逆变器原理电路解析-12V直流变成220V交流电

逆变器

逆(ni)变(bian)器(qi)(qi)原理电路(lu)解(jie)析，将12V直流(liu)变(bian)成(cheng)(cheng)220V交流(liu)电。逆(ni)变(bian)器(qi)(qi)是(shi)把直流(liu)电能（电池、蓄(xu)电瓶）转变(bian)成(cheng)(cheng)定频(pin)定压或调频(pin)调压交流(liu)电（一般(ban)为220V,50Hz正弦(xian)波）的转换器(qi)(qi)。它由逆(ni)变(bian)桥(qiao)、控制逻(luo)辑(ji)和(he)滤波电路(lu)组成(cheng)(cheng)。

将220V交(jiao)流(liu)电(dian)转变为(wei)24V、36V、48V都比较简(jian)单，只需要使用变压器的原理。电(dian)磁互感，就(jiu)可以获得不同的电(dian)压。

设闭合电(dian)路是(shi)一个(ge)n匝(za)线圈(quan)，且穿过每匝(za)线圈(quan)的磁通量变化(hua)率(lv)都相同，这时相当于n个(ge)单匝(za)线圈(quan)串(chuan)联而成，因此感应电(dian)动势变为

根据公式可知，E就是电动势，也就是电压。因为不变，只要铁块两端的线圈数量n不一样就可以达到变压的效果。

将(jiang)交(jiao)流(liu)(liu)电(dian)(dian)转变(bian)为直(zhi)流(liu)(liu)电(dian)(dian)只(zhi)要加上二极管(guan)就可以达到需(xu)要的(de)(de)效果(guo)，二极管(guan)是一(yi)(yi)种具(ju)有两个电(dian)(dian)极的(de)(de)装(zhuang)置，只(zhi)允(yun)许电(dian)(dian)流(liu)(liu)由单一(yi)(yi)方向流(liu)(liu)过(guo)，许多的(de)(de)使用(yong)是应用(yong)其整流(liu)(liu)的(de)(de)功能。然后再利用(yong)变(bian)压(ya)(ya)器原理就可以将(jiang)220V交(jiao)流(liu)(liu)电(dian)(dian)转变(bian)成12V直(zhi)流(liu)(liu)电(dian)(dian)，以及(ji)我们手机充电(dian)(dian)器的(de)(de)5V直(zhi)流(liu)(liu)输出电(dian)(dian)压(ya)(ya)。

那么如何将12V直流转换成220V交流电呢？

首先(xian)我们来(lai)了(le)解一(yi)下(xia)逆变器，什(shen)么是逆变器？逆(ni)变器(qi)(qi)(qi)是(shi)(shi)把直流(liu)(liu)电(dian)能(neng)（电(dian)池、蓄电(dian)瓶(ping)）转(zhuan)变成(cheng)交(jiao)流(liu)(liu)电(dian)（一(yi)(yi)般为(wei)220V,50Hz正弦波(bo)）。它(ta)(ta)由(you)逆(ni)变桥、控制逻辑和滤波(bo)电(dian)路组成(cheng)。是(shi)(shi)一(yi)(yi)种DC to AC的(de)变压器(qi)(qi)(qi)，它(ta)(ta)其(qi)实与转(zhuan)化器(qi)(qi)(qi)是(shi)(shi)一(yi)(yi)种电(dian)压逆(ni)变的(de)过(guo)程(cheng)。转(zhuan)换器(qi)(qi)(qi)是(shi)(shi)将电(dian)网(wang)的(de)交(jiao)流(liu)(liu)电(dian)压转(zhuan)变为(wei)稳定(ding)的(de)12V直流(liu)(liu)输出，而逆(ni)变器(qi)(qi)(qi)是(shi)(shi)将Adapter输出的(de)12V直流(liu)(liu)电(dian)压转(zhuan)变为(wei)高频的(de)高压交(jiao)流(liu)(liu)电(dian)。然后(hou)我们看一(yi)(yi)下整个过(guo)程(cheng)的(de)电(dian)路图：

12V直(zhi)流(liu)(liu)(liu)→高频升压→220V直(zhi)流(liu)(liu)(liu)→全(quan)桥(qiao)整流(liu)(liu)(liu)→220V直(zhi)流(liu)(liu)(liu)→逆变桥(qiao)逆变→220V交流(liu)(liu)(liu)

高频升压逆变控制电路：

（1）脚(jiao)第一组放大(da)(da)器(qi)(qi)的(de)(de)(de)同相(xiang)输(shu)(shu)入(ru)端，检(jian)测(ce)输(shu)(shu)出(chu)(chu)电(dian)(dian)(dian)流(liu)，与3个0.33R 电(dian)(dian)(dian)阻分压，当电(dian)(dian)(dian)流(liu)过大(da)(da)时(shi)，分压电(dian)(dian)(dian)阻上的(de)(de)(de)电(dian)(dian)(dian)压超过（2）脚(jiao)基准电(dian)(dian)(dian)压，（3）脚(jiao)放大(da)(da)器(qi)(qi)输(shu)(shu)出(chu)(chu)端输(shu)(shu)出(chu)(chu)高电(dian)(dian)(dian)平(ping)，（3）脚(jiao)为(wei)高电(dian)(dian)(dian)平(ping)时(shi)，电(dian)(dian)(dian)路(lu)进入(ru)保护状态。（2）脚(jiao)为(wei)比较器(qi)(qi)的(de)(de)(de)反(fan)相(xiang)输(shu)(shu)入(ru)端，接（14）脚(jiao)基准，作比较器(qi)(qi)的(de)(de)(de)参(can)考电(dian)(dian)(dian)压，外部输(shu)(shu)入(ru)端的(de)(de)(de)控(kong)制(zhi)(zhi)信号可输(shu)(shu)入(ru)至脚(jiao)（4）的(de)(de)(de)截(jie)止时(shi)间(jian)(jian)控(kong)制(zhi)(zhi)端（也叫死(si)区(qu)时(shi)间(jian)(jian)控(kong)制(zhi)(zhi)），与脚(jiao)（1）、（2）、（15）、（16）误差放大(da)(da)器(qi)(qi)的(de)(de)(de)输(shu)(shu)入(ru)端，其输(shu)(shu)入(ru)端点的(de)(de)(de)抵补电(dian)(dian)(dian)压为(wei)120mV，其可限制(zhi)(zhi)输(shu)(shu)出(chu)(chu)截(jie)止时(shi)间(jian)(jian)至最小值(zhi)，大(da)(da)约为(wei)最初(chu)锯齿波周期时(shi)间(jian)(jian)的(de)(de)(de)4%。

当13脚的(de)(de)输出模控制(zhi)端(duan)(duan)接地时(shi)，可(ke)获得(de)(de)96%最(zui)大(da)工作周期，而当(13)脚接制(zhi)参考(kao)电(dian)压时(shi)，可(ke)获得(de)(de)48%最(zui)大(da)工作周期。如(ru)果我们(men)在第(di)4脚截止时(shi)间控制(zhi)输入端(duan)(duan)设定(ding)一(yi)个(ge)固定(ding)电(dian)压，其(qi)范围(wei)由0V至3.3V之间，则附加的(de)(de)截止时(shi)间一(yi)定(ding)出现在输出上。  （5）、（6）脚是一(yi)个(ge)固定(ding)频(pin)率(lv)的(de)(de)脉冲宽(kuan)度(du)调(diao)制(zhi)电(dian)路，内置了线性锯齿波振荡器(qi)，振荡频(pin)率(lv)可(ke)通过(guo)外部(bu)的(de)(de)一(yi)个(ge)电(dian)阻和一(yi)个(ge)电(dian)容进行调(diao)节，其(qi)振荡频(pin)率(lv)如(ru)下：

输(shu)出(chu)(chu)(chu)脉(mai)冲(chong)的宽度是(shi)通过电(dian)(dian)容CT上的正极(ji)(ji)性锯(ju)齿波(bo)电(dian)(dian)压与(yu)另外两个控制信号(hao)(hao)进行比较来实现。功率输(shu)出(chu)(chu)(chu)管Q1和Q2受控于或非门(men)。当(dang)(dang)双稳触发器的时钟信号(hao)(hao)为(wei)低电(dian)(dian)平时才会(hui)被选通，即只有在锯(ju)齿波(bo)电(dian)(dian)压大(da)(da)于控制信号(hao)(hao)期间才会(hui)被选通。当(dang)(dang)控制信号(hao)(hao)增(zeng)大(da)(da)，输(shu)出(chu)(chu)(chu)脉(mai)冲(chong)的宽度将减小。（7）脚接地端，（8）、（11）脚是(shi)Q1和Q2内部(bu)开关管的集电(dian)(dian)极(ji)(ji)，在此电(dian)(dian)路(lu)中接电(dian)(dian)源，(9)、(10)脚为(wei)Q1、Q2的发射(she)极(ji)(ji)，作开关管驱(qu)动(dong)输(shu)出(chu)(chu)(chu)端，接下图(tu)中Q1与(yu)Q2外部(bu)放大(da)(da)电(dian)(dian)路(lu)。

以驱(qu)动(dong)后(hou)极推(tui)挽(wan)电(dian)(dian)路(lu)(lu)。（12）脚(jiao)(jiao)(jiao)电(dian)(dian)源端，(13）脚(jiao)(jiao)(jiao)为输(shu)出(chu)控制端，接(14)脚(jiao)(jiao)(jiao)基准(zhun)电(dian)(dian)压(ya)时(shi)两路(lu)(lu)输(shu)出(chu)脉冲相(xiang)差(cha)180方位，每路(lu)(lu)输(shu)出(chu)量大约(yue)200MA的驱(qu)动(dong)推(tui)挽(wan)或半(ban)桥式电(dian)(dian)路(lu)(lu)。(15)、脚(jiao)(jiao)(jiao)第二组放大器的反(fan)相(xiang)输(shu)入(ru)端，接基准(zhun)电(dian)(dian)压(ya)， （16)脚(jiao)(jiao)(jiao)同相(xiang)输(shu)入(ru)端，检(jian)测电(dian)(dian)源电(dian)(dian)压(ya)。当电(dian)(dian)压(ya)过高超过（15)脚(jiao)(jiao)(jiao)参考电(dian)(dian)压(ya)时(shi)，（3）脚(jiao)(jiao)(jiao)输(shu)出(chu)高电(dian)(dian)平，电(dian)(dian)路(lu)(lu)进入(ru)保护状态。

高频升压逆变电路及整流：

这是一个推挽式拓扑(pu)逆变电(dian)路(lu)，当E1驱动脉冲(chong)驱动时(shi)，Q1导(dao)通(tong)(tong)，使VT3、VT6导(dao)通(tong)(tong)，VT7、VT8截止(zhi)，此(ci)时(shi)电(dian)路(lu)进(jin)行正半周(zhou)波(bo)形放大，变压(ya)器升压(ya)到次(ci)级，通(tong)(tong)过高(gao)频(pin)整流管整流，当E2脉冲(chong)驱动时(shi)，Q2导(dao)通(tong)(tong)，驱动VT7、VT8导(dao)通(tong)(tong)。VT3、VT6截止(zhi)，进(jin)得负半周(zhou)波(bo)形放大。经(jing)升压(ya)变压(ya)器升压(ya)后，高(gao)频(pin)整流。

（此VT3\6\7\8以推挽方式存(cun)在于电路中，各负(fu)责(ze)正负(fu)半周的波形放大任务，电路工作时，两(liang)只(zhi)对称的功率开关管每次只(zhi)有一对导通(tong)，所以导通(tong)损耗小效率高。推挽输(shu)出既可以向负(fu)载(zai)灌电流.）

逆变桥逆变：

最后(hou)由(you)TL494CN芯片的5脚外(wai)接(jie)点容(rong)C3和6脚外(wai)接(jie)电(dian)(dian)阻(zu)R15决定脉宽频(pin)率为(wei)(wei)(wei)F=1.1÷(0.1×220)KHZ=50HZ控(kong)制Q10、Q11、Q13、Q14工作在50HZ的频(pin)率下，将220V直流电(dian)(dian)逆变为(wei)(wei)(wei)220V/50HZ的交流电(dian)(dian)，上图将完成这部(bu)分功(gong)能(neng)。TL494正向时，IC2控(kong)制Q3为(wei)(wei)(wei)饱(bao)和导通状(zhuang)(zhuang)(zhuang)态，Q4为(wei)(wei)(wei)截(jie)止(zhi)状(zhuang)(zhuang)(zhuang)态，由(you)于Q3为(wei)(wei)(wei)饱(bao)和导通状(zhuang)(zhuang)(zhuang)态，则Q10为(wei)(wei)(wei)饱(bao)和导通状(zhuang)(zhuang)(zhuang)态。由(you)于Q4处于截(jie)止(zhi)状(zhuang)(zhuang)(zhuang)态，Q11因栅极(ji)无正偏(pian)压而处于截(jie)止(zhi)状(zhuang)(zhuang)(zhuang)态，同时Q14因栅极(ji)无正偏(pian)压而处于截(jie)止(zhi)状(zhuang)(zhuang)(zhuang)态， Q13为(wei)(wei)(wei)饱(bao)和导通状(zhuang)(zhuang)(zhuang)态。

此时(shi)220V直流(liu)电(dian)(dian)(dian)经(jing)VT6沿XAC插(cha)座到负载再经(jing)VT10接地，形成正半周期电(dian)(dian)(dian)流(liu)；反向时(shi)，IC2控制(zhi)Q3为截(jie)止状(zhuang)态(tai)(tai)，Q4为饱(bao)和导(dao)通状(zhuang)态(tai)(tai)，由于Q3为截(jie)止状(zhuang)态(tai)(tai)，则Q10、Q13因栅极无正偏(pian)压而处于截(jie)止状(zhuang)态(tai)(tai)，由于Q4为饱(bao)和导(dao)通状(zhuang)态(tai)(tai)，Q11处于饱(bao)和导(dao)通状(zhuang)态(tai)(tai)，同时(shi)Q14处于饱(bao)和导(dao)通状(zhuang)态(tai)(tai)，Q11因栅极无正偏(pian)压而处于截(jie)止状(zhuang)态(tai)(tai)。此时(shi)220V直流(liu)电(dian)(dian)(dian)经(jing)VT9沿XAC插(cha)座到负载再经(jing)VT7接地，形成负半周期电(dian)(dian)(dian)流(liu)；这样接将220V直流(liu)电(dian)(dian)(dian)成功(gong)转变为220V/50HZ交流(liu)电(dian)(dian)(dian)输出供负载使用。

电路中的保护电路：

电(dian)(dian)(dian)路中采用双(shuang)运放比(bi)较放大(da)器(qi)(qi)LM358来控制(zhi)(zhi)输(shu)(shu)出(chu)(chu)过(guo)(guo)(guo)流保(bao)护，输(shu)(shu)出(chu)(chu)电(dian)(dian)(dian)压(ya)(ya)(ya)过(guo)(guo)(guo)低(di)保(bao)护电(dian)(dian)(dian)路，TL431在此设制(zhi)(zhi)2.5V基准电(dian)(dian)(dian)压(ya)(ya)(ya)，给比(bi)较器(qi)(qi)同(tong)(tong)相(xiang)输(shu)(shu)入(ru)端(duan)(duan)(duan)作参(can)考(kao)电(dian)(dian)(dian)压(ya)(ya)(ya)，第一组运放的(de)同(tong)(tong)相(xiang)输(shu)(shu)入(ru)端(duan)(duan)(duan)接(jie)输(shu)(shu)出(chu)(chu)电(dian)(dian)(dian)流检测(ce)，反相(xiang)输(shu)(shu)入(ru)端(duan)(duan)(duan)接(jie)参(can)考(kao)电(dian)(dian)(dian)压(ya)(ya)(ya)，当电(dian)(dian)(dian)流过(guo)(guo)(guo)大(da)，比(bi)较器(qi)(qi)输(shu)(shu)入(ru)电(dian)(dian)(dian)压(ya)(ya)(ya)升高，当超过(guo)(guo)(guo)2.5V时(shi)，输(shu)(shu)出(chu)(chu)端(duan)(duan)(duan)输(shu)(shu)出(chu)(chu)高电(dian)(dian)(dian)平，送入(ru)IC1的(de)3脚，IC关闭(bi)输(shu)(shu)出(chu)(chu)。第二组运放同(tong)(tong)相(xiang)输(shu)(shu)入(ru)端(duan)(duan)(duan)接(jie)参(can)考(kao)电(dian)(dian)(dian)压(ya)(ya)(ya)，反相(xiang)输(shu)(shu)入(ru)端(duan)(duan)(duan)接(jie)输(shu)(shu)出(chu)(chu)电(dian)(dian)(dian)压(ya)(ya)(ya)，当电(dian)(dian)(dian)压(ya)(ya)(ya)过(guo)(guo)(guo)低(di)，检测(ce)分(fen)压(ya)(ya)(ya)后电(dian)(dian)(dian)压(ya)(ya)(ya)低(di)于2.5V时(shi)，输(shu)(shu)出(chu)(chu)端(duan)(duan)(duan)输(shu)(shu)出(chu)(chu)高电(dian)(dian)(dian)平，Q1导通(tong)，蜂鸣器(qi)(qi)报警(jing)。

逆变器的工作效率

逆(ni)变(bian)(bian)器(qi)(qi)在工作时其(qi)本身也要消耗(hao)一部(bu)分电力(li)，因此(ci)，它的(de)输(shu)入功(gong)率(lv)(lv)要大于(yu)它的(de)输(shu)出功(gong)率(lv)(lv)。逆(ni)变(bian)(bian)器(qi)(qi)的(de)效(xiao)率(lv)(lv)即是(shi)逆(ni)变(bian)(bian)器(qi)(qi)输(shu)出功(gong)率(lv)(lv)与(yu)输(shu)入功(gong)率(lv)(lv)之(zhi)比(bi)，即逆(ni)变(bian)(bian)器(qi)(qi)效(xiao)率(lv)(lv)为输(shu)出功(gong)率(lv)(lv)比(bi)上输(shu)入功(gong)率(lv)(lv)。如一台逆(ni)变(bian)(bian)器(qi)(qi)输(shu)入了(le)100瓦(wa)的(de)直流(liu)(liu)电，输(shu)出了(le)90瓦(wa)的(de)交(jiao)流(liu)(liu)电，那么，它的(de)效(xiao)率(lv)(lv)就是(shi)90%。

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