Changgeng Zhang

Design and Analysis of a Novel 3-D Magnetization Structure for Laminated Silicon Steel

A novel 3-D magnetic properties tester for laminated silicon steel specimen has been designed and constructed. The magnetization structure is the critical part of the tester especially for the magnetic properties of the laminated silicon steel in perpendicular direction of grain oriented. To guarantee the experimental precision and accurately analyze the 3-D magnetic properties of the laminated silicon steel, a symmetrical 3-D magnetic flux path in the magnetization structure fit for given dimension of specimen has been calculated and modeled. Magnetic flux in each direction has been homogenized and concentrated on the top of the core poles through finite element analysis. Therefore, magnetic properties in each direction of the laminated specimen can be really concerned and analyzed in practical engineering.

Measurement of Three-Dimensional Magnetic Properties With Feedback Control and Harmonic Compensation

Three-dimensional (3-D) magnetic fluxes exist in rotating electric machines and T-joints of three-phase power transformers, and may cause local overheating in these devices. In this paper, 3-D magnetic properties of the core materials are measured by an improved 3-D magnetic property tester. First, the 3-D magnetization system is modeled by the voltage and flux linkage equations. Their parameters including the self and mutual inductances and nonlinear impedance are analyzed by the finite element analysis and measured by experiments. Second, a magnetic feedback method in the frequency domain is proposed to obtain the desired magnetization loci. Third, when the specimen is in deep magnetic saturation, the harmonics of magnetic flux density waveform would affect the shape of the corresponding magnetic field strength loci and the accuracy of loss computation. Thus, a waveform compensation method is proposed to eliminate the effects of harmonics. Fourth, the tensor effects of H coils are eliminated by averaging the results of clockwise and counterclockwise rotational experiments. Finally, the 3-D magnetic test system with feedback control, harmonics compensation, and automated data processing is developed. By using the 3-D magnetic tester, samples of nonoriented silicon sheet steel are measured with various excitation models and the results are more reliable than those obtained by experiments without feedback and harmonics compensation.

Anomalous Loss Modeling and Validation of Magnetic Materials in Electrical Engineering

By using statistical approaches, a calculation model of anomalous loss in magnetic materials is built on the basis of the production of anomalous loss and domain wall motion. Based on that, a macrophysical interpretation of this model is described in detail, and a testing method to determine the microstatistical characteristic parameters is proposed due to the pure anomalous loss obtained by the separation of total experimental core losses in electrical steel sheets. Meanwhile, the characteristics of the coefficient of anomalous loss are analyzed. In addition, rotating anomalous loss can be extended in this model. Therefore, under trusted error range, the separated and predicted values of alternating and three-dimensional rotating anomalous losses are compared and analyzed, respectively. The results clearly underline the necessity of achieving more accurate loss coefficients.

Optimization of output power and transmission efficiency of magnetically coupled resonance wireless power transfer system

Magnetically coupled resonance (MCR) wireless power transfer (WPT) system is a promising technology in electric energy transmission. But, if its system parameters are designed unreasonably, output power and transmission efficiency will be low. Therefore, optimized parameters design of MCR WPT has important research value. In the MCR WPT system with designated coil structure, the main parameters affecting output power and transmission efficiency are the distance between the coils, the resonance frequency and the resistance of the load. Based on the established mathematical model and the differential evolution algorithm, the change of output power and transmission efficiency with parameters can be simulated. From the simulation results, it can be seen that output power and transmission efficiency of the two-coil MCR WPT system and four-coil one with designated coil structure are improved. The simulation results confirm the validity of the optimization method for MCR WPT system with designated coil structure.

Structural design and output characteristic analysis of magnetostrictive tactile sensor for robotic applications

A novel magnetostrictive tactile sensor has been designed according to the transduction mechanism of cilia and Villari effect of iron-gallium alloy. The tactile sensor consists of a Galfenol beam, a pair of permanent magnets, a Hall sensor and a signal processing system. Compared with the conventional tactile sensor, our proposed tactile sensor can not only detect the contact-force, but also sense stiffness of an object. The performance and measurement range of tactile sensor have theoretically been analyzed and experimentally investigated. The results have revealed that the sensibility of tactile sensor for sensing force is up to 22.81mV/N at applied bias magnetic field of 2.56kA/m. Moreover, the sensor can effectively discriminate objects with different stiffness. The sensor is characterized by high sensitivity, good linearity, and quick response. It has the potential of being miniaturized and integrated into the finger of a robotic hand to realize force sensing and object recognition in real-time.

A novel 3D space vector PWM control method for 3D magnetic property measurement apparatus

This paper presents a novel three-dimension space vector pulse width modulation (3D-SVPWM) control method for the 3D magnetic property measurement apparatus. Arbitrary 3D magnetic flux density can be obtained by carrier-based PWM technique independently in each axis and vector summation of three axis. The proposed 3D-SVPWM which directly obtains 3D flux density is more efficient and lower harmonic flux root meam square(RMS) than carrier-based PWM technique. Core losses in motor supplied by PWM inverter is greatly different from that supplied by ideal sinusoidal power supply. So the magnetic material measurement supplied by PWM inverter is closer to the real engineering situation. Firstly, the tetrahedron-based and cube-based space state vector are proposed and analyzed. Secondly, the SVPWM method is extended from 2D vector space to the 3D vector space. Thirdly, the optimization switching pulse sequence for 3D-SVPWM is researched. At last, the simulation proves that the three-level 3D-SVPWM drive for 3D magnetic property measurement is efficient.

Magnetic properties modeling of soft magnetic composite materials using two-dimensional vector hybrid hysteresis model

A 2-D vector hybrid hysteresis model for a soft magnetic composite (SMC) material is established, which is combined with classical Preisach model and Stoner-Wohlfarth (S-W) model. The rotational magnetic properties of SMC materials were studied using the vector model, and the computed results were compared with the experimental measurement. It is shown that the vector hybrid model can effectively simulate the rotational magnetic properties under low magnetization fields.

Finite element analysis of displacement actuator based on giant magnetostrictive thin film

With the rapid development of science and technology, mechanical and electrical equipment become more and more miniature. In order to achieve precise control in less than 1cm3, the giant magnetostrictive thin film has become a research hotspot. The micro displacement actuator with planar and arc film is designed by the dynamic coupling model based on J-A model and magneto-mechanical effect method which is proposed in this paper. The different structure and thickness of films are analyzed by COMSOL Multiphysics software when the current flows through driving coil. After comparing the simulation results with the test ones, it can be seen that the coupling model is accurate and the structure is reliable. At the same time, MATLAB is used to fit the current density-displacement curve and higher order equation is obtained, and then the feasibility of design can be verified. The actuator with arc structure had advantages of small volume, fast response, high precision, easy integration, etc., which has a broad ap...

Magnetic measurement of soft magnetic composites material under 3D SVPWM excitation

The magnetic properties measurement and analysis of soft magnetic material under the rotational space-vector pulse width modulation (SVPWM) excitation are key factors in design and optimization of the adjustable speed motor. In this paper, a three-dimensional (3D) magnetic properties testing system fit for SVPWM excitation is built, which includes symmetrical orthogonal excitation magnetic circuit and cubic field-metric sensor. Base on the testing system, the vector B and H loci of soft magnetic composite (SMC) material under SVPWM excitation are measured and analyzed by proposed 3D SVPWM control method. Alternating and rotating core losses under various complex excitation with different magnitude modulation ratio are calculated and compared.The magnetic properties measurement and analysis of soft magnetic material under the rotational space-vector pulse width modulation (SVPWM) excitation are key factors in design and optimization of the adjustable speed motor. In this paper, a three-dimensional (3D) magnetic properties testing system fit for SVPWM excitation is built, which includes symmetrical orthogonal excitation magnetic circuit and cubic field-metric sensor. Base on the testing system, the vector B and H loci of soft magnetic composite (SMC) material under SVPWM excitation are measured and analyzed by proposed 3D SVPWM control method. Alternating and rotating core losses under various complex excitation with different magnitude modulation ratio are calculated and compared.

Core loss calculation for magnetic materials employed in SMPS under rectangular voltage excitations

Magnetic materials are widely used in switching-mode power supplies (SMPS) and magnetic components in SMPS usually work under two typical rectangular excitations (with or without the period of zero voltage). Extensive experimental results have shown that there is quite a difference of core loss between sinusoidal excitations and rectangular excitations, which means the traditional core loss calculation methods are no longer applicable. In this paper, two formulas for core loss calculation under the above rectangular excitations are derived based on the Improved Generalized Steinmetz Equation (IGSE). Core loss of different magnetic materials, under both sinusoidal excitations and rectangular excitations with different frequencies and duty cycles, are measured. Experimental results show that the formulas are accurate enough and very useful to predict the core loss.