Analysis and design of resonant frequency control systems with applications.

摘要

Resonant systems arise in many areas throughout science and engineering. Some examples of systems which must be excited at resonance for optimal performance include ultrasonic motors, inductive heating loads, cavity resonators, and cyclotrons. Due to disturbances such as environmental conditions, load variation and degradation, the resonant frequency of these systems can shift, resulting in loss of performance. This necessitates employment of a resonant frequency control system that maintains lock between the excitation frequency and the resonant frequency.; In this thesis, three resonant frequency control methods are investigated. The first uses nonlinear feedback with a phase lead compensator to start and sustain oscillation at the resonant frequency of the system. The second method varies the excitation frequency to track the resonant frequency of the system by seeking the frequency corresponding to a local maximum of the magnitude response. The third method varies a parameter in the resonant system to tune the resonant frequency to the excitation frequency by seeking the parameter value corresponding to a local maximum of the magnitude response. Non-linear models of these control systems are developed and linearized to obtain tractable models for analysis and design. In addition, design guidelines are provided and results are illustrated through two applications: a novel RF plasma ignition system, and a dynamic vibration absorber. Simulation results are presented for the dynamic vibration absorber and the developed RF plasma ignition system to illustrate the effectiveness of the proposed control methods. Also, experimental results for the proposed ignition system are presented to further demonstrate the features of the proposed methods and the viability of the ignition system.