The successful grad student

This article is a collection of tips and an overview of the process through which all graduate students pass during their journey. Before starting a graduate program, it is important to realize that this is a long-term investment in career. Once the students are in graduate school, it is necessary to structure their personal life to fit the demands of the program. A graduate program starts by the choice of the advisor during the first year. Sometimes this is done even before the student is accepted into the program. During the program, interaction with the colleagues and professors is necessary. Getting to know them is essential to the program and to the life. Reading may not be enough. Read, analyze, criticize, discuss, implement. During reading note making is good. A good practice is to have a printed copy of the paper and annotate the thoughts and observations on it. Establishing the schedule with deadlines and trying to follow it. Participating in conferences and scientific events is essential. Organizing the thoughts and discussion with the colleagues drive out the fear. Students should produce at least one paper for a good conference that it will pave the way for success. This can be considered the minimal requirement to emphasize the importance/relevance of the thesis.     

SRM inverter topologies: a comparative evaluation

Several inverter power circuits suitable for switched reluctance motor (SRM) drives are analyzed and compared. Five inverter circuits are considered with the objective of establishing the most appropriate topology for an SRM drive. The comparison is based on the peak voltage and peak current ratings of the DC link components. Because the power converter choice depends on the motor design, the converter analysis and selection are done for a high-speed, 6/2 SRM suitable for a spindle drive and a high-torque 8/6 motor. Experimental results obtained for a high-torque drive are included     

高精度数字式电能比较仪的研制

介绍一种新型用电器耗电比较仪的研制,阐述了其工作原理和设计要点。使用PHILIPS公司OTP型单片机P87LPC762作为数据处理芯片,电路新颖实用。     

A comparative evaluation of new silicon carbide diodes and state-of-the-art silicon diodes for power electronic applications

Recent progress in silicon carbide (SiC) material has made it feasible to build power devices of reasonable current density. This paper presents results including a comparison with state-of-the-art silicon diodes. Switching losses for two silicon diodes (a fast diode, 600 V, 50 A, 60 ns Trr), an ultrafast silicon diode (600 V, 50 A, 23 ns Trr), and a 4H-SiC diode (600 V, 50 A) are compared. The effect of diode reverse recovery on the turn-on losses of a fast insulated gate bipolar transistor (IGBT) are studied both at room temperature and at 150 /spl deg/C. At room temperature, SiC diodes allow a reduction of IGBT turn-on losses by 25% compared to ultrafast silicon diodes and by 70% compared to fast silicon diodes. At 150 /spl deg/C junction temperature, SiC diodes allow turn-on loss reductions of 35% and 85% compared to ultrafast and fast silicon diodes, respectively. The silicon and SiC diodes are used in a boost converter with the IGBT to assess the overall effect of SiC diodes on the converter characteristics. Efficiency measurements at light load (100 W) and full load (500 W) are reported. Although SiC diodes exhibit very low switching losses, their high conduction losses due to the high forward drop dominate the overall losses, hence reducing the overall efficiency. Since this is an ongoing development, it is expected that future prototypes will have improved forward characteristics.     

More DOE awards for advanced hydrogen and fuel cell R&D projects

Another slice of the much larger pie of US fuel cell money promised by President Bush has been served up by Secretary of Energy Spencer Abraham, with the selection of 13 more organizations to receive $75 million in cost-shared awards to fund new research in advanced fuel cell technology for vehicles, buildings and other applications. Combined with recent awards to 11 firms and universities of $21m for hydrogen storage, production and sensor technologies, DOE has awarded a total of $96m to 24 organizations in new awards in support of President Bush’s FreedomCAR and Hydrogen Fuel Initiatives.This is a short news story only. Visit www.re-focus.net for the latest renewable energy industry news     

A comparative evaluation of harmonic reduction techniques inthree-phase utility interface of power electronic loads

Power electronic loads inject harmonic currents into the utility system. This paper presents a comparative evaluation of harmonic reduction techniques which satisfy the current harmonic limits specified by the IEEE Standard 519, and at the same time provide a regulated DC output voltage. The techniques considered include active and hybrid filters, and various current waveshaping approaches for a three-phase utility interface. These techniques are compared in terms of their complexity (number of switches) and their component ratings. Based on the application requirements and the cost of active and passive components, this paper enables the estimation of the minimum cost topology