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Passive Clamp Auxiliary Converter Converter

Posted on:2010-07-15Degree:MasterType:Thesis
Country:ChinaCandidate:W XieFull Text:PDF
GTID:2192360278469385Subject:Power electronics and electric drive
Abstract/Summary:PDF Full Text Request
Nowadays, phase-shift control FB-ZVS-PWM controller attracts more and more attention. This converter employs phase-shift control to provide ZVS conditions to the primary switches utilizing circuit parasitic such as the switch junction capacitance and the Trans former leakage inductance. Many advantages such as simple circuit and ZVS without additional resonant components make this converter widely adopted for many applications where MOSFETs are used as switching devices. However, the ZVS range is limited unless the leakage inductance is large. The large leakage inductance results in effective duty cycle loss. Moreover, FB-ZVZCS-PWM is advanced which IGBTs are used as switching devices, in this topology, the leading legs operates in ZVS mode while the lagging legs operates in ZCS mode.This dissertation provides the analysis and comparison of these converters, it also refers to the improvement of these converters. Based on the analysis of their characteristics, this paper confirmed the primary blue print and proposed a new topology. This topology can achieve an extreme wide load range under soft switching for both leading and lagging legs, as well as minimized the pre-stored energy of main circuit, so the current stress would be minished.The small signal model of the proposed ZVZCS converter is derived based on the small signal model of Buck converter, and incorporating the effects introduced by the auxiliary circuit which consists of a Trans former leakage inductance and auxiliary capacitors to achieve ZVZCS. Its dynamic performance is analyzed by Matlab, the results validate the accuracy of the analysis and design consideration.The transfer function in the discrete-time domain is derived using the small-signal model, and the effects on the leakage inductance, time delay and sampling time are then analyzed, which provide a strong theoretical basis for the system parameters and digital controller design.
Keywords/Search Tags:soft switching, full bridge topology, small signal analysis, digital control
PDF Full Text Request
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