Advanced Materials Research Vols. 860-863

Abstract: This paper presents an equivalent magnetic circuit model to predict the leakage effect, especially the end leakage effect, of surface-mounted permanent magnet synchronous machine (SPMSM) in rim-driven marine current power (RMCP) system. The end leakage effect is usually neglected in most conventional permanent magnet (PM) machines. However, it is significant in the electrical generator of RPCM due to the short axial length. The idealized path and analytical expressions of end leakage permeance are given in this paper. Finite Element Method (FEM) 3D/2D and experimental values are presented to validate the proposed analytical model. With no need for the time-consuming FEM-3D calculation, a correction factor base on the analytical mode is proposed to adjust the results (e.g. back-EMF, torque) of conventional design when end leakage is ignored in the calculation. The calculation results and experimental values show that the proposed analytical model is accurate to analyze the leakage effects of SPMSM in RMCP system.

Abstract: Micro-hydro as a new energy technology, has good prospects for development.On some occasions which dont control, the generator usually choose self-excited induction generator.The paper presents a method which the asynchronous motor can instead of the induction generator, and calculate compensation capacitance of the self-excited induction generator. Finally,this paper verified by experiments, which the changes of the output voltage and frequency and the changes of harmonic by changing the resistive load, when the asynchronous generator open-loop runs. The results show that,this method has feasibility and validity.

Abstract: The data processing of static engine noise test, especially the elimination of ground reflection to access the free-field sound pressure level, has been defined as one of the basic steps in aircraft noise prediction on the noise certification procedure by ICAO^[1,. Based on the importance of the method, this paper will study the impact of the ground reflection effects on the aircraft engine noise experimental, especially made a detailed overview for the calculation method of reflective index.This paper also gives the method of fixing this effect to get the free field sound pressure level, while making experiments to verify the feasibility of this method, so that make the noise analysis and prediction according to the noise certification procedures.

Abstract: In this paper, the design principle of inductive current transformer is introduced at first. Then an inductive current transformer is produced by applying the structure of two-stage inductive voltage divider. And finally, the error of the sample machine is given through examine test, and the suggestion for improving the machine is given based on the data. The data from the sample machine shows that: without compensation winding, the error level of 1200 ampere-turn of inductive current transformer can reach 0.1 level, after adding the compensation winding, it can reach 0.02 level. The design and data have laid a foundation for the future design of inductive current transformer with higher level of accuracy.

Abstract: As the feature of faulty signal in high voltage direct current transmission technology based on voltage source converter (VSC-HVDC) system is complicated to extract and its difficult to carry on the fault diagnosis. On the basis of the PSCAD simulation model of VSC-HVDC system, the DC current faulty signal is analyzed. Then, the wavelet analysis method was adopted to extract the eigenvector of faulty signal, and combined with method of Bayesian regularization back-propagation (BRBP) neural networks, the system fault was identified. The simulation results show that the method is more efficiently and more rapidly than the adding momentum BP neural network on the VSC-HVDC system faults diagnosing.

Abstract: This study is to suggest using multiple transmission coils to improve the energy transfer efficiency of a wireless energy transfer (WET) system which aims to power electronic appliances such mobile phones, labtops, iPads, etc, without using cables. The original WET system consists of a large room-size transmission coil transferring energy wirelessly to a small receiver coil built insider an electronic appliance. The newly proposed system is to replace the single transmission coil with 3 orthogonally aligned transmission coils. The aim is to create a multi-oriented magnetic field so that energy transfer efficiency will be relatively more stable when the receiver coil changes in orientation. Our simulation results show that at some worse-situation orientations of the receiver coil, the increase in transfer efficiency is many folds, from 0.4% in the worse situation to a 2.75% after using the multiple-transmission-coil method. This, to some extent, safeguards the wireless charging process from a large power drop to a much smaller power drop during possible random motions of the receiver. But, on the other hand, the improvements obtained from the proposed system in the normal high-efficiency situations are not very significant.

Abstract: A simple fractional order nonlinear supercapacitors (SCs) electrical model has been established, taking into account the parameter variation, diffusion control and Faraday process. Frequency responses resulting from impedance spectroscopies around various operating voltages demonstrated that a SC exhibits a nonlinear behaviour in relation to the operating voltage. The model parameters are identified using fractional vector fitting and then a nonlinear model taking voltage dependency into account is obtained. Through building fractional order differential operator module in Simulink, the numerical solution of fractional order nonlinear calculus equation can be obtained directly. The model accuracy is verified through a comparison with the charging and discharing experimental results.

Abstract: The filtering method is proposed to diminish magnetic interference caused by ocean waves in marine magnetic survey. Variation characteristic of waves magnetic field about height and wind speed is analysed. Because waves magnetic field has similar frequency band with ships magnetizing field, wavelet packet transform is used to diminish the disturbing effect of wave. Simulation result indicates that the magnetic interference is removed effectively and ship magnetizing filed can be got in high precision, thus the method has great guiding meaning for practical marine magnetic survey.

Abstract: This paper presents a projection based on the true three-dimensional imaging display system. We analyzed true three-dimensional image display system imaging space construction, and proposed a new light emitting structure method of volume pixels (voxel), and also discussed feasibility employing local state-space model - Givone-Roessor model to compute the voxel variables. The mechanical structure is simple and the cost is inexpensive; the field angle is so larger that can display almost half a sphere except the zenith point; and the voxels constructor is easy to implement by micro controller due to the small amount of GR model calculation.

Abstract: Research on the wide-band modelling method of the grounding grid and the analysis of the electromagnetic transients on the grounding grid has significant practical meaning on the engineering problems, e.g. overvoltage protection, insulation coordination and electromagnetic interference and the increasing levels of capacity in the power and communication systems. This paper presents strategies which establish the equivalent circuit for computing the transient performance of grounding grid base on fractional order differential theory, which takes into account the fractional frequency characteristics of soil permittivity. In order to validate the presented method, an example is considered and the transient responses are compared with the results obtained by the method of moments.