Switch mode emulation of large value capacitors in the rotor circuit to improve the induction motor performance.

Suciu, C., 2000. Switch mode emulation of large value capacitors in the rotor circuit to improve the induction motor performance. PhD, Nottingham Trent University.

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This thesis describes an investigation into enhancing the performance of induction motors by secondary reactance control without injecting to or extracting energy from the rotor as in the case of double fed machines.

Firstly, a space-vector model of the motor is used to investigate the changes in performance induced by the insertion of equal capacitance in each secondary phase. The effect of the secondary capacitance is to introduce leading vars into the rotor. A set of equations that simplifies simulation of an induction motor performance, in both the short circuited rotor mode and with externally modified rotor impedance, are developed. The simulations showed that impractical high values for capacitors are required to phase advance the rotor current to achieve performance enhancement.

Electronic methods of achieving phase advance have been researched from literature and appraised. These methods were found not suitable for this application. A novel method using Pulse Width Modulated (PWM) controlled H-bridge with bi-directional switches and a capacitor as central component is presented in this thesis for controlling the phase angle in high power, low frequency RL circuits. The system increases the capacitive effect by several orders and thus reduces the physical size of the capacitor required.

The technique was applied to a low power induction motor. The results showed an enhancement of the motor performance.

The duty ratio and its resolution are dependent on the rotor circuit parameters that vary with the motor load. Fuzzy control for the duty ratio to achieve the required phase angle is investigated. Verification is presented by experimentation in a single-phase circuit.

Item Type: Thesis
Description: The research programme was carried out in collaboration with Transilvania University of Brasov, Romania
Creators: Suciu, C.
Date: 2000
ISBN: 9781369313116
Divisions: Schools > School of Architecture, Design and the Built Environment
Record created by: Jeremy Silvester
Date Added: 02 Sep 2020 10:33
Last Modified: 15 Jun 2023 10:18
URI: https://irep.ntu.ac.uk/id/eprint/40612

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