Computer numerical control vertical machining centre feed drive modelling using the transmission line technique

This study presents a novel application of the Transmission Line Matrix Method (TLM) for the modelling of the dynamic behaviour of non-linear hybrid systems for CNC machine tool drives. The application of the TLM technique implies the dividing of the ball-screw shaft into a number of identical elements in order to achieve the synchronisation of events in the simulation, and to provide an acceptable resolution according to the maximum frequency of interest. This entails the use of a high performance computing system with due consideration to the small time steps being applied in the simulation. Generally, the analysis of torsion and axial dynamic effects on a shaft implies the development of independent simulated models. This study presents a new procedure for the modelling of a ball-screw shaft by the synchronisation of the axial and torsion dynamics into the same model. The model parameters were obtained with equipments such as laser interferometer, ball bar, electronic levels, signal acquisition systems etc. The MTLM models for single and two-axis configurations have been simulated and matches well with the measured responses of machines. The new modelling approach designated the Modified Transmission Line Method (MTLM) extends the TLM approach retaining all its inherent qualities but gives improved convergence and processing speeds. Further work since, not the subject of this paper, have identified its potential for real time application

An educational tool to assist the design process of switched reluctance machines

The design of electric machines is a hot topic in the syllabuses of several undergraduate and graduate courses. With the development of hybrid and electrical vehicles, this subject is gaining more popularity, especially in electrical engineering courses. This paper presents a computeraided educational tool to guide engineering students in the design process of a switched reluctance machine (SRM). A step-by-step design procedure is detailed and a user guide interface (GUI) programmed in the Matlab® environment developed for this purpose is shown. This GUI has been proved a useful tool to help the students to validate the results obtained in their lecture assignments, while aiding to achieve a better understanding of the design process of electric machines. A validation of the educational tool is done by means of finite element method (FEM) simulations.Postprint (author's final draft

Control design toolbox for large scale variable speed pitch regulated wind turbines

The trend towards large multi-MW wind turbineshas given new impetus to the development of wind turbine controllers.Additional objectives are being placed on the controllermaking the specification of the control system more complex. A new toolbox, which assists with most of the control design cycle,has been developed. Its purpose is to assist and guide the control system designer through the design cycle, thereby enabling faster design. With the choice of control strategy unrestricted,the toolbox is sufficiently flexible to support the design processfor the aforementioned more complex specifications