International Journal of Applied Electromagnetics and Mechanics - Volume Pre-press, issue Pre-press

Authors: Liu, Zenghua | Li, Aili | Bin, Wu | He, Cunfu

Article Type: Research Article

Abstract: Electromagnetic acoustic transducers (EMATs) have been widely applied in non-destructive tests for structural health monitoring. This paper proposes a flexible surface wave electromagnetic acoustic transducer (FSW-EMAT), which uses flexible rubber magnets instead of hard permanent magnets, in order to achieve the defects detection of steel pipe or other ferromagnetic structures with a certain surface curvature. Traditional EMATs mainly consist of three parts: magnet, coil and metal specimen to be tested. Permanent magnets or electromagnets are generally used to produce the strong magnetic flux density. However, the two kinds of magnets are not suitable for the defect detection of metal specimens …with a certain curvature. The proposed FSW-EMAT in this paper adopts a flexible magnet, which is a mixture of rubber and iron powder and has strong flexibility to fit the bent specimen. The proposed FSW-EMAT can be easily applied in the testing of curved structural component and detect axial and circumferential defects by rotating the transducer. Show more

Keywords: Nondestructive testing, electromagnetic acoustic transducer, surface wave, pipe detection

DOI: 10.3233/JAE-190043

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-17, 2019

Authors: Chen, Wei | Wu, Guichu | Li, Yan | Ma, Jien

Article Type: Research Article

Abstract: This paper proposes a coupled finite element analysis of magnetic-thermal fields using an adaptive single-mesh method. To avoid errors from the data transfer and the mesh reconstruction due to different mesh requirements for the magnetic and thermal analysis, this proposed method built single mesh for both analyses. The results of the coupled parameters were transmitted through the single mesh between magnetic and thermal fields. According to the characteristics of the magnetic and the thermal distribution, the master-slave node method was employed to simplify the original element matrix into the magnetic and the thermal matrices, where slave nodes were no longer …solved in the solving process. Results of the slave nodes were expressed by their mater nodes using weight coefficients to regain the results of the original element matrix. A permanent magnet machine was introduced to validate the proposed method with both the commercial software and the experimental tests. Compared to the commercial software, the time cost was reduced by more than 8.0% when a higher accuracy of the thermal analysis was obtained. Show more

Keywords: Coupled analysis, finite element analysis, master-slave method, single mesh, thermal analysis

DOI: 10.3233/JAE-180093

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-14, 2019

Authors: Wang, Huimin | Wang, Tong | Zhang, Xuefeng | Guo, Liyan

Article Type: Research Article

Abstract: As the traditional flux-weakening control strategies have some limitations, such as poor parameter robustness, non-ideal dynamic performance in the constant power region and so on, a new control strategy based on the formula-based feedforward control and the voltage feedback control is proposed. In this strategy, the given reference values of the flux-weakening currents are first calculated by the simplified formulas used in feedforward control, improving the processing speed of the controller by reducing the computational complexity. Then the reference value of the d axis current is compensated by the fuzzy-PI feedback controller, avoiding operating point drifts caused by the …change or inaccurate of parameters in the actual. On this basis, a switching strategy is proposed to achieve a smooth switching between the constant torque and the constant power operation region. The experimental results show that the proposed control strategy has excellent performances, such as strong robustness to parameter perturbation, ideal dynamic performance in the flux-weakening region, smooth switching between the operation regions and so on. Show more

Keywords: Interior Permanent Magnet Synchronous Motor (IPMSM), flux-weakening, fuzzy-PI controller

DOI: 10.3233/JAE-190014

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-13, 2019

Authors: Yin, Rui | Shi, Yan | Di, Changan

Article Type: Research Article

Abstract: Aiming at the problems of complex structure and slow response of the existing hydraulic active suspension actuator, an electromagnetic linear actuator (EMLA) with simple structure, stable operation is designed in this paper. Based on completing the structural design of the EMLA, the two-dimensional finite element model is established by using the finite element software JMAG, and transient analysis of EMLA is carried out, including analyses of no-load magnetic field and thrust force characteristics. The prototype is trial-produced, and its thrust force characteristics are measured on a designed test bench. The experimental values are close to the simulated values, which verifies …the correctness of the model. Finally, by analyzing the variation of the electromagnetic thrust force under different loading currents, this paper obtains the thrust force constant of the EMLA (183N/A). Show more

Keywords: Electromagnetic linear actuator, JMAG finite element, prototype, thrust force characteristics

DOI: 10.3233/JAE-190070

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-12, 2019

Authors: Zhang, Haijun | Zhang, Hua | Ma, Qiang | Han, Haifeng | Wang, Shuhong

Article Type: Research Article

Abstract: Frequency Response Analysis (FRA) is an effective diagnosis approach to detect the winding mechanical faults in power transformer. For understanding the FRA signatures of transformer windings quantitatively, this paper uses the sensitivity method to study the characteristics of frequency response function (FRF) in equivalent circuit of transformer windings. The sensitivity expressions of FRF can be determined by adjoint network method and Tellegen theorem, which reflects the influence of electric parameter changes on FRA signature under winding faults and within a wide-frequency band (10 Hz to 2 MHz). To verify the sensitivity calculation, a two-winding transformer model with seven discs was established and …taken as an example. The results indicate that FRF sensitivity data can provide the valuable insights about how the frequency responses are affected quantitatively with respect to the electric parameter changes or different winding faults. The method and sensitivity analysis discussed in this paper may be useful for diagnosing and predicting different mechanical deformation faults of transformer windings. Show more

Keywords: Transformer winding, equivalent circuit, frequency response, sensitivity analysis

DOI: 10.3233/JAE-190038

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-11, 2019

Authors: Ding, Li | Zhang, Jiasheng | Lin, Aiguo

Article Type: Research Article

Abstract: In order to ensure the safety of fluid flow in deep-water submarine pipelines, a safe and energy-saving built-in skin effect electric heat tracing technology was adopted as the thermal management strategy. By analyzing the multi-physics conditions of the electromagnetic field-temperature field in the heating state of pipelines, the corresponding control equations were derived, and the physical model was established using the transient electromagnetic-temperature coupling field of Ansys Workbench. Simultaneously, we calculated the equivalent parameters of the oil pipeline and heating cable as the load when the system is heated to different temperatures. Thus, the main circuit parameters of the power …supply for the built-in skin effect electric tracing system were designed, thus providing the theoretical guidance for the key performance optimization. For regulating the output power of the built-in skin effect electric heat tracing system, the nonlinear active disturbance rejection control strategy was newly adopted to achieve closed-loop power regulation based on the Buck chopper, and the system has the advantages of fast dynamic response and strong anti-interference ability. Finally, the feasibility of the proposed control system was verified by simulation. Show more

Keywords: Built-in, electric heat tracing system, coupled field, finite element analysis, ADRC

DOI: 10.3233/JAE-190001

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. 1-15, 2019

Authors: Dou, Yu | Li, Yongjian | Zhu, Jianguo | Wang, Lixiang | Li, Angxuan | Zhang, Changgeng

Article Type: Research Article

Abstract: Accurate magnetic properties measurement of the magnetic materials plays an increasingly important role in electromagnetic devices design and optimization at high frequency. In this paper, the effects of high-frequency winding are mainly evaluated by theoritical and numerical analysis. Considering the skin effect in excitation winding, an equivalent model for the AC resistance of the copper foil winding is established, which determined the optimum thickness of copper foil under different excitation frequency. Then based on the finite element analysis, the segmented excitation windings with copper foil is designed, which can reduce the influence of high frequency and distributed capacitance. Moreover, the …segmented windings are wrapped around by ferromagnetic plates, which can restrain the fringing effect and ensure that the excitation frequency can be up to several kilohertz. Show more

Keywords: Distributed capacitance, skin effect, proximity effect, foil winding

DOI: 10.3233/JAE-190137

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. S1-S8, 2019

Authors: Li, Yongjian | Jiang, Baolin | Zhang, Changgeng | Liu, Yang | Gong, Xuehai

Article Type: Research Article

Abstract: Based on a closed-circuit testing equipment, eddy current loss measurement method of the permanent magnetic material is proposed and studied in this paper. The tested material sample is NdFeB, which has been widely used in electrical machines. The NdFeB is usually coated with corrosion-resistant metal, such as highly conductive zinc and copper to resist corrosion in practical use. The coating material may influence the eddy current loss of the permanent magnet. In this situation, eddy current losses of the NdFeB sample with and without coating are measured and compared with sinusoidal excitation at different frequencies. The experimental results provide very …important reference in electrical machine design. Show more

Keywords: Permanent magnetic material, B-H loop, eddy current

DOI: 10.3233/JAE-191145

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. S1-S10, 2019

Authors: Chazal, Hervé | Geoffroy, Olivier | Galopin, Nicolas | Kedous-Lebouc, Afef

Article Type: Editorial

DOI: 10.3233/JAE-193000

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. S1-S1, 2019

Authors: Zurek, Stan | Rygał, Roman

Article Type: Research Article

Abstract: Magnetic field strength H is often measured with so-called H-coils. These are typically wound with a wire on flat thin paramagnetic formers, which allows them to be placed as close as possible to the surface of the magnetic sample under test. However, such wire-wound H-coils are not completely immune to off-axis H components. This paper presents a novel concept of an H-coil design which significantly improves the immunity to off-axis components. Such H-coils can be made by utilising the precision of printed-circuit boards (PCB) and experimental results are shown for a prototype. PCB technology opens the possibility of …making precisely aligned large H-coils, easy extrapolation of values towards the surface of the sample and accommodating wires for B-coils. Show more

Keywords: H-coil, magnetic field strength, measurement uncertainty, rotational power loss

DOI: 10.3233/JAE-199329

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. Pre-press, no. Pre-press, pp. S1-S8, 2019