Advanced Materials Research Vols. 846-847

Abstract: In order to adapt to the development of smart substation metering technology , and to improve the efficiency and quality of the on-site calibration of the electronic transformer. On the basis of the existing calibration system, combined with wireless transmission and of new synchronization technologies, focused on the IEC 61850 data and precision clock wireless transmission device to achieve difficult problems in-depth analysis, then the implementation of electronic transformer on-site wireless calibration system is proposed.

Abstract: It is necessary that the grid-connected inverter was set up in wind power, in order to convey energy generated in wind power to the grid. There are many sorts of inverters, but only two sorts of inverters suit wind power system, which are current-source inverter and voltage-source inverter, and only the later is being widely used. Their configuration, principle, control and characteristic were analyzed in this paper. Results have shown that, voltage-source grid-connected inverter has been the core of the commutation control configuration of direct-driven wind power, which is decided by the peculiarity of itself.

Abstract: Fault is classified when the thyristor open in three phase bridge rectifier circuit in this paper,Circuit simulation model is established based on Matlab/Simulink,and for a variety of open circuit fault is simulinked,extracted all kinds of fault feature vector, provided the theory of mathematical basis for intelligent fault diagnosis.

Abstract: The inverter energy storage spot welding machine with wave control can weld initiating explosive device of aerospace system, and guarantee a stable and reliable welding quality by high frequency pulse current. Beginning with theoretical basis of inverter high frequency pulse current welding, the paper analyzes the given signal of inverter hardware, welding parameter and other experiment data to ensure the stability and safety of inverter energy storage spot waveform control.

Abstract: The paper conducts optimal design for reflective intensity-type optical sensing. It designs two holes on the back of sensor probe which reduces system damping due to diaphragm and space air. It sets reference circuit and realizes the light intensity compensation by the way of comparing ratio specific value of measuring circuit and reference circuit. According to the symmetry requirement of photoelectric detection circuit, the paper designs photoelectric detection treatment circuit. The experiment shows that intensity compensation method can compensate well the power fluctuation of light source and temperature drift caused by long-time operation of sensor.

Abstract: Sneak circuit analysis method is moving to intelligent and automation direction, the method based on network flow simulation has some representation. With the expansion of the circuit system topology and the increasement of the component's amount, the analysis time increases and the efficiency is difficult to be guaranteed. To solve this situation, the circuit system can be divided into some blocks for analysis. Based on the network flow simulation model, the adjacency matrix of circuit system is established. The analysis matrix of circuit system is obtained by the simplification of the adjacency matrix; use the analysis matrix as the network model for circuit system partition analysis. Select appropriate point from the network cutting point as the partition point, the circuit system can be divided into some sub-blocks by removing these points. Circuit system stratified analysis principle is proposed; determine the division method and analysis objectives of each convention level. This method can correctly analysis sneak circuit problem for circuit system, effectively reduce the analysis time and improve the analysis efficiency. It can be taken as an effective complement of sneak circuit analysis method based on network flow simulation for engineering application.

Abstract: In this work, the methodology and procedures of lifetime prediction for power IGBT modules are presented. Firstly, we discuss the long term reliability tests of power modules for developing lifetime models, and review some reported lifetime models. Then, the procedures of lifetime prediction in real applications are addressed, which include power loss calculations based on the actual mission profile, the conversion of power loss profile to temperature profile according to the module's thermal properties, the temperature cycles counting by Rainflow algorithm, and lifetime calculation by the fatigue linear accumulation damage theory. Finally, the lifetime of a 3300V/800A IGBT module manufactured by Dynex Semiconductor of China Southern Railway applied in metro traction systems is predicted.

Abstract: This paper presents a new topology of main circuit based on soft switching technology of ZVS-PWM. At present, hard switching is applied in most inverters. Because the switching power isnt equal to zero, a great number of losses on the switching are generated when the switching at a high frequency. To solve the fault of hard switching, this paper presents that apply the inverter circuits based on soft switching technology of ZVS-PWM to high frequency APF, which will decrease switching losses and noise greatly. The proposed topology and operation principle of the control method is discussed in detail, finally simulated results verify the effect of research.

Abstract: 4H-SiC JBS diode with breakdown voltage higher than 6.5 kV has been successfully fabricated on 4H-SiC wafers with epitaxial layer. In this paper, the simulation, the fabrication, and the electrical characteristics of 4H-SiC JBS diode were reported. The drift layer thickness and doping are 55 μm and 9×10¹⁴ cm³ respectively. 60 floating guard rings edge were fabricated as termination. The on-state voltage was 4 V at J_F = 7A.

Abstract: High voltage 4H-SiC Ni Schottky junction barrier schottky (JBS) diode with breakdown voltage of 1000V and forward current of 1A has been fabricated. A low reverse leakage current below 4.7×10^-6A/cm² at the bias voltage of-1000V has been obtained. The forward on-state current was 1A at V_F = 2.2V. The chip is 1.3mm×1.3mm. The turn-on voltage is about 1.4V. The on-state resistance is 14.5mΩ·cm². The doping and thickness of the N-type drift layer and the device structure have been performed by numerical simulations. The SiC JBS devices have been fabricated and the processes were in detail. The die was assembled in a SMB package. The thickness of the N-epilayer is 10μm, and the doping concentration is 4×10¹⁵cm³. A floating guard rings edge termination have been used to improve the effectiveness of the edge termination technique. By using WTi/Au multilayer metal structure, the double side Au process of 4H-SiC JBS diode is formed. We use the PECVD Si_xN_y/SiO₂ as the passivation dielectric and a non photosensitive polyamide as the passivation in the end.