Lagrange modelling and control for a linear DC machine
Date
2019-09-12
Authors
Ngwako, Mohlalakoma Therecia
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Abstract
Modelling of electric machines is often a very challenging task due to the underlying
electromagnetic fields. The nature of the magnetic field is that they are
typically time varying and have operational issues such as saturation, hysteresis,
nonlinearities and coupling etc. Further, attempts to shape the fields e.g. into sinusoidal
waveforms, e.g. with salient poles are never perfect. Losses such as eddy
current losses among others compound to the problem of accurately modelling the
underlying electromagnetic interactions of an electric machine.
The goal of this research is to utilize a dynamic energy based modelling technique
to circumvent a number of the electric machine modelling challenges. Lagrange
analysis is proposed to demonstrate its two key challenges namely; dynamic energy
balance via Lagrangian energy equations and follow on Euler-Lagrangian state
analysis. Secondly input and instantaneous rate of dissipation Euler-Lagrange
model formulation and analysis incorporates a degree of freedom analysis to perform
the physical model order analysis. This Lagrangian analysis is to be demonstrated
on modelling a linear DC machine controlled for various performance criteria
such as speed control, current control and power control. Further proposed
results and analysis are for a pair of linear DC machines one of which is a gravity
fed generator whose aim is to electrically drive the tandem DC machine up a slope
under various control criteria.
Overall the novelty of this work is in utilizing the Lagrangian analysis to model
a linear DC machine and also to utilize the same analysis to reduce the model
complexity by systematically reducing the model order.
Description
A Dissertation submitted in fulfillment of the requirements for the degree of Master of Science in Engineering in the School of Electrical and Information Engineering
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Citation
Ngwako, Mohlalakoma Therecia. (2019). Lagrange modelling and control for linear DC machine. University of the Witwatersrand, https://hdl.handle.net/10539/29364