利盈娱乐(中国)创新平台有限公司

MOS管开关电源电(dian)路主要包括输入电(dian)网滤波(bo)器(qi)。输入整流(liu)(liu)滤波(bo)器(qi)、逆变(bian)器(qi)、输出整流(liu)(liu)滤波(bo)器(qi)。控制电(dian)路、保护电(dian)路。它们的功能介绍(shao)如下。

(1)输入(ru)电(dian)(dian)网滤(lv)波(bo)器：消除来自电(dian)(dian)网的干(gan)扰，如(ru)电(dian)(dian)动机(ji)的启(qi)动、电(dian)(dian)器的开(kai)关、雷(lei)击等产生(sheng)(sheng)的干(gan)扰，同时(shi)也防止开(kai)关电(dian)(dian)源产生(sheng)(sheng)的高频噪声阻电(dian)(dian)网扩散。

(2)输入整流滤(lv)波器：对电(dian)(dian)网输入电(dian)(dian)压进行整流滤(lv)波，为变换器提供盲流电(dian)(dian)压。

(3)逆变器：是开(kai)关电(dian)源的(de)(de)关键部(bu)分(fen)，它把(ba)直(zhi)流(liu)电(dian)压变换成高频交流(liu)电(dian)压，并且起(qi)到(dao)将输出部(bu)分(fen)与(yu)输入电(dian)网隔离的(de)(de)作用。

(4)输出整(zheng)流滤波(bo)器：将变换(huan)器输出的(de)高频交流电(dian)压整(zheng)流滤波(bo)后得到(dao)需要的(de)直流电(dian)压，同时还防止高频噪声对(dui)负(fu)载的(de)干扰。

 （5)控制电路：检(jian)测输(shu)(shu)出直流电压(ya)(ya)，并将其与基准电压(ya)(ya)比较后(hou)进行放大(da)；调制振荡器的脉冲(chong)宽度，从(cong)而(er)控制变换器以保持(chi)输(shu)(shu)出电压(ya)(ya)的稳定(ding)。

(6)保护电路：当开关电源发生过电压、过电流短路时，保护电路使开关电源停止工作以保护负载和电源本身。
线(xian)性电(dian)(dian)(dian)源(yuan)(yuan)一般是将输(shu)(shu)出(chu)(chu)电(dian)(dian)(dian)压(ya)取样后与参(can)考电(dian)(dian)(dian)压(ya)起送入比较(jiao)电(dian)(dian)(dian)压(ya)放大(da)器，此(ci)电(dian)(dian)(dian)压(ya)放大(da)器的(de)输(shu)(shu)出(chu)(chu)作为电(dian)(dian)(dian)压(ya)调整管的(de)输(shu)(shu)入，用以(yi)控制调整管使其结(jie)电(dian)(dian)(dian)压(ya)随输(shu)(shu)入的(de)变(bian)化(hua)而变(bian)化(hua)，从而调整其输(shu)(shu)出(chu)(chu)电(dian)(dian)(dian)压(ya)。但(dan)开(kai)关(guan)电(dian)(dian)(dian)源(yuan)(yuan)足通过(guo)改变(bian)调整管的(de)开(kai)关(guan)的(de)时间(jian)（即占空比）来改变(bian)输(shu)(shu)出(chu)(chu)电(dian)(dian)(dian)压(ya)的(de)。开(kai)关(guan)电(dian)(dian)(dian)源(yuan)(yuan)与线(xian)性电(dian)(dian)(dian)源(yuan)(yuan)的(de)主要(yao)性能比较(jiao)如表1-2所示。

线性电源与自来水管类似，由于没有开关介入，使得上水管一直在放水，如果有多的水，就会漏出来，这就是我们经常看到的某些线性电源的MOS管发(fa)热(re)量(liang)很(hen)大，用不(bu)完(wan)的(de)电能全部转(zhuan)换(huan)成了热(re)能。从这个角度来看，线性(xing)电源的(de)转(zhuan)换(huan)效率就非常(chang)低了，而且(qie)热(re)量(liang)高时，

元件的(de)寿命势(shi)必(bi)要下降(jiang)(jiang)，影(ying)响最终(zhong)的(de)使(shi)(shi)用效(xiao)果。由(you)于(yu)线性(xing)电源的(de)功(gong)率(lv)器件工作在线性(xing)状态，所以其(qi)工作效(xiao)率(lv)低(di)(di)，一般为50% - 60%。线性(xing)电源的(de)工作方(fang)式，使(shi)(shi)得从高(gao)压变(bian)低(di)(di)压必(bi)须(xu)有降(jiang)(jiang)压变(bian)压器，再(zai)经过整流输出直(zhi)流电压，这(zhei)样就造成其(qi)体积很(hen)大(da)，笨重(zhong)，效(xiao)率(lv)低(di)(di)、发热量也大(da)。当然，线性(xing)电源也有优点：纹波小，调整效(xiao)率(lv)好，对外干扰小，适合用于(yu)模拟电路、各类放大(da)器领域。

而开(kai)关电源(yuan)的功率器件工作在开(kai)关状态（一开(kai)一关，频率非常快(kuai)，一般平(ping)板开(kai)关电源(yuan)的频率为100 - 200kHz，模块电源(yuan)为300- - 500kHz），同时(shi)它对变压(ya)器有要求，需要用高磁导率的材料来制作变压(ya)器。

总之，与线性电(dian)源(yuan)相比(bi)，MOS开关(guan)电(dian)原理的(de)功率(lv)转换效率(lv)高，可(ke)达(da)65% -90%（最好的(de)VICOR开关(guan)电(dian)源(yuan)模(mo)块的(de)效率(lv)高达(da)99%），发热少，功率(lv)体积系数可(ke)达(da)60 - lOOW/dm3，对电(dian)网电(dian)压大范围变化具有很强的(de)适(shi)应(ying)性，电(dian)压、负载稳(wen)定度高，输出电(dian)压保持时间长达(da)20ms;

开关(guan)(guan)电(dian)(dian)源(yuan)不需要(yao)工(gong)频变(bian)压(ya)器，工(gong)作频率(lv)高(gao)，所(suo)需的(de)(de)滤波(bo)电(dian)(dian)容(rong)、电(dian)(dian)感小(xiao)，因(yin)此其体积小(xiao)，质量轻，动态响应速度(du)快；开关(guan)(guan)电(dian)(dian)源(yuan)的(de)(de)开关(guan)(guan)频率(lv)都在20kHz以上，超(chao)出人(ren)耳的(de)(de)听(ting)觉范围，没有(you)令人(ren)心烦的(de)(de)噪声；开关(guan)(guan)电(dian)(dian)源(yuan)可(ke)以采用(yong)有(you)效的(de)(de)功(gong)(gong)牢因(yin)数(shu)校正技术(shu)，使功(gong)(gong)率(lv)因(yin)数(shu)达到0.9以上，高(gao)的(de)(de)甚(shen)至(zhi)达到0.99（安圣的(de)(de)HD4850整(zheng)流模(mo)块）。这(zhei)些使得开关(guan)(guan)电(dian)(dian)源(yuan)在通信(xin)电(dian)(dian)源(yuan)领域(yu)已大量取代线性电(dian)(dian)源(yuan)。

开关电(dian)(dian)源的(de)主(zhu)要缺点就(jiu)是(shi)线路(lu)(lu)复杂，输出(chu)纹波较大，开关电(dian)(dian)源电(dian)(dian)路(lu)(lu)问世之(zhi)初(chu)，其控(kong)制线路(lu)(lu)都是(shi)由(you)分立元(yuan)件或运算放大器等(deng)集成电(dian)(dian)路(lu)(lu)组成的(de)，元(yuan)件多，线路(lu)(lu)复杂，随之(zhi)产生的(de)可靠(kao)性差等(deng)原因严(yan)重(zhong)影(ying)响了开关电(dian)(dian)源的(de)广泛(fan)应(ying)用。

MOS管开关电源的发展依赖于元器件和磁性材料的发展。20世纪70年代后期，随着半导体技术(shu)的(de)(de)高(gao)度发(fa)展(zhan)，高(gao)反(fan)压(ya)快(kuai)速功率开(kai)关(guan)(guan)(guan)管使(shi)无工频变压(ya)器(qi)的(de)(de)开(kai)关(guan)(guan)(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)迅速实用(yong)化(hua)。而集(ji)成电(dian)(dian)(dian)(dian)(dian)路(lu)的(de)(de)迅速发(fa)展(zhan)为开(kai)火电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)控制(zhi)电(dian)(dian)(dian)(dian)(dian)路(lu)的(de)(de)集(ji)成化(hua)奠定了基础。陆(lu)续(xu)涌现出(chu)的(de)(de)开(kai)关(guan)(guan)(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)专(zhuan)用(yong)的(de)(de)脉(mai)冲调制(zhi)电(dian)(dian)(dian)(dian)(dian)路(lu)，如(ru)SG3525和(he)TI494等为开(kai)关(guan)(guan)(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)提供了成本低、性(xing)能优良可靠(kao)、使(shi)用(yong)方便的(de)(de)集(ji)成控制(zhi)电(dian)(dian)(dian)(dian)(dian)路(lu)芯片，从而使(shi)得开(kai)关(guan)(guan)(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)的(de)(de)电(dian)(dian)(dian)(dian)(dian)路(lu)由复杂变为简单。目前(qian)，开(kai)关(guan)(guan)(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)的(de)(de)输出(chu)纹波已降(jiang)至(zhi)1OOmV以下．射频干(gan)扰(rao)和(he)电(dian)(dian)(dian)(dian)(dian)磁(ci)干(gan)扰(rao)也被抑制(zhi)到很(hen)低的(de)(de)水平上总之，随着(zhe)电(dian)(dian)(dian)(dian)(dian)力电(dian)(dian)(dian)(dian)(dian)子技术(shu)的(de)(de)发(fa)展(zhan)，开(kai)关(guan)(guan)(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)的(de)(de)缺点(dian)(dian)正逐步被克(ke)服，其优点(dian)(dian)也得以充(chong)分发(fa)挥。尤(you)其在当(dang)前(qian)能源(yuan)(yuan)(yuan)比较紧张的(de)(de)情况下，开(kai)关(guan)(guan)(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)的(de)(de)高(gao)效率能够(gou)在节能上做出(chu)很(hen)大(da)的(de)(de)贡献。正因为开(kai)关(guan)(guan)(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)具有这(zhei)些优点(dian)(dian)，所以它得到了蓬勃的(de)(de)发(fa)展(zhan)。

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