教学课程资源库 更多>>

关键词： PLC技术   变频器   节能控制   中央厨房   排风系统  

摘要： 中央厨房是餐饮和食品行业发展的必然趋势,但传统的中央厨房为烹饪设备配套的排风机都是按照设备最大排风量所设计的,而大型排风机的耗电量非常高,并不是每个设备都同时处于使用状态下,不能根据实际需求及时地调整排风机功率,容易造成极大的资源浪费。为解决这一问题,将可编程逻辑控制器(PLC)技术引入中央厨房中,通过预设的编程规则,配合前端部署的传感器群,实现按需排风,以达到节能降耗的效果。本文以中央厨房排烟系统的变频器控制为例,结合硬件配置与程序设计,展示了PLC在中央厨房排风系统节能方面的独特价值和应用潜力。

关键词： 变频器   应用   维护  

摘要： 变频器作为一种在船闸电机拖动中广泛应用的调速节能设备,选型应用及检查维护十分重要,本文从基本类型选择、控制方式、加减速设置、检查维护要点、典型故障处理等方面入手,提出了较为全面的建议,为通用变频器在船闸电机拖动中的应用提供了有效地参考。

关键词： 电机调速   变频器   行车   安全  

摘要： 本文详细介绍了安川变频器在宁波钢铁热轧厂磨辊间起重机运行机构中的应用,讲述了其改造方案、工作原理、功能等,分析了其应用后的效益。其应用可大幅提升起重设备的安全性能,增加智能故障诊断,减少故障时间,降低维护成本。

关键词： 超低排放改造   协调控制   脱硫塔   逻辑组态   炉膛负压   引风机   变频控制   动叶  

摘要： 实施背景我厂600MW流化床机组于2020年进行了超低排放改造工作,在工程最后阶段,由于各种原因设计方和组态调试方未给出我厂变频器动叶与变频控制的协调控制方案。我厂组织试验研究,确定方案,由我进行逻辑组态及调试。大型循环流化床引风机动叶与变频器协调控制,此种控制方式控制的被调量较多,可以控制炉膛负压,可以控制脱硫塔入口负压,可以控制脱硫塔出口负压.

关键词： 变频器   漏电流   零序电流保护  

摘要： 阐述变频器工作原理和主电路结构,变频器漏电流产生原因,探讨影响漏电流大小的因素,煤矿对漏电保护的要求,分析漏电保护方法有附加直流电源检测、零序电流保护法、零序功率方向法。

关键词： 双馈风力发电机   变速恒频   控制策略  

摘要： 本文通过研究双馈异步风力发电机的控制策略,来实现双馈风力发电机的变速恒频,并对其运行过程进行仿真分析。文中根据建立的双馈风力发电机数学模型研究其控制策略,本文研究的是转子侧基于定子电压定向的控制策略,对双馈异步风力发电机定子侧输出的有功和无功功率进行解耦控制。和转子侧基于定子磁链定向的控制策略相比,这种控制方法减少了定子磁链的计算,减小了误差。通过此控制方式,使用Matlab/Simulink软件搭建了双馈异步风力发电机的仿真模型,通过仿真验证了该控制策略可以有效地对有功和无功进行独立控制。

关键词： 绝缘栅双极晶体管   功率半导体器件   功率晶体管   饱和电压   栅极驱动   开关电源   电子开关   三端  

摘要： 绝缘栅双极晶体管(IGBT,Insulated Gate Bipolar Transistor)是一种三端功率半导体器件,主要用作电子开关,在较新的器件中以结合高效和快速开关而闻名。IGBT通过在单个器件中组合用于控制输入的隔离栅极FET和作为开关的双极功率晶体管,将MOSFET的简单栅极驱动特性与双极晶体管的高电流和低饱和电压能力相结合。IGBT用于中到大功率应用,如开关电源、牵引电机控制和感应加热。

关键词： Condition monitoring   degradation   insulated-gate bipolar transistors (IGBT)   reliability  

摘要： Condition monitoring (CM) of the components with highest probability of failure in converter circuits can significantly contribute to having a long-term reliable operation. Insulated-gate bipolar transistors (IGBTs) are considered as one of the most fragile parts with the highest failure rates in many power electronics applications. This article proposes a real-time CM technique for assessing the IGBT gate oxide degradation level. The proposed technique is based on the device turn-OFF delay time interval, which as we discovered, decreases during the device gate oxide degradation (DGOD) process. Therefore, this article proposes a practical fully analogue circuit to capture the device turn-OFF delay time and convert it to a dc voltage as the final output of the CM circuit. The DGOD precursor output can be effectively used to assess the health status of IGBT gate oxide layer during the device real-time operation. Two different types of 600 V/60 A discrete IGBTs from different manufacturers are used in the experimental verification process. In addition, the proposed CM technique is applied to a 500 W boost dc-dc converter to evaluate the applicability of the proposed CM technique to real-world converter operation. The results indicate that the proposed DGOD precursor shows a 50% change when the device experiences full gate oxide degradation.

关键词： Insulated-gate bipolar transistor (IGBT)   Cell temperature measurement   Thermoreflectance imaging (TRI)   Technology computer aided design (TCAD)  

摘要： -Temperature characterization of power semiconductors is a hot topic in power electronics. Nevertheless, the transient temperature field inside an IGBT cell is highly difficult to measure. In this study, we presented a method combining metallographic technology and Thermoreflectance Imaging (TRI) to measure the temperature distribution inside IGBT cells during switching. First, the IGBT module was prepared to achieve a well longitudinal section and its electrical characteristics were verified. Subsequently, the double-pulse test was performed on the IGBT sample and the temperature distributions along the ground section were measured through TRI. The result indicates that the temperature along the cross-section can be observed through TRI. The experimental results are confirmed to be consistent with the TCAD simulations on electro-thermal behavior. The proposed method for the first time achieves the direct temperature measurement inside the cells of power devices on a micro-nano temporal-spatial scale, and it can serve as an effective tool for analysis like temperature evaluation, aging analysis and TCAD modeling.

关键词： Degradation state analysis   Apparent junction temperature   Voltage rise time   High-frequency model  

摘要： The multi-chip parallel insulated gate bipolar transistor (IGBT) is the core device in large-capacity power electronic equipment, but its operational reliability is of considerable concern to industry. The application of IGBT online degradation state analysis technology can be beneficial to the improvement of system reliability. The failure mechanism of IGBT devices is discussed in this paper, and a technique for analyzing the degradation state of IGBT based on apparent junction temperature is proposed. First, the distortion consistency of the voltage rise time in various failures is discussed, and the junction temperature dependence of the voltage rise time is then demonstrated. Subsequently, an apparent junction temperature model based on the voltage rise time is established (the fitting accuracy is as high as 94.3%). From the high-frequency model in the switching process of the device, an online extraction technology of key parameters (e.g., voltage rise time) is developed. Finally, an experimental platform for IGBT degradation state estimation is established, and the feasibility of IGBT degradation state estimation based on apparent junction temperature is proved, especially the degradation of bonding-wire and the gate-oxide-layer. The experimental results show that the proposed IGBT degradation state estimation technique based on apparent junction temperature is a reliable online estimation method with non-contact, high accuracy, and comprehensiveness.