Abstract
ABSTRACTAn inverter-fed electrodynamic shaker system is developed in this dissertation. First, the requirements of switching power and control for shaker are comprehended from the studies of its structure, operation principle and dynamic modelling. Then a switching-mode inverter with sophisticated current-controlled pulse width modulated (PWM) switching scheme is designed for powering the armature of shaker. Good sinusoidal current waveform tracking characteristics are obtained within the frequency range from 5Hz to 2kHz, which is specified typically for an electrodynamic shaker. Additionally, a zero-voltage transition (ZVT) technique is employed to reduce the switching losses and voltage stresses of inverter switches. On the other hand, for improving the line drawn power quality, an isolated soft-switching mode rectifier (SSMR) is developed and used as the input stage of the inverter. The proposed SSMR consists of a power factor correction (PFC) ZVT-PWM converter followed by a transformer-coupled zero voltage switching (ZVS) dc/dc converter. The latter stage can be omitted if the electric galvanic isolation is not required. Through applying the proposed soft-switching and PFC control approaches, soft switchings of converter switches and sinusoidal line drawn current with near unity power factor are obtained.The satisfactory vibration acceleration control of shaker over wide frequency range is considered to be more challenged due to the switching power excitation. So finally, a sophisticated acceleration control scheme being capable of waveform and magnitude regulation controls is proposed to lessen the undesired harmonic vibration of the inverter-fed shaker. In acceleration waveform control, the feedback controller is augmented with feedforward controller and robust controller for obtaining good waveform tracking performance. As to the magnitude regulation control, the amplitude of sinusoidal acceleration is accurately controlled to be equal to the setting value.In the development of the proposed soft-switching inverter and SSMR, circuit operations and the derivations of governed equations in various modes are described in detail. And accordingly, the circuit design procedures are derived. As to the current and acceleration controllers, their theoretic basis, designs, practical considerations and implementations are presented. Having tested the effectiveness of all the designed circuits and controllers by simulations, their performances are further demonstrated by some measured results.