一种逆变CO2焊机IGBT驱动电路设计

根据逆变CO2焊机IGBT的工作特点,分析了逆变CO2焊机IGBT的驱动要求,设计了一套由分离元件构成的逆变CO2焊机IGBT驱动电路.由DSP产生的两路PWM信号首先经分频电路进行分频,再经电气隔离与电压调整电路进行信号调理,最后经变压器隔离放大电路进行电气隔离和电压调整放大,最终可获得逆变焊机IGBT安全可靠工作的PWM驱动信号.根据设计,制作了全套驱动电路,采用20 kHz工作频率进行试验.试验结果表明,获得的IGBT驱动信号的栅极正负偏压、栅极电压上升时间以及信号同步性和抗干扰性均符合设计要求,能够安全可靠地驱动逆变CO2焊机IGBT工作.     

逆变弧焊电源IGBT模块的设计和选型

影响逆变弧焊机可靠性的因素很多,开关元器件(如IGBT)的选型设计是其中的关键.根据实践经验,通过分析IGBT的结构特点、参数选择、缓冲电路、保护方法、散热设计、工作环境和保管运输等方面,阐述了IGBT在实际使用过程中可能造成损坏的原因;详细介绍了逆变弧焊机IGBT模块的选型设计原则和注意事项;重点给出了IGBT模块安全工作区和温升的设计原则及测试方法.实际应用结果表明,这些方法和途径十分有效,提高了逆变弧焊机的可靠性.     

提高IGBT逆变焊机性能的研究

在对IGBT逆变焊机主电路、驱动保护电路深入分析的基础上，提出了提高焊机可靠性的途径，并据此研制了400A移相全桥零压开关逆变焊机。     

信息动态

为提高大功率数字埋弧焊机全桥逆变主电路中IGBT短路保护的准确性和焊机的可靠性,对其逆变主电路中IGBT的短路模式进行了分析,设计了一款IGBT驱动器.通过采用抗干扰的IGBT短路试验测试方案,准确、可靠的完成了IGBT短路保护测试.与Concept公司的2SC0106T驱动器短路保护测试结果对比后,结果表明,设计的IGBT驱动器短路保护功能良好,保护时间短,关断电压尖峰小,抗干扰能力强,有一定的工程应用价值.     

数字式逆变埋弧焊机IGBT短路保护的试验研究

为提高大功率数字埋弧焊机全桥逆变主电路中IGBT短路保护的准确性和焊机的可靠性,对其逆变主电路中IGBT的短路模式进行了分析,设计了一款IGBT驱动器。通过采用抗干扰的IGBT短路试验测试方案,准确、可靠的完成了IGBT短路保护测试。与Concept公司的2SC0106T驱动器短路保护测试结果对比后,结果表明,设计的IGBT驱动器短路保护功能良好,保护时间短,关断电压尖峰小,抗干扰能力强,有一定的工程应用价值。     

弧焊逆变电源本脉冲反馈控制

由于IGBT（Insulated gate bipolar transistor)较其它电力电子器件开关频率高，载流容量大，开通损耗小，饱和压降低等优点，已逐渐成为逆变焊机的主流，为了提高IG-BT逆变电源的可靠性，设计了本脉冲反馈技术的控制电路，该电路实现整个电弧负载变化范围内焊接电流的无超调快速控制，既可满足焊接静特性和动特性要求，又可保证逆变弧焊电源的可靠性，本电路适用于单端正激式，半板式和全桥式逆变焊机等。     

焊机中IGBT元件的选择与应用

研制一种ZX7-160 直流逆变焊接电源.介绍了HGTG12N60A4的静态和动态性能以及安全工作范围,并从IGBT的器件电容、热响应性能等方面介绍了IGBT的选型原则.设计的焊接电源采用单管并联单端正激型主电路,给出了逆变频率的选择要点,重点分析了栅极驱动电路的设计以及门板驱动电阻的计算和功率要求、保护吸收电路各元件的计算以及注意事项.结果表明,所设计的焊机性能稳定,应用前景广阔.     

基于CPLD的全桥移相技术在逆变焊机中的应用

作为逆变焊机的重要组成部分,驱动电路发出驱动脉冲去控制功率器件(IGBT),从而调节逆变焊机的输出电压。介绍了基于CPLD的全桥移相零电压开关驱动技术,指出CPLD技术的优点,并详细分析了电路结构、工作原理。测试结果表明,使用CPLD设计IGBT驱动波形,控制方便、灵活。系统控制精度高、可靠性高。     

全数字化IGBT逆变焊机系统设计

设计了基于DSP和单片机的全数字化IGBT逆变焊机系统.该系统的主电路采用IGBT逆变技术,控制系统采用主从式控制结构,同时阐述了该控制系统硬件和软件的设计方法,以及主从控制系统的通信问题.     

埋弧焊过程的单片机控制技术及其应用

研制开发出一种单片机控制的新型IGBT逆变埋弧自动焊机。对该焊机的主电源结构、小车行走控制电路、送丝电路、单片机控制电路以及焊接过程控制软件等的设计作了较详细的介绍。     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

An Easy Way to Quantify the Adhesion Energy of Nanostructured Cu/X(X=Cr,Ta,Mo,Nb,Zr) Multilayer Films Adherent to Polyimide Substrates

An approach based on film buckling under simple uniaxial tensile testing was utilized in this paper to quantitatively estimate the interfacial energy of the nanostructured multilayer films(NMFs) adherent to flexible substrates. The interfacial energies of polyimide-supported NMFs are determined to be *5.0 J/m2 for Cu/Cr, *4.1 J/m2 for Cu/Ta,*2.8 J/m2 for Cu/Mo, *1.1 J/m2 for Cu/Nb, and *1.2 J/m2 for Cu/Zr NMFs. Furthermore, a linear relationship between the adhesion energy and the interfacial shear strength is clearly demonstrated for the Cu-based NMFs, which is highly indicative of the applicability and reliability of the modified models.     

High-Speed Friction Stir Welding of SiC_p/Al–Mg–Si–Cu Composite

A 17 vol% SiCp/Al–Mg–Si–Cu composite plate with a thickness of 3 mm was successfully friction stir welded(FSWed) at a very high welding speed of 2000 mm/min for the first time. Microstructural observation indicated that the coarsening of the precipitates was greatly inhibited in the heat-affected zone of the FSW joint at high welding speed, due to the significantly reduced peak temperature and duration at high temperature. Therefore, prominent enhancement of the hardness was achieved at the lowest hardness zone of the FSW joint at this high welding speed, which was similar to that of the nugget zone. Furthermore, the ultimate tensile strength of the joint was as high as 369 MPa, which was much higher than that obtained at low welding speed of 100 mm/min(298 MPa). This study provides an effective method to weld aluminum matrix composite with superior quality and high welding efficiency.