详解继电器原理特性与继电驱动电路设计技巧

继电(dian)器(qi)是(shi)一种电(dian)子控(kong)制(zhi)器(qi)件(jian)，它(ta)具有控(kong)制(zhi)系(xi)统（又称输(shu)入(ru)回(hui)路）和被控(kong)制(zhi)系(xi)统（又称输(shu)出回(hui)路），通(tong)常应用于自(zi)动(dong)控(kong)制(zhi)电(dian)路中，它(ta)实际(ji)上(shang)是(shi)用较小的(de)电(dian)流(liu)去控(kong)制(zhi)较大电(dian)流(liu)的(de)一种“自(zi)动(dong)开(kai)关”。故(gu)在电(dian)路中起着自(zi)动(dong)调节、安全保(bao)护、转换电(dian)路等作用。

一、继电器（relay）的工作原理和特性

1、电磁继(ji)电器的工作(zuo)原理和(he)特性(xing)

电(dian)磁(ci)(ci)式继(ji)电(dian)器(qi)一(yi)(yi)般由铁(tie)芯(xin)(xin)、线(xian)(xian)(xian)圈、衔(xian)铁(tie)、触(chu)点簧片(pian)等(deng)组成的(de)(de)(de)。只要在(zai)线(xian)(xian)(xian)圈两(liang)端加(jia)上一(yi)(yi)定(ding)的(de)(de)(de)电(dian)压，线(xian)(xian)(xian)圈中就(jiu)会(hui)(hui)流过一(yi)(yi)定(ding)的(de)(de)(de)电(dian)流，从而产生电(dian)磁(ci)(ci)效(xiao)应，衔(xian)铁(tie)就(jiu)会(hui)(hui)在(zai)电(dian)磁(ci)(ci)力(li)吸(xi)引(yin)的(de)(de)(de)作(zuo)用下克服返回弹簧的(de)(de)(de)拉力(li)吸(xi)向(xiang)铁(tie)芯(xin)(xin)，从而带动衔(xian)铁(tie)的(de)(de)(de)动触(chu)点与静触(chu)点（常开触(chu)点）吸(xi)合(he)。当线(xian)(xian)(xian)圈断电(dian)后，电(dian)磁(ci)(ci)的(de)(de)(de)吸(xi)力(li)也(ye)随(sui)之消失(shi)，衔(xian)铁(tie)就(jiu)会(hui)(hui)在(zai)弹簧的(de)(de)(de)反作(zuo)用力(li)返

回(hui)原来(lai)的位置，使动触(chu)点(dian)(dian)(dian)(dian)与原来(lai)的静(jing)触(chu)点(dian)(dian)(dian)(dian)（常闭(bi)触(chu)点(dian)(dian)(dian)(dian)）释放(fang)。这样吸合(he)、释放(fang)，从而达(da)到了(le)在电(dian)(dian)路中的导通(tong)、切(qie)断的目的。对于(yu)继(ji)电(dian)(dian)器(qi)的“常开(kai)、常闭(bi)”触(chu)点(dian)(dian)(dian)(dian)，可(ke)以(yi)这样来(lai)区分：继(ji)电(dian)(dian)器(qi)线圈未通(tong)电(dian)(dian)时处于(yu)断开(kai)状态(tai)的静(jing)触(chu)点(dian)(dian)(dian)(dian)，称为“常开(kai)触(chu)点(dian)(dian)(dian)(dian)”；处于(yu)接通(tong)状态(tai)的静(jing)触(chu)点(dian)(dian)(dian)(dian)称为“常闭(bi)触(chu)点(dian)(dian)(dian)(dian)”。

2、电路原理

继电器是一种当(dang)输入量变化到某一定(ding)值时，其(qi)触头（或(huo)电路(lu)）即接(jie)通 或(huo)分断交直流小容量控(kong)制回路(lu)。

由(you)永久磁(ci)(ci)铁保(bao)持(chi)释放状态，加(jia)上工作(zuo)电压后，电磁(ci)(ci)感应使衔(xian)铁与永久磁(ci)(ci)铁产生(sheng)吸引和排(pai)斥力(li)矩，产生(sheng)向下的运(yun)动，最后达到吸合状态。

3、 晶体管驱(qu)动(dong)驱(qu)动(dong)电路

当晶体(ti)管用来(lai)驱(qu)动继电器时(shi)，推荐(jian)用NPN三(san)极管。具体(ti)电路如下(xia)：

当输入高电平时，晶(jing)体管T1饱和导(dao)通(tong)，继电器线圈(quan)通(tong)电，触点(dian)吸合。

当(dang)输入低电平时，晶体管T1截止，继电器线圈断(duan)电，触点断(duan)开(kai)。

电路(lu)中各元器件的作用(yong)(yong)：晶(jing)体(ti)管(guan)T1为控制开关；电阻(zu)R1主要(yao)起(qi)限流(liu)作用(yong)(yong)，降低晶(jing)体(ti)管(guan)T1功(gong)耗；电阻(zu)R2使晶(jing)体(ti)管(guan)T1可靠(kao)截止；二(er)极管(guan)D1反向(xiang)续流(liu)，为三极管(guan)由(you)导(dao)通转向(xiang)关断时为继电器线圈中的提供泄放通路(lu)，并将其电压箝位在+12V上。

4、集成电路(lu)驱(qu)动电路(lu)

目(mu)前(qian)已使用(yong)多(duo)个驱动(dong)晶体(ti)管集成的(de)集成电路(lu)(lu)，使用(yong)这种集成电路(lu)(lu)能简化驱动(dong)多(duo)个继电器的(de)印(yin)制板的(de)设计过程。现在我(wo)司所(suo)用(yong)驱动(dong)继电器的(de)集成电路(lu)(lu)主要(yao)有TD62003AP。

当(dang)2003输(shu)(shu)入端为高电平时，对应的(de)输(shu)(shu)出(chu)口输(shu)(shu)出(chu)低电平，继电器(qi)线圈(quan)两端通电，继电器(qi)触(chu)点(dian)吸合；

当2003输(shu)入端为低电平时，对应的输(shu)出口呈高(gao)阻态，继电器(qi)线圈两(liang)端断电，继电器(qi)触点断开。

24V 继电器的驱动电路(lu)

继(ji)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器串联 RC  电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)：这种形式主要应用于继(ji)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器的(de)(de)额定工作(zuo)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)低于电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)的(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)中(zhong)。当电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)闭合(he)(he)时，继(ji)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器线(xian)(xian)(xian)圈(quan)(quan)由(you)于自感现象会产生电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)动势阻(zu)碍(ai)线(xian)(xian)(xian)圈(quan)(quan)中(zhong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)的(de)(de)增(zeng)大，从而延长(zhang)了(le)吸合(he)(he)时间，串联上  RC 电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)后则可(ke)以缩短(duan)吸合(he)(he)时间。原理是电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)闭合(he)(he)的(de)(de)瞬间，电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容 C 两端电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)不(bu)能突变(bian)可(ke)视为短(duan)路(lu)，这样就将(jiang)比继(ji)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器线(xian)(xian)(xian)圈(quan)(quan)额定工作(zuo)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)高的(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)加到(dao)线(xian)(xian)(xian)圈(quan)(quan)上，  从而加快了(le)线(xian)(xian)(xian)圈(quan)(quan)中(zhong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)增(zeng)大的(de)(de)速(su)度，使(shi)继(ji)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)器迅速(su)吸合(he)(he)。电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)源稳(wen)定之(zhi)后电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容 C 不(bu)起(qi)作(zuo)用，电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu) R 起(qi)限流(liu)(liu)作(zuo)用。

二、继电器额定工作电压的选择

继电(dian)(dian)器(qi)(qi)额定工(gong)作电(dian)(dian)压(ya)是继电(dian)(dian)器(qi)(qi)最主要的一项技术(shu)参数。在(zai)使用继电(dian)(dian)器(qi)(qi)时，应(ying)该首先考虑所在(zai)电(dian)(dian)路（即继电(dian)(dian)器(qi)(qi)线圈所在(zai)的电(dian)(dian)路）的工(gong)作电(dian)(dian)压(ya)，继电(dian)(dian)器(qi)(qi)的额定工(gong)作电(dian)(dian)压(ya)应(ying)等于所在(zai)电(dian)(dian)路的工(gong)作电(dian)(dian)压(ya)。

一般所在电(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的(de)工作(zuo)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)是继电(dian)(dian)(dian)(dian)(dian)(dian)器额(e)定工作(zuo)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)的(de)0.86。注意(yi)所在电(dian)(dian)(dian)(dian)(dian)(dian)路(lu)的(de)工件电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)千(qian)万不(bu)能超过(guo)继电(dian)(dian)(dian)(dian)(dian)(dian)器额(e)定工作(zuo)电(dian)(dian)(dian)(dian)(dian)(dian)压(ya)(ya)，否则(ze)继电(dian)(dian)(dian)(dian)(dian)(dian)器线圈(quan)容易(yi)烧毁(hui)。另(ling)外，有些集成电(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，例(li)如NE555电(dian)(dian)(dian)(dian)(dian)(dian)路(lu)是可以直接驱动(dong)继电(dian)(dian)(dian)(dian)(dian)(dian)器工作(zuo)的(de)，而有些集成电(dian)(dian)(dian)(dian)(dian)(dian)路(lu)，例(li)如  COMS 电(dian)(dian)(dian)(dian)(dian)(dian)路(lu)输出电(dian)(dian)(dian)(dian)(dian)(dian)流小，需要加一级晶体(ti)管(guan)放大电(dian)(dian)(dian)(dian)(dian)(dian)路(lu)方可驱动(dong)继电(dian)(dian)(dian)(dian)(dian)(dian)器，这就应考(kao)虑(lv)晶体(ti)管(guan)输出电(dian)(dian)(dian)(dian)(dian)(dian)流应大于继电(dian)(dian)(dian)(dian)(dian)(dian)器的(de)额(e)定工作(zuo)电(dian)(dian)(dian)(dian)(dian)(dian)流。

1、晶体(ti)管驱动电路

当晶体(ti)(ti)(ti)管用来驱动继电器(qi)时，必须将晶体(ti)(ti)(ti)管的(de)发(fa)射极接(jie)地(di)。具体(ti)(ti)(ti)电路如下：

2 、原理简介

NPN 晶体(ti)(ti)管(guan)驱动(dong)时(shi)：当(dang)晶体(ti)(ti)管(guan) T1基极被输入高电(dian)平时(shi)，晶体(ti)(ti)管(guan)饱和(he)导通，集电(dian)极变为低电(dian)平，因此继电(dian)器(qi)线圈通电(dian)，触(chu)点 RL1吸合。当(dang)晶体(ti)(ti)管(guan)  T1基极被输入低电(dian)平时(shi)，晶体(ti)(ti)管(guan)截止，继电(dian)器(qi)线圈断电(dian)，触(chu)点 RL1断开。

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