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(ru)电(dian)网滤(lv)(lv)波器(qi)(qi)。输入(ru)整流滤(lv)(lv)波器(qi)(qi)、逆变器(qi)(qi)、输出整流滤(lv)(lv)波器(qi)(qi)。控制电(dian)路、保护电(dian)路。它们的(de)功能(neng)介绍如下。

(1)输入电(dian)(dian)网(wang)滤波器：消除来自电(dian)(dian)网(wang)的干(gan)扰，如(ru)电(dian)(dian)动机的启(qi)动、电(dian)(dian)器的开(kai)关(guan)、雷击等产生(sheng)(sheng)的干(gan)扰，同(tong)时(shi)也防(fang)止开(kai)关(guan)电(dian)(dian)源产生(sheng)(sheng)的高频噪(zao)声阻电(dian)(dian)网(wang)扩(kuo)散。

(2)输(shu)入整流滤波器：对电(dian)网输(shu)入电(dian)压进行整流滤波，为变换(huan)器提(ti)供盲流电(dian)压。

(3)逆(ni)变器(qi)：是开关电(dian)(dian)源的关键部(bu)分，它把直(zhi)流电(dian)(dian)压(ya)变换成高频交流电(dian)(dian)压(ya)，并(bing)且(qie)起到将输出部(bu)分与输入(ru)电(dian)(dian)网隔离的作(zuo)用。

(4)输出整(zheng)流(liu)滤波器：将变换器输出的高频(pin)交流(liu)电(dian)压整(zheng)流(liu)滤波后得(de)到(dao)需要的直流(liu)电(dian)压，同时还(hai)防止(zhi)高频(pin)噪声(sheng)对负载的干扰。

（5)控制(zhi)电路(lu)：检测输(shu)出(chu)直流电压，并将其(qi)与基准电压比较后(hou)进行放(fang)大；调制(zhi)振(zhen)荡器的(de)脉冲宽度(du)，从而控制(zhi)变换器以保持输(shu)出(chu)电压的(de)稳定。

(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(xing)电(dian)(dian)(dian)(dian)源一般是将输(shu)出(chu)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)取样后(hou)与参考(kao)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)起送(song)入比(bi)较电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)放(fang)大器，此电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)放(fang)大器的输(shu)出(chu)作为电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)调整管(guan)的输(shu)入，用以(yi)控制调整管(guan)使其结(jie)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)随输(shu)入的变化而变化，从而调整其输(shu)出(chu)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)。但开关(guan)电(dian)(dian)(dian)(dian)源足通过改(gai)变调整管(guan)的开关(guan)的时(shi)间（即占空比(bi)）来改(gai)变输(shu)出(chu)电(dian)(dian)(dian)(dian)压(ya)(ya)(ya)(ya)的。开关(guan)电(dian)(dian)(dian)(dian)源与线(xian)性(xing)电(dian)(dian)(dian)(dian)源的主要性(xing)能比(bi)较如表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管发热量很大，用不完的(de)电能全部转(zhuan)换(huan)成了(le)热能。从这个(ge)角(jiao)度来看(kan)，线性(xing)电源的(de)转(zhuan)换(huan)效率(lv)就非(fei)常低了(le)，而且热量高时，

元(yuan)件的(de)寿命(ming)势必要下(xia)降(jiang)，影响最终的(de)使用效(xiao)果。由于线(xian)性(xing)电源(yuan)的(de)功率器件工(gong)作(zuo)在线(xian)性(xing)状(zhuang)态，所以其工(gong)作(zuo)效(xiao)率低(di)，一般为(wei)50% - 60%。线(xian)性(xing)电源(yuan)的(de)工(gong)作(zuo)方式，使得从高压变低(di)压必须有(you)降(jiang)压变压器，再(zai)经过整(zheng)流(liu)输出直(zhi)流(liu)电压，这样就造成其体积(ji)很大，笨重，效(xiao)率低(di)、发热量也大。当然，线(xian)性(xing)电源(yuan)也有(you)优点：纹波小，调整(zheng)效(xiao)率好，对外干扰小，适合(he)用于模拟电路、各类放大器领域。

而(er)开关(guan)(guan)电源的功率器(qi)(qi)(qi)件工作(zuo)在开关(guan)(guan)状态（一(yi)开一(yi)关(guan)(guan)，频(pin)率非常快，一(yi)般平(ping)板开关(guan)(guan)电源的频(pin)率为(wei)100 - 200kHz，模块电源为(wei)300- - 500kHz），同时(shi)它对变压(ya)器(qi)(qi)(qi)有(you)要(yao)求，需要(yao)用高磁导率的材料来制作(zuo)变压(ya)器(qi)(qi)(qi)。

总之，与线(xian)性(xing)电(dian)(dian)源(yuan)相比，MOS开关电(dian)(dian)原理(li)的(de)功率(lv)转换效(xiao)率(lv)高(gao)，可达(da)(da)65% -90%（最好的(de)VICOR开关电(dian)(dian)源(yuan)模块的(de)效(xiao)率(lv)高(gao)达(da)(da)99%），发热少，功率(lv)体积系(xi)数(shu)可达(da)(da)60 - lOOW/dm3，对电(dian)(dian)网电(dian)(dian)压(ya)大(da)范围变化具有(you)很强(qiang)的(de)适(shi)应性(xing)，电(dian)(dian)压(ya)、负载(zai)稳定度(du)高(gao)，输出电(dian)(dian)压(ya)保持时间长达(da)(da)20ms;

开(kai)(kai)关电(dian)(dian)源(yuan)不(bu)需(xu)要工频(pin)(pin)变压器，工作频(pin)(pin)率(lv)高，所需(xu)的滤波电(dian)(dian)容、电(dian)(dian)感(gan)小，因此其体积小，质量轻，动态(tai)响应(ying)速(su)度快；开(kai)(kai)关电(dian)(dian)源(yuan)的开(kai)(kai)关频(pin)(pin)率(lv)都在20kHz以(yi)上，超出人耳(er)的听觉(jue)范围，没(mei)有令人心烦的噪声；开(kai)(kai)关电(dian)(dian)源(yuan)可以(yi)采用有效的功(gong)牢因数校正技(ji)术，使功(gong)率(lv)因数达到0.9以(yi)上，高的甚(shen)至达到0.99（安圣的HD4850整流模块）。这(zhei)些使得开(kai)(kai)关电(dian)(dian)源(yuan)在通信电(dian)(dian)源(yuan)领域已大量取代线(xian)性电(dian)(dian)源(yuan)。

开(kai)关(guan)电(dian)源(yuan)的(de)主(zhu)要缺点就(jiu)是(shi)线(xian)路(lu)(lu)复(fu)杂(za)，输出(chu)纹波较大，开(kai)关(guan)电(dian)源(yuan)电(dian)路(lu)(lu)问(wen)世之初，其控制线(xian)路(lu)(lu)都(dou)是(shi)由分立元件(jian)或运算放大器(qi)等集成电(dian)路(lu)(lu)组成的(de)，元件(jian)多，线(xian)路(lu)(lu)复(fu)杂(za)，随之产(chan)生的(de)可(ke)靠(kao)性差等原因严(yan)重(zhong)影响了开(kai)关(guan)电(dian)源(yuan)的(de)广泛应用。

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，随着半导体技术的(de)高(gao)度发展，高(gao)反压(ya)快速(su)(su)功率开(kai)关(guan)管(guan)使(shi)无工频(pin)变压(ya)器的(de)开(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)迅速(su)(su)实用化。而集成电(dian)(dian)(dian)(dian)(dian)路(lu)的(de)迅速(su)(su)发展为(wei)开(kai)火电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)控制(zhi)电(dian)(dian)(dian)(dian)(dian)路(lu)的(de)集成化奠定了(le)基础。陆续涌(yong)现出(chu)(chu)的(de)开(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)专用的(de)脉(mai)冲(chong)调(diao)制(zhi)电(dian)(dian)(dian)(dian)(dian)路(lu)，如SG3525和(he)TI494等(deng)为(wei)开(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)提供了(le)成本低、性(xing)能(neng)优良可靠、使(shi)用方便的(de)集成控制(zhi)电(dian)(dian)(dian)(dian)(dian)路(lu)芯片，从而使(shi)得开(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)的(de)电(dian)(dian)(dian)(dian)(dian)路(lu)由复杂变为(wei)简单。目(mu)前(qian)(qian)，开(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)的(de)输出(chu)(chu)纹(wen)波已(yi)降(jiang)至1OOmV以(yi)(yi)下．射(she)频(pin)干扰和(he)电(dian)(dian)(dian)(dian)(dian)磁干扰也(ye)被抑制(zhi)到(dao)(dao)很(hen)低的(de)水(shui)平(ping)上总之，随(sui)着电(dian)(dian)(dian)(dian)(dian)力电(dian)(dian)(dian)(dian)(dian)子技术的(de)发展，开(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)的(de)缺点(dian)正逐步被克服，其(qi)优点(dian)也(ye)得以(yi)(yi)充分发挥。尤其(qi)在(zai)当前(qian)(qian)能(neng)源(yuan)(yuan)(yuan)(yuan)比较紧(jin)张的(de)情(qing)况下，开(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)的(de)高(gao)效率能(neng)够(gou)在(zai)节能(neng)上做出(chu)(chu)很(hen)大的(de)贡(gong)献。正因为(wei)开(kai)关(guan)电(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)(yuan)(yuan)具有这些优点(dian)，所以(yi)(yi)它得到(dao)(dao)了(le)蓬(peng)勃的(de)发展。

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