變頻器的核心它主要是通過高速電力電子開關來產生一定寬度和極性的PWM或SPWM控(kong)製(zhi)信(xin)號(hao)。這(zhe)種(zhong)具(ju)有(you)很(hen)陡(dou)邊(bian)沿(yan)的(de)脈(mai)衝(chong)信(xin)號(hao)會(hui)產(chan)生(sheng)很(hen)強(qiang)的(de)電(dian)磁(ci)輻(fu)射(she),尤(you)其(qi)是(shi)輸(shu)出(chu)電(dian)路(lu),它(ta)們(men)將(jiang)以(yi)各(ge)種(zhong)方(fang)式(shi)把(ba)自(zi)已(yi)的(de)能(neng)量(liang)傳(chuan)播(bo)出(chu)去(qu),幹(gan)攏(long)周(zhou)邊(bian)設(she)備(bei)的(de)正(zheng)常(chang)工(gong)作(zuo),嚴(yan)重(zhong)地(di)超(chao)出(chu)了(le)電(dian)磁(ci)兼(jian)客(ke)標(biao)準(zhun)的(de)極(ji)限(xian)值(zhi)要(yao)求(qiu)。因(yin)此(ci),變(bian)頻(pin)器(qi)生(sheng)產(chan)廠(chang)家(jia)為(wei)用(yong)戶(hu)製(zhi)造(zao)了(le)一(yi)些(xie)專(zhuan)用(yong)設(she)備(bei)來(lai)抑(yi)製(zhi)變(bian)頻(pin)器(qi)產(chan)生(sheng)的(de)電(dian)磁(ci)幹(gan)擾(rao),以(yi)達(da)到(dao)質(zhi)檢(jian)標(biao)準(zhun),確(que)保(bao)變(bian)頻(pin)器(qi)及(ji)其(qi)它(ta)設(she)備(bei)的(de)安(an)全(quan)運(yun)行(xing)。諧(xie)波(bo)的(de)傳(chuan)播(bo)途(tu)徑(jing)大(da)致(zhi)為(wei)兩(liang)種(zhong),一(yi)種(zhong)是(shi)傳(chuan)導(dao);另一種是輻射。解決傳導幹擾的辦法主要是在電路中把傳導的高頻電流濾掉或者隔離;解決輻射幹擾就是對輻射源或被幹擾的線路進行屏蔽。
變bian頻pin係xi統tong的de供gong電dian電dian源yuan與yu其qi他ta設she備bei的de供gong電dian電dian源yuan相xiang互hu獨du立li,或huo在zai變bian頻pin器qi和he其qi他ta用yong電dian設she備bei的de輸shu入ru側ce安an裝zhuang隔ge離li變bian壓ya器qi,切qie斷duan諧xie波bo電dian流liu。電dian動dong機ji和he變bian頻pin器qi之zhi間jian電dian纜lan應ying穿chuan鋼gang管guan敷fu設she或huo用yong鎧kai裝zhuang電dian纜lan,並bing與yu其qi他ta弱ruo電dian信xin號hao在zai不bu同tong的de電dian纜lan溝gou分fen別bie敷fu設she,避bi免mian輻fu射she幹gan擾rao。信xin號hao線xian采cai用yong屏ping蔽bi線xian,且qie布bu線xian時shi與yu變bian頻pin器qi主zhu回hui路lu控kong製zhi線xian錯cuo開kai一yi定ding距ju離li(至少20cm以上),qieduanfusheganrao。bianpinqishiyongzhuanyongjiedixian,qieyongcuduanxianjiedi,linjinqitadianqishebeidedixianbixuyubianpinqipeixianfenkai,shiyongduanxian。zheyangnengyouxiaoyizhidianliuxieboduilinjinshebeidefusheganrao。shiyongbianpinqishi,yinjiedibuzhengqueeryinqideganlongjiantishiyoufasheng,weicishouxianyaozaigainianshangfenqingshenmeshi“安全接地”和“電磁幹擾接地”,尤其是在高頻區域,由於“趨膚效應”在接頭處將呈現高阻狀態,造成接地不良,使係統對外幹擾信號增強,對外影響變得敏感。
在防止電磁幹擾接地時,需要實現低阻抗連接。具體操作時應注意以下兩點:在使用機殼作為公共地時,需要除淨連接點處的油漆或其它塗料,以確保低阻抗連接。不同接地點間盡可能使用短的扁平線連接在一起(因扁平線的高頻低阻特性較好),bingyaojingchangjianzhasuoyoudejiedidian,yifangzhituoluohuosongdongxianxiangfasheng。bianpinqianzhuangyukongzhiguinei,jinengpingbixiangwaifushenengliang,younengfangzhiwaijiedianciganraodejinru。jutishigongshiyingzhuyijike、電纜屏蔽層及電動機外殼三者應可靠連接在一起。
zengjiashurudiankangqi,yibanyingcaiyongwuyuandiankangqi,mudezaiyuzhiyunxutedingdepinlvxinhaotongguo,zuzhiganraoxinhaoyuan。bingbangzhuxishouzhongzaishebeitourushichanshengdelangyongdianyahezhudianyuandedianyajianfeng。2%阻(zu)抗(kang)進(jin)線(xian)電(dian)抗(kang)器(qi)通(tong)常(chang)已(yi)足(zu)以(yi)能(neng)夠(gou)吸(xi)收(shou)電(dian)壓(ya)峰(feng)值(zhi)並(bing)在(zai)多(duo)數(shu)應(ying)用(yong)情(qing)況(kuang)下(xia)能(neng)避(bi)免(mian)變(bian)頻(pin)器(qi)有(you)害(hai)的(de)停(ting)機(ji)。還(hai)能(neng)保(bao)護(hu)變(bian)頻(pin)器(qi)內(nei)部(bu)直(zhi)流(liu)回(hui)路(lu)電(dian)容(rong)器(qi)不(bu)至(zhi)於(yu)過(guo)熱(re)和(he)由(you)於(yu)吸(xi)收(shou)浪(lang)湧(yong)漏(lou)電(dian)壓(ya),而(er)減(jian)少(shao)壽(shou)命(ming),並(bing)且(qie)增(zeng)加(jia)電(dian)源(yuan)阻(zu)抗(kang)。4%zukangjinxiandiankangqizuishiyijiangdiyoubianpinqichanshengdexiebopinlvdianliu,hainengshiganlongxinhaobunengtongguodixianchuanboerbeifanshehuiganraoyuan。anzhuangshurudiankangqishiyingjinliangkaojinbianpinqi,bingyuqigongjiban。ruoliangzhejulichaoguobianpinqishiyongshuomingshuguidingdebiaozhun,yingyongbianpingxianlianjie。
輸出電抗器裝於變頻器的輸出端(U﹑V&W),以(yi)允(yun)許(xu)電(dian)機(ji)在(zai)長(chang)電(dian)纜(lan)的(de)情(qing)況(kuang)下(xia)運(yun)行(xing)。在(zai)變(bian)頻(pin)器(qi)輸(shu)出(chu)端(duan)串(chuan)接(jie)電(dian)抗(kang)器(qi),可(ke)以(yi)解(jie)決(jue)電(dian)機(ji)過(guo)熱(re)和(he)噪(zao)聲(sheng)汙(wu)染(ran)。采(cai)用(yong)了(le)輸(shu)出(chu)電(dian)抗(kang)器(qi),可(ke)省(sheng)去(qu)在(zai)變(bian)頻(pin)器(qi)與(yu)電(dian)機(ji)之(zhi)問(wen)的(de)屏(ping)蔽(bi)電(dian)纜(lan)。這(zhe)樣(yang)做(zuo)不(bu)僅(jin)降(jiang)低(di)了(le)成(cheng)本(ben),而(er)且(qie)能(neng)很(hen)好(hao)的(de)抑(yi)製(zhi)變(bian)頻(pin)器(qi)對(dui)外(wai)產(chan)生(sheng)的(de)幹(gan)擾(rao),這(zhe)是(shi)使(shi)用(yong)電(dian)抗(kang)器(qi)的(de)主(zhu)耍(shua)優(you)點(dian)。
輸出電抗器的電感補償可使電機電纜相-對-相和相-對-地的分布電容。由於電機電纜長度增加,電機電纜的總分布電容也隨時增加,該分布電容與變頻器輸出端的殘餘電壓峰值(由於變頻器輸出器件IGBT切換),導致電流峰值流回變頻器。這些電流峰值會引起變頻器有害的跳閘,安裝了輸出電抗器都可以避免。
電抗器被裝於變頻器的輸出端,以允許帶長電纜運行,電抗器補償了電纜中的分布電容。
其它措施:1)使用屏蔽電纜削弱電磁感應和靜電感應。2)在逆變電路直流側的正、負端到地線間跨接100n以下的電容器。此種方法特別適用幹7.5KW以下的用電設備。3)將控製線、信號線與電源線分開,通常距離應在200mm以上,如果控製線必須與電源線交叉,則應盡量使交叉角接近90度。
手機版|
關注公眾號|

下載手機APP

