全数字化全软开关DC-DC变换器及其电弧负载的耦合机理

项目名称： 全数字化全软开关DC-DC变换器及其电弧负载的耦合机理

项目编号： No.50807005

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 沙德尚

作者单位： 北京理工大学

项目金额： 20万元

中文摘要： 对于全数字多功能焊接电源的关键核心开展工作。电弧负载对于功率电路的动态性能提出了苛刻的要求，提高变换器的开关频率是有效的手段。因此主电路只能采用MOSFET。本课题提出了适应高压直流输入的高频软开关主功率电路，即串联全桥型主电路结构和原边串联模块化DC-DC变换器。对于串联全桥型移相全桥软开关主电路，为了提高电弧负载下主电路可靠性，提出了三闭环双电流环控制思路，其中中间环为平均电流环，最内环为峰值电流环，建立了主电路的小信号模型。对于原边串联模块化DC-DC变换器，提出了交叉反馈电流控制，占空比交叉控制新思路。在不采样每个输入模块直流电压的情况下可以实现模块电流功率的均分控制。 对于短路过渡气体保护焊，提出了准恒压自然过渡波控新思路，短路和燃弧的判断并不是靠检测输出反馈电压，但实现了短路和燃弧的自然过渡。焊接过程稳定。对于脉冲气体保护焊，提出了三闭环控制思路，实现了干深长，弧长和输出电压的解耦控制，同时提出了针对前件变量未知的T-S模糊系统设计了一类模糊观测器，并把它应用到GMAW系统中，快速有效地实现了对弧长观测。对于变速送丝双脉冲焊，也提出了稳定的控制方法，焊接过程稳定，焊缝成形美

中文关键词： 焊接电源；直流-直流变换器；功率均分；气体保护焊；解耦

英文摘要： The project concertrates on the key technology of full-digitalized multi-function welding power.For the arc load, the good dynamic performance is needed for the power circuit. Increasing switching frequency is effecive and therefore only power Mosfets can be used in this occasion. A topology is proposed to meet the requirements of high frequency,high dc input voltage applications.To improve the reliabitlty of the power circuit, a three-loop closed control is proposed,where the middle loop is average-current loop,and the inner loop is peak current loop.Small-signal mode is established for this kind of power circuit.For the input-series connected modular dc-dc converters, a cross feedback output current sharing control and duty cycle exchanging control are proposed to achieve power sharing balance among the constitutent modules without sensing the individual input voltages. A novel full digital waveform control scheme called quasi-constant voltage control is presented. Short circuit and arc ignition process are not judged according to the output voltage and transfer process between them is smooth.A three closed loop control is proposed to achieve decoulping ammong the dropout, arc length and output voltage.A class of fuzzy observer is designed for the T-S fuzzy system with immeasurable premise variable, which is applied for the arc length observing in the GMAW system. The simulation results are given and illustrate the validity of this approach.A control method for double pulsed GMAW based on varying speed is proposed in this paper.The welding process is stable while welding bead is excellent.

英文关键词： welding power;DC-DC converter;power sharing;Gas metal arc welding(GMAW);decoupling