MOS管-MOS管短路(lu)保(bao)护(hu)电(dian)路(lu)以及短路(lu)保(bao)护(hu)电(dian)路(lu)原理图(tu)汇总-KIA MOS管
信(xin)息来(lai)源：本站 日期：2018-07-19
交流电源电压(ya)正常时(shi)，继电器吸合(he)，接通负(fu)载（Rfz）回(hui)路(lu)(lu)。当负(fu)载发(fa)生短(duan)路(lu)(lu)故障时(shi)，KA两端电压(ya)迅速下(xia)降，KA释放，切断负(fu)载回(hui)路(lu)(lu)。同时(shi)，发(fa)光二极管(guan)VL点亮，指示(shi)电路(lu)(lu)发(fa)生短(duan)路(lu)(lu)。
这(zhei)是一(yi)个自(zi)锁(suo)的保护电(dian)(dian)路，短路时(shi)：Q3极被(bei)拉低(di)，Q2导通(tong)，形(xing)成(cheng)自(zi)锁(suo)，迫使(shi)Q3截(jie)止，Q3截(jie)至(zhi)后(hou)面负(fu)(fu)载(zai)(zai)没有(you)电(dian)(dian)压，这(zhei)时(shi)有(you)没有(you)负(fu)(fu)载(zai)(zai)已经(jing)没有(you)关系了，所以(yi)即使(shi)拿(na)掉负(fu)(fu)载(zai)(zai)也不(bu)会有(you)输出。要想拿(na)掉负(fu)(fu)载(zai)(zai)后(hou)恢复(fu)输出，可以(yi)在Q3得(de)CE结(jie)上接一(yi)个电(dian)(dian)阻(zu)，取1K左(zuo)右。
C2和c3很(hen)重要，在自锁后，重启电(dian)(dian)路就靠这两(liang)个电(dian)(dian)容，否则(ze)启动失(shi)败。原理是(shi)上(shang)电(dian)(dian)时(shi)，电(dian)(dian)容两(liang)端(duan)电(dian)(dian)压不能突变，C2使(shi)得Q2基极在上(shang)电(dian)(dian)瞬间(jian)保(bao)(bao)持(chi)高电(dian)(dian)平，使(shi)得Q2不导(dao)通。C3则(ze)使(shi)得上(shang)电(dian)(dian)瞬间(jian)Q3基极保(bao)(bao)持(chi)低电(dian)(dian)平，使(shi)得Q3导(dao)通Vout有电(dian)(dian)压。这样R5位(wei)高电(dian)(dian)平，锁住导(dao)通。
由于电(dian)(dian)(dian)(dian)(dian)(dian)网(wang)自身(shen)原因或电(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)输(shu)入接线不(bu)可靠(kao)，开(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)有时(shi)会(hui)出现缺(que)相(xiang)运行(xing)的情况，且掉相(xiang)运行(xing)不(bu)易被及(ji)时(shi)发现。当电(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)处于缺(que)相(xiang)运行(xing)时(shi)，整流(liu)(liu)桥(qiao)某一臂无电(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)，而其它臂会(hui)严(yan)重过流(liu)(liu)造成损坏，同时(shi)使逆(ni)变器工作出现异常，因此必须对缺(que)相(xiang)进行(xing)保(bao)护。检(jian)测(ce)电(dian)(dian)(dian)(dian)(dian)(dian)网(wang)缺(que)相(xiang)通常采用(yong)电(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)互(hu)感器或电(dian)(dian)(dian)(dian)(dian)(dian)子缺(que)相(xiang)检(jian)测(ce)电(dian)(dian)(dian)(dian)(dian)(dian)路。由于电(dian)(dian)(dian)(dian)(dian)(dian)流(liu)(liu)互(hu)感器检(jian)测(ce)成本高(gao)、体(ti)积大(da)，故(gu)开(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)中一般采用(yong)电(dian)(dian)(dian)(dian)(dian)(dian)子缺(que)相(xiang)保(bao)护电(dian)(dian)(dian)(dian)(dian)(dian)路。图5是一个简单的电(dian)(dian)(dian)(dian)(dian)(dian)子缺(que)相(xiang)保(bao)护电(dian)(dian)(dian)(dian)(dian)(dian)路。三(san)(san)相(xiang)平(ping)衡时(shi)，R1～R3结点H电(dian)(dian)(dian)(dian)(dian)(dian)位很低，光(guang)耦合输(shu)出近似为零电(dian)(dian)(dian)(dian)(dian)(dian)平(ping)。当缺(que)相(xiang)时(shi)，H点电(dian)(dian)(dian)(dian)(dian)(dian)位抬高(gao)，光(guang)耦输(shu)出高(gao)电(dian)(dian)(dian)(dian)(dian)(dian)平(ping)，经比较(jiao)器进行(xing)比较(jiao)，输(shu)出低电(dian)(dian)(dian)(dian)(dian)(dian)平(ping)，封锁驱(qu)动信(xin)号。比较(jiao)器的基(ji)准可调，以(yi)便调节缺(que)相(xiang)动作阈值。该缺(que)相(xiang)保(bao)护适用(yong)于三(san)(san)相(xiang)四线制，而不(bu)适用(yong)于三(san)(san)相(xiang)三(san)(san)线制。电(dian)(dian)(dian)(dian)(dian)(dian)路稍加变动，亦可用(yong)高(gao)电(dian)(dian)(dian)(dian)(dian)(dian)平(ping)封锁PWM信(xin)号。
图是一种(zhong)用(yong)于三相(xiang)(xiang)(xiang)三线制电(dian)(dian)(dian)(dian)源缺(que)(que)相(xiang)(xiang)(xiang)保护(hu)电(dian)(dian)(dian)(dian)路，A、B、C缺(que)(que)任何一相(xiang)(xiang)(xiang)，光耦器输(shu)出电(dian)(dian)(dian)(dian)平低(di)于比(bi)较(jiao)器的(de)反相(xiang)(xiang)(xiang)输(shu)入端(duan)的(de)基准电(dian)(dian)(dian)(dian)压(ya)，比(bi)较(jiao)器输(shu)出低(di)电(dian)(dian)(dian)(dian)平，封锁(suo)PWM驱动(dong)信号(hao)，关闭电(dian)(dian)(dian)(dian)源。比(bi)较(jiao)器输(shu)入极性稍加变(bian)动(dong)，亦可(ke)用(yong)高电(dian)(dian)(dian)(dian)平封锁(suo)PWM信号(hao)。这(zhei)种(zhong)缺(que)(que)相(xiang)(xiang)(xiang)保护(hu)电(dian)(dian)(dian)(dian)路采用(yong)光耦隔离强电(dian)(dian)(dian)(dian)，安全可(ke)靠，RP1、RP2用(yong)于调节缺(que)(que)相(xiang)(xiang)(xiang)保护(hu)动(dong)作阈(yu)值。
在(zai)(zai)某些直流(liu)/直流(liu)转(zhuan)换器(qi)(qi)中(zhong)(zhong)，芯(xin)片(pian)上的逐周期限(xian)(xian)流(liu)措施在(zai)(zai)短(duan)(duan)路(lu)(lu)(lu)(lu)期间(jian)可能(neng)不(bu)足(zu)以(yi)(yi)防止故(gu)障发生。一(yi)个(ge)(ge)非同(tong)步升(sheng)压(ya)转(zhuan)换器(qi)(qi)可通(tong)(tong)过(guo)电(dian)(dian)(dian)感器(qi)(qi)和箝(qian)(qian)位二极(ji)管(guan)(guan)来提供一(yi)条(tiao)从输(shu)(shu)入(ru)端(duan)到短(duan)(duan)路(lu)(lu)(lu)(lu)处的直接通(tong)(tong)路(lu)(lu)(lu)(lu)。当负(fu)载(zai)存在(zai)(zai)短(duan)(duan)路(lu)(lu)(lu)(lu)时(shi)，不(bu)管(guan)(guan)集成(cheng)电(dian)(dian)(dian)路(lu)(lu)(lu)(lu)中(zhong)(zhong)限(xian)(xian)流(liu)保护功能(neng)如何，流(liu)过(guo)负(fu)载(zai)通(tong)(tong)路(lu)(lu)(lu)(lu)的极(ji)大(da)电(dian)(dian)(dian)流(liu)可能(neng)会损坏箝(qian)(qian)位二极(ji)管(guan)(guan)、电(dian)(dian)(dian)感器(qi)(qi)和集成(cheng)电(dian)(dian)(dian)路(lu)(lu)(lu)(lu)。在(zai)(zai)一(yi)个(ge)(ge) SEPIC（单(dan)端(duan)初级电(dian)(dian)(dian)感变换器(qi)(qi)）电(dian)(dian)(dian)路(lu)(lu)(lu)(lu)中(zhong)(zhong)，耦合电(dian)(dian)(dian)容会中(zhong)(zhong)断这条(tiao)道(dao)路(lu)(lu)(lu)(lu)。因此，当负(fu)载(zai)存在(zai)(zai)短(duan)(duan)路(lu)(lu)(lu)(lu)时(shi)，也(ye)(ye)就(jiu)不(bu)存在(zai)(zai)电(dian)(dian)(dian)流(liu)从输(shu)(shu)入(ru)端(duan)流(liu)到输(shu)(shu)出(chu)端(duan)的直接通(tong)(tong)路(lu)(lu)(lu)(lu)。但(dan)是，如果所(suo)要(yao)求的最短(duan)(duan)导通(tong)(tong)时(shi)间(jian)比专用负(fu)载(zai)周期还短(duan)(duan)，则(ze)电(dian)(dian)(dian)感器(qi)(qi)电(dian)(dian)(dian)流(liu)和开关电(dian)(dian)(dian)流(liu)就(jiu)会迅速增大(da)，造成(cheng)集成(cheng)电(dian)(dian)(dian)路(lu)(lu)(lu)(lu)故(gu)障、输(shu)(shu)入(ru)端(duan)过(guo)载(zai)，或(huo)两(liang)种情况兼而有(you)之。甚(shen)至在(zai)(zai)某些降压(ya)稳压(ya)器(qi)(qi)中(zhong)(zhong)，负(fu)载(zai)周期的种种限(xian)(xian)制(zhi)有(you)时(shi)也(ye)(ye)会使(shi)开关导通(tong)(tong)时(shi)间(jian)过(guo)长，以(yi)(yi)致(zhi)无法(fa)(fa)在(zai)(zai)输(shu)(shu)出(chu)短(duan)(duan)路(lu)(lu)(lu)(lu)时(shi)保持控制(zhi)，特别是在(zai)(zai)极(ji)高频(pin)率集成(cheng)电(dian)(dian)(dian)路(lu)(lu)(lu)(lu)的输(shu)(shu)入(ru)电(dian)(dian)(dian)压(ya)非常高的时(shi)候。使(shi)用单(dan)个(ge)(ge)晶体管(guan)(guan)方法(fa)(fa)，可以(yi)(yi)在(zai)(zai)负(fu)载(zai)过(guo)载(zai)或(huo)短(duan)(duan)路(lu)(lu)(lu)(lu)致(zhi)使(shi)电(dian)(dian)(dian)感电(dian)(dian)(dian)流(liu)开始(shi)失控时(shi)，将(jiang) VC 脚（误差放大(da)器(qi)(qi)的输(shu)(shu)出(chu)端(duan)）电(dian)(dian)(dian)压(ya)下拉，这样就(jiu)可以(yi)(yi)防止 SEPIC 电(dian)(dian)(dian)路(lu)(lu)(lu)(lu)发生短(duan)(duan)路(lu)(lu)(lu)(lu)故(gu)障。
高可靠性短(duan)路(lu)保护(hu)电(dian)(dian)(dian)路(lu)的实现电(dian)(dian)(dian)路(lu)如(ru)图1所示，其(qi)中VMP是线性稳压(ya)器(qi)(qi)的功(gong)率(lv)(lv)MOS管(guan)(guan)，R1、R2为(wei)(wei)稳压(ya)器(qi)(qi)的反馈电(dian)(dian)(dian)阻;VMO和VMP管(guan)(guan)是电(dian)(dian)(dian)流(liu)镜电(dian)(dian)(dian)路(lu)，VMOS管(guan)(guan)以一(yi)定(ding)的比(bi)例(li)复制功(gong)率(lv)(lv)管(guan)(guan)的电(dian)(dian)(dian)流(liu)，通过电(dian)(dian)(dian)阻R4转化为(wei)(wei)检测电(dian)(dian)(dian)压(ya);晶(jing)体(ti)管(guan)(guan)VM1完成(cheng)(cheng)电(dian)(dian)(dian)平(ping)移位功(gong)能，最后接入由(you)VM8～VM12等MOS管(guan)(guan)组(zu)成(cheng)(cheng)的比(bi)较(jiao)器(qi)(qi)的正(zheng)(zheng)输入端（Vinp），比(bi)较(jiao)器(qi)(qi)的负(fu)(fu)输入端（Vinm）与输出端（0UT）相连;VM13、VM14组(zu)成(cheng)(cheng)二极(ji)管(guan)(guan)连接形式(shi)为(wei)(wei)负(fu)(fu)载的共源(yuan)级放大电(dian)(dian)(dian)路(lu);VM14和VMp1构成(cheng)(cheng)电(dian)(dian)(dian)流(liu)镜电(dian)(dian)(dian)路(lu);晶(jing)体(ti)管(guan)(guan)VMp1完成(cheng)(cheng)对功(gong)率(lv)(lv)管(guan)(guan)VMP的开关(guan)控制，正(zheng)(zheng)常工作时，VMp1的栅级电(dian)(dian)(dian)位（Vcon）为(wei)(wei)高电(dian)(dian)(dian)平(ping)，不会影响系统的正(zheng)(zheng)常工作，短(duan)路(lu)发生(sheng)时，Vcon将(jiang)为(wei)(wei)低电(dian)(dian)(dian)平(ping)，使功(gong)率(lv)(lv)管(guan)(guan)关(guan)断。
当短(duan)(duan)(duan)(duan)(duan)路(lu)(lu)(lu)(lu)(lu)发(fa)(fa)生(sheng)时(shi)(shi)，比较(jiao)(jiao)器(qi)(qi)的(de)(de)负(fu)(fu)输(shu)(shu)入(ru)端(duan)(duan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)（Vinm）为(wei)0 V;同(tong)时(shi)(shi)VM1管(guan)将(jiang)(jiang)(jiang)导通，因(yin)此(ci)比较(jiao)(jiao)器(qi)(qi)的(de)(de)正(zheng)输(shu)(shu)入(ru)端(duan)(duan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)大于0 V，最终比较(jiao)(jiao)器(qi)(qi)的(de)(de)输(shu)(shu)出节点电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)（Vcom）为(wei)高(gao)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)，在(zai)MOS管(guan)VM13、VM14作(zuo)用(yong)下，控制信(xin)号(hao)Vcon将(jiang)(jiang)(jiang)为(wei)低电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)，最终VMP管(guan)的(de)(de)栅极(ji)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)将(jiang)(jiang)(jiang)升高(gao)，进而关断(duan)(duan)P功(gong)率管(guan)，实(shi)(shi)现(xian)短(duan)(duan)(duan)(duan)(duan)路(lu)(lu)(lu)(lu)(lu)保护(hu)。实(shi)(shi)现(xian)短(duan)(duan)(duan)(duan)(duan)路(lu)(lu)(lu)(lu)(lu)保护(hu)后，VM1管(guan)将(jiang)(jiang)(jiang)关断(duan)(duan);VM3和VM4组成(cheng)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)镜，晶(jing)体管(guan)VM2的(de)(de)作(zuo)用(yong)是保证电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)(lu)在(zai)短(duan)(duan)(duan)(duan)(duan)路(lu)(lu)(lu)(lu)(lu)期(qi)间(jian)（VM1管(guan)关断(duan)(duan)），比较(jiao)(jiao)器(qi)(qi)正(zheng)输(shu)(shu)入(ru)端(duan)(duan)的(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)始(shi)终高(gao)于比较(jiao)(jiao)器(qi)(qi)的(de)(de)负(fu)(fu)输(shu)(shu)入(ru)端(duan)(duan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)（即使(shi)(shi)系统存在(zai)地平(ping)(ping)面噪声(sheng)），从而使(shi)(shi)Vcon电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)始(shi)终为(wei)低电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)，确保电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)(lu)在(zai)短(duan)(duan)(duan)(duan)(duan)路(lu)(lu)(lu)(lu)(lu)发(fa)(fa)生(sheng)期(qi)间(jian)始(shi)终都(dou)能关断(duan)(duan)P功(gong)率管(guan)，实(shi)(shi)现(xian)保护(hu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)(lu)的(de)(de)高(gao)可靠(kao)性(xing)。同(tong)时(shi)(shi)当短(duan)(duan)(duan)(duan)(duan)路(lu)(lu)(lu)(lu)(lu)发(fa)(fa)生(sheng)时(shi)(shi)（即Vcon信(xin)号(hao)为(wei)低电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)），VM7管(guan)正(zheng)常(chang)工作(zuo)，VM5管(guan)将(jiang)(jiang)(jiang)导通，有(you)一定的(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)流(liu)向0UT端(duan)(duan);因(yin)此(ci)一旦短(duan)(duan)(duan)(duan)(duan)路(lu)(lu)(lu)(lu)(lu)消除（即0UT端(duan)(duan)接(jie)有(you)负(fu)(fu)载(zai)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)），VM5管(guan)将(jiang)(jiang)(jiang)对负(fu)(fu)载(zai)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)容和负(fu)(fu)载(zai)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)阻(zu)组成(cheng)的(de)(de)并联RC网络充电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)，0UT端(duan)(duan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)压(ya)升高(gao)，Vcon信(xin)号(hao)将(jiang)(jiang)(jiang)变(bian)为(wei)高(gao)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)平(ping)(ping)，电(dian)(dian)(dian)(dian)(dian)(dian)(dian)(dian)路(lu)(lu)(lu)(lu)(lu)自动恢复正(zheng)常(chang)状(zhuang)态。
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