This thesis presents a torque control mechanism for switched reluctance machine
(SRM) drives. The proposed mechanism is capable of maintaining ripple free torque
control while minimizing the copper loss or mode-0 radial force or both at a fixed
switching frequency.
In the proposed approach, the torque control problem is addressed by splitting
it into two parts. The first part consists of identification of optimum phase current
references while the second part incorporates the design of an efficient current controller.
For the identification of optimum phase current references, three algorithms
are presented in the form of a developmental process. The nature of the online optimization
problem is demonstrated using a simple 2-dimensional gradient descent
method. Subsequently, a parametric form gradient descent algorithm is presented
which transforms the original optimization problem into two 1-dimensional problems,
viz. torque error minimization and identification of optimum search direction. This
method yields improved computational efficiency and accuracy. The third algorithm
incorporates projection using equality constraint on the phase torque contributions to
achieve a 1-dimensional solution process. Although this algorithm takes more iteration
as compared to the parametric form gradient descent algorithm, it demonstrates greater accuracy and computational efficiency. A comparative analysis of these algorithms
is performed in at different operating conditions in terms of the torque ripple
magnitude and computational effort.
The thesis also presents a comprehensive analysis of well known control techniques
for application in SRM current control in discrete-time domain. This analysis also
presents a comparative evaluation of these control techniques under different operating
conditions. On account of this analysis, several recommendations pertaining to
the performance improvement are presented.
Finally, a digital sliding-mode based model-free current controller suitable for fixed
switching frequency operation is presented. The proposed controller is capable of
providing a consistent dynamic response over wide operating range without utilizing
any model information. The reference current tracking performance of this controller
is verified through simulation studies in MATLAB/Simulink® environment and over
a 1.2kW, 100V, 2500RPM, 12/8 experimental SRM drive. / Thesis / Doctor of Philosophy (PhD)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/26848 |
| Date | January 2021 |
| Creators | Dhale, Sumedh |
| Contributors | Emadi, Ali, Nahid-Mobarakeh, Babak, Electrical and Computer Engineering |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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