IGBT的驱动和过流保护电路的研究

本文首先谈论了IGBT的驱动电路的基本要求和过流保护分析,然后运用IGBT集电极退饱和原理,提供了一个采用分立元件构成的IGBT驱动电路和过流保护电路.仿真和试验结果证明了所设计驱动电路的可行性.     

利用贴片式保险丝实现过流保护

本文介绍了贴片式保险丝的原理、性能参数,说明其稳定性和可重复性中存在的问题,并给出了一种采用薄膜技术生产贴片式保险丝以克服以上问题的方法。     

一种降压型DC-DC的过流保护电路的设计

本文设计了一种用于降压型DC-DC转换器的过流保护电路.它采用折叠式共源共栅差分放大器对电感电流进行采样,并转换成电压输出到限流比较器.Hspice仿真结果表明该电路工作可靠、性能优良,可广泛应用于功率开关器件保护电路中.     

避免DC-DC电源输出端带大电容满载启动时发生过流保护的方法

DC-DC开关电源在输出端带大电容满载启动时,如果电流检测电路设计不当很容易发生因输出端采取过流保护而不能正常启动的现象。就该问题,本文提出了一种简单的方法,仅增加数个元件就可以避免在输出端带大电容满载起动时出现过流保护,从而保证了DC- DC开关电源即使输出端带大电容也可以实现正常的满载启动。     

伺服控制系统的过流报警保护电路设计

提出了一种新颖实用的过流报警和保护电路,给出了其组成部分和电路图及其工作原理。该电路已成功地应用于机电液伺服控制系统的过流报警和保护系统中。     

皮带机速度保护传感器

皮带机速度保护传感器是皮带输送机的一种新型且简易的设备安全保护装置，它能准确检测出皮带的速度，及时正确地发出皮带失速或打滑的继电信号，文中介绍了该传感器的结构和控制原理，给出主要技术参数。     

本安电源过压、过流保护次序选择研究

过压-过流保护和过流-过压保护是本安电源过压、过流保护次序的2种形式,为研究不同的保护次序形式对本安电源安全性能的影响,建立了本安电源火花放电等效模型,确定了影响保护次序选择的本质安全性能因素。在发生过压、过流或同时发生过压与过流3种情况下,分别比较研究了2种保护次序的保护电路的性能,研究结果表明,在本安电源的设计中,过压、过流保护次序的选择并不是随机任意的,而是有原则可循的:过压保护电路的类型决定了本安电源过压、过流保护次序的选择,在设计中,首先要判断过压保护电路的类型,如果过压保护电路的类型是短路型,本安电源保护电路应设计成过流-过压的保护次序,否则应设计成过压-过流保护次序,过压-过流保护次序的保护电路截止关断时间更短,其保护效果更好,本安电源的安全性能更高。     

PTC热敏电阻的应用

本文简要介绍了PTC热敏电阻的应用特性,给出了它的一些典型应用实例。     

霍尔传感器编程器的设计

介绍了该传感器的特性,着重介绍了该传感器的编程方法以及利用ARM芯片STM32的软硬件设计方案。当编码协议发生改变时,只需对编码指令作少量修改,具有很强的灵活性。目前,该设计在产品中已得到实际应用。     

基于VCE检测的阈值可调型IGBT过流保护设计

IGBT光耦驱动芯片的去饱和检测端阈值电压固定不可调,一般为6.5 V~10 V,此阈值保留的IGBT过流余量较大,难以将过载电流限制在过流发生的初期,给应用造成不便。提出一种通过改变PWM波占空比调整检测阈值的方法,设计了采用光耦、电压基准TL431和比较器LM2903的低成本方案,并详细分析了该电路的保护原理。该电路具有简单可靠、调试方便、利于生产等优点。实验表明,IGBT过流检测电路能迅速、准确地响应并动作,使IGBT在不同的过流情况下得到及时有效的保护。     

A new contactless trackball design using Hall effect sensors

In this paper, a new trackball design based on a non-contacting motion detection mechanism is analyzed. It utilizes the hysteresis phenomenon of magnetic grade steel. In this design, the ball and a pair of electromagnets are made from magnetic grade stainless steel material. The electromagnets are placed outside and near to the ball surface. They record the magnetic information onto the ball surface. A Hall sensor, acting as a magnetic field detector, is placed inside each electromagnet. As the ball moves, the magnetic field recorded onto the ball surface produces instantaneous changes in the Hall sensor output. This output is then converted into a suitable format in order to determine the speed and direction of motion of the ball. Tests have been performed to check the viability of this technique. The promising test results have lead to the successful development of a prototype trackball.     

光化学氧传感器技术的研究进展

综述了近年来国内外光化学氧传感器技术的研究及应用情况,简要介绍了光化学氧传感器的原理及响应机理,详细讨论了荧光敏感物质和支持体系的进展,并展望了光化学氧传感器的发展趋势.     

长周期光纤光栅化学传感器研究进展

阐述了长周期光纤光栅(LPFG)化学传感器的结构与传感机理,介绍了LPFG化学传感器在化学溶液浓度测量方面的应用;讨论了光纤光栅化学传感器的最新研究热点——LPFC薄膜传感器;展望了LPFG化学传感器今后的发展方向。     

一种便携式TiO2薄膜乙醇气敏传感器的研制

研制了一种适合于乙醇检测的新型TiO2基薄膜气敏传感器.敏感材料是采用直流磁控反应溅射法制备在Al2O3陶瓷管上的TiO2薄膜,薄膜经过退火处理(500℃、3 h)后,得到对乙醇蒸汽具有很好选择性和灵敏度的锐钛矿相TiO2,其最佳工作温度为270℃左右,响应时间2 s,恢复时间3 s.测量电路采用以ARM7为核的LPC2131微控制器实时监测电源电压,自动调整占空比,从而实现对加热温度的精确控制.通过测量敏感薄膜的电阻,并与乙醇气体浓度进行校准,最终显示被测气体的浓度.整个传感器采用低功耗设计,具备报警功能,同时提供了一个友好的用户界面.     

Oxygen sensors based on a new design concept for amperometric solid state devices

A new design for all-solid amperometric detectors was tested as an oxygen sensor in the 1%–25% v/v concentration range. The design consisted of both the working (WEs) and counter electrodes (CEs) being vacuum-deposited as non-porous Au layers on the same face of a Nafion® membrane and in contact with the gas sample. Both a three-electrode device (the reference electrode being a strip of Ag/AgCl inserted between the two Au layers) and a two-electrode one were tested. In the former case, the sensor exhibited good linearity with oxygen concentration, response times comparable to a commercial sensor but a strong dependence on humidity. The origin of the latter is not due to ohmic losses but rather to the loss of catalytic activity with decreasing water contact in the polymer. The two-electrode device exhibits signal saturation at high oxygen concentrations, which is interpreted by limitations imposed by the CE reactivity. In both cases, oxygen reduction led to an exponential current rise over a wide potential range indicating very high mass transport rates and implying that the electroactive gas reacts at the line formed by the gas/solid electrolyte/metal layer interface.     

一种新型扭矩传感器的研制

介绍了一种以微小弹性扭臂的电桥法为基础的新型微小扭矩传感器。它利用4片等厚的弹性臂测量微小扭矩作用下的形变,通过计算机串口通信,实现了数据的记录与读出。经实验,该传感器能够在0～40mN·m的测量范围内,达到0.01mN·m的测量准确度。     

表面等离子共振传感器的研究进展

表面等离子体是在金属和电介质交界面上所形成的电荷层,在电磁波的激励下表面等离子体发生共振现象,影响电磁波的传播。根据这一原理制作的表面等离子共振传感器可对化学和生物等量进行探测。介绍了表面等离子共振传感器的工作原理和最新研究进展。由于具有体积小、准确度高、抗电磁干扰能力强和可用于遥测等优点,SPR传感器将有广泛的应用前景。     

Development of smart sensors system for machine fault diagnosis

Machine fault diagnosis is a traditional maintenance problem. In the past, the maintenance using tradition sensors is money-cost, which limits wide application in industry. To develop a cost-effective maintenance technique, this paper presents a novel research using smart sensor systems for machine fault diagnosis. In this paper, a smart sensors system is developed which acquires three types of signals involving vibration, current, and flux from induction motors. And then, support vector machine, linear discriminant analysis, k-nearest neighbors, and random forests algorithm are employed as classifiers for fault diagnosis. The parameters of these classifiers are optimized by using cross-validation method. The experimental results show that smart sensor system has the similar performance for applying in intelligent machine fault diagnosis with reduced product cost. Developed smart sensors have feasibility to apply for intelligent fault diagnosis.     

Self-deployment of mobile sensors on a ring

Mobile sensors can self-deploy in a purely decentralized and distributed fashion, so as to reach in a finite time a state of static equilibrium in which they uniformly cover the environment. We consider the self-deployment problem in a ring (e.g., a circular rim); in particular we investigate under what conditions the problem is solvable by a collection of identical sensors without a global coordinate system, however capable of determining the location (in their local coordinate system) of the other sensors within a fixed distance (called visibility radius). A self-deployment is exact   if within finite time the distance between any two consecutive sensors along the ring is the same, d$d$; it is ?$?$-approximate   if within finite time the distance between two consecutive sensors is between d−?$d-?$ and d+?$d+?$.