《项目三单相交流压调调光灯电路》由会员分享,可在线阅读,更多相关《项目三单相交流压调调光灯电路(62页珍藏版)》请在金锄头文库上搜索。
1、单相交流调压调光灯电路Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试一、任务描述与目标双向晶闸管是由普通晶闸管派生出来的,在交流电路中可以代替一组反并联的普通晶
2、闸管,只需一个触发电路。因其具有触发电路简单、工作性能可靠的优点,在交流调压、无触点交流开关、温度控制、灯光调节及交流电动机调速等领域中应用广泛,是一种比较理想的交流开关器件。本次任务的目标如下。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyrig
3、ht 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试u熟悉双向晶闸管的结构。u明白双向晶闸管型号的含义。u会判断器件的好坏并能说明原因。u掌握双向晶闸管的触发方式。u会根据电路要求选择双向晶闸管。u在小组实施项目过程中培养团队合作意识。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyrig
4、ht 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试二、相关知识 (一)双向晶闸管的结构及测试1双向晶闸管的结构双向晶闸管的外形与普通晶闸管类似,有塑封式、螺栓式、平板式。但其内部是一种NPNPN 5层结构的3端器件。它有2个主电极T1、T2,1个门极G。常见的双向晶闸管外形及引脚排列如下图所示。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Creat
5、ed with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0
6、. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试双向晶闸管的内部结构、等效电路及图形符号如图所示。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty
7、 Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试双向晶闸管的其结构示意图如上图 (a)所示,N4与P1表面用金属膜连通构成一个阳极;N2与P2也用金属膜连通为另一阳极T1;N3与P2一部分引出公共门极G,门极G与一个阳极在同一侧引出。由此可以看出,双向晶闸管相当于两个晶闸管反并联(P1N1P2N2和P2N1P1N4),不过它只有一个门极G。如果不考虑G极的不同,把它分割成上图(b)所示,如图(c)所示连接。图(d)和(e)分别为双向晶闸管等效电路和图形符号。Evaluation only.Evaluation only. Created
8、 with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试2双向晶闸管测试(1)双向晶闸管电极的判定。一般可先从元器件外形识别引脚排列,如引脚排列图所示。多数的小型塑封双向晶闸管,面对印字面,引脚朝下,则从左向右的排列顺序依次为主电极T1、主电极T2、
9、控制极(门极)。但是也有例外,所以有疑问时应通过检测作出判别。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试 确定第二阳极T2。G极与T1极靠近,距T2极较远。
10、因此,G-T1之间的正、反向电阻都很小。用万用表R1挡或R10挡测任意两脚之间的电阻,如下图所示。只有在G-T1之间呈现低阻,正、反向电阻都很小(约100欧姆),而T2-G、T2-T1之间的正、反向电阻均为无穷大。这表明,如果测出某脚和其他两脚都不通,就肯定是T2极。另外,采用TO-220封装的双向晶闸管,T2极通常与小散热板连通,据此亦可确定T2极。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides
11、for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试 区分T1和G。测量T1、G极间正、反向电阻,读数相对较小的那次测量的黑表笔所接的引脚为第一阳极T1,红表笔所接引脚为控制极G。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.
12、Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试(2)双向晶闸管的好坏测试。 将万用表置于R100挡或R1k挡,测量双向晶闸管的T1、T2之间的正、反向电阻应近似无穷大(),测量T1与G之间的正、反向电阻也应近似无穷大()。如果测得的电阻都很小,则说明被测双向晶闸管的极间已击穿或漏电短路,性能不良,不宜使用。Evaluation only.Evaluation only. Created w
13、ith Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试 将万用表置于R1挡或R10挡,测量双向晶闸管T1与G之间的正、反向电阻,若读数在几十欧至一百欧之间,则为正常,且测量G、Tl间正向电阻(如图1-20所示)时的读数要比反向电阻稍微小一些。如果测得G
14、、T1间的正、反向电阻均为无穷大(),则说明被测晶闸管已开路损坏。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试(二)双向晶闸管的特性与主要参数1双向晶闸管的特
15、性双向晶闸管有正反向对称的伏安特性曲线。正向部分位于第象限,反向部分位于第象限如图。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试从曲线中可以看出,第和第象限内
16、具有基本相同转换性能。双向晶闸管工作时,它的T1和T2间加正(负)压,若门极无电压,只要T1和T2间电压低于转折电压,它就不会导通,处于阻断状态。若门极加一定的正(负)压,则双向晶闸管在T1和T2间电压小于转折电压时被门极触发导通。Evaluation only.Evaluation only. Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0.Created with Aspose.Slides for .NET 3.5 Client Profile 5.2.0.0. Copyright 2004-2011 Aspose Pty Ltd.Copyright 2004-2011 Aspose Pty Ltd.任务一 双向晶闸管及其测试2双向晶闸管的主要参数双向晶闸管的主要参数中只有额定电流与普通晶闸管有所不同,其他参数定义相似。由于双向晶闸管工作在交流电路中,正反向电流都可以流过,所以它