An integrated starter/alternator (ISA) has been proposed for the future 42 V PowerNet, which combines both starter and alternator functions into a single electrical machine with bidirectional power flow ability. This thesis presents analysis, design, modeling and experimental results of the direct torque controlled ISA system based on a low voltage induction machine. The classical direct torque controlled ISA based on switching-table is systematically for an ISA evaluated in this thesis. The simulation and experimental results show that the direct torque control (DTC) concept can be successfully extended to the ISA application. An improved DTC of the ISA based on direct stator flux vector is presented to reduce the drawbacks of high torque and flux ripples of the classical DTC. Robust design of the controller ensures the system is not sensitive to the variation of rotor resistance. By controlling the electromagnetic torque of the induction machine quickly, the required dc bus voltage can be well regulated within the 42 V PowerNet specifications. Another improved DTC of the ISA with direct torque and flux control is also studied. Compared to the direct flux vector control scheme, the calculation of the commanded voltage vector in this scheme only requires the derivative of the stator flux magnitude, which is a dc quantity. In addition, both torque and flux are regulated directly with two independent closed-loops. This scheme is relatively insensitive to the noise. The thesis proposed compensation methods to reduce the effects of switch voltage drops and dead-time on the estimation of the stator flux. Experimental results confirm that the estimation error is reduced with compensation for both motoring and generating modes of the ISA. A closed-loop type of sliding mode flux observer is proposed to reduce the estimation error of the stator flux. Both Simulation and experimental results confirm that the proposed sliding mode observer is insensitive to the stator resistance variation and sensor offsets. A loss minimized scheme with power factor control for the ISA is proposed in this thesis. It provides a simple solution for the efficiency improvement of the induction machine without requiring any speed or load information. The effectiveness of the direct torque controlled induction machine for an integrated starter/alternator system has thus been confirmed and well supported by the studies presented in this thesis.

Synchronous machines provide a practical way to control reactive power consumption of a plant. One of the main advantages of using synchronous motors in a plant is their ability to generate reactive power for plant loads. A new control scheme for synchronous motor excitation systems is developed to automate reactive power consumption. The system performs adaptive control based on the real time data and keeps the power factor within a specified range. The system can also be used to improve voltage drop during large induction motor starts. Power system behavior as a result of applying the adaptive control is studied under different operating scenarios using power system analysis software. Results and conclusions are based on mathematical simulation and experimental measurements of a prototype system. / Graduation date: 2003

No description available.

Thesis (M.E.)--University of Adelaide, Dept. of Electrical Engineering, 1970.

Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 134-135).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 122-123).

Thesis (M.S.)--University of Wisconsin--Madison, 1968. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Excitation system models suitable for use in large-scale system stability studies are presented. Important limiters and supplementary controls are also included. The model structures presented are intended to facilitate the use of field test data as a means of obtaining model parameters. The models are valid for frequency deviations of ±5% from rated frequency and oscillation frequencies up to 3 Hz. / "IEEE Std 421.5 -2005 (Revision of IEEE Std 421.5-1992)." "Recognized as an American National Standard (ANSI)." "Approved 29 December 2005, American National Standards Institute ; approved 25 October 2005, IEEE-SA Standards Board." "Published 21 April 2006."--P. [ii]. "SH95364 ; SS95364"--P. [ii] Includes bibliographical references.

In this thesis, resynchronization of a synchronous machine from a slipping state is considered. A set of equations for the slipping machine are developed. Slip tests on a dynamic test model are done to compare with computed results. A critical damping necessary for resynchronization is investigated, and an expression is derived. Tests are again carried out on a power system set up on the dynamic test model to verify the result. Finally, a nonlinear optimal control is developed and implemented on the test model. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate

In this dissertation a new model for the synchronous machine is presented. This model, based on non-standard test data, allows for the appropriate modelling of the frequency dependent behaviour of the damper windings. The non-standard test data consist of frequency responses, either measured or calculated. The form of these responses will automatically determine the order of the resulting model. Saturation effects in the synchronous machine are also modelled with this new method. The model was successfully tested in both an electromagnetic transients program (EMTP) and in a stability program. It was found that when frequency response measurements are used directly, the model is more accurate than when using the standard data from the manufacturer or data estimated to match approximately the frequency response measurements. It was also ascertained that this model could be used to speed up the solution in a stability program, both by allowing the user to match the order of the model to the required accuracy depending on the event and integration step, and by modifying the input frequency response data to minimize the discretization error made when using large integration steps. / Applied Science, Faculty of / Electrical and Computer Engineering, Department of / Graduate