Modeling of Capacitor Impedance in Switching Converters

Switched capacitor (SC) converters are gaining acceptance as alternatives to traditional, inductor-based switching power converters. Proper design of SC converters requires an understanding of all loss sources and their impacts on circuit operation. In the present work, an equivalent resistance method is developed for analysis, and equivalent resistance formulae are presented for various modes of operation. Quasiresonant converters are explored and compared to standard SC converters. Comparisons to inductor-based switching power converters are made. A number of capacitor technologies are evaluated and compared for applications to both SC converters and inductor-based converters. The resulting model can be used to accurately predict and optimize converter performance in the design phase

Study protocol: national research partnership to improve primary health care performance and outcomes for Indigenous peoples

Background Strengthening primary health care is critical to reducing health inequity between Indigenous and non-Indigenous Australians. The Audit and Best practice for Chronic Disease Extension (ABCDE) project has facilitated the implementation of modern Continuous Quality Improvement (CQI) approaches in Indigenous community health care centres across Australia. The project demonstrated improvements in health centre systems, delivery of primary care services and in patient intermediate outcomes. It has also highlighted substantial variation in quality of care. Through a partnership between academic researchers, service providers and policy makers, we are now implementing a study which aims to 1) explore the factors associated with variation in clinical performance; 2) examine specific strategies that have been effective in improving primary care clinical performance; and 3) work with health service staff, management and policy makers to enhance the effective implementation of successful strategies. Methods/Design The study will be conducted in Indigenous community health centres from at least six States/Territories (Northern Territory, Western Australia, New South Wales, South Australia, Queensland and Victoria) over a five year period. A research hub will be established in each region to support collection and reporting of quantitative and qualitative clinical and health centre system performance data, to investigate factors affecting variation in quality of care and to facilitate effective translation of research evidence into policy and practice. The project is supported by a web-based information system, providing automated analysis and reporting of clinical care performance to health centre staff and management. Discussion By linking researchers directly to users of research (service providers, managers and policy makers), the partnership is well placed to generate new knowledge on effective strategies for improving the quality of primary health care and fostering effective and efficient exchange and use of data and information among service providers and policy makers to achieve evidence-based resource allocation, service planning, system development, and improvements of service delivery and Indigenous health outcomes.Ross Bailie, Damin Si, Cindy Shannon, James Semmens, Kevin Rowley, David J Scrimgeour, Tricia Nage, Ian Anderson, Christine Connors, Tarun Weeramanthri, Sandra Thompson, Robyn McDermott, Hugh Burke, Elizabeth Moore, Dallas Leon, Richard Weston, Haylene Grogan, Andrew Stanley and Karen Gardne

Thoughts animals can think, attributing beliefs and describing content

grantor: University of TorontoOne of the problems that arises in attempts to attribute thoughts to non-human animals is that is difficult to find sentences of human language that accurately express the content of those thoughts. I argue that semantic theories that do not depend on an understanding of propositional content as being linguistic in nature can provide a helpful perspective from which to approach questions about the content of the beliefs of non-language-using animals. In particular, I consider Robert Stalnaker's possible worlds semantics and the situation semantics of Jon Barwise and John Perry. I argue that both of these theories provide ways of understanding the content of beliefs on which it is far more plausible that non-human animals have beliefs than theories that take propositions to be linguistically structured. I further argue, however, that Barwise and Perry's account is ultimately more helpful than Stalnaker's and avoids some significant problems faced by possible worlds theories. In my approach to these topics, I consider the plausibility, on various influential theories of mind, of the idea that animals have beliefs and I provide an exposition of Jonathan Bennett's account of what types of animal behavior justify the attribution of beliefs. I conclude by arguing that the combined work of Bennett, Stalnaker, and Barwise and Perry can be used to address a line of reasoning I refer to as the specificity argument. According to the specificity argument, if an animal cannot express its beliefs in language, it is impossible to attribute content to any belief one might attribute to it with enough precision to make sense of claims that the animal has one belief rather than another. It is then concluded that non-language-using animals do not have beliefs. I use the work discussed above to show that the specificity argument does not, by itself, show that non-human animals do not have beliefs. As well, the approach to understanding content that I consider will be helpful in considerations of the content of non-language users in general, and is a promising first step in the assessment of many arguments against the claim that animals have beliefs.Ph.D

IGBT and Diode Loss Estimation under Hysteresis Switching

This paper presents a power loss estimation method for insulated-gate bipolar transistors (IGBTs) and diodes that operate under hysteresis switching. The method relies on datasheet information and three measurements in a phase leg: phase current, one IGBT switching gate signal, and the dc bus voltage across the phase leg. No parasitic models, thermal analysis, or slow simulations are required, and measurements can be provided from simulations or experiments. The method is validated for periodic pulsewidth modulation, then for aperiodic hysteresis switching. Results show that the proposed method is accurate while maintaining simplicity. It is promising for implementation in combined thermoelectric simulations and design optimization

TILAS: A Simple Analysis Tool for Estimating Power Losses in an IGBT-Diode Pair under Hysteresis Control in Three-Phase Inverters

Several techniques for analyzing and estimating power losses in insulated-gate bipolar transistors (IGBTs), diodes, MOSFETs, and other power electronics switching devices are known. Most of the approaches in the literature deal with periodic pulse width modulation (PWM) switching schemes. This paper presents a simple analysis tool to estimate these losses under aperiodic switching schemes, e.g. hysteresis. The tool aims to simplify such an analysis with two main measurements-the load current of a converter phase leg and the gate switching waveform of the upper IGBT of that phase. No model estimations, thermal analyses, or slow simulations are required. Consistency between results from the proposed tool and a commercially available tool designed by an IGBT manufacturer is shown. A periodic frequency is proposed to adapt available software used with periodic switching schemes to aperiodic switching schemes. Experimental tests from an inverter application are presented here

Twenty-ninth annual report of the Power Affiliates Program.

Includes bibliographical references