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TEACHING POWER ELECTRONICS AT MONASH UNIVERSITY IN AN AUSTRALIAN CONTEXT
Peter Freere 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-
A summary is given of conventional electrical engineering university education and a description of the employment scene for the graduates. The training requirements of graduates for three different industrial employers are given and the steps taken to meet some of these requirements are explained in detail. The steps taken include two training programmes, one an undergraduate final year course and the other a graduate training programme. The final year course teaches to design and construct a real product to specifications, whereas the graduate training programme employs a new graduate or postgraduate student on industrial projects which can be closely supervised for maximum benefit. Both programmes are described in detail and the conclusion developed as to future requirements.<br/>
Effect of AC Inductance on a Phase Shifted DC-DC Bridge Converter
Peter Freere,Wang Kong,Donald Grahame Holmes 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-
Phase shifted DC-DC converters are a well established topology for producing an isolated DC output supply. However, the conventional topology with a DC output LC filter has some practical difficulties when issues such as diode reverse recovery effects, diode voltage ratings for wide ranging input voltages, and common mode EMI caused by the switched transformer output are considered. In many applications, these difficulties can be mitigated by moving the output filter inductor to the AC side before the bridge rectifier. However, this leads to alternative constraints of increased filter series voltage drop and higher filter capacitor current ripple. This paper presents design equations and a design process to determine which of these alternative filter arrangements better suits a particular DC-DC converter application.
P. Freere 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
This paper looks at aspects of the torque, switching frequency, minimum transistor conduction state times when using hysteresis current control to drive a vector controlled permanent magnet synchronous motor. Implications of the zero voltage vector on the switching frequency is considered. For a motor with little ability to flux weaken, a phase advance method of increasing high speed performance is demonstrated.
Past and Present Definitions of the Energy and Protein Requirements of Ruminants
Corbett, J.L.,Freer, M. Asian Australasian Association of Animal Productio 2003 Animal Bioscience Vol.16 No.4
The genesis of methods for defining the nutritional value of feeds and the nutrient requirements of animals, and their development in the late 19th and early 20th centuries in Europe and the USA are outlined. Current energy and protein feeding systems for ruminants are described. Particular reference is made to the Australian systems which are applicable to grazing animals as well as to those given prepared feeds, and enable the effective nutritional management of a imals at pasture by means of the decision support tool GrazFeed. The scheme for predicting intakes by cattle and sheep from pastures allows for the effects of selective grazing on the composition of the feed eaten, and for reduction in herbage intake when a supplementary feed is consumed. For herbage of any given concentration of metabolizable energy (ME) in the feed dry matter the changes with season of year in the net efficiency of use of the ME for growth and fattening and in the yield of microbial crude protein, g/MJ ME, which both vary with latitude, are defined. An equation to predict the energy requirements for maintenance (MEm) of both cattle and sheep includes predictions of the additional energy costs incurred by grazing compared with housed animals and the cost, if any, of cold stress. The equation allows for the change in MEm with feed intake. A flexible procedure predicts the composition of liveweight gain made by any given breed or sex of cattle and sheep at any stage of growth, and the variation with rate of gain. Protein requirements for maintenance, production including wool growth, and reproduction, are related to the quantities of microbial true protein and undegraded dietary protein truly digested in the small intestine.
Taek il Oh,Peter Freere 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
This paper investigates the optimum configuration of a single phase induction motor to operate as a self excited generator. A single phase induction machine has two windings called the main and auxiliary winding. If those two windings are combined, the machine can produce up to its rated power at rated voltage when operating as a generator. This paper models a single phase induction machine as a generator. The experimental results support the computer simulation results and the modeling of a single phase induction generator. The optimal configuration was investigated.
Lowe, Tristan,Azough, Feridoon,Freer, Robert The Korean Ceramic Society 2003 한국세라믹학회지 Vol.40 No.4
Ceramics of xCaTiO$_3$-(1-x)Li$_{0.5}$Nd$_{0.5}$TiO$_3$(xCT-(1-x)LNT) series have been prepared by the mixed oxide route. Powders were calcined at 110$0^{\circ}C$ ; cylindrical specimens were fired at temperatures in the range 1300-150$0^{\circ}C$. Sintered products were typically 90-95% dense. The microstructures were dominated by angular grains typically 1.3${\mu}{\textrm}{m}$ to 3.5 ${\mu}{\textrm}{m}$ in size. Twinning in the microstructures was analysed using Electron Back Scattered Diffraction (EBSD). Microwave dielectric properties of xCT-(1-x)LNT at 2.1 GHz ($\varepsilon$$_{r}$, Qxf, and $\tau$r) were 170,3800 GHz and 744 ppm/$^{\circ}C$ for pure CaTiO$_3$ and 80,2000 GHz and -240 ppm/$^{\circ}C$ for LNT. The $\tau$r decreases almost linearly from 744 for pure CaTiO$_3$ to -240 for pure LNT.LNT.T.
Experimental and Simulation Results for Sliding Mode Dynamic Wind Turbine Control using a DC Chopper
G.Riahy,P.Freere,D.G.Holmes 전력전자학회 2001 ICPE(ISPE)논문집 Vol.2001 No.10
Wind speeds can vary rapidly and wind turbines cannot easily follow these variations because of their inertia and aerodynamic characteristics. For maximum energy extraction, the turbine blades should operate at their optimum tip speed ratio, but with rapid changes in wind speed, this is usually not possible. To improve the energy extraction from turbulent wind, it is necessary to establish an effective measure of the high frequency component of the wind, and then to use this measure to optimise the operation of the turbine controller for maximum energy extraction. This paper presents an approach for combining readings from three anemometers into a composite wind speed measurement, and using this signal to control the operation of a permanent magnet generator to achieve maximum energy extraction. The method combines simulation and experimental investigations into a heuristic algorithm, and demonstrates its effectiveness with field trials.<br/>
K. Gurung,P. Freere 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
This paper addresses the effect of low power factor load on the voltage regulation of a three phase self excited induction generator feeding a single phase load. The steady state model of an induction generator based on symmetrical component and rotating field theories has been used for the purpose of analysis and comparison. The simulated results are supported by experimental results.