International Journal of Applied Electromagnetics and Mechanics - Volume 56, issue 4

Authors: Slimene, Marwa Ben | Khlifi, Mohamed Arbi

Article Type: Research Article

Abstract: This paper presents, first a d-q purely mixed model including the mutual leakage flux and a digital field oriented control of a double star induction motor using a two-level six-phase inverter; seconds a PI regulator to control the speed and the stator current of DSIM. To achieve a control of this machine two voltage source inverter of PWM techniques are introduced. A comparison with a traditionally (PI) controller is discussed. Extensive simulation is performed and it is shown that the reduction of the current harmonics is in essence almost the same as in another recently developed DFOC scheme. However, the …achieved torque ripple reduction makes the scheme superior when compared to the existing approaches. At the same time, developed scheme retains qualities of conventional DFOC schemes, such as simple structure and fast response. Its additional beneficial feature is the easiness of implementation. Show more

Keywords: Field oriented control (FOC), double star induction motor (DSIM), Six-phase, current regulated pulse with modulation (CRPWM)

DOI: 10.3233/JAE-160136

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 4, pp. 511-520, 2018

Authors: Xu, Lizhong | Zheng, Fengjie

Article Type: Research Article

Abstract: The chaotic vibration has more important effect on the dynamic performance of the railgun system. It will cause violent vibrations and noise of the mechanical system and also cause large current oscillation in the electric system for the railgun. In this paper, the nonlinear electromechanical coupled dynamics equations for the railgun system are proposed. Using the equations, the nonlinear dynamic performance of the railgun system is investigated. Results show that under some conditions, quasi-periodic vibration and chaotic vibration could occur in the railgun system. The rail current, the distance between two rails, the rail thickness and rail width have effects …on the nonlinear vibration of the railgun system. To obtain good dynamic performance of the railgun system, these parameters should be chosen properly. These results are useful in maximizing the power density of the railgun and ensuring launch accuracy. Show more

Keywords: Railgun, chaotic vibration, bifurcation, electromechanical coupled

DOI: 10.3233/JAE-160142

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 4, pp. 521-531, 2018

Authors: Ansari, Zain A. | Abu-Nabah, Bassam A. | Alkhader, Maen

Article Type: Research Article

Abstract: Advantages offered through eddy current technology provide a promising solution to assess metallic coating thicknesses over nonmagnetic metals. Existing single- and multi-frequency impedance-based eddy current techniques are sensitive to both coating/substrate combinations and lift-off deviations from those used over the coated calibration blocks. The adoption of apparent eddy current conductivity (AECC) spectroscopy demonstrated the potential benefits to overcome these limitations and deliver one-order of magnitude improvement in coating thickness estimation within a ± 25.4 μ m lift-off range. To meet the plane-wave approximation, this technique requires capturing the AECC spectrum over a broad frequency range using …a relatively large coil design, which makes the technique less practical. This study takes the AECC-based technology a step further to operate at a single frequency in assessing metallic coating thicknesses of such nonmagnetic-layered structures. The criteria for reducing the coil diameter and selecting the inspection frequency are demonstrated in agreement with the plane-wave approximation and COMSOL simulations. Moreover, a new AECC-based inversion model is developed and validated for single-frequency AECC measurements over different coating thicknesses relevant to the industry. Show more

Keywords: Nonmagnetic, coating thickness, eddy current, nondestructive testing, inversion

DOI: 10.3233/JAE-170037

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 4, pp. 533-547, 2018

Authors: Qamar, Aamir | Yang, Fan | Xu, Naidong | Shah, Syed Ahmar

Article Type: Research Article

Abstract: Location and topology of substation grounding grids are critical for its regular tests and safe operation. Schematic drawing of the grounding grid is prone to getting lost or damaged. As excavation is costly and time consuming, locating substation grounding grid is important. This paper proposes a novel method to locate substation grounding grid by using the derivative method and the concept of locating a geometrical object in polar coordinate system. Due to rectangular structure of grounding grid, its location can also be determined from the location of its single branch. Simulation and experimental results verify that the proposed method is …feasible and accurate to solve the inverse problem regarding the location of substation grounding grid. Show more

Keywords: Derivative, grounding grid, location, magnetic flux density

DOI: 10.3233/JAE-170054

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 4, pp. 549-558, 2018

Authors: Li, Xiangchao | Cai, Lujin | Xu, Xiaopei

Article Type: Research Article

Abstract: Lightning overvoltage may affect the signal transmission and damage terminal equipment. In order to solve this problem, the signal system Surge Protection Devices (SPDs) is designed by analyzing the signal transmission characteristic and the design theory of SPDs. The impulse tests are performed on the SPDs using a combined wave generator. Residual voltages and sharing currents are measured and discussed by considering impulse voltages, DC breakdown voltages of downstream SPDs and decoupling resistances. The blind zone of the signal system SPDs is also discussed in detail. In addition, the SPDs are equivalent to a two-port network, and the influence of …distributed capacitance of the SPDs on signal transmission is analyzed for the first time through experiments. Cut-off frequency is measured and discussed by considering DC breakdown voltages of downstream SPDs and decoupling resistances. From the two experiments, the results indicate that increasing the decoupling resistance can decrease residual voltage and sharing current, but will reduce the cut-off frequency. Decreasing the DC voltage of downstream SPDs will have a similar effect. So the decoupling resistance and the DC breakdown voltage of downstream SPDs resistance need to be considered carefully in designing signal system SPDs. The sufficient research of signal system SPDs in this paper has a certain reference value in lightning protection. Show more

Keywords: Signal system SPDs, blind zone, sharing current, residual voltage, transmission characteristic, lightning protection

DOI: 10.3233/JAE-170069

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 4, pp. 559-571, 2018

Authors: Zhu, Ye | Luo, Yu

Article Type: Research Article

Abstract: Various industrial applications require fully coupled electromagnetic-thermal-structural (ETS) solution. However, the fully coupled ETS technique has rarely been reported. This is mainly due to the difficulty of transferring the displacement from a structural analysis to an electromagnetic analysis in many commercial FEM codes. In this paper, a fully coupled ETS model was constructed with a morphing technique to consider this transfer. This model and a conventional segregated model were then applied to simulate induction heating process of plate bending. It is found that the results with the fully coupled model significantly differed from those with the segregated one. The difference …can be attributed to the fact that the former model has changed the air gap between the inductor and the plate in the electromagnetic analysis. Furthermore, the proposed model was modified to compare with the segregated model that has been validated by highly precise experiment. The comparison shows the good agreement. Show more

Keywords: Morphing, ETS fully coupling, induction heating, plate forming

DOI: 10.3233/JAE-170076

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 4, pp. 573-583, 2018

Authors: Pfützner, Helmut | Shilyashki, Georgi | Windischhofer, Andreas

Article Type: Research Article

Abstract: The physical state of laminated soft magnetic machine cores has high technical and economical relevance, in particular if advanced materials are involved, as in the case of transformer cores. Experimental analyses tend to be restricted to core surface regions due to the high expenditure of interior arrangements of sensors. Further, the latter cause inter-laminar spaces, as a reason of artefacts. The paper presents a completely novel sensor concept that avoids the above problems. A magnetic detection band of e.g. 1 m length consists of different kinds of sensors. They are arranged on a substrate foil by combined 2D/3D-printing, the total …band thickness being below 100 μ m. Using the ends as handles, the band is located through the core. Electric connection sockets to electronics remain outside, thus avoiding increased inter-laminar spacing. They also allow for later failure diagnostics, by permanently arranged bands. Sensors concern local distributions of magnetic flux, losses, temperature, strains and vibrations. Manufacturing is aimed on versatile low-cost products. This paper describes procedures that are focused on flux sensors, in particular for in-plane flux that represents the most complex sensor type. For the first time, it enables interior measurements in non-destructive ways. Show more

Keywords: Induction sensors, magnetic sensors, nano-crystalline ribbons, 3D printing

DOI: 10.3233/JAE-170101

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 4, pp. 585-594, 2018

Authors: Xu, Zheng | Qi, Jinfeng | Guo, Pan | Cui, Xianjun | Wu, Jiamin

Article Type: Research Article

Abstract: Based on the equivalent magnetic dipole theory, a method for designing gradient coils of the Halbach magnet is proposed. Minimizing the energy consumption of the gradient coil is set as the optimal object, and the variance between the calculated and expected magnetic fields is taken as the penalty function. In this way, a quadratic optimization problem that cannot easily satisfy the magnetic field constraint condition can be easily transformed into an unconstrained optimization problem. By using the lsqnonlin optimization toolbox of Matlab, the distribution of the stream function on the cylindrical surface is calculated, and the three gradient coils of …the Halbach magnet are obtained according to the contour of the stream function. To validate the designed coils, the Biot-Savart law is applied to calculate the distribution of the magnetic field. The results show that the magnetic field distribution agrees well with the design object. The gradient coils are fabricated and the magnetic field distributions in the region of interest are measured. The measured data are almost similar with the calculated data, and the measured gradient uniformity of x ⁢ ( y ) and z coils are 4.47% and 2.34%, respectively, which are less than 5% of the commercial gradient coil requirements. Show more

Keywords: Equivalent magnetic dipole method, gradient coils, magnetic resonance, Halbach magnet

DOI: 10.3233/JAE-170115

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 4, pp. 595-604, 2018

Authors: Li, Chong | Xing, Jichun

Article Type: Research Article

Abstract: The mesh-type harmonic piezoelectric motor has advantages of low speed, large torque and long lifetime. However, the nonlinear axial forces of driving part affect the dynamic performance of the motor, which can result in a motor with a deteriorated load-capability. Hence, to deal with the above problem, the effects of nonlinear axial forces on chaotic vibration are investigated in this paper. Firstly, applying dynamic theory of continuous system, the nonlinear dynamic equations contains nonlinear axial forces of the driving system for a mesh-type piezoelectric motor are established. And then, using Runge-Kutta numerical method, the effects of nonlinear axial forces on …chaotic vibrations of the system are investigated. The results show that the chaotic vibrations occur in driving system of the motor under some parameters. The vibration displacements of the driving system become larger when considering nonlinear axial forces of displacement amplification mechanism. Under the effect of nonlinear axial forces, the chaotic vibrations occur easily when the system parameter is much smaller. The results can be used to predict the dynamic load and optimize power density of the mesh-type harmonic piezoelectric motor. Show more

Keywords: Chaotic vibration, piezoelectric motor, nonlinear axial forces, nonlinear dynamic

DOI: 10.3233/JAE-170118

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 4, pp. 605-622, 2018

Authors: Deng, Xianming | Liu, Na | Sun, Yuanda | Li, Shaowu | Ye, Zongbin

Article Type: Research Article

Abstract: A novel surface-mounted outer rotor transverse flux permanent-magnet motor (SMOR-TFPM) with simple structure and good performance is proposed in this paper. The basic structure and operating principle of the motor are introduced. According to the deficiency of the SMOR-TFPM electrical performance, this paper presents an improved design of the stator so that the motor performance is improved by transforming parts of the leakage flux into the main flux. The finite element model of the motor is established, the influence of the relevant parameters on the no-load magnetic leakage coefficient is optimally analyzed based on the three-dimensional finite element method. The …main parameters design of a three-phase and fifteen-pair-pole SMOR-TFPM is completed based on the improved design and optimization analysis. The coupling relationship of the interphase magnetic field is verified. Besides, the motor torque characteristics are researched and analyzed. The results prove that the structure and dimensions design of the motor is reasonable and the characteristics are stable, which has a certain feasibility. Show more

Keywords: Transverse flux permanent-magnet motor, structure improvement, magnetic leakage coefficient, torque characteristics, finite element analysis

DOI: 10.3233/JAE-170122

Citation: International Journal of Applied Electromagnetics and Mechanics, vol. 56, no. 4, pp. 623-635, 2018