Advanced Materials Research Vols. 546-547

Abstract: A kind of measurement method of impulse grounding resistance is proposed. The measurement method of impulse grounding resistance is also analyzed and discussed theoretically. The hardware and software scheme of measurement system is given. The method of simulation of thunder current and transformation calculation is better than the method of work-frequency measurement by the analysis and comparison. By using the method, the thundering course can not only be simulated , but also the impulse grounding resistance can be calculated directly in the scene. In the end, a simulation result is given. Simulation result show that the method proposed in the paper is effective and feasible.

Abstract: Applying non-grid-connected wind power to high energy consuming industry has broad development prospects. This paper presents a compound DC power transmission net to realize high efficiency and reduce the loss. This net consists of current source converter (CSC) based on naturally commutated thyristor and voltage source converter (VSC) based on IGBT. Super capacitor connected to the load side stabilizes the wind power fluctuation. The coordinated control strategy of wind power, energy storage device and load is provided. Simulation results based on real wind power shows the validity of the system.

Abstract: The thesis designs a new kind of electrical system of thread rolling machine. The design bases on the grating, microchip and has quick response, which overcomes the drawback of the electrical system basing on PLC.

Abstract: The paper made a comprehensive analysis on a variety of driving environment and driver’s intention for HEB, studied the typical driver manipulation features, proposed the identification method which integrated the driving environment and the operation of the driver and different shift strategy. For Beijing driving cycling as an example, using the integrated platform of AVL/Cruise and Matlab/Simulink to simulate the operation of HEV under different shift strategy in a number of traffic circulation condition, the results proved that the shift strategy based on the driver’s intention identification not only enable HEV to implement the intention of driver but also access to better fuel economy.

Abstract: Interior permanent magnet synchronous motors can be applied to applications requiring wide-speed operation by means of flux-weakening control. While due to the fixed capacity of PWM inverter, the high speed operation range of interior permanent magnet synchronous motor (IPMSM) is mainly limited by the saturation of current regulator. In constant power region, in stead of the available voltage that controls the armature current vector, the current vector sometimes becomes uncontrollable in transient operations because of the current regulator saturation. In order to extend its operation range, the current vector control algorithm of IPM motor over the base speed operation is proposed in this paper which includes the decoupling current control and the voltage command compensation. Also this paper introduces a judgment method to monitor if the current regulator has gone into saturation or not. Finally on the basis of simulation results, the effectiveness of this control strategy is further confirmed by real drive tests.

Abstract: This paper proposes a parallel PFC technology which is shunted between the power supply and the load. Parallel inverters with frequency-doubling carrier phase shifted SPWM technique is used as the main circuit structure to reduce the device currents rate and switch stress and enhance the equivalent switch frequency. The phase angle of the source current reference is determined by the source voltage, while the magnitude of that is obtained from controlling the DC side capacitor voltage of the inverter. The PFC is realized by inner current loop P control and outer voltage loop PI control for its simple arithmetic, good robustness. The simulation and experimental results show that this system can achieve a high power factor of 0.99 and low total harmonic distortion with linear or nonlinear load. So the validity and efficiency of the proposed parallel PFC technology are confirmed by the numerical results.

Abstract: This paper introduces a power factor correction (PFC) main circuit adopting novel full bridge topology, in which the clamped capacitor limits voltage stress on the switch tube, reduces output voltage ripple, and improves the response velocity; TMS320F2812 series DSP, produced by TI company, is used as the main control device in this system, and the DSP fixes the switch frequency at 20kps. It uses alternate sampling method to avoid the switching noise taken into the system. And then, both the validity of the theoretical analysis and the effectiveness of the control strategy are verified by the prototype test.

Abstract: In view of existing situation of the inconsistent power system model, a method of CIM modeling for power secondary system is given, based on better understanding and the analysis of the primary system CIM modeling. Combined with the particular characters of the secondary system, it establishes CIM model for the transformer protection of the secondary networks. Then it shows the method is proper and feasible. Some important issue about further research is put forward as well.

Abstract: With conventional high voltage current limiting fuse, the rated current is usually below 200 A. The rated current of the state of the art arc triggering hybrid current limiting fuse is only 600 A, with its interrupting capability being 25 kA, and still can’t meet the requirements of modern industrial application. With the arc triggering hybrid current limiting fuses, the major obstacle to higher rated current and interrupting capability lies in the long operation time of the arc trigger. Increasing the current density of arc trigger notches can effectively improve the operation speed of the trigger. Simulation and parameter optimization of the arc trigger are conducted by using ANSYS 11.0 to attain the optimal fuse element structure. In this study, the notch current density of the arc trigger was as high as 3300 A/mm², and the trigger can be used in the hybrid current limiting fuse of rated 35 kV, 2 kA and 40 kA interrupting capability.

Abstract: The technology of soft-switching can improve stability ,reliability and efficiency of the inverting spot welding power supply .In this paper ,a new kind of topology of zero-voltage switching spot welding power supply is proposed ,which is auxiliary circuit in paralleling with the lagging lag ,so it can afford auxiliary current of soft switch .With the relationship between circuit state of every working mode of main circuit and main circuit parameters in new topology ,the ability of searching optimal overall situation of ACA is used to optimize circuit parameters ,and it turns out to confirm the advantage of this topology .