Applied Mechanics and Materials Vols. 397-400

Abstract: A simple, fast, and reliable characterization method for measuring junction temperature (Tj) on high power GaN-based light emitting diodes (LED) was presented in this study. Thermal characteristics of high power Light-emitting-diode have been analyzed by using a three-dimensional thermal conduction model. Maximum operation temperature has also been calculated. The induced thermal behaviors of the best package processes for LED device with diamond film were investigated by finite element analysis (FEA) and by experimental measurement. The large change of forward operation voltage with temperature in light emitting diodes is advantageously used to measure junction temperature. Using this method, junction temperature (Tj) of LED under various structures and chip mounting methods was measured. It was found that the junction temperature can be reduced considerably by using diamond film substrates to replace sapphire substrate. In this study, the junction temperature can be decreased by about 14.3% under 1.5W power and decreased by about 15.9% under 1W power for 1mm square die. The thermal resistance (RT) can be measured to be 14.8°C/W under 1.5W power and 16.6°C/W under 1.W power.

Abstract: On-machine measurement (OMM) is an important part of closed-loop manufacturing (CLM) system. How to achieve real-time measurement operation and measurement result integration claimed by CLM is a major issue that concerns software and hardware vendors. This paper proposed a STEP-NC compatible on-machine measurement system that was compatible with interoperable data model. In the beginning, information model of the system was proposed referring to current data model standards supporting closed-loop manufacturing. After that, a hierarchical process planning approach was present to plan the OMM process. Object-oriented macro programs were utilized to post process the planned inspection information and ensure the correct measuring result correlation. Besides, inspection items and measurement points were uniformly and uniquely identified to ensure the accurate and reliable associations of measurement results with the design model. At last, a STEP-NC compatible on-machine measurement prototype system was developed based on CATIA, and the validity and practicality of the proposed on-machine measurement system was demonstrated with an aeronautic test part.

Abstract: By analyzing the bearing raceway ultra-lapping process and equipment, we can set up an automatic device replacing oilstone and automatic detection mechanism of machining precision. By adapting the modular method to define respectively various functions of the automatic cycle processing module, automatic device replacing oilstone module, detection module, machining precision of automatic machine automatic feeding module, machine automatic feeding module, network monitoring module, and analyzing those functions to find logical relationship between the modules, we aim at establishing communication between these modules. Through the use of embedded microprocessor and its application software, connected by the CNC system and the external host computer network, we can realize long-distance control and unmanned operation, long-distance processing program transmission, long-distance diagnosis and repair services, technical services, and coordinating and efficient operation of each functional module of ultra-lapping process, eventually establishing the bearing raceway lapping unmanned manufacturing system, improving the efficiency and stability of the equipment, saving human resources, creating conditions for constructing unmanned automatic production system for bearing.

Abstract: In this paper, a scheme of remote control equipment based on Industrial Ethernet is designed, which provides a communication interface selection of remote control for self-development users. This design has the characteristics of simple, flexibility, reliability, and it can be run in Linux system.

Abstract: This paper based on ARMV7 architecture of Fujitsu's architecture M3 series MB9BF506R 32-bit processors as a combination lock master control chip, a reasonable analysis of the new architecture based on the practical method to realize electronic combination lock, this paper proposes a new design concept - based on multiple jurisdictions real-time monitoring system of security, added with special customized mobile phone validation in the form of fingerprint access and data transmission function, effectively strengthen the safety and reliability of electronic password system, on the current electronic combination lock industry progress of developmental significance.

Abstract: Real-time simulation on the Modular Multilevel Converter (MMC) VSC-HVDC is one of the most important and difficult technologies in the area of power electronics research. After introduction and analysis on the RTDS simulation technologies for MMC VSC-HVDC study, this paper sets up the simulation model for MMC VSC-HVDC with inter control and researches on its operation and fault characteristics. Moreover, the simulation and testing system for MMC VSC-HVDC with physical control is also set up. The testing result should that, the voltage balancing method and phase disposition (PD) control strategy of the physical MMC control system perform well duing the test.

Abstract: A kind of three carrier PWM control method is put forward for improved Z-source inverter. The switches are controlled by comparing three carrier and three reference waves. The shoot-through zero state are injected in the time when traditional zero vector worked. The voltage gain is determined by the dc offset voltage of carrier wave when the modulation index is constant. Boost factor is made independent of the modulation index. And the switching loss is reduced. The voltage stress on the capacitances and switches are analyzed in detail. Simulation results show that this method possesses better control performance.

Abstract: Came from the principle of brushless doubly-fed machine, combined the space vector pulse width modulation, modeled bidirectional PWM converter with unity power factor and feed-forward decoupling control using MATLAB/SIMULINK, studied the simulation characteristics, the results confirmed the correctness and effectiveness of the model, and provided reference for further research of the control scheme.

Abstract: With the development of flexible HVDC technology in the world, back-to-back HVDC system based on MMC topology have more attention. A high power back-to-back flexible HVDC prototype has been developed to assess performance and reliability of construction of converter valve segment. Valve normal working condition (rated conditions rated voltage, current, temperature), valve transient working condition (temporary overvoltage, overcurrent), valve fault protection and anti-interference ability are accessed. Performance and reliability of control and protection equipment are assessed. The design of control and protection strategy is optimized. The correctness of main circuit design is tested.

Abstract: Modern high and new technology and informatization have made increasingly high demand on transient power quality. The article first outlined the classification of transient power quality problems, introduced the concept of customer power technology, and pinpointed that this technology serves an effective means to solve transient power quality problems. This paper also discussed in a comprehensive way a number of customer power technologies capable of improving transient power quality which have seen the widest application in researches and practices, and analyzed its working principle, researching status as well as key technologies. The paper ended with a brief summarization of the latest research developments in this field.