| Summary: | 碩士 === 國立臺北科技大學 === 機電整合研究所 === 92 === The objective of this thesis is to use the structured singular value in robust control theory to analyze the performance indices of multimodule DC-DC buck converters system. First, we adopt the energy conservation theorem to derive practical performance specifications used in power electronics, such as ripple, efficiency and output voltage level. Since the component values in modules of parallel system are usually different and then deteriorate the performance, according to the cases: (1) characteristics in each module are identical, (2) characteristics in each module are different, mathematical models are established respectively. By using the models, linear fractional transform techniques are employed to conduct the LFT models of performance indices. As a result, the allowable variation range of the circuit components in parallel converters can be found to retain the pre-specified performance requirement.
Also, the current distribution in each module of parallel converters is one of the most concerned problems. To analyze the problem, the current distribution error is defined as a performance index in this thesis. This performance index represents the current difference of modules in steady state, and it is the smaller the better. Using similar linear fractional transform techniques, the model of current distribution error is built and the tolerant arrange of component values is found for the given distribution error specification.
From computer simulations, it is shown that the variation ranges of the circuit component are found by the proposed method for keeping the robustness of performance indices.
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