Applied Mechanics and Materials Vol. 392

Abstract: The rails of the medium-low speed maglev system are entirely manufactured by roller milling, and eddy current in the rail can be induced when relative movement between the electromagnet and the rail manifests. The eddy current reduces the magnetic field in the air gap between the electromagnet and the rail, which, as a result, decreases the levitation force; and higher speed will cause more levitation force lost. Moreover, the eddy current produces a drag force which is opposite to the propulsion force generated by the linear inductive motor. In this paper, based on the electromagnetism, the formulae for the levitation force and the drag force of the electromagnet are deduced when the eddy current in the rail is taken account. Simulations based on the model of the maglev vehicle on the Tangshan maglev test line are also performed. The results indicates that the levitation force is significantly affected by the eddy current in the rail, and when v = 200 km/h, the levitation force of a single electromagnet is reduced by 35.6%; meanwhile, the drag force increases dramatically as the speed increases, but when the speed exceeds 100 km/h, the drag force stops increasing, and it equals 2.28% of the stationary levitation force.

Abstract: A hybrid bus power supply project is presented in this paper, compared with the characters of current bus power supply. The paper establishes a dual power supply ( engine and bus power supply) hybrid bus power distribution simulation model, and analyses the requirements of the power supply for hybrid bus. In order to analyses the requirements of HEV bus power supply, the model is under the theory of HEV control strategies.

Abstract: In this paper a speed tracking controller is designed for Permanent Magnet Synchronous Motor (PMSM) integrated starter generator (ISG) operation in the starter based on adaptive backstepping technique. The PMSM drive system is often faced with some parameter variations and unknown disturbances. The designed controller can make the internal combustion engine (ICE) reach ignition speed quickly and meet the torque small pulsating and speed goes smoothly requirements. Then establish the controller model and simulate the ISG operation in the starter. Some simulation results verify the feasibility and illustrate the performance of the controller under the various conditions.

Abstract: This paper presents the design of a new bi-directional DC-DC converter topology, which solves the problem that the IGBT current stress. The DC-DC converter uses soft-switching technology. By adopting the suggested method, the voltage stress and the switching loss of the IGBT can be reduced considerably. Moreover, the topology is very simple, we can analyze and build the topology electric circuit very easily. Finally, this paper uses Simulink module of Matlab software to simulate the process, and shows the experimental result. And the result shows us the DC-DC converter has great efficiency.

Abstract: The introduction of DC/AC converter based on buck regulator is firstly shown, and the analysis of the converters working principle is taken. The control method applied for DC/AC converter based on buck regulator is studied also. The control effect of the open-loop proportional-differential control and closed-loop proportional-integral control are compared by using PSIM software. The parameters adopted in the realistic simulation, waveforms such as voltage of modulation reference and load were given. The simulation results proved that adopting the DC/AC converter could achieve a good performance and can gain a line frequency as 50Hz and the correctness of theoretical analysis.

Abstract: Aimed at salient pole machine synchronous motor, the relationship between the current, voltage, flux and torque were analyzed quantitatively, the simplified mathematical model based on abc three-phase variables was established, and it was converted into the model under d/q coordinates which is easily for computer control, finally, it is simulated by Matlab/Simulink.

Abstract: Superbuck converter is a high-order converter, which has the unique advantage of the continuous input current, but increases the complexity of nonlinear phenomena of the system. This paper applies sample-data model to analyze the nonlinear dynamics of Superbuck converter with peak current control. The Jacobian matrix of the sample-data model is acquired to analyze the stability of the converter. On the other hand, the bifurcation analysis is carried out with the reference current as a bifurcation parameter based on the sample-data model. Several representative waveforms are captured from simulation, which verify the analytical results.

Abstract: To improve the flexibility of compensation and the precision of three-phase shunt active power filter (APF). A double-loop compound current controller was proposed, which repetitive controller as the outer loop, the PI controller as the inner loop. Design method in detail, dynamic response and steady-state characteristic in analysis. And put forward the compound control strategy, which combine selective harmonic detection based on multiple synchronous rotating coordinates with double-loop compound controller, achieved the compensation of zero steady-state error and selective harmonic currents. Both simulation and experimental results verify the effectiveness and correctness of the content.

Abstract: The effects of the misalignment between the inner-rod axis and the outer-wall axis in an open coaxial waveguide are studied by means of the software CST microwave studio. Results show that the field amplitude and S parameter of TEM mode decreased with the oblique misalignment angle increased. But the effect is little. While the oblique misalignment angle is up to, the field profile of TEM mode is affected largely. So in the practical of engineering applications, we should try to avoid the occurrence of oblique eccentric between the inner rod and outer wall during to technological factors.

Abstract: The effect of inner-rod oblique misalignment in a 9-GHz open coaxial resonator is studied by means of the software CST microwave studio. Results show that the oblique eccentric between the inner rod and outer wall have substantial influences on the field profile, resonant frequency, and Q factors of an open coaxial resonator. And the oblique misalignment has more serious effect than the parallel misalignment. So in the practical of engineering applications, we should try to avoid the occurrence of eccentric between the inner rod and outer wall during to technological factors.