Resonant DC/DC Converters: Modeling, Control Strategies, Simulation, and Experimental Studies

Resonant power converters are switched RLC circuits where the switching action creates oscillatory current and voltage waveforms at the resonant frequency of the circuit . There are two basic types of resonant converters: the series type and the parallel type. In the series resonant converter the output i s connected in series with the resonating elements which are comprised of the resonant inductor and capacitor. In the parallel resonant converter, the voltage across the capacitor is sensed and coupled to the output port. The output parameter (voltage in the series resonant converters or current in the parallel resonant converters) and the switching frequency characterize the operation of resonant converters. An accurate analysis of series and parallel resonant converters i s given i n terms of these parameters. In this thesis, resonant converters with lumped losses are analyzed. State-plane portraits are generated from the solutions of circuit equations of these second order system, whereby the steady state, system dynamics, and the peak stresses are determined. Equation for the switching boundary i s given under the lossless assumption. Control strategies for the resonant converters are discussed and a novel method of control, optimal control, is proposed in controlling the parallel resonant converters. Typical circuits are simulated by using SPICE2 and Interactive Circuit Design Program (ICD). A parallel resonant converter was built. The simulation and the experimental results verify the analytical results

Strategy Selection for Product Service Systems Using Case-based Reasoning

A product service system integrates products and services in order to lower environmental impact. It can achieve good eco-efficiency and has received increase in the last decade. This study focuses on strategy selection for product service system design. Case-based reasoning is utilized to provide suggestions for finding an appropriate strategy. To build a case database, successful PSS cases from the literature and websites were collected and formulated. Twelve indices under three categories were analyzed and selected to describe cases. A lot of successful PSS cases and their information were collected. Forty seven cases were used in this study because of the completeness of information. The analytic hierarchic process is used to find the relative weights of the factors that relate to the selection of customers. These weights are used in calculating the similarity in the case-based reasoning process. The successful strategy of the most similar case is extracted and recommended for PSS strategy determination. More than 90% of tested cases obtained an appropriate strategy from the most similar case. Finally, two new products are introduced to find the best strategy for product service system design and development using the proposed case-based reasoning system