Izu a, anyị ga-aga n'ihu na akụkọ nke izu gara aga.

1.2 Kapasitọm Elektrolytic

Dielectric eji eme ihe na electrolytic capacitors bụ aluminum oxide nke aluminom rere site na nchara nke aluminom, nke nwere dielectric constant nke 8 ruo 8.5 na ike dielectric na-arụ ọrụ nke ihe dị ka 0.07V/A (1µm = 10000A). Agbanyeghị, ọ gaghị ekwe omume iru ọkpụrụkpụ dị otu a. Ọkpụrụkpụ nke oyi akwa aluminom na-ebelata ikike (ike kpọmkwem) nke electrolytic capacitors n'ihi na a ga-akpụrịrị foil aluminom iji mepụta ihe nkiri aluminom oxide iji nweta ezigbo njirimara nchekwa ike, elu ahụ ga-emepụtakwa ọtụtụ elu na-adịghị nhata. N'aka nke ọzọ, resisivity nke electrolyte bụ 150Ωcm maka obere voltaji na 5kΩcm maka nnukwu voltaji (500V). Resistive dị elu nke electrolyte na-egbochi ugbu a RMS nke electrolytic capacitor nwere ike iguzogide, nke na-abụkarị 20mA/µF.

Maka ihe ndị a, a na-emepụta capacitors electrolytic maka oke voltaji nke 450V nkịtị (ụfọdụ ndị nrụpụta na-emepụta maka 600V). Ya mere, iji nweta voltaji dị elu, ọ dị mkpa ijikọta capacitors n'usoro. Agbanyeghị, n'ihi ọdịiche dị na mgbochi mkpuchi nke capacitor electrolytic ọ bụla, a ga-ejikọ resistor na capacitor ọ bụla iji dozie voltaji nke capacitor ejikọtara usoro ọ bụla. Na mgbakwunye, capacitors electrolytic bụ ngwaọrụ polarized, mgbe voltaji azụ etinyere gafere ugboro 1.5 Un, mmeghachi omume electrochemical na-eme. Mgbe voltaji azụ etinyere ogologo oge, capacitor ga-awụpụ. Iji zere ihe a, a ga-ejikọ diode n'akụkụ capacitor ọ bụla mgbe ejiri ya. E wezụga nke ahụ, nguzogide voltaji nke capacitors electrolytic na-abụkarị ugboro 1.15 Un, ndị dị mma nwekwara ike iru ugboro 1.2 Un. Ya mere, ndị na-emepụta ihe kwesịrị ịtụle ọ bụghị naanị voltaji ọrụ na-adịgide adịgide kamakwa voltaji mmụba mgbe ha na-eji ha. Na nchịkọta, enwere ike ise tebụl ntụnyere dị n'etiti ihe nkiri na ihe ndị na-eme ka electrolytic dị na ya, lee Fig.1.

2. Nyocha Ngwa

Ndị na-etinye DC-Link dị ka nzacha chọrọ nhazi ọkụ eletrik dị elu na ikike dị elu. Ihe atụ bụ sistemụ draịva moto bụ isi nke ụgbọala ike ọhụrụ dịka ekwuru na Fig.3. Na ngwa a, onye na-etinye DC-Link na-arụ ọrụ nke na-agbanwe njikọ, sekit ahụ nwekwara ọkụ eletrik dị elu. Ihe nkiri ahụ nwere uru nke inwe ike iguzogide nnukwu ọkụ eletrik (Irms). Were paramita ụgbọala ike ọhụrụ 50~60kW dịka ọmụmaatụ, paramita ndị a bụ ndị a: voltaji ọrụ 330 Vdc, voltaji ripple 10Vrms, ọkụ eletrik ripple 150Arms@10KHz.

Mgbe ahụ, a na-agbakọ ikike eletriki kacha nta dị ka:

Nke a dị mfe itinye n'ọrụ maka imewe ihe nkiri capacitor. Ọ bụrụ na ejiri electrolytic capacitors, ọ bụrụ na a tụlee 20mA/μF, a na-agbakọ ikike kacha nta nke electrolytic capacitors ka o wee mezuo paramita ndị dị n'elu dịka ndị a:

Nke a chọrọ ọtụtụ capacitors electrolytic n'otu oge ejikọtara iji nweta capacitance a.

N'ọrụ voltaji karịrị akarị, dịka ụgbọ okporo ígwè dị mfe, bọs eletriki, ụgbọ okporo ígwè, wdg. Ebe ọ bụ na ejikọtara ike ndị a na pantograph locomotive site na pantograph, njikọ dị n'etiti pantograph na pantograph na-akwụsị oge n'oge njem njem. Mgbe ha abụọ na-adịghị na kọntaktị, a na-akwado ọkụ eletrik site na DC-L ink capacitor, mgbe emeghachiri kọntaktị ahụ, a na-emepụta oke voltaji. Nke kacha njọ bụ mwepụ zuru oke site na DC-Link capacitor mgbe a kwụsịrị ya, ebe voltaji mwepụta hà nhata voltaji pantograph, na mgbe emeghachiri kọntaktị ahụ, oke voltaji sitere na ya fọrọ nke nta ka ọ bụrụ ugboro abụọ nke Un a na-arụ ọrụ. Maka capacitors fim, enwere ike ijikwa DC-Link capacitor na-enweghị ntụle ọzọ. Ọ bụrụ na ejiri capacitors electrolytic, oke voltaji bụ 1.2Un. Were metro Shanghai dị ka ihe atụ. Un=1500Vdc, maka capacitor electrolytic iji tụlee voltaji bụ:

Mgbe ahụ, a ga-ejikọ capacitors isii 450V n'usoro. Ọ bụrụ na ejiri nhazi capacitor ihe nkiri mee ihe na 600Vdc ruo 2000Vdc ma ọ bụ ọbụna 3000Vdc, ọ ga-adị mfe inweta. Na mgbakwunye, ike ọ bụrụ na capacitor ahụ agbapụta kpamkpam, na-emepụta mwepụ sekit dị mkpirikpi n'etiti elektrọd abụọ ahụ, na-emepụta nnukwu ọkụ inrush site na capacitor DC-Link, nke na-adịkarị iche maka capacitors electrolytic iji mezuo ihe achọrọ.

Tinyere nke a, ma e jiri ya tụnyere ndị na-enye electrolytic capacitors, enwere ike imepụta ndị na-enye DC-Link film capacitors iji nweta obere ESR (nke na-adịkarị n'okpuru 10mΩ, na ọbụna obere <1mΩ) na onwe-inductance LS (nke na-adịkarị n'okpuru 100nH, na n'ọnọdụ ụfọdụ n'okpuru 10 ma ọ bụ 20nH). Nke a na-enye ohere ka etinyere ihe nkiri DC-Link ozugbo na modulu IGBT mgbe etinyere ya, na-enye ohere ka etinyere ihe mgbochi bọs ahụ na ihe nkiri DC-Link capacitor, si otú a na-ewepụ mkpa ọ dị maka ihe na-enye IGBT absorber capacitor raara onwe ya nye mgbe ọ na-eji ihe nkiri capacitors, na-azọpụta onye nrụpụta nnukwu ego. Fig.2. na 3 na-egosi nkọwapụta teknụzụ nke ụfọdụ ngwaahịa C3A na C3B.

3. Mmechi

N'oge mbụ, DC-Link capacitors bụkarị electrolytic capacitors n'ihi ọnụ ahịa na nha ha.

Agbanyeghị, ike iguzogide ọkụ eletrik na ike iguzogide ọkụ eletrik na-emetụta ike iguzogide ọkụ eletrik (ESR dị elu karịa capacitors fim), yabụ ọ dị mkpa ijikọ ọtụtụ capacitors electrolytic n'usoro na n'usoro iji nweta ikike buru ibu ma mezuo ihe achọrọ maka ojiji voltaji dị elu. Na mgbakwunye, n'ịtụle mgbanwe nke ihe electrolyte, a ga-agbanwe ya mgbe niile. Ngwa ike ọhụrụ na-achọkarị ndụ ngwaahịa nke afọ 15, yabụ a ga-agbanwe ya ugboro 2 ruo 3 n'oge a. Ya mere, enwere nnukwu ọnụ ahịa na nsogbu na ọrụ mgbe erechara nke igwe ahụ dum. Site na mmepe nke teknụzụ mkpuchi metallisation na teknụzụ capacitor fim, o kwere omume ịmepụta capacitors nzacha DC nwere ikike dị elu nwere voltaji site na 450V ruo 1200V ma ọ bụ karịa na ihe nkiri OPP dị oke mkpa (2.7µm kacha dị gịrịgịrị, ọbụna 2.4µm) site na iji teknụzụ vaporization fim nchekwa. N'aka nke ọzọ, njikọta nke capacitors DC-Link na ogwe bọs na-eme ka imewe modulu inverter dịkwuo obere ma na-ebelata nke ukwuu inductance nke sekit ahụ iji mee ka sekit ahụ dịkwuo mma.