MOS管电子开关电路(lu)图-MOS管开关电路(lu)图大全以及(ji)电路(lu)设计(ji)原理详解-KIA MOS管
信(xin)息来源：本站 日期：2018-07-21
电(dian)(dian)子开关电(dian)(dian)源的电(dian)(dian)路组成如下：
开(kai)关电(dian)(dian)(dian)(dian)源的主要电(dian)(dian)(dian)(dian)路(lu)是(shi)由(you)输(shu)入电(dian)(dian)(dian)(dian)磁干扰滤(lv)波器（EMI）、整(zheng)流(liu)滤(lv)波电(dian)(dian)(dian)(dian)路(lu)、功率变换电(dian)(dian)(dian)(dian)路(lu)、PWM控(kong)(kong)制器电(dian)(dian)(dian)(dian)路(lu)、输(shu)出(chu)整(zheng)流(liu)滤(lv)波电(dian)(dian)(dian)(dian)路(lu)组成。IC根据输(shu)出(chu)电(dian)(dian)(dian)(dian)压和(he)电(dian)(dian)(dian)(dian)流(liu)时刻调整(zheng)着⑥脚锯(ju)形波占空比(bi)的大(da)小，从而不乱了整(zheng)机的输(shu)出(chu)电(dian)(dian)(dian)(dian)流(liu)和(he)电(dian)(dian)(dian)(dian)压。从R3测(ce)得的电(dian)(dian)(dian)(dian)流(liu)峰(feng)值信号介入当前工作周(zhou)(zhou)波的占空比(bi)控(kong)(kong)制，因(yin)此(ci)是(shi)当前工作周(zhou)(zhou)波的电(dian)(dian)(dian)(dian)流(liu)限制。
Q1的(de)栅极受控电(dian)压为锯形波，当其(qi)占空比(bi)越大时(shi)(shi)，Q1导(dao)通时(shi)(shi)间越长，变(bian)压器(qi)所储存(cun)的(de)能(neng)量也就越多；当Q1截止时(shi)(shi)，变(bian)压器(qi)通过D1、D2、R5、R4、C3开释能(neng)量，同时(shi)(shi)也达到了(le)(le)磁场(chang)复位(wei)的(de)目的(de)，为变(bian)压器(qi)的(de)下一(yi)次(ci)存(cun)储、传递能(neng)量做(zuo)好(hao)了(le)(le)预备(bei)。在开关管Q1关断时(shi)(shi)，变(bian)压器(qi)的(de)原边线圈易产生尖(jian)(jian)峰(feng)电(dian)压和尖(jian)(jian)峰(feng)电(dian)流(liu)，这些元件组合一(yi)起，能(neng)很好(hao)地吸收尖(jian)(jian)峰(feng)电(dian)压和电(dian)流(liu)。
1:输(shu)入滤波电(dian)(dian)(dian)路：C1、L1、C2组(zu)成的双π型滤波网络主(zhu)要是对输(shu)入电(dian)(dian)(dian)源(yuan)(yuan)的电(dian)(dian)(dian)磁噪(zao)声(sheng)及杂(za)波信号进行(xing)按捺，防(fang)止对电(dian)(dian)(dian)源(yuan)(yuan)干(gan)扰(rao)，同(tong)时也防(fang)止电(dian)(dian)(dian)源(yuan)(yuan)本(ben)身产生的高频杂(za)波对电(dian)(dian)(dian)网干(gan)扰(rao)。Z1通(tong)常将MOS管的GS电(dian)(dian)(dian)压限制在18V以下，从(cong)而保护了MOS管。因瞬时能(neng)量(liang)全消耗(hao)(hao)在RT1电(dian)(dian)(dian)阻上，一定时间后(hou)温(wen)(wen)度升高后(hou)RT1阻值(zhi)减（RT1是负温(wen)(wen)系数元件），这时它消耗(hao)(hao)的能(neng)量(liang)非常小(xiao)，后(hou)级电(dian)(dian)(dian)路可正常工(gong)作(zuo)。C3、C4 为安规电(dian)(dian)(dian)容，L2、L3为差模电(dian)(dian)(dian)感。
2:输(shu)入滤(lv)波(bo)电(dian)(dian)(dian)(dian)路(lu)：C1、L1、C2、C3组成的(de)双(shuang)π型(xing)滤(lv)波(bo)网络(luo)主要是(shi)对(dui)输(shu)入电(dian)(dian)(dian)(dian)源(yuan)的(de)电(dian)(dian)(dian)(dian)磁噪声及杂波(bo)信号进(jin)行按捺，防止(zhi)对(dui)电(dian)(dian)(dian)(dian)源(yuan)干扰，同(tong)时也防止(zhi)电(dian)(dian)(dian)(dian)源(yuan)本身产生(sheng)的(de)高频(pin)杂波(bo)对(dui)电(dian)(dian)(dian)(dian)网干扰。
3:工作原理：R4、C3、R5、R6、C4、D1、D2组成(cheng)缓冲器，和开关MOS管并接，使(shi)开关管电(dian)(dian)压应力减(jian)少，EMI减(jian)少，不发生二次击穿。辅助电(dian)(dian)路(lu)(lu)有输入过欠压保(bao)护(hu)电(dian)(dian)路(lu)(lu)、输出(chu)过欠压保(bao)护(hu)电(dian)(dian)路(lu)(lu)、输出(chu)过流保(bao)护(hu)电(dian)(dian)路(lu)(lu)、输出(chu)短路(lu)(lu)保(bao)护(hu)电(dian)(dian)路(lu)(lu)等。
图(tu)中(zhong)电(dian)(dian)(dian)(dian)池的(de)(de)(de)(de)(de)(de)(de)正电(dian)(dian)(dian)(dian)通(tong)(tong)(tong)过(guo)开(kai)(kai)关S1接(jie)(jie)到(dao)场效应管(guan)Q1的(de)(de)(de)(de)(de)(de)(de)2脚(jiao)(jiao)源极(ji)(ji)(ji)，由于(yu)Q1是一个(ge)P沟道管(guan)，它(ta)的(de)(de)(de)(de)(de)(de)(de)1脚(jiao)(jiao)栅(zha)极(ji)(ji)(ji)通(tong)(tong)(tong)过(guo)R20电(dian)(dian)(dian)(dian)阻(zu)(zu)提供(gong)一个(ge)正电(dian)(dian)(dian)(dian)位电(dian)(dian)(dian)(dian)压(ya)(ya)，所以不(bu)(bu)能通(tong)(tong)(tong)电(dian)(dian)(dian)(dian)，电(dian)(dian)(dian)(dian)压(ya)(ya)不(bu)(bu)能继(ji)续通(tong)(tong)(tong)过(guo)，3v稳压(ya)(ya)IC输(shu)入(ru)脚(jiao)(jiao)得不(bu)(bu)到(dao)电(dian)(dian)(dian)(dian)压(ya)(ya)所以就(jiu)不(bu)(bu)能工(gong)(gong)作不(bu)(bu)开(kai)(kai)机！这(zhei)时(shi)，如果(guo)我们按下SW1开(kai)(kai)机按键时(shi)，正电(dian)(dian)(dian)(dian)通(tong)(tong)(tong)过(guo)按键、R11、R23、D4加到(dao)三(san)(san)极(ji)(ji)(ji)管(guan)Q2的(de)(de)(de)(de)(de)(de)(de)基极(ji)(ji)(ji)，三(san)(san)极(ji)(ji)(ji)管(guan)Q2的(de)(de)(de)(de)(de)(de)(de)基极(ji)(ji)(ji)得到(dao)一个(ge)正电(dian)(dian)(dian)(dian)位，三(san)(san)极(ji)(ji)(ji)管(guan)导通(tong)(tong)(tong)（前面(mian)讲到(dao)三(san)(san)极(ji)(ji)(ji)管(guan)的(de)(de)(de)(de)(de)(de)(de)时(shi)候已经(jing)讲过(guo)），由于(yu)三(san)(san)极(ji)(ji)(ji)管(guan)的(de)(de)(de)(de)(de)(de)(de)发射极(ji)(ji)(ji)直(zhi)接(jie)(jie)接(jie)(jie)地，三(san)(san)极(ji)(ji)(ji)管(guan)Q2导通(tong)(tong)(tong)就(jiu)相当于(yu)Q1的(de)(de)(de)(de)(de)(de)(de)栅(zha)极(ji)(ji)(ji)直(zhi)接(jie)(jie)接(jie)(jie)地，加在它(ta)上面(mian)的(de)(de)(de)(de)(de)(de)(de)通(tong)(tong)(tong)过(guo)R20电(dian)(dian)(dian)(dian)阻(zu)(zu)的(de)(de)(de)(de)(de)(de)(de)电(dian)(dian)(dian)(dian)压(ya)(ya)就(jiu)直(zhi)接(jie)(jie)入(ru)了地，Q1的(de)(de)(de)(de)(de)(de)(de)栅(zha)极(ji)(ji)(ji)就(jiu)从高电(dian)(dian)(dian)(dian)位变为(wei)低电(dian)(dian)(dian)(dian)位，Q1导通(tong)(tong)(tong)电(dian)(dian)(dian)(dian)就(jiu)从Q1同(tong)过(guo)加到(dao)3v稳压(ya)(ya)IC的(de)(de)(de)(de)(de)(de)(de)输(shu)入(ru)脚(jiao)(jiao)，3v稳压(ya)(ya)IC就(jiu)是那个(ge)U1输(shu)出(chu)(chu)3v的(de)(de)(de)(de)(de)(de)(de)工(gong)(gong)作电(dian)(dian)(dian)(dian)压(ya)(ya)vcc供(gong)给(ji)主(zhu)控(kong)，主(zhu)控(kong)通(tong)(tong)(tong)过(guo)复位清0，读取固件程(cheng)序检测等一系列动(dong)作，输(shu)处一个(ge)控(kong)制(zhi)电(dian)(dian)(dian)(dian)压(ya)(ya)到(dao)PWR_ON再通(tong)(tong)(tong)过(guo)R24、R13分压(ya)(ya)送(song)(song)到(dao)Q2的(de)(de)(de)(de)(de)(de)(de)基极(ji)(ji)(ji)，保持Q2一直(zhi)处于(yu)导通(tong)(tong)(tong)状态(tai)，即使你松开(kai)(kai)开(kai)(kai)机键断(duan)开(kai)(kai)Q1的(de)(de)(de)(de)(de)(de)(de)基极(ji)(ji)(ji)电(dian)(dian)(dian)(dian)压(ya)(ya)，这(zhei)时(shi)候有(you)主(zhu)控(kong)送(song)(song)来的(de)(de)(de)(de)(de)(de)(de)控(kong)制(zhi)电(dian)(dian)(dian)(dian)压(ya)(ya)保持着(zhe)，Q2也(ye)就(jiu)一直(zhi)能够处于(yu)导通(tong)(tong)(tong)状态(tai)，Q1就(jiu)能源源不(bu)(bu)断(duan)的(de)(de)(de)(de)(de)(de)(de)给(ji)3v稳压(ya)(ya)IC提供(gong)工(gong)(gong)作电(dian)(dian)(dian)(dian)压(ya)(ya)！SW1还同(tong)时(shi)通(tong)(tong)(tong)过(guo)R11、R30两(liang)个(ge)电(dian)(dian)(dian)(dian)阻(zu)(zu)的(de)(de)(de)(de)(de)(de)(de)分压(ya)(ya)，给(ji)主(zhu)控(kong)PLAYON脚(jiao)(jiao)送(song)(song)去时(shi)间(jian)长短、次数不(bu)(bu)同(tong)的(de)(de)(de)(de)(de)(de)(de)控(kong)制(zhi)信号，主(zhu)控(kong)通(tong)(tong)(tong)过(guo)固件鉴别是播(bo)放、暂停、开(kai)(kai)机、关机而输(shu)出(chu)(chu)不(bu)(bu)同(tong)的(de)(de)(de)(de)(de)(de)(de)结(jie)果(guo)给(ji)相应的(de)(de)(de)(de)(de)(de)(de)控(kong)制(zhi)点，以达(da)到(dao)不(bu)(bu)同(tong)的(de)(de)(de)(de)(de)(de)(de)工(gong)(gong)作状态(tai)！
下图是两种MOS管的(de)典型应用：其中第一种NMOS管为高电平(ping)导通，低(di)电平(ping)截断，Drain端接后(hou)面(mian)电路(lu)的(de)接地端；第二种为PMOS管典型开关电路(lu)，为高电平(ping)断开，低(di)电平(ping)导通，Drain端接后(hou)面(mian)电路(lu)的(de)VCC端。
为(wei)了满足(zu)如图所示高端MOS管(guan)的(de)驱(qu)动(dong)(dong)，经(jing)常会采用变(bian)(bian)压器驱(qu)动(dong)(dong)，有时(shi)为(wei)了满足(zu)安全隔离也使用变(bian)(bian)压器驱(qu)动(dong)(dong)。其(qi)中R1目(mu)的(de)是抑制(zhi)PCB板上寄生的(de)电(dian)感与C1形成LC振(zhen)荡，C1的(de)目(mu)的(de)是隔开直流，通过交(jiao)流，同时(shi)也能防(fang)止磁(ci)芯(xin)饱和(he)。
如图所示为常用(yong)的(de)小功率(lv)驱动(dong)电路(lu)，简单可靠成(cheng)本低。适(shi)用(yong)于不(bu)要(yao)求隔离的(de)小功率(lv)开关(guan)设备。如图所示驱动(dong)电路(lu)开关(guan)速度(du)很快(kuai)，驱动(dong)能力强，为防止(zhi)两(liang)个MOSFET管(guan)直(zhi)通，通常串接(jie)一个0.5～1Ω小电阻用(yong)于限流，该电路(lu)适(shi)用(yong)于不(bu)要(yao)求隔离的(de)中功率(lv)开关(guan)设备。这两(liang)种电路(lu)特点是结构简单。
功率(lv)MOSFET属于(yu)电(dian)(dian)(dian)(dian)压型控制器(qi)件，只(zhi)要栅极和源极之(zhi)间(jian)施(shi)加的电(dian)(dian)(dian)(dian)压超过其(qi)阀值(zhi)电(dian)(dian)(dian)(dian)压就(jiu)会导(dao)通。由于(yu)MOSFET存在结电(dian)(dian)(dian)(dian)容，关(guan)断时(shi)其(qi)漏(lou)源两(liang)端电(dian)(dian)(dian)(dian)压的突然上升将会通过结电(dian)(dian)(dian)(dian)容在栅源两(liang)端产(chan)生干扰电(dian)(dian)(dian)(dian)压。常用(yong)的互补驱动电(dian)(dian)(dian)(dian)路(lu)的关(guan)断回路(lu)阻抗(kang)小，关(guan)断速(su)度较快，但它不能提供负压，故抗(kang)干扰性较差。为了提高(gao)电(dian)(dian)(dian)(dian)路(lu)的抗(kang)干扰性，可在此(ci)种驱动电(dian)(dian)(dian)(dian)路(lu)的基础上增(zeng)加一级有V1、V2、R组成的电(dian)(dian)(dian)(dian)路(lu)，产(chan)生一个负压，电(dian)(dian)(dian)(dian)路(lu)原理(li)图(tu)如图(tu)所示。
电(dian)(dian)路原理(li)如(ru)图所(suo)(suo)示(shi)(shi)，N3为(wei)去磁绕组(zu)，S2为(wei)所(suo)(suo)驱动(dong)的(de)功(gong)率管。R2为(wei)防止(zhi)功(gong)率管栅极(ji)、源极(ji)端电(dian)(dian)压振荡(dang)的(de)一个阻(zu)尼电(dian)(dian)阻(zu)。因(yin)不要(yao)(yao)求漏感较小(xiao)(xiao)(xiao)(xiao)(xiao)，且(qie)从速(su)度(du)(du)方(fang)面(mian)考虑，一般R2较小(xiao)(xiao)(xiao)(xiao)(xiao)，故在分(fen)(fen)析中忽(hu)略不计。其等效电(dian)(dian)路图如(ru)图所(suo)(suo)示(shi)(shi)脉冲(chong)不要(yao)(yao)求的(de)副边并联一电(dian)(dian)阻(zu)R1，它做(zuo)为(wei)正激变(bian)换器的(de)假负载，用于消除关(guan)(guan)(guan)断(duan)期间输出(chu)电(dian)(dian)压发生振荡(dang)而误导通(tong)(tong)。同(tong)时(shi)(shi)它还(hai)可(ke)以(yi)作为(wei)功(gong)率MOSFET关(guan)(guan)(guan)断(duan)时(shi)(shi)的(de)能量泄放(fang)回(hui)路。该驱动(dong)电(dian)(dian)路的(de)导通(tong)(tong)速(su)度(du)(du)主要(yao)(yao)与被驱动(dong)的(de)S2栅极(ji)、源极(ji)等效输入电(dian)(dian)容的(de)大(da)小(xiao)(xiao)(xiao)(xiao)(xiao)、S1的(de)驱动(dong)信号的(de)速(su)度(du)(du)以(yi)及S1所(suo)(suo)能提(ti)供的(de)电(dian)(dian)流大(da)小(xiao)(xiao)(xiao)(xiao)(xiao)有(you)关(guan)(guan)(guan)。由(you)仿真及分(fen)(fen)析可(ke)知，占空比D越小(xiao)(xiao)(xiao)(xiao)(xiao)、R1越大(da)、L越大(da)，磁化电(dian)(dian)流越小(xiao)(xiao)(xiao)(xiao)(xiao)，U1值越小(xiao)(xiao)(xiao)(xiao)(xiao)，关(guan)(guan)(guan)断(duan)速(su)度(du)(du)越慢。该电(dian)(dian)路具有(you)以(yi)下优点：①电(dian)(dian)路结构(gou)简(jian)单可(ke)靠，实现(xian)了隔离(li)驱动(dong)。②只需单电(dian)(dian)源即可(ke)提(ti)供导通(tong)(tong)时(shi)(shi)的(de)正、关(guan)(guan)(guan)断(duan)时(shi)(shi)负压。③占空比固(gu)定时(shi)(shi)，通(tong)(tong)过合理(li)的(de)参数设计，此驱动(dong)电(dian)(dian)路也具有(you)较快的(de)开关(guan)(guan)(guan)速(su)度(du)(du)。该电路(lu)存(cun)在的缺点：一(yi)是由于(yu)隔离变(bian)压器副边需要(yao)噎嗝假负载(zai)防振荡，故电路(lu)损耗较大;二是当占(zhan)空比变(bian)化(hua)时(shi)关断速度变(bian)化(hua)较大。脉宽较窄时(shi)，由于(yu)是储存(cun)的能(neng)量(liang)减少(shao)导(dao)致MOSFET栅极(ji)的关断速度变(bian)慢。
如图(tu)所示，V1、V2为(wei)(wei)互补工作，电(dian)(dian)(dian)容(rong)C起隔(ge)(ge)离直流的作用，T1为(wei)(wei)高(gao)频、高(gao)磁(ci)率的磁(ci)环或磁(ci)罐(guan)。导通时隔(ge)(ge)离变压器上的电(dian)(dian)(dian)压为(wei)(wei)（1-D）Ui、关断时为(wei)(wei)DUi，若主功率管S可靠导通电(dian)(dian)(dian)压为(wei)(wei)12V，而隔(ge)(ge)离变压器原副边匝比N1/N2为(wei)(wei)12/［（1-D）Ui］。为(wei)(wei)保证导通期间GS电(dian)(dian)(dian)压稳定C值可稍取(qu)大些(xie)。该电(dian)(dian)(dian)路(lu)具有(you)以(yi)下优(you)点：
①电路结构简单可(ke)靠(kao)，具有(you)电气隔离作用。当脉宽变(bian)化(hua)时，驱动的关(guan)断能力不会随着变(bian)化(hua)。
②该电(dian)路只需一个(ge)电(dian)源(yuan)，即(ji)为单电(dian)源(yuan)工作。隔直电(dian)容C的(de)作用可以在关(guan)断所驱动(dong)的(de)管子时(shi)提供一个(ge)负(fu)压，从而加速了功率管的(de)关(guan)断，且有较高的(de)抗干扰能力。
但该(gai)(gai)电路存在的(de)一个较大(da)缺(que)点是输出(chu)电压(ya)(ya)的(de)幅值(zhi)会随着占(zhan)空(kong)比(bi)(bi)的(de)变(bian)(bian)化而变(bian)(bian)化。当D较小(xiao)(xiao)时，负向电压(ya)(ya)小(xiao)(xiao)，该(gai)(gai)电路的(de)抗干扰性变(bian)(bian)差，且正(zheng)向电压(ya)(ya)较高(gao)，应该(gai)(gai)注意(yi)使其(qi)幅值(zhi)不超(chao)过(guo)MOSFET栅(zha)极(ji)的(de)允许电压(ya)(ya)。当D大(da)于(yu)0.5时驱动电压(ya)(ya)正(zheng)向电压(ya)(ya)小(xiao)(xiao)于(yu)其(qi)负向电压(ya)(ya)，此时应该(gai)(gai)注意(yi)使其(qi)负电压(ya)(ya)值(zhi)不超(chao)过(guo)MOAFET栅(zha)极(ji)允许电压(ya)(ya)。所以该(gai)(gai)电路比(bi)(bi)较适用于(yu)占(zhan)空(kong)比(bi)(bi)固定或占(zhan)空(kong)比(bi)(bi)变(bian)(bian)化范围(wei)不大(da)以及占(zhan)空(kong)比(bi)(bi)小(xiao)(xiao)于(yu)0.5的(de)场合。
电路(lu)构成如图(tu)11所(suo)示。其中UC3724用来(lai)产生高频(pin)(pin)(pin)载(zai)波信号，载(zai)波频(pin)(pin)(pin)率由电容CT和(he)电阻RT决定。一(yi)般载(zai)波频(pin)(pin)(pin)率小于600kHz，4脚和(he)6脚两端产生高频(pin)(pin)(pin)调制(zhi)波，经(jing)高频(pin)(pin)(pin)小磁(ci)环变压器(qi)隔(ge)离后(hou)送到(dao)UC3725芯(xin)片7、8两脚经(jing)UC3725进行(xing)调制(zhi)后(hou)得(de)到(dao)驱(qu)动(dong)信号，UC3725内部有一(yi)肖特(te)基整流(liu)桥同时将7、8脚的(de)高频(pin)(pin)(pin)调制(zhi)波整流(liu)成一(yi)直流(liu)电压供驱(qu)动(dong)所(suo)需(xu)功率。一(yi)般来(lai)说载(zai)波频(pin)(pin)(pin)率越高驱(qu)动(dong)延(yan)时越小，但(dan)太(tai)高抗干扰变差;隔(ge)离变压器(qi)磁(ci)化(hua)电感(gan)越大磁(ci)化(hua)电流(liu)越小，UC3724发热越少，但(dan)太(tai)大使(shi)匝数增多导致寄生参数影(ying)响变大，同样会使(shi)抗干扰能力(li)降(jiang)低(di)。
根据实(shi)验数据得出：
对(dui)于(yu)开(kai)关(guan)频(pin)率(lv)小(xiao)于(yu)100kHz的(de)信(xin)号(hao)一般取(qu)（400～500）kHz载波(bo)频(pin)率(lv)较(jiao)好，变压器选(xuan)用较(jiao)高(gao)磁(ci)导如5K、7K等(deng)高(gao)频(pin)环(huan)形磁(ci)芯(xin)，其原(yuan)边磁(ci)化(hua)电(dian)(dian)感(gan)小(xiao)于(yu)约1毫亨左(zuo)右为好。这种驱动(dong)电(dian)(dian)路(lu)仅适(shi)合(he)(he)于(yu)信(xin)号(hao)频(pin)率(lv)小(xiao)于(yu)100kHz的(de)场(chang)合(he)(he)，因信(xin)号(hao)频(pin)率(lv)相对(dui)载波(bo)频(pin)率(lv)太高(gao)的(de)话，相对(dui)延时太多，且所需驱动(dong)功率(lv)增大，UC3724和UC3725芯(xin)片发(fa)热温升较(jiao)高(gao)，故100kHz以(yi)上开(kai)关(guan)频(pin)率(lv)仅对(dui)较(jiao)小(xiao)极电(dian)(dian)容(rong)的(de)MOSFET才可以(yi)。对(dui)于(yu)1kVA左(zuo)右开(kai)关(guan)频(pin)率(lv)小(xiao)于(yu)100kHz的(de)场(chang)合(he)(he)，它是(shi)一种良好的(de)驱动(dong)电(dian)(dian)路(lu)。该电(dian)(dian)路(lu)具有以(yi)下特点(dian)：单电(dian)(dian)源工作，控制(zhi)信(xin)号(hao)与驱动(dong)实(shi)现(xian)隔离(li)，结构简(jian)单尺寸较(jiao)小(xiao)，尤其适(shi)用于(yu)占(zhan)空比变化(hua)不确定或信(xin)号(hao)频(pin)率(lv)也变化(hua)的(de)场(chang)合(he)(he)。
