Mechanical and Electrical Technology IV

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Authors: Deng Liang Cheng, Wei Rong Jiang, Jian Wei Mei
Abstract: To solve the key technology of automotive lithium battery charging system, a new kind of smart portable on-board charger is developed. This battery charger takes single-chip machine of freescale as system control chip, realizes closed-loop control of bus voltage by the voltage pulse width modulation chip TL494, realizes charger output with constant voltage, constant current and switch without disturbances by the current pulse width modulation chip UC3846, achieves master-slave control mode for multi–parallel machines through the CAN bus technology. In addition, the microcontroller program realizes the process monitoring and fuzzy PID regulation, the charging process has multiple intelligent protection and external regulatory functions. The experimental results show that with dual regulations of the software and hardware, the charger has the advantages of stable reliability, flexible operation and precise intelligence, an effective exploration of the battery charging technology is carried out.
Authors: Xiao Ming Wu, Yan Fang Yang
Abstract: Currently there is a lot of material presented on the selection of different conditions and specific formula in order to select accumulator parameters. Yet these formulas are calculated in different degree of approximation and assumptions. This paper mainly considers the effect of the poly index and temperature to the working parameters in the charge process; and designs the software package of parameter selection of the accumulators. The key index formula is derivated, and the more accurate total volume V0 can be given trough computation. It is accurate basis for the selection of the accumulator.
Authors: Xiao Wei Wang
Abstract: The paper proposes a design scheme of movement encoder with low cost and high performance. The scheme can provide higher precise rotor position signal for motor by a hall-effect latch and a linear hall-effect sensor, and it can also provide rotational speed and direction of motor by a winding with full pole distance, at last we deduce a torque balance equation based on speed and acceleration of motor. The study shows that the scheme with low cost have much higher position precision than traditional rotational transformer and hall-effect position sensor, and it does not exist amplitude error and phase error, function error is small. It is very worthy to the wide application of motor of electric bicycle, wind-driven generator, electric car, and servomotor, etc.
Authors: Xia Liu, Rui Feng Yang, Jian Fang Jia
Abstract: The aero load simulator is a typical application of electric dynamic load simulator in the engineering. It is important half hardware-in-loop simulation equipment, which is often used to simulate the aerodynamic torque load on the missile rudder or elevon actuators in the flight. The mathematical model of the electric dynamic load simulator is built using the physical modeling method. The influence of the rudder performance on the model was considered, and modeled it as the disturbance channel in the model. The electric dynamic load simulator is a typical coupled system. Under the different simplification, the validity of the model is verified by the actual experiment.
Authors: Jian Wang, Kui Hua Wu, Feng Wang, Zhi Hui Li, Qing Song Niu, Zhi Zhen Liu
Abstract: With the popularity of electric vehicles, a large number of charging stations connected to the grid, will bring about tremendous influence on the power, voltage and current of grid. This paper briefly introduces several common types of charging mode, and analyzes the characteristics of them. According to statistics, a resistive model of charging stations, simulating the regional power grid with a IEEE34 node model, has been established to forecast the daily load curve, using Monte Carlo simulation. An analysis is performed for a power grid to demonstrate the impacts of the daily load curve considering different power of charging stations, which are under coordinated charging conditions, to indicate the harm of uncoordinated charging and put forward solutions.
Authors: Bao Dong Bai, Bing Yin Qu, De Zhi Chen, Bo Zhang, Wu Hao Jia
Abstract: As the manufacturing technology of transformer getting more and more mature, issue of its vibration and noise is getting more and more attention. The vibration is more obviously when the transformer is running with DC Bias. 3D field-circuit coupling models of single-phase three-column power transformer was created by ANSYS. The simulating distributions of core magnetic flux density were obtained when the model was running with DC bias current of 0A, 0.9A and 2.6A. So were the modal shapes and curve of vibration-frequency of the transformer model. The theoretical guidance of reducing transformer vibration was obtained after analyzing the simulation result.
Authors: Mao Fa Gong, Wen Hua Xia, Guo Liang Li, Xing Zhen Bai, Lan Bing Li
Abstract: Sympathetic inrush may cause the mal-operation of differential protection. Aiming at this problem, based on the characteristic that sympathetic inrush contains a lot of aperiodic component and high harmonics, this paper proposes to use Hilbert Huang transform to identify sympathetic inrush. Firstly, the mathematical model of sympathetic inrush is established to analyze its characteristic. Then Hilbert transform is used to obtain harmonic contents of sympathetic inrush and internal fault current. According to the proportion of fundamental to current, sympathetic current can be identified and differential protection can be blocked. The simulation results show that this method has better reliability and sensitivity than the second harmonic restraint scheme. Besides, it has a good ability against TA saturation.
Authors: Zhi Hui Li, Qing Zhi Jian, Hang Chen, Xue Long Du, Zhi Zhen Liu
Abstract: As the energy crisis becoming more and more serious, electric vehicles has become an important way to solve this problem. The difference of Popularity, type, charge time, charge style and charge characteristics of Electric vehicles make different effect on the Regional power grid, especially quick charge technology. In this paper, through the establishment of regional power grid model and the forecast of quick charge station load curve, we analysis the impact of charge station on voltage of the user side, furthermore, we analysis voltage loss and impulse current when the large power charger connected to the power grid, and verify the analysis by simulation. In order to reduce the impact on the grid, we should rationally plan the charge station and the reactive power compensation, thus enhance stability of power system.
Authors: Gui Hua Qiao, Hua Jun Dong, Min Li, Wen Liang Dong, Xin Wei Zhou
Abstract: The forms and the V-I characteristics of vacuum arc have great influence in the vacuum circuit breakers’ protection and control of power system. An experimental set-up was thus designed for vacuum switching arc measurement of V-I characteristics was used and an image collection system was designed to collect the images of vacuum arc used high-speed camera CMOS with the experimental setup, the V-I characteristics and forms of vacuum arc was researched, the curve of V-I was drawn and the images was analyzed. All these provide experimental basis for the analysis on basic physical theory of vacuum switching arc.
Authors: Xian Jun Shi, Ling Shun Liu, Shao Lei Zhou
Abstract: Multi-motor drive system is one important area of the motion control research. In this paper, the working principle of single-inverter driving the series-connected system of two double Y-shift 30 ° PMSM is proposed. In order to achieve the better decouple operating of the two series-connected motors and improving the DC bus utilization, a novel control method of BFV-SVPWM for the system is presented. In Matlab/Simulink environment, variable-speed operations are simulated to verify that the proposed BFV-SVPWM control is strategy feasibility and superiority.

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