (MS) is a property of electrical steel and causes the vibration of motor cores, the primary cause being electromagnetic forces. To implement the model, the vibration of a PMSM core was numerically analyzed under excitation with different frequencies. The speed and vibration were measured simultaneously by pulse and accelerometer sensors, and the variation of speed and vibration features was analyzed by Fast Fourier Transformation (FFT) versus Revolutions per minute (RPM). The numerically analyzed results showed that the vibration due to MS is important, and the magnitude of vibration is related to the operating speed. Vibration and speeds of the motor were tested and analyzed. The results showed that there is a vibration peak in the range of 600-2000 r/min (30-100 Hz), which is acceptable in calculation.

Element-free Galerkin modeling of giant magnetostrictive thin films

A meshless method called the element-free Galerkin method (EFGM) is introduced into the calculation of magnetostrictive thin film. With the finite element method (FEM), the distortion of the elements will decrease the precision, so EFGM is used to solve this problem. Two different magnetomechanical coupling models are proposed and a thin film cantilever is simulated with these two modeling methods. At last, the results are compared with the experiment data to illustrate the performance of EFGM and the correctness of the models.

Research on Three-Dimensional Stress Distribution of Reactor Core

Gapped iron-core reactors can obtain larger inductance, but they make larger vibration and noise than other kinds of reactors. On vibration dampers, many researchers kept their eyes on vibration isolation structures or vibration isolation materials. However, they did not compute reactor core vibration under fundamental frequency voltage or harmonic one. Because stress is the inherent reason of vibration and noise, this paper proposes a finite-element model for reactor core stress calculation based on the Maxwell stress theory. The model can handle reactor exciting currents, not only fundamental frequency but also superposition of fundamental frequency with different harmonics. Because core materials have different magnetic characteristics under different excitation conditions, this paper tested multigroup H-B curves to support the simulation. Then, the finite-element method is used to calculate the magnetic field and Maxwell stress distribution. Finally, the frequency spectrum of the stress is analyzed to provide a theory basis for further analysis of vibration and noise reduction in gapped iron-core reactors.

Magnetoelastic Numerical Analysis of Permanent Magnet Synchronous Motor Including Magnetostriction Effects and Harmonics

This paper investigates the vibration characteristic of a permanent magnet synchronous motor (PMSM) including magnetostriction (MS) and harmonics, which are the potential cause of additional vibration and noise from PMSM. First, a strong coupled model between the magnetic field and the mechanical deformation in the stator is built based on the piezomagnetic laws. Then, the vibration analysis of a 1.5 kW PMSM is carried out in finite element by using the model and measured MS curves. And finally, the vibration of a 1.5 kW PMSM is tested and both analysis and measured results indicate that MS and harmonics are significant and must be accounted for motor core electromagnetic design.