A wannan makon za mu ci gaba da labarin makon da ya gabata.

1.2 Electrolytic capacitors

Dielectric amfani da electrolytic capacitors ne aluminum oxide kafa ta lalata aluminum, tare da dielectric akai-akai na 8 zuwa 8.5 da kuma aiki dielectric ƙarfi na game da 0.07V/A (1µm=10000A).Duk da haka, ba zai yiwu a cimma irin wannan kauri ba.Kauri na aluminum Layer yana rage ƙarfin ƙarfin (takamaiman capacitance) na masu ƙarfin lantarki saboda foil ɗin aluminum dole ne a tsara shi don samar da fim ɗin aluminum oxide don samun kyawawan halayen ajiyar makamashi, kuma farfajiyar za ta samar da wurare da yawa marasa daidaituwa.A daya hannun, da resistivity na electrolyte ne 150Ωcm ga low irin ƙarfin lantarki da 5kΩcm ga high ƙarfin lantarki (500V).Mafi girman juriya na electrolyte yana iyakance ƙarfin RMS na yanzu wanda ƙarfin lantarki zai iya jurewa, yawanci zuwa 20mA/µF.

Don waɗannan dalilai an tsara masu amfani da wutar lantarki don matsakaicin ƙarfin lantarki na 450V na hali (wasu masana'antun guda ɗaya suna ƙira don 600V).Saboda haka, domin samun mafi girma voltages ya zama dole a cimma su ta hanyar haɗa capacitors a cikin jerin.Duk da haka, saboda bambancin juriya na insulation na kowane capacitor electrolytic, dole ne a haɗa resistor zuwa kowane capacitor don daidaita wutar lantarki na kowane jerin da aka haɗa capacitor.Bugu da kari, electrolytic capacitors sune na'urori masu polarized, kuma lokacin da wutar lantarki da aka yi amfani da ita ta wuce sau 1.5 Un, ana samun amsawar electrochemic.Lokacin da wutar lantarki da aka yi amfani da ita ta yi tsayi sosai, capacitor zai zube.Don guje wa wannan lamari, yakamata a haɗa diode kusa da kowane capacitor lokacin amfani da shi.Bayan haka, ƙarfin ƙarfin ƙarfin lantarki na masu ƙarfin lantarki shine gabaɗaya sau 1.15 Un, kuma masu kyau zasu iya kaiwa sau 1.2 Un.Don haka ya kamata masu zanen kaya suyi la'akari ba kawai ƙarfin ƙarfin aiki na tsaye ba amma har ma da ƙarfin haɓaka lokacin amfani da su.A taƙaice, ana iya zana tebur ɗin kwatancen mai zuwa tsakanin capacitors na fim da masu ƙarfin lantarki, duba Fig.1.

2. Binciken Aikace-aikace

DC-Link capacitors kamar yadda masu tacewa suna buƙatar ƙira mai girma na yanzu da babban ƙarfin ƙira.Misali shine babban tsarin tuƙi na sabon motar makamashi kamar yadda aka ambata a cikin Fig.3.A cikin wannan aikace-aikacen capacitor yana taka rawar yankewa kuma da'irar tana da babban yanayin aiki.Fim ɗin DC-Link capacitor yana da fa'idar iya jure manyan igiyoyin aiki (Irms).Dauki 50 ~ 60kW sabon makamashi abin hawa a matsayin misali, sigogi kamar haka: aiki ƙarfin lantarki 330 Vdc, ripple ƙarfin lantarki 10Vrms, ripple halin yanzu 150Arms@10KHz.

Sannan ana lissafin mafi ƙarancin ƙarfin lantarki kamar:

Wannan yana da sauƙi don aiwatarwa don ƙirar capacitor na fim.Idan aka yi la'akari da cewa ana amfani da capacitors na electrolytic, idan an yi la'akari da 20mA/μF, ana ƙididdige mafi ƙarancin ƙarfin ƙarfin lantarki don saduwa da sigogi na sama kamar haka:

Wannan yana buƙatar masu ƙarfin lantarki da yawa a layi daya da aka haɗa don samun wannan ƙarfin.

A cikin aikace-aikacen fiye da ƙarfin lantarki, irin su jirgin ƙasa mai sauƙi, bas ɗin lantarki, jirgin karkashin kasa, da dai sauransu. La'akari da cewa an haɗa waɗannan wutar lantarki zuwa locomotive pantograph ta hanyar pantograph, hulɗar tsakanin pantograph da pantograph ba ta daɗe a lokacin tafiyar sufuri.Lokacin da ba a tuntuɓar su biyun, wutar lantarki tana samun goyan bayan tawada tawada capacitor na DC-L, kuma lokacin da aka dawo da lambar, za a samar da over-voltage.Mafi munin lamarin shine cikakken fitarwa ta DC-Link capacitor lokacin da aka cire haɗin, inda ƙarfin fitarwa yayi daidai da ƙarfin lantarki na pantograph, kuma lokacin da aka dawo da lamba, sakamakon over-voltage ya kusan sau biyu ƙimar aiki Un.Don capacitors na fim za a iya sarrafa capacitor na DC-Link ba tare da ƙarin la'akari ba.Idan ana amfani da capacitors electrolytic, over-voltage shine 1.2Un.Dauki Shanghai metro a matsayin misali.Un = 1500Vdc, don wutar lantarki don la'akari da ƙarfin lantarki shine:

Sa'an nan kuma za a haɗa capacitors shida 450V a jere.Idan aka yi amfani da ƙirar capacitor na fim a cikin 600Vdc zuwa 2000Vdc ko ma 3000Vdc ana samun sauƙin samu.Bugu da kari, makamashi a cikin yanayin cikar cajin capacitor yana samar da wani ɗan gajeren da'irar fitarwa tsakanin na'urorin lantarki guda biyu, yana haifar da babban juzu'i ta hanyar capacitor na DC-Link, wanda yawanci ya bambanta ga masu ƙarfin lantarki don biyan buƙatun.

Bugu da kari, idan aka kwatanta da electrolytic capacitors DC-Link capacitors film capacitors za a iya tsara don cimma sosai low ESR (yawanci kasa 10mΩ, har ma da ƙananan <1mΩ) da kuma kai-inductance LS (yawanci kasa 100nH, kuma a wasu lokuta kasa 10 ko 20nH) .Wannan yana ba da damar shigar da capacitor na fim na DC-Link kai tsaye a cikin tsarin IGBT lokacin da aka yi amfani da shi, yana ba da damar shigar da mashaya bas a cikin capacitor na fim na DC-Link, don haka kawar da buƙatar keɓaɓɓiyar IGBT absorber capacitor lokacin amfani da capacitors na fim, adanawa. mai zanen kuɗi mai mahimmanci.Hoto.2.da 3 suna nuna ƙayyadaddun fasaha na wasu samfuran C3A da C3B.

3. Kammalawa

A cikin farkon kwanakin, DC-Link capacitors sun kasance galibi masu ƙarfin lantarki saboda farashi da la'akari da girman.

Duk da haka, electrolytic capacitors suna shafar irin ƙarfin lantarki da halin yanzu jure iyawa (mafi girma ESR idan aka kwatanta da fim capacitors), don haka wajibi ne a haɗa da dama electrolytic capacitors a cikin jerin da a layi daya domin samun babban iya aiki da kuma saduwa da bukatun na high ƙarfin lantarki amfani.Bugu da ƙari, la'akari da rashin daidaituwa na kayan lantarki, ya kamata a maye gurbin shi akai-akai.Sabbin aikace-aikacen makamashi gabaɗaya suna buƙatar rayuwar samfur na shekaru 15, don haka dole ne a maye gurbinsa sau 2 zuwa 3 a wannan lokacin.Saboda haka, akwai babban farashi da rashin jin daɗi a cikin sabis na tallace-tallace na gaba ɗaya.Tare da haɓaka fasahar suturar ƙarfe da fasahar capacitor na fim, an sami yuwuwar samar da manyan capacitors masu ƙarfi na DC tare da ƙarfin lantarki daga 450V zuwa 1200V ko ma mafi girma tare da fim ɗin OPP mai bakin ciki (mafi ƙarancin 2.7µm, har ma da 2.4µm) ta amfani da aminci film vaporization fasahar.A daya hannun, hadewar DC-Link capacitors tare da mashaya bas yana sa injin inverter ya ƙirƙira mafi ƙanƙanta kuma yana rage ɓoyayyen inductance na da'ira don haɓaka kewaye.