【作者】 朱国荣；

【导师】 康勇； 段善旭；

【作者基本信息】 华中科技大学 ， 电气工程， 2009， 博士

【摘要】 近年来逆变式弧焊电源有了很大的进展和长足的进步，但也存在着不少问题，其中之一就是逆变式弧焊电源的谐波干扰问题。谐波问题本身又包括两个方面：一是高频谐波问题，采用软开关方式，不仅可以有效消除高频干扰的产生，而且由于开关损耗的减少而使逆变式弧焊电源的效率和可靠性进一步得到提高；二是低频谐波问题，由于逆变式弧焊电源对电网来说，本质上是一个大的整流电源，输入电流波形畸变严重，需要进行功率因数校正和降低谐波畸变率。从国内外发展情况看，具有可靠性、高效性、电磁兼容性、先进焊接工艺性的智能型绿色焊接电源已经成为未来焊接电源的发展方向。针对特种弧焊电源对整流系统输出电压等级、输入电流谐波畸变率以及功率因数等需求，本文研究了轴向分裂自耦变压器的多脉波整流技术，分析了这种拓扑在空载和负载两种情况下的输出特性，以及输入电压畸变对系统性能的影响。针对三相不控整流系统中输入不平衡电压对系统的影响，分析了不平衡输入电压对不控整流换流过程切换点的影响，精确推导出系统输入电压的不平衡度与开关函数的精确关系，得出开关函数偏移角与负序初相角呈正弦函数关系，三个开关函数偏移角的三条曲线互差120度，正弦的幅值与负序占正序的比例值呈线性关系的结论，这一结论为精确分析不控整流电路中不平衡输入对系统性能的影响提供了分析工具。利用精确的开关函数，推导了多脉波整流系统输入不平衡电压与输出电压非特征谐波的精确关系，进而得到电阻、电感负载时系统输入电流与输入电压不平衡度的关系，为精确地选择滤波元件做了有意义的探索。仿真和实验验证了理论分析的正确性。大功率逆变式弧焊电源大多应用移相全桥ZVS软开关拓扑，针对移相全桥ZVS软开关拓扑结构特点，建立了全波整流抽头变压器的等效模型，并将移相全桥ZVS软开关拓扑结构开关过程的分析统一于基于变压器等效模型的结构，给基于移相全桥ZVS电路的各种电路结构的分析提供了一种新的思路。然后，基于此等效电路模型做了如下研究：精确定义了滞后桥臂实现ZVS的谐振电感和并联电容必须满足的充要条件；分析了非理想工作情况下的过渡过程；分析了变压器原副边漏感对工作过程的不同阶段的不同影响。仿真和实验验证了理论分析的正确性，为后续工作者提供了很好的参考价值。随着微处理器的迅速发展，数字控制因控制策略的灵活性和强大的决策能力得到越来越多的应用，复杂、智能的算法得以实现，但同时，数字控制本身也带来了一些问题，本文为移相全桥控制系统的分析提供了一种简单直观可行的控制模型，为移相全桥ZVS数字化控制提供理论分析基础，且致力于研究数字化过程引起系统性能下降的原因：零阶保持过程对移相全桥ZVS电源开环频率特性以及闭环控制稳定性的影响；滞后一拍控制对移相全桥ZVS电源闭环控制稳定性的影响。通过分析得出以下结论：(1)零阶保持过程改变了移相全桥ZVS电源开环频率特性，使得欠阻尼系统随采样周期和电源阻尼振荡频率呈现出周期性规律；而使得过阻尼系统随着采样周期呈现单调规律；(2)零阶保持过程改变了移相全桥ZVS电源闭环系统稳定性，相对于模拟控制稳定范围大大降低；(3)滞后一拍控制改变了数字移相全桥ZVS电源闭环稳定性，稳定范围进一步减小。仿真验证了理论分析的正确性。基于特种弧焊电源的工程要求和工艺要求，本文最后研制了高功率因数、低谐波畸变的软开关弧焊电源，设计了数字化控制系统，实验验证了理论分析的正确性。更多还原

【Abstract】 Great advancements have been made in the area of the arc-welding inverter power source in recent years. However, there are still some problems, and one of them is the harmonic interference of the arc-welding inverter power source. The harmonic interference includes two sides. One is the high frequency harmonics interference, which can be eliminated by using soft switching mode. Meanwhile, the efficiency and reliability of the arc-welding inverter power source could be improved by using soft switching mode. The other is low frequency harmonics interference. The arc-welding inverter power source is in essence a power rectifier to the electric network, so the input current distorts seriously, and the power factor correction and the harmonic distortion factor reduction are necessary. From the internal and international developments’ standpoint, the intelligent green welding power source with high reliability, efficiency and electromagnetic compatibility is the developing direction of the welding power source.This dissertation focuses on the research of the multiple pulses rectifying technology based on the axial splitting autotransformer, used in the special arc-welding power source, with special voltage level, low harmonic distortion and high power factor. The characteristics of each magnetic element in the rectifier are analyzed in detail, as well as the relation between the input current distortion, the output voltage ripple and the system parameters. In addition, the system performance when the input voltage distorts is also analyzed. In the three-phase no controlled rectifier system, the unbalanced input voltage will influence the switching point. To the influence, the exact relation between the imbalance of the input voltage and the switching function is deduced for the first time. The deviation angle of the switching function has the sine curve relation with the initial phase angle between the negative sequence and the positive sequence, and the three curves of the three switching functions deviation angles are three phase symmetry. Meanwhile, the amplitude of the sine curve has the linear relation with the proportion that the negative sequence relatives to the positive sequence. Therefore, the exact relation between the unbalanced input voltage and the noncharacteristic harmonics of the output voltage in the 12-pulse rectifier system is obtained. In addition, the relation between the input current and the imbalance of the input voltage is obtained, which could help to choose the filter elements and exactly analyze the characteristics of the no controlled rectifier circuit. The theoretic analysis is verified by the simulation and experiment results.The topological structure of the Phase-Shift Full-Bridge ZVS (PS-FB-ZVS) is widely used in high power arc welding power source. A uniform equivalent circuit model is built, which offers a new method to analyze different circuit organizations based on PS-FB-ZVS circuit and a universal equivalent model for the tapped transformer. Based on the equivalent circuit model, there are some researches are engaged in this dissertation: the necessary and sufficient condition, which resonance inductors and parallel capacitors should meet to realize the ZVS of lag bridges, is exactly defined in this dissertation; the transient process under the nonideal switching work is analyzed, as well as the different influences to the working process which are produced by the leakage inductance of the transformer, and the influences which are produced by the interturn capacitance of the transformer, the parasite capacitance of output rectifiers and output buffer capacitors. The theoretic analysis is verified by the simulation and provides the reference meaning to future researchers.With the rapid development of the microprocessor, digital control is increasingly used due to its strategic flexibility and strong decision ability, and complex and intelligent arithmetic is realized. However, digital control also brings some problems. This dissertation is focused on the research of the causes which decrease the performance of the digital controlled PS-FB-ZVS induced by the process of zero hold and sample. There’re two main causes. One is the change of the property arising from the process of the zero hold. The influence of the process of the zero hold is analyzes, also its influence on open loop frequency property and the system close loop stability of PS-FB-ZVS. Another one is the effect of the delay arising from the sample and calculation. To resolve this problem, one-step-delay control is always adopted. The influence of this control method on the system close loop stability is also analyzed.These analysis show there’re three key causes effecting the digital controlled PS-FB-ZVS’s performance: (1) The process of the zero hold changes the open-loop frequency property of the PS-FB-ZVS that is for under damp systems, the property varies periodically with sample time changing and for over damp systems, varies monotonously; (2) The process of the zero hold changes the system’s stability and the stable zone lessens greatly; (3) The one-step-delay control method changes the system’s stability too. Simulations and experiments verify the lightness of the analysis and the feasibility of the proposed control strategy.Based on the requirements of the special arc welding power source, the soft switching arc welding power source with high power factor and low harmonic distortion is researched and developed in this dissertation. The digital control system is designed, and the theoretic analysis is verified by the experiments.更多还原