光耦合器的缺點是要使用發光二極管(LED)

，其光強度會隨著時間推移和溫度變化而降低，這就會帶來設計和可靠性問題。新型且更魯棒的數字隔離器不使用LED，xiaochulekekaoxingwenti，gaishanlejueyuannengli，keyuguangouheqixiangpimei。zhezhongshuzigeliqideyoushishiduigaoyashunbiandekangraodugengqiang
，nenggougenghaodimanzudianjikongzhiyingyongdeyaoqiu。benwenjiangxiangxishuomingcileixinxingshuzigeliqidegongzuoyuanli，yijizaishangshuyingyongzhongqixianjindegongnengruheshengguoguangouheqi。

 

應用

 

根據應用的性能和功率水平，以及具體的控製和隔離方案
，電機驅動有各種各樣的係統設計。圖1suoshiweinibianqihuodiduandianjiqudongqichangyongdegelitongxinkuangtu。zaigaixitongzhong，kongzhiqidianweiyugonglvjixiangtong
，tongxinjiekoubeigeli，yinweizhetongchangshiyigejiaodisuduqiejiaojiandandejiekou。zaicileixitongzhong，gonglvnibianqikenengjuyoudiduanzhajiqudongqi
，zhexiequdongqibuxuyaogeli
，yinweiqiyudianjikongzhimokuaigongxiangtongyijiedi。gaoduanqudongqikeyigeli
，danyekeyishiyongdianpingzhuanhuanzhileidejishu，youqishidanggonglvnibianqidianyabushitaigaoshi。zaicikuangtuzhong
，dianjikongzhiqibushiyonggeli，zhijieliandaonibianqifankui。danggonglvshuipingjiaogaoshi，shiyongzhezhongjiagouhuiyoujuxianxing。kaiguanxinhaozaidianjishangchanshengdeewaizaoshengkenenghuiyanmeiyonglaijiancedianjidianliudefankuixinhao，jinerkenengyinqidianjishikong。

 

對於較高性能驅動
，例如工業電機和火車牽引電機中使用的大型多相驅動
，將會需要隔離控製和通信
，如圖2suoshi。zaicixitongkuangtuzhong
，chuyukangzaohetigaotongxinsududeyuanyin
，kongzhihetongxinjunweiyugelizhadeanquance。yinweidianjikongzhimokuaiweiyugelizhadeanquance，suoyiquanbuzhajiqudongqidouxuyaogeli。tedinggelidianyaheanquanyaoqiuyoujutijiagouhegelizhaweizhijueding。zaikuangtuzhong

，nibianqifankuiyonglaibangzhukongzhidianjiqudong
，shidianjikongzhizuizhongyaodefangmianzhiyi。rutusuoshi，nibianqifankuilianjiedaosanxiangjiaoliudianjideliangxiangzhongdedianliuceliangjiedianiV和iW。在zai隔ge離li控kong製zhi和he通tong信xin係xi統tong圖tu中zhong，逆ni變bian器qi反fan饋kui必bi須xu跨kua隔ge離li柵zha連lian接jie，故gu而er這zhe裏li也ye需xu要yao隔ge離li。在zai許xu多duo高gao功gong率lv電dian機ji應ying用yong中zhong，架jia構gou會hui要yao求qiu對dui三san相xiang電dian機ji的de高gao電dian壓ya進jin行xing增zeng強qiang隔ge離li，防fang止zhi用yong戶hu接jie觸chu到dao高gao電dian壓ya。此ci類lei增zeng強qiang隔ge離li應ying用yong具ju有you極ji大da的de隔ge離li電dian壓ya要yao求qiu
，可ke能neng需xu要yao隔ge離li器qi增zeng大da內nei部bu絕jue緣yuan厚hou度du（取決於材料）。

 

絕緣

 

隔離器的絕緣能力是指其在工作壽命中耐受高壓的能力。在相同的環境條件、dianyashunbianhedianyaboxingxia
，butongleixingdegelicailiaojuyoubutongdejueyuannengli。guangouheqiyouyujueyuancenghou，naiyanengliqiang，bingqiejuyoushushiniandexianchangshiyonglishi，chengweiyejieguanyongdejingdiangaoyageliqi。guangouheqishiyongmosuliaozuoweijueyuanjiezhi
，suliaochengxinggongyikenenghuizaijueyuancengzhongchanshengkongxi，zhehuizaochengbufenfangdianbingyinqijueyuanshixiao。youyuzhegeyuanyin
，renzhengjigouduijueyuangaoyaceshideyaoqiuhuibaokuobufenfangdianceshi。yuguangouheqibutong
，shuzigeliqiliyongneibujueyuancengzuoweiyuanbiangelizha，zhexiejueyuancengshizaijiedingmingqueqiegaodushoukongdebandaotizhizaogongyizhongshengchande。zhejiuxiaochulejueyuanzhongdekongxi，jueyuanjiegoubiandejiandandeduo，erqiegengweilubang。

 

數字隔離器不使用LED，不存在LED可ke靠kao性xing問wen題ti。隨sui著zhe工gong藝yi改gai進jin，絕jue緣yuan層ceng厚hou度du和he組zu成cheng越yue來lai越yue優you化hua，數shu字zi隔ge離li器qi也ye就jiu更geng加jia魯lu棒bang。某mou些xie數shu字zi隔ge離li器qi使shi用yong薄bo層ceng二er氧yang化hua矽gui來lai產chan生sheng高gao介jie電dian強qiang度du絕jue緣yuan，這zhe已yi廣guang泛fan用yong作zuo半ban導dao體ti芯xin片pian上shang的de絕jue緣yuan體ti。二er氧yang化hua矽gui絕jue緣yuan的de缺que點dian是shi它ta與yuIC構成一個整體，IC受(shou)損(sun)時(shi)，隔(ge)離(li)也(ye)可(ke)能(neng)受(shou)損(sun)。使(shi)用(yong)聚(ju)酰(xian)亞(ya)胺(an)絕(jue)緣(yuan)可(ke)克(ke)服(fu)二(er)氧(yang)化(hua)矽(gui)的(de)這(zhe)種(zhong)限(xian)製(zhi)，聚(ju)酰(xian)亞(ya)胺(an)半(ban)導(dao)體(ti)工(gong)藝(yi)已(yi)使(shi)用(yong)數(shu)十(shi)年(nian)，可(ke)幫(bang)助(zhu)實(shi)現(xian)強(qiang)健(jian)可(ke)靠(kao)的(de)集(ji)成(cheng)電(dian)路(lu)。聚(ju)酰(xian)亞(ya)胺(an)內(nei)部(bu)絕(jue)緣(yuan)屬(shu)於(yu)後(hou)期(qi)處(chu)理(li)，具(ju)有(you)獨(du)立(li)的(de)完(wan)整(zheng)性(xing)。如(ru)果(guo)ICshousun，dulidejuxianyaanjueyuanrenghuiwanhaowusun。fenduocengzhizaoshi，juxianyaankeyongzuodianjiqudongyingyongkenengxuyaodezengqiangjueyuan。shiyongshuzigeliqidegongchengshixuyaozhizaoshangtigongquanshoumingshuju，yizhengmingqijiandeshijian、溫度、濕度和電壓性能能夠應對取代光耦合器的挑戰。

 

 

Input Rectifier輸入整流器AC Line交流線路Power Inverter功率逆變器AC Motor交流電機Gate Drive柵極驅動Inverter Feedback逆變器反饋PWM TimerPWM定時器Motor Control (Algorithms and Drivers)電機控製（算法和驅動器）Position Feedback位置反饋Isolated Power隔離電源SELV PowerSELV電源Safety Isolation安全隔離Safety Earth安全接地System and Communications (RTOS, Protocols, and Stacks)係統和通信（RTOS、協議和堆棧）Command and Network命令和網絡圖1.隔離通信電機控製框圖

 

 

Input Rectifier輸入整流器AC Line交流線路Power Inverter功率逆變器AC Motor交流電機Isolated Power隔離電源SELV PowerSELV電源Gate Drive柵極驅動Inverter Feedback逆變器反饋Safety Isolation安全隔離PWM TimerPWM定時器Motor Control (Algorithms and Drivers)電機控製（算法和驅動器）Position Feedback位置反饋Safety Earth安全接地System and Communications (RTOS, Protocols, and Stacks)係統和通信（RTOS
、協議和堆棧）Command and Network命令和網絡圖2.隔離控製和通信電機控製框圖

 

環境

 

dianjikongzhiyingyongdehuanjingtiaojiankenengbaokuojiduanwenduheshidu。yiliecheqianyindianjiweilikeyishuomingqizhongdeyixiejiduanqingkuang。jiashejichefadongjizaihanlengdedongriliqianyinzheyichangchuanmanzaichexiangzaishanqutieguishangxingshi。huanjingwendukenengdiyu−40°C
，dianjibaoluzaiyanhandeshiwaikongqizhong
，zheshiliechejinruyitiaochangchangdesuidao
，youyufadongjichanshengdereliang

，dianjihefadongjizhouweidewendukenenghuixunsushangsheng。dianjijiqijueyuantibixunengzaizhezhongjiduanwenduxiagongzuo
，erqienengkefushijiantuiyihewendubianhuadailaidebuliyingxiang。zhongsuozhouzhi，guangouheqidexingnenghuisuizhewendubianhuaerjiangdi
，qineibuLEDchanshengdeguanglianghejianceqihuodedeshuchuxinhaohuisuizheshijiantuiyihewendubianhuaerjianshao。yongzuoduotongdaogeliqishi，guangouheqidetongdaojianshipeihuisuizheshijiantuiyierzengda。xiangbizhixia，shuzigeliqibuyilaiyujianceneibuLED的信號，而是利用半導體IC工藝製造可靠的電路，由此跨越隔離柵收發數字信號。

 

數字隔離器

 

數字隔離器結構和技術如圖3中zhong的de示shi例li框kuang圖tu所suo示shi。根gen據ju具ju體ti架jia構gou，數shu字zi隔ge離li器qi響xiang應ying輸shu入ru邏luo輯ji電dian平ping或huo輸shu入ru脈mai衝chong。可ke使shi用yong不bu同tong方fang法fa編bian碼ma和he解jie碼ma信xin號hao
，以yi便bian跨kua越yue隔ge離li柵zha收shou發fa邏luo輯ji數shu據ju。脈mai衝chong編bian碼ma技ji術shu如ru圖tu4所示
，其優點是當編碼和解碼脈衝之間的時間較長時，低數據速率下消耗的電源電流較低。載波技術如圖5所示
，即所謂開關鍵控(OOK)，其在低數據速率時消耗的電流多於脈衝編碼方法。在較高數據速率（10 Mbps以上）時
，OOK方法消耗的電源電流少於脈衝編碼技術。OOK技術相比於脈衝編碼技術的優勢在於，OOK技術的邏輯更簡單
，故而傳播延遲更低，最大數據速率更高。脈衝編碼技術的缺點是：如ru果guo外wai部bu噪zao聲sheng擾rao亂luan了le輸shu出chu數shu據ju

，這zhe種zhong狀zhuang況kuang會hui持chi續xu一yi微wei秒miao或huo更geng長chang時shi間jian
，直zhi至zhi內nei部bu糾jiu錯cuo邏luo輯ji糾jiu正zheng錯cuo誤wu或huo出chu現xian新xin的de數shu據ju沿yan。對dui於yu電dian機ji控kong製zhi應ying用yong，這zhe可ke能neng意yi味wei著zhe柵zha極ji驅qu動dong器qi開kai關guan或huo反fan饋kui控kong製zhi信xin號hao會hui在zai一yi定ding時shi間jian內nei失shi控kong，該gai時shi間jian足zu夠gou長chang
，以yi至zhi於yu開kai關guan電dian路lu或huo電dian機ji驅qu動dong可ke能neng受shou損sun。利li用yongOOK技ji術shu，如ru果guo電dian壓ya瞬shun變bian擾rao亂luan數shu據ju
，這zhe種zhong擾rao亂luan隻zhi會hui在zai噪zao聲sheng出chu現xian的de短duan暫zan時shi間jian內nei幹gan擾rao數shu據ju輸shu出chu，因yin為wei信xin號hao是shi被bei持chi久jiu不bu變bian地di驅qu動dong的de。此ci外wai
，由you於yu架jia構gou較jiao簡jian單dan
，OOK數字隔離器可以設計得非常魯棒，不懼電機控製應用中的電氣噪聲。

 

圖3.數字隔離器框圖

 

圖4.數字隔離器：脈衝編碼數據架構

 

圖5.數字隔離器：開關鍵控數據架構

 

抗擾度

 

在zai大da型xing電dian機ji應ying用yong中zhong
，當dang電dian機ji控kong製zhi開kai關guan電dian路lu在zai橋qiao電dian壓ya中zhong產chan生sheng步bu進jin變bian化hua時shi

，隔ge離li柵zha上shang的de共gong模mo電dian壓ya變bian化hua可ke能neng會hui產chan生sheng噪zao聲sheng。隔ge離li器qi耐nai受shou此ci高gao壓ya擺bai率lv電dian壓ya瞬shun變bian且qie隔ge離li器qi輸shu出chu不bu受shou幹gan擾rao的de能neng力li，便bian是shi共gong模mo瞬shun變bian抗kang擾rao度du(CMTI)。光耦合器的CMTI可ke能neng不bu是shi很hen高gao，因yin為wei其qi接jie收shou元yuan件jian非fei常chang敏min感gan
，易yi受shou容rong性xing耦ou合he效xiao應ying影ying響xiang。光guang耦ou合he器qi的de容rong性xing耦ou合he是shi一yi種zhong單dan端duan結jie構gou
，信xin號hao和he噪zao聲sheng隻zhi有you一yi條tiao路lu徑jing跨kua越yue隔ge離li柵zha。這zhe就jiu要yao求qiu信xin號hao頻pin率lv必bi須xu遠yuan高gao於yu預yu期qi的de噪zao聲sheng頻pin率lv，以yi便bian隔ge離li柵zha電dian容rong對dui信xin號hao提ti供gong低di阻zu抗kang，而er對dui噪zao聲sheng提ti供gong高gao阻zu抗kang。當dang電dian機ji控kong製zhi信xin號hao頻pin率lv較jiao低di時shi（通常低於16 kHz），共模瞬變的高頻成分會高於信號頻率
，其幅度可能足以擾亂光耦合器輸出。考察圖6所(suo)示(shi)的(de)基(ji)於(yu)變(bian)壓(ya)器(qi)的(de)數(shu)字(zi)隔(ge)離(li)器(qi)
，變(bian)壓(ya)器(qi)有(you)一(yi)個(ge)差(cha)分(fen)輸(shu)入(ru)結(jie)構(gou)，其(qi)為(wei)輸(shu)入(ru)信(xin)號(hao)和(he)噪(zao)聲(sheng)提(ti)供(gong)了(le)不(bu)同(tong)的(de)傳(chuan)輸(shu)路(lu)徑(jing)，因(yin)此(ci)必(bi)然(ran)具(ju)有(you)更(geng)大(da)的(de)共(gong)模(mo)噪(zao)聲(sheng)抗(kang)擾(rao)度(du)
，而(er)且(qie)不(bu)存(cun)在(zai)光(guang)耦(ou)合(he)器(qi)要(yao)求(qiu)信(xin)號(hao)頻(pin)率(lv)高(gao)於(yu)噪(zao)聲(sheng)頻(pin)率(lv)的(de)限(xian)製(zhi)。改(gai)進(jin)的(de)電(dian)氣(qi)噪(zao)聲(sheng)抗(kang)擾(rao)度(du)使(shi)得(de)器(qi)件(jian)能(neng)在(zai)高(gao)噪(zao)聲(sheng)環(huan)境(jing)下(xia)可(ke)靠(kao)地(di)工(gong)作(zuo)。圖(tu)7顯示了電機控製開關期間共模瞬變的高橋電壓和快速dV/dt的開關噪聲
，數字隔離器必須能抵抗這種幹擾。示波器波形顯示，對於開關鍵控架構的變壓器耦合數字隔離器
，要擾亂數據，從GND2到GND1的快速共模瞬變(CMT)須高於150 kV/μs，而且隔離器輸出受擾亂的時間非常之短，隻有區區3 ns。實現超高CMTI的關鍵在於發送器必須不斷產生差分載波信號
，並且接收器必須具有很高的輸入共模變化抗擾度。

 

圖6.變壓器耦合數字隔離器框圖

 

圖7.電機控製應用中的共模瞬變dV/dt

 

浪湧保護能力

 

電機控製應用中可能出現高壓瞬變或浪湧，此類浪湧的峰值可能超過10,000 V
，而上升時間僅有1.2 μs。guangouheqitongguohenhoudeneibujueyuancenglaimanzulangyongbaohuyaoqiu。duiyucaiyongeryanghuaguideshuzigeliqi，weishineibuyinglibuzhiyinqiliefeng，kezhichengdejueyuanhoudushiyouxianzhide。caiyongjuxianyaandeshuzigeliqijueyuankeyigaishanlangyongbaohunengli，fenweiduocengzhizaoqiezonghouduwei30 μm的聚酰亞胺絕緣業已證明非常有效。在圖8中，30 μm聚酰亞胺的浪湧測試結果表明它非常魯棒，可以耐受±20 kV峰值。

 

圖8.聚酰亞胺絕緣浪湧測試結果

 

總結

 

表1中的隔離器對比顯示了在惡劣的電機應用環境中，數字隔離器的性能優於光耦合器。對於擾亂電機控製的電壓瞬變，光耦合器的抗擾度(CMTI)最小值隻有10 kV/μs，而數字隔離器的抗擾度要高出許多倍。光耦合器及其LED老化問題使得其工作溫度一般以85°C為限

，但數字隔離器的工作溫度可以達到125ºC。本文說明了此類數字隔離器的工作原理，以及在電機控製應用中其先進的功能如何勝過光耦合器。

 

表1.電機控製應用的隔離器比較

 

 

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