電動機驅動技術的發展與起重機勢能的利用
毋庸置疑,起重機械的用途決定了它在工作期間存在著大量的勢能和電能的相互轉換過程。直至20世紀90niandaizhongqi,guoneiqizhongjiqudongjishurengzhuyaoshiyoujitiaosujishu。gaijishucaiyonghuahuanshijiaoliudiandongji,tongguogaibianchuanjiezaidiandongjizhuanzihuiluzhongdewaijiedianzu,yigaibiandiandongjidelijutexing,congerdadaodiandongjiqidonghetiaosudemude,zhezhongjishudexingnengjiaocha。dangshidewujitiaosujishuzhuyaoshiyongzhiliudiandongji,tongguokekongguitiaozhengdiandongjidianshudedianyashixianwujitiaosu。houlaiyouchuxianlejiaoliuhuahuandiandongjidewujitiaosujishu,tashiyizhongjiangdiandongjidianshutiaoyahegaibiandiandongjilijutexingxiangjie合的方法。不管是直流電動機還是交流電動機調速裝置,均可以四象限運行,電流可雙向流動,即從電源到電動機,從電動機到電源,因而,勢能和電能的相互轉換利用不存在問題。但這時的問題主要是功率因數低,電磁諧波較大。由於存在大量的無功電流和諧波電流,在供電裝置側的額外損耗較為嚴重。
20世紀90年代後期,交流變頻器技術的發展日趨成熟。交流變頻調速的對象是鼠籠式異步電動機,其成本低、維護便利、tiaosuxingnengyouyue。tongshi,bianpinqizishenketigongwugongdianliu,juyouhengaodegonglvyinshu,duidianwangdechongjihenxiao,suoyidaliangdeqizhongjixiecaiyonglejiaoliubianpintiaosujishu。
使用交流變頻調速技術限製了勢能到電能的轉換利用。這是由當時變頻技術自身的特點所決定的:變頻器采用二極管整流,整流源輸出的直流電經電容濾波後再經過三相IGBT橋(qiao)路(lu)逆(ni)變(bian)為(wei)三(san)相(xiang)頻(pin)率(lv)可(ke)變(bian)的(de)交(jiao)流(liu)電(dian)供(gong)往(wang)電(dian)動(dong)機(ji),當(dang)電(dian)動(dong)機(ji)工(gong)作(zuo)在(zai)發(fa)電(dian)狀(zhuang)態(tai)時(shi),由(you)勢(shi)能(neng)轉(zhuan)換(huan)成(cheng)的(de)電(dian)能(neng)隻(zhi)能(neng)回(hui)饋(kui)到(dao)直(zhi)流(liu)側(ce)的(de)電(dian)容(rong),而(er)不(bu)能(neng)通(tong)過(guo)二(er)極(ji)管(guan)整(zheng)流(liu)電(dian)路(lu)回(hui)饋(kui)到(dao)電(dian)網(wang),因(yin)此(ci),剩(sheng)餘(yu)的(de)電(dian)能(neng)隻(zhi)能(neng)通(tong)過(guo)直(zhi)流(liu)側(ce)的(de)直(zhi)流(liu)斬(zhan)波(bo)器(qi)流(liu)向(xiang)外(wai)接(jie)電(dian)阻(zu),轉(zhuan)變(bian)成(cheng)熱(re)能(neng)而(er)消(xiao)耗(hao)掉(diao),以(yi)免(mian)電(dian)容(rong)充(chong)電(dian)過(guo)多(duo),造(zao)成(cheng)電(dian)壓(ya)過(guo)高(gao)而(er)損(sun)壞(huai)設(she)備(bei)。進(jin)入(ru)21世shi紀ji以yi後hou,國guo外wai的de許xu多duo電dian氣qi公gong司si在zai直zhi流liu電dian再zai次ci逆ni變bian回hui饋kui到dao電dian網wang的de技ji術shu方fang麵mian有you了le進jin一yi步bu發fa展zhan,並bing開kai始shi在zai國guo內nei應ying用yong。但dan是shi在zai我wo國guo進jin行xing這zhe些xie技ji術shu推tui廣guang的de國guo外wai公gong司si都dou是shi原yuan來lai在zai中zhong國guo進jin行xing變bian頻pin器qi產chan品pin推tui廣guang的de公gong司si,他ta們men將jiang電dian能neng回hui饋kui裝zhuang置zhi集ji成cheng在zai自zi已yi公gong司si生sheng產chan的de變bian頻pin器qi整zheng流liu源yuan內nei部bu,即ji:將直流整流和直流回饋電網的2個功能集成在一起,用同一套IGBT裝置完成電流的雙向流動。這種產品技術先進、性能優良,但其較高的售價限製了該產品和技術的推廣應用。
經(jing)過(guo)十(shi)幾(ji)年(nian)交(jiao)流(liu)變(bian)頻(pin)技(ji)術(shu)的(de)推(tui)廣(guang),國(guo)內(nei)已(yi)有(you)眾(zhong)多(duo)的(de)起(qi)重(zhong)機(ji)采(cai)用(yong)變(bian)頻(pin)驅(qu)動(dong)技(ji)術(shu),從(cong)而(er)使(shi)大(da)量(liang)的(de)勢(shi)能(neng)被(bei)轉(zhuan)換(huan)為(wei)熱(re)能(neng)而(er)浪(lang)費(fei)掉(diao)。如(ru)果(guo)能(neng)將(jiang)這(zhe)些(xie)勢(shi)能(neng)變(bian)成(cheng)電(dian)能(neng)並(bing)回(hui)收(shou)進(jin)供(gong)電(dian)電(dian)網(wang),對(dui)國(guo)家(jia)經(jing)濟(ji)的(de)貢(gong)獻(xian)是(shi)不(bu)可(ke)估(gu)量(liang)的(de)。據(ju)保(bao)守(shou)估(gu)算(suan),質(zhi)量(liang)為(wei)430t的重物每下降11TI,即可向電網回饋電能1kW·h。若以上海港集裝箱碼頭的貨櫃處理量估算,1台集裝箱場地起重機1年的勢能回收發電量可達6萬kW·h以上;若以1台應用於火力發電廠的生產能力為1000Wh的抓鬥卸船機為例,僅考慮空抓鬥下降的勢能,按照每年工作2200h計算,每年可向電網提供的電能也在6萬kW·h以上。
顯(xian)而(er)易(yi)見(jian),起(qi)重(zhong)機(ji)工(gong)作(zuo)過(guo)程(cheng)中(zhong)的(de)勢(shi)能(neng)是(shi)一(yi)種(zhong)對(dui)環(huan)境(jing)無(wu)任(ren)何(he)汙(wu)染(ran)的(de)綠(lv)色(se)能(neng)源(yuan),回(hui)收(shou)由(you)勢(shi)能(neng)轉(zhuan)換(huan)的(de)電(dian)能(neng)對(dui)未(wei)來(lai)社(she)會(hui)經(jing)濟(ji)的(de)發(fa)展(zhan)有(you)重(zhong)要(yao)意(yi)義(yi)。但(dan)如(ru)前(qian)所(suo)述(shu),目(mu)前(qian)國(guo)外(wai)公(gong)司(si)提(ti)供(gong)的(de)IGBTnenglianghuikuibianpinxitongjiagebufei,zaihenduogongchengxiangmuzhong,zuizhongyonghujunhuikaolvyicixingtouziguodawenti。yinci,dalituiguangqizhongjijienengjishu,chulejishubenshendezhangzhiwai,haibixukefuguogaodetouzichengbenwenti.
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