In this paper, two three-phase three-level Neutral Point Clamped (NPC) converters connected back-to-back are used for a direct drive wind power generator. A permanent magnet synchronous generator (PMSG) is used as the...
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ISBN:
(纸本)9781424449354
In this paper, two three-phase three-level Neutral Point Clamped (NPC) converters connected back-to-back are used for a direct drive wind power generator. A permanent magnet synchronous generator (PMSG) is used as the generator, which is driven by the wind turbine. Main problem of voltage unbalance in each electrolyte capacitor is controlled by using a simple chopper control circuit. A simple hardware method for balancing the Neutral Point (NP) voltage is proposed, which allows enhanced ride-through performance. This method can effectively balance the NP voltage without the limitations of modulation methods and load conditions. It also provides increased ride-through capabilities for the inverter during input voltage sags. Because of the NP balancing, the necessary size of the dc-bus capacitors is reduced. Here, MATLAB/SIMULINK simulation results are presented for the validity of proposed scheme.
As electronic packages become increasingly complex, designing and building a cost-effective, robust product in a timely manner has become one of the biggest challenges facing packaging specialists. The increased need ...
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ISBN:
(纸本)9781424412525
As electronic packages become increasingly complex, designing and building a cost-effective, robust product in a timely manner has become one of the biggest challenges facing packaging specialists. The increased need for higher silicon density drives packaging engineers to use stacked die (SCSP) and stacked package (POP) configurations. Some of key material challenges related to these packages include: DDF Die Attach Film thin die stacking processes, FOW Die Attach Film for same-size die stacking, Spacer Die Attach Paste, an alternative to FOW for reduced cost, Molding compounds with targeted performance for thin stacked die packages, "Material Sets" in which the above products are combined to ensure system compatibility, reliability, and ultimately a much lower total cost of ownership overall In this paper, we discuss the "materials systems" approach used to identify and optimize the packaging materials needed to address these challenges for complex high density IC packaging. Examples highlight the need for materials systems optimization as well as the need to collaborate with packaging engineers early in the design stage of a new package.
We consider the problem of estimating the position of an indoor wireless transmitter. Based on Angle of Arrival (AOA) readings from several base stations, a wireless transmitter's position has traditionally been d...
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We consider the problem of estimating the position of an indoor wireless transmitter. Based on Angle of Arrival (AOA) readings from several base stations, a wireless transmitter's position has traditionally been determined using a least-squares approach. In particular, care is taken to ensure that the least-squares estimator is unbiased. Unbiased estimators are known minimize the difference between the estimate and the average value of the readings, not the actual value. Biased estimators, in contrast, have been shown to result in a lower mean-squared error, which in turn produces more accurate position estimates. We propose the use of a biased estimator to augment the traditional least-squares approach, and develop a methodology to obtain this estimator. Using real data from a commercial indoor Ultra-Wideband (UWB) Real Time Location System (RTLS), we show that our estimator produces more accurate position estimates than the traditional unbiased estimator. We also show that our simple estimator performs comparably to more complex positioning algorithms.
We present a framework for the formal evaluation of human teleoperator skill level in a systematic fashion, aiming to quantify how skillful a particular operator is for a well-defined task. Our proposed framework has ...
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ISBN:
(纸本)9781450399708
We present a framework for the formal evaluation of human teleoperator skill level in a systematic fashion, aiming to quantify how skillful a particular operator is for a well-defined task. Our proposed framework has two parts. First, the tasks used to evaluate skill levels are decomposed into a series of domain-specific primitives, each with a formal specification using signal temporal logic. Secondly, skill levels are automatically evaluated along multiple dimensions rather than a singular number. These dimensions include robustness, efficiency, resilience and readiness for each primitive task. We provide an initial evaluation for the task of taking-off, hovering, and landing in a drone simulator. This preliminary evaluation shows the value of a multi-dimensional evaluation of human operator performance.
Energy deposition rate in ion chambers for tritium measurements has been theoretically studied using Monte-Carlo ***-Carlo code MCNP5 was employed to evaluate the influence of gas composition, chamber size and wall ma...
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Energy deposition rate in ion chambers for tritium measurements has been theoretically studied using Monte-Carlo ***-Carlo code MCNP5 was employed to evaluate the influence of gas composition, chamber size and wall material on energy deposition rate.
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