Applied Mechanics and Materials Vols. 229-231

Abstract: The paper is to design and implement parallel operation of paralleled inverters with interleaved phase shift. For parallel operation, one inverter is used as master module to transmit synchronization signals to trigger the external interrupts of two microcontrollers for synchronous operation to slave module. In this paper, the design of voltage controlled loop feedback controller by proportional-integral controller is employed to have fast transient response with different load conditions. It is proposed that interleaved phase shift for parallel inverters could reduce output voltage ripple of inverter and increase the system response. The experimental results show that the proposed inverter provided a voltage output with low harmonic distortion by the proposed interleaving phase-shift parallel inverter scheme.

Abstract: According to IEC60060-1, IEC60060-2 requirements, on-site tests for the high voltage apparatus can not be achieved due to many external factors such as the huge impulse voltage source and external electrical and magnetic fields, weather condition, etc. Therefore, IEC60060-3 points out the impulse waveforms for the high voltage apparatus during on-site tests, one of the impulse waveforms is the oscillating switching impulse, but the oscillating switching impulse source with high amplitude is a bulky test equipment which is not suitable for the on-site test, consequently the demands for portable oscillating switching impulse source is urgent. This paper presents that the high oscillating switching impulse voltage can be generated by a low oscillating switching impulse voltage with the power transformer which is the test object, the simulation and experiment results show this method can be used for the power transformer during oscillating switching impulse on-site test.

Abstract: ANSYS12.1 software is applied to the generator frame modeling and the static and dynamics performance analysis of the frame. The frame is calculated to find the max stress and the first six frequency, and based on the results, some suggestions is put forward for the optimization design.

Abstract: With the increasing energy requirements, IEE, CAS (Yan Peng’s team) proposes a new wave direct generating power way of liquid metal magnetohydrodynamic (LMMHD). The principle of the new power generating way was introduced and the design and numerical simulation of magnet was described in the paper, which is used to a power generating apparatus of 5 kW.

Abstract: This paper presents numerical results in the form of graphs of the power reflection coefficients for electromagnetic signals normally incident upon a conductive plane covered with two layers of inhomogeneous plasma slabs. The plasma electron density varies only in the direction perpendicular to the plane. Parameters considered in the computation cover a relatively wide range and the functional dependence of the power reflection coefficients on these parameters is studied. The results indicate that in a rather broad frequency range, the electromagnetic attenuations by the double slabs obviously excel the sum of attenuations resulted from two plasma layers when each layer exits respectively. The structure presented is easy to set up, which is instructive for plasma stealth.

Abstract: In order to further improve the power supply system reliability of low voltage high current vehicle generator, hybrid excitation is used and the permanent magnets are added between the main magnetic poles body and pole shoes. Aiming at reply the problem of limited installation space, the asymmetric pole structure, non-uniform commutating pole, single wave windings playing a role of the pressure line and oblique brush etc are investigated for improving commutation. This paper researched on the distribution of the flux line, the waveform of the air gap magnetic field, and analysis inner magnetic field at the loading by hybrid excitation and no loading by permanent magnet excitation alone respectively with the method of finite element. The results reveal that the magnetic field established by several excitation systems is still symmetric and uniform although the asymmetric structure, so it ensures the provision of suitable medium space for mechanical and electrical energy conversion. By comparing the permanent magnets excitation alone and hybrid excitation in a generator magnetic field distribution and air gap magnetic field waveform, the permanent magnet excitation and electricity excitation realized the superposition of magnetic field, and common establish main generator magnetic field. Hybrid excitation also reduces the current density of excitation coils and improves the heat dissipating performance compared with electrically excited alone. Through the performance analysis of the hybrid excitation, the output voltage waveform is very stable. The curve of auxiliary excitation current along with velocity variation provide important basis for excitation control devices and the development of control algorithm. It will help to improve the stability, reliability and security of the generator, the results can provide key technical support to the development of low-voltage high-current hybrid excitation vehicle generator.

Abstract: Electro-explosive device (EED) is easily influenced by electromagnetic interference (EMI) in war-field. To study the electromagnetic susceptibility of EED, the method based on full-wave physical modeling and resonance effect simulation is presented. The EMS of non-contact fuse is analyzed as an example. The test data validate the correction of the EMS analysis method, which is of great value for reference to Electromagnetic compatibility (EMC) design of EED.

Abstract: A control scheme based on the load harmonic current feed-forward compensation for three-phase pulse width modulated (PWM) voltage source inverter is presented. This control scheme is designed to improve the quality of the three-phase inverter output voltage under nonlinear load. The model of the control system in the d-q coordinate system is established based on the traditional double loop control where the feed-forward current is taken from a band pass filter. In order to analyze this compensation method, the system is divided in to two subsystems and each subsystem is analyzed, and the structure of the output harmonic current feed-forward compensation channel is given. Simulation and experimental result validate that the proposed feed-forward compensation method has a good steady state performance and dynamic responses.

Abstract: We study the electrolytic flow in a system of coplanar parallel electrodes subjected to an AC field. The model system has been thoroughly examined numerically for a large range of frequencies of the applied potential where we find a peak in the spectrum of the velocity magnitude at high frequencies along with exhibition of a pronounced peak at lower frequencies. Interestingly the first peak in the velocity spectrum shifts to lower frequencies while the second peak to higher frequencies with increasing distance from the electrode edge which suggests a formation of a non-planar electric double layer structure at higher frequencies.

Abstract: Electrical drives play a vital role in industrial and domestic applications, so these drives must be more efficient and easy to control. Conventional control methods are well established and nearly fulfill all demands of modern electrical drives but there is still a need to improve these controllers. In this paper it is proposed that the conventional field oriented controllers can be replaced by Model Predictive Controllers (MPC) which are currently being used as process controllers. These MPC controllers are preferred over conventional field oriented controllers because they can predict future behavior of system and according to that predicted value they can adjust their present input in order to minimize the error signal. The major drawback of conventional MPC is that a lot of mathematical iterations are required to predict the future behavior of system so Laguerre function’s based MPC model is used to reduce the mathematical effort and results are validated for a three phase induction motor.