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关键词： PLC   控制系统   西门子变频器G120   Profibus-DP通信  

摘要： 为了保障2.9以下小规格铝合金单丝的生产,提升设备完整率,升级铝合金拉丝机变频器控制系统,以提升设备自动化程度、整体性能、单位产能发挥,降低企业综合维护成本及能耗。根据目前高规格铝合金单丝的工艺技术要求及设备现状,结合目前西门子控制器及变频器的更新换代情况,设计一套融合现有西门子主流变频器G120的全自动多规格铝合金拉丝机变频器控制系统。该控制系统以西门子300系列PLC基础,搭载数字量/模拟量输入输出模块,通过Profibus-DP通信连接多台变频器,通过操作台上的西门子TP1200触摸屏对整个铝合金拉丝机的运行状态进行操作控制与监测。该控制系统实现了对淘汰变频器的更新换代、铝合金拉丝机控制系统的升级,保障2.9以下小规格铝合金的规模生产,实现全自动模式下最大拉丝速度达到20m/s。实践证明,升级后的全自动铝合金拉丝机采用新式变频器G120的控制系统,实现老旧设备设计更新换代,具有控制精度高、能耗低、运行稳定等优点。

关键词： 永磁同步电机   采样率   矢量控制   滑模变结构控制   趋近率  

摘要： 针对永磁同步电机(PMSM)速度环比例积分(PI)控制算法在变工况时的不足,提出一种分数阶双幂次快速趋近率滑模控制算法,并研究不同采样率对永磁同步电机的滑模控制(SMC)性能影响。对最小相位系统进行采样率的理论分析,通过多阶线性矩阵不等式可以得到最佳采样周期,理论分析了新型趋近率的可达性和存在性。搭建仿真模型,验证其能有效改善变工况时超调量大、过渡时间长等不足。试验结果表明,针对响应时间、超调量等性能有相对最优的采样率,证明了误差估计稳定收敛的最佳采用周期存在。该研究适用于工程应用。

关键词： 感应电机   新息理论   自适应扩展卡尔曼滤波   矢量控制  

摘要： 提出了一种基于新息理论的自适应扩展卡尔曼滤波(IT-AEKF)感应电机转速估计方法,实现了优化的感应电机无速度传感器矢量控制。该转速估计方法使用新息序列对系统噪声协方差矩阵进行在线估计和自适应调节,实时地跟踪系统模型的变化,使系统模型与实际模型更加匹配。所提出的方法提高了系统模型对于实际系统以及外部环境变化的适应性,也满足对于低速的估计要求,进而提高系统的稳态精度和抗粗差性能,使系统遇到干扰时更快收敛。实验结果验证了算法的正确性和有效性。

关键词： 电梯变频器   变频器故障   安全技术  

摘要： 随着我国社会经济的飞速发展,电梯的使用愈发广泛,尤其是高层建筑与超高层建筑的大规模出现,电梯已成为日常生活不可或缺的垂直交通工具。电梯产业高速发展的同时也带来诸多难以回避的新问题,电梯变频技术广泛应用后电梯的乘坐舒适性得到了极大的提升,但随着变频器不同品牌质量参差不齐,投用时间越来越长,其本身老化所带来的故障也日渐凸显。若不能及时处理,将影响电梯运行的安全性、稳定性及其舒适性。在本文中,笔者将会针对电梯变频器故障的安全技术进行初步分析与探讨,希望借此可对相关从业人员起到一定借鉴价值。

关键词： 主动热管理   结温平滑   损耗控制   可靠性  

摘要： IGBT作为功率变流器的核心器件,被广泛应用于电动汽车、轨道交通、航空航天和电力系统等领域,由于功率变流器的运行环境复杂多变,处理功率大幅波动,导致IGBT内部结温发生剧烈变化,器件在热应力持续作用下引起疲劳老化失效,进而影响系统运行可靠性的问题已受到业界的普遍关注和高度重视。近年来,国内外学者围绕如何通过内部热管理来平抑功率器件的结温波动、延长运行寿命展开了大量的研究工作,从不同的角度提出各种主动热管理方法,这对延缓功率器件疲劳老化速率、提升器件运行可靠性有着重要意义。该文分别从功率器件层面和变流器运行控制层面系统性地阐述和归纳现有IGBT主动热管理方法的原理和特点,并基于IGBT器件寿命评估模型对各类主动热管理方法的效果进行量化评估,从热应力缓解程度、实现难度、寿命延长倍数和适用范围等多角度进行综合对比分析,并对IGBT器件主动热管理方法的进一步研究提出建议,为IGBT器件健康管理和运行可靠性的提升提供参考意义。

关键词： PLC   变频器   建筑中央空调   节能改造   高层建筑   冷却水泵   冷却塔风机  

摘要： 中央空调是现代高层建筑中重要的电气设施,发挥着制冷系统抵消室内环境热负荷、制热系统提供室内环境所需热量的重要作用,能够为业主提供更为舒适、高效与便捷的建筑环境,有助于提高业主日常生活质量。与此同时,中央空调系统的运行能耗较大,普遍占据高层建筑80%以上的电能消耗量,建筑总体使用成本有待降低。文章首先梳理了PLC与变频器的节能原理,对PLC及变频器在高层建筑中央空调节能改造项目中的应用情况开展探讨,包括冷水机组节能改造、空调水系统变水量调节、冷却水泵节能改造、冷却水与冷冻水系统节能改造、冷却塔风机和中央空调系统末端节能改造。

ISBN: (纸本)9787121428791

关键词： Insulated gate bipolar transistors   Temperature measurement   Loading   Voltage measurement   Fatigue   Monitoring   Thermal loading   Bond-wire lift-off   converter   power semiconductor   reliability   solder layer fatigue  

摘要： Thermal stress of the power semiconductor is one of the most important indicators for the reliability assessment of power electronics-based power systems. The mapping of the Insulated-Gate Bipolar Transistor (IGBT) junction temperature is usually required to analyze the thermal stress and loss dissipation. However, it is difficult to identify inherent mechanisms of the bond-wire and solder layer failure modes in IGBT power modules. In order to solve the problem, an online method to identify inherent mechanisms of the bond-wire and solder layer failure modes in IGBT power modules is proposed. This method can separate the root causes of the bond-wire lift-off and solder layer fatigue by measuring the on-state voltage drop through a sinusoidal loading current based on an H-bridge circuit, together with its corresponding control and measurement. By comparing the on-state voltage drop at the intersection current and the peak current of the converter, the wear-out conditions of the IGBT power modules can be monitored in real-time with the determination of different failure modes. Finally, experimental results are presented in order to verify the effectiveness and feasibility of the proposed method.

关键词： Sensors   Insulated gate bipolar transistors   Voltage   Logic gates   Voltage control   High-voltage techniques   Signal resolution   Insulated gate bipolar transistor (IGBT)   local voltage sensing (LVS) mode   potential barrier   voltage sensor  

摘要： Collector-emitter voltage (V-ce) detection of insulated gate bipolar transistors (IGBTs) is important for safety-critical and mission-critical power applications. The conventional voltage sensing method is characterized by the detection range from 0 V to the rated voltage in the application (V-r), which is limited by the contradiction between the dynamic range of the signal and the ADC resolution in high voltage situations. This letter proposes a novel local voltage sensing (LVS) mode, in which the detection range is from V-st to V-r, where V-st is a controllable starting point for the sensed voltage. Based on the LVS mode, a novel controllable voltage sensor structure is given, which can provide a sensing signal that is a scaled version of the large V-ce when V-ce >= V-st. V-st can be controlled by applying a negative voltage to a control electrode gate (V-G2). An analytical model is derived to understand the mechanism of the sensor and simplify the design. The effects of internal and external parameters on the sensing characteristics are simulated using Medici & TS4. Furthermore, the sensor is incorporated into a prototype 1200-V IGBT. The test results show that, under the condition of V-G2 = 0 V or V-G2 = -1 V, V-st and nonlinear error are 622 V and 3.9% or 708 V and 3.4%, respectively, and the experimental data agree with the analytical model results. Finally, an application of dc-bus voltage monitoring using the LVS mode is presented.

关键词： Temperature sensors   Temperature measurement   Threshold voltage   Insulated gate bipolar transistors   Temperature   Degradation   Logic gates   Multichip IGBT module   temperature sensitive electric parameters (TSEPs)   Miller platform duration   threshold voltage   junction temperature  

摘要： With the development of high power converters, the safe operation of large IGBT modules with parallel chips is of increasing importance. In a multichip module, uneven solder layer degradation translates into higher thermal resistance for some of the chips, leading to junction temperature differences between them. However, the specific meaning of a virtual junction temperature extracted from any external electric characteristic parameter of the module is not yet clear. This paper studies the physical meanings of the temperatures estimated by the threshold voltage and the Miller platform duration as well as the quasi turn- off delay time. Experimental results show that the temperature estimated from the threshold voltage is close to the highest temperature of all the chips, while that estimated from the Miller platform duration or quasi turn-off delay time is close to the average chip temperature. Making use of the difference between the two, this paper proposes a new method to monitor the initial solder layer degradation in the multichip IGBT module. Such a method using combined temperature sensitive electric parameters (TSEPs) is verified for different levels of degradation.