Kuliviki siqhubekela phambili ngendatshana yeviki ephelileyo.

1.2 Ama-Electrolytic capacitors

I-dielectric esetshenziswa kuma-electrolytic capacitor i-aluminium oxide eyakhiwe ukugqwala kwe-aluminium, ene-dielectric constant engu-8 kuya ku-8.5 namandla asebenzayo e-dielectric cishe angu-0.07V/A (1µm=10000A).Nokho, akunakwenzeka ukufeza ukushuba okunjalo.Ugqinsi longqimba lwe-aluminium lunciphisa isici somthamo (umthamo othize) wama-electrolytic capacitor ngoba ucwecwe lwe-aluminium kufanele luqoshwe ukwenza ifilimu ye-aluminium oxide ukuze kutholwe izici ezinhle zokugcina amandla, futhi indawo engaphezulu izokwakha izindawo eziningi ezingalingani.Ngakolunye uhlangothi, ukumelana ne-electrolyte kungu-150Ωcm ku-voltage ephansi kanye no-5kΩcm ku-voltage ephezulu (500V).Ukumelana okuphezulu kwe-electrolyte kukhawulela i-RMS yamanje i-electrolytic capacitor engakwazi ukumelana nayo, ngokuvamile iye ku-20mA/µF.

Ngenxa yalezi zizathu ama-electrolytic capacitor aklanyelwe amandla kagesi aphezulu angu-450V ejwayelekile (abanye abakhiqizi ngabanye baklama i-600V).Ngakho-ke, ukuze uthole ama-voltage aphezulu kuyadingeka ukuwafinyelela ngokuxhuma ama-capacitor ochungechungeni.Kodwa-ke, ngenxa yomehluko wokumelana nokufakwa kwe-insulation ye-electrolytic capacitor ngayinye, i-resistor kufanele ixhunywe ku-capacitor ngayinye ukuze kulinganiswe i-voltage yochungechunge ngalunye lwe-capacitor exhunyiwe.Ngaphezu kwalokho, ama-electrolytic capacitor angamadivayisi ahlukanisiwe, futhi lapho i-voltage ehlanekezayo esetshenzisiwe idlula izikhathi ezi-1.5 Un, ukusabela kwe-electrochemic kwenzeka.Lapho i-voltage ehlanekezayo esetshenzisiwe isinde ngokwanele, i-capacitor izochitheka.Ukuze ugweme lesi simo, i-diode kufanele ixhunywe eduze kwe-capacitor ngayinye lapho isetshenziswa.Ngaphandle kwalokho, ukumelana nokuphakama kwe-voltage yama-electrolytic capacitor ngokuvamile izikhathi ezingu-1.15 nge-Un, kanti amahle angafinyelela izikhathi ezingu-1.2 nge-Un.Ngakho-ke, abaklami akufanele bacabangele i-voltage yokusebenza engashintshi kuphela kodwa futhi ne-voltage ekhuphukayo lapho bewasebenzisa.Kafushane, ithebula elilandelayo lokuqhathanisa phakathi kwama-capacitor wefilimu nama-electrolytic capacitors lingadonswa, bheka i-Fig.1.

2. Ukuhlaziywa Kwezicelo

Ama-capacitor e-DC-Link njengezihlungi adinga imiklamo ephezulu yamanje kanye nomthamo ophezulu.Isibonelo uhlelo oluyinhloko lokushayela imoto yemoto yamandla entsha njengoba kushiwo ku-Fig.3.Kulolu hlelo lokusebenza i-capacitor idlala indima yokuhlukanisa futhi isifunda sibonisa ukusebenza kwamanje okuphezulu.Ifilimu i-DC-Link capacitor inenzuzo yokukwazi ukumelana nemisinga emikhulu yokusebenza (Irms).Thatha amapharamitha emoto yamandla amasha angu-50~60kW njengesibonelo, amapharamitha ami kanje: i-voltage yokusebenza engu-330 Vdc, i-ripple voltage 10Vrms, i-ripple current 150Arms@10KHz.

Bese umthamo omncane kagesi ubalwa njengalokhu:

Lokhu kulula ukukusebenzisa ekwakhiweni kwe-film capacitor.Uma kucatshangwa ukuthi ama-electrolytic capacitor asetshenziswa, uma kucatshangelwa u-20mA/μF, amandla amancane ama-electrolytic capacitor abalwa ukuze ahlangabezane nemingcele engenhla kanje:

Lokhu kudinga ama-electrolytic capacitor amaningi ngokuhambisana axhunywe ukuze kutholwe leli khono.

Kuzinhlelo ze-over-voltage, ezifana nesitimela esilula, ibhasi likagesi, indlela ehamba ngaphansi, njll. Ngokucabangela ukuthi la mandla axhunywe ku-locomotive pantograph nge-pantograph, ukuthintana phakathi kwe-pantograph ne-pantograph kwenzeka ngezikhathi ezithile phakathi nohambo lwezokuthutha.Uma bobabili bengaxhumani, ukunikezwa kwamandla kusekelwa i-DC-L inki capacitor, futhi lapho othintana naye ebuyiselwa, i-over-voltage iyakhiqizwa.Icala elibi kakhulu ukukhishwa okuphelele kwe-DC-Link capacitor lapho inqanyulwa, lapho i-voltage yokukhipha ilingana ne-voltage ye-pantograph, futhi lapho ukuthintana kubuyiselwa, umphumela we-over-voltage cishe izikhathi ezimbili ezikalwe ngokusebenza kwe-Un.Kuma-capacitor wefilimu i-DC-Link capacitor ingaphathwa ngaphandle kokucatshangelwa okwengeziwe.Uma kusetshenziswa ama-electrolytic capacitor, i-over-voltage ingu-1.2Un.Thatha i-Shanghai metro njengesibonelo.I-Un=1500Vdc, ukuze i-electrolytic capacitor icabangele i-voltage yile:

Bese kuthi ama-capacitor ayisithupha e-450V azoxhunywa ngochungechunge.Uma idizayini ye-filimi capacitor isetshenziswa ku-600Vdc kuya ku-2000Vdc noma ngisho ne-3000Vdc ifinyelelwa kalula.Ukwengeza, amandla endabeni yokukhipha ngokugcwele i-capacitor enza ukukhishwa kwesifunda esifushane phakathi kwama-electrode amabili, okukhiqiza amandla amakhulu okungena nge-DC-Link capacitor, evame ukuhluka kuma-electrolytic capacitor ukuze ahlangabezane nezidingo.

Ukwengeza, uma kuqhathaniswa nama-electrolytic capacitor DC-Link film capacitor ingaklanywa ukuzuza i-ESR ephansi kakhulu (imvamisa ibe ngaphansi kuka-10mΩ, ngisho nangaphansi kuka-<1mΩ) kanye ne-self-inductance LS (imvamisa ibe ngaphansi kuka-100nH, futhi kwezinye izimo ngaphansi kuka-10 noma 20nH) .Lokhu kuvumela i-DC-Link film capacitor ukuthi ifakwe ngqo kumojula ye-IGBT uma isetshenziswa, okuvumela ibha yebhasi ukuthi ihlanganiswe ne-DC-Link film capacitor, ngaleyo ndlela kuqedwe isidingo se-IGBT absorber capacitor ezinikele lapho usebenzisa ama-capacitor amafilimu, ukonga. umklami inani elibalulekile lemali.Fig.2.futhi oku-3 kubonisa ukucaciswa kobuchwepheshe kweminye imikhiqizo ye-C3A ne-C3B.

3. Isiphetho

Ezinsukwini zokuqala, ama-DC-Link capacitor ayengama-electrolytic capacitor ngenxa yokucatshangelwa kwezindleko nosayizi.

Kodwa-ke, ama-electrolytic capacitors athintwa amandla kagesi kanye namandla okumelana namanje (i-ESR ephakeme kakhulu uma iqhathaniswa nama-capacitor efilimu), ngakho-ke kuyadingeka ukuxhuma ama-electrolytic capacitor amaningana ochungechungeni nokuhambisana ukuze kutholwe umthamo omkhulu futhi kuhlangatshezwane nezidingo zokusetshenziswa kwamandla kagesi aphezulu.Ngaphezu kwalokho, kucatshangelwa ukuvuthwa kwezinto ezibonakalayo ze-electrolyte, kufanele kushintshwe njalo.Ukusetshenziswa kwamandla amasha ngokuvamile kudinga impilo yomkhiqizo yeminyaka eyi-15, ngakho-ke kufanele kushintshwe izikhathi ezi-2 kuya kwezi-3 ngalesi sikhathi.Ngakho-ke, kunezindleko ezinkulu kanye nokuphazamiseka emsebenzini emva kokuthengisa kwawo wonke umshini.Ngokuthuthukiswa kobuchwepheshe bokuhlanganisa i-metalization kanye nobuchwepheshe be-film capacitor, kube nokwenzeka ukukhiqiza ama-capacitor okuhlunga e-DC anamandla kagesi ukusuka ku-450V ukuya ku-1200V noma ngaphezulu ngefilimu ye-OPP ezacile kakhulu (i-thinnest 2.7µm, ngisho no-2.4µm) kusetshenziswa ubuchwepheshe bokuphepha befilimu bokushisa.Ngakolunye uhlangothi, ukuhlanganiswa kwe-DC-Link capacitor nebha yebhasi kwenza idizayini yemojula ye-inverter ihlangane kakhudlwana futhi kunciphisa kakhulu inductance elahlekile yesekethe ukuze kwandiswe isekethe.