| Abstrakt: |
This paper describes the development and application of a tool created in MathCAD® to illustrate the internal workings of a synchronous machine on video. Upon receiving a set of parameters and preferences, the tool creates an interactive animation of the currents, magnetic flux, and physical rotation of the machine. The tool even recommends the best settings to obtain a movie that loops to simulate continuous rotation in a fast or slow motion. This enables the student to see what a finite element program might reveal about a synchronous machine but requires only the same MathCAD® readily available on a university-wide license. The program has an attractive level of sophistication. For example, its inputs are the following: physical dimensions, number of poles and slots, air gap width, frequency, positive and negative sequence inputs, appropriate motor or generator sign convention, power and torque output, resistances, reactances, simulation time and time step, and calculation density. The tool then builds and displays an appropriate physical cross-section diagram of the stator created from the given dimensions, showing a correct number of slots with their windings properly pitched. It calculates a complete lumped parameter d-q model, displaying its particulars on request. The tool then creates the rotor from the given dimensions, with windings appropriately placed, pitched, and skewed. The rotor has a calculation burden appropriate for the animation. The program calculates flux linkage, illustrating it as an animated distribution of arrows similar to the manner in which finite element programs show this. The density of the points for flux linkage analysis and the information that their arrow distribution shows is another usercontrolled option, based on assigned permeabilities and calculated topology. Calculations are based on a Biot-Savart model of the magnetic, consistent with Maxwell's equations. The program updates these with every time step as the machine rotates. A plotting algorithm, specially developed to illustrate the results, shows an animated illustration of the machine's currents, magnetic fluxes, and rotation. The tool calculates a companion phasor diagram to help explain the machine's state and the interaction of its voltages, currents, and lumped parameter model of internal behaviors. This collaborating phasor diagram can be displayed next to the animated cross section illustration of the machine. Animation controls, as with all inputs and controls, are available on a graphical user interface. The tool is intended not to replace finite element analysis, but to provide an illustration of appropriate results gained at no extra cost to the college student who is already using MathCAD®. It is appropriate for use in classroom and instructional settings and likely pertains to the college undergraduate or graduate levels. In presenting this paper, we will show the animation, we will provide assessment data from use with students, and we will provide a link for download of the tool. We have employed this program in college classroom demonstrations, but not for student use on projects yet. Student reaction, taken anecdotally so far and not rigorously sampled, enthusiastically supports the program's value for illustrating machine behavior and for gaining familiarity with the output of a finite element program. Faculty reaction to this program has likewise been quite enthusiastic, reinforcing with comments its value as a means to illustrate elementary synchronous machine functions without the price tag of a finite element software package. [ABSTRACT FROM AUTHOR] |
