Abahlinzeki beyunithi yamabhuleki bakukhumbuza ukuthi ngokuthuthukiswa kokukhiqizwa kwezimboni ezishintshayo, imvamisa yokusetshenziswa kweziguquli zefrikhwensi ibilokhu ikhula. Ukuze kuzuzwe ukusebenza kahle kokukhiqiza okuphezulu, kuvame ukudingekile ukwandisa okokusebenza okusekelayo kweziguquli zefrikhwensi, njengamayunithi okubhuleka adla amandla nama-resistors amabhuleki, ukuze kuthuthukiswe ukusebenza kahle kokukhiqiza. Ngokusekelwe kuzici, ukushiyeka, kanye nokwakheka kokubhuleka okudla amandla kuziguquli zefrikhwensi, lesi sihloko sihlaziya izindlela zokukhetha zokuthuthukisa zamayunithi okubhuleka asebenzisa amandla kanye neziphikisayo zamabhuleki kuziguquli zefrikhwensi.
1. Ukubhuleka kokusetshenziswa kwamandla kwe-frequency converter
Indlela esetshenziselwa i-braking yokusetshenziswa kwamandla ukufaka ingxenye yeyunithi yokubhuleka ohlangothini lwe-DC lwesiguquli sefrikhwensi, edla amandla kagesi avuselelwe ku-resistor yokubhuleka ukuze kuzuzwe ukubhuleka. Lena indlela eqondile nelula kakhulu yokucubungula amandla avuselelwe. Isebenzisa amandla avuselelwe ku-resistor ngokusebenzisa isekethe yebhuleki yokusetshenziswa kwamandla ezinikele futhi iguqulela amandla ashisayo. Lesi resistor sibizwa nge-resistance braking.
Izici zokubhuleka kokusetshenziswa kwamandla ziyisekethe elula kanye nenani eliphansi. Kodwa-ke, phakathi nenqubo yokubhuleka, njengoba ijubane lemoto lincipha, amandla e-kinetic wesistimu yokushayela nawo ayancipha, okuholela ekwehleni komthamo wokuvuselela kanye ne-torque yokubhuleka yemoto. Ngakho-ke, ezinhlelweni zokudonsa ezine-inertia ephezulu, kuvamile ukuhlangana nesimo "sokukhasa" ngesivinini esiphansi, esithinta ukunemba kwesikhathi sokupaka noma isikhundla. Ngakho-ke, ukusebenzisa amandla amabhuleki kusebenza kuphela endaweni yokupaka enemithwalo evamile. Amabhuleki okusebenzisa amandla ahlanganisa izingxenye ezimbili: iyunithi yokubhuleka kanye ne-resistor yokubhuleka.
(1) Iyunithi yamabhuleki
Umsebenzi weyunithi yokubhuleka uwukuxhuma isekethe yokulahla amandla lapho i-voltage Ud yesekethe ye-DC idlula umkhawulo oshiwo, okuvumela isekethe ye-DC ukuthi ikhulule amandla ngendlela yamandla ashisayo ngemva kokudlula ku-resistor braking. Iyunithi ye-braking ingahlukaniswa ngezinhlobo ezimbili: eyakhelwe ngaphakathi nangaphandle. Uhlobo olwakhelwe ngaphakathi lufanele iziguquli zemvamisa yenhloso evamile yamandla aphansi, kuyilapho uhlobo lwangaphandle lufanele iziguquli zefrikhwensi yamandla aphezulu noma izimo zokusebenza ezinezidingo ezikhethekile zokubhuleka. Empeleni, awukho umehluko phakathi kwalokhu okubili. Iyunithi yokubhuleka isebenza "njengeswishi" yokuxhuma isixhasi sokubhuleka, esihlanganisa i-transistor yamandla, isekethe yokuqhathanisa isampula ye-voltage, nesekethe yokushayela.
(2) I-Braking resistor
I-Braking resistor iyinkampani yenethiwekhi esetshenziselwa ukusebenzisa amandla okuvuselela emoto kagesi ngendlela yamandla ashisayo, ahlanganisa amapharamitha amabili abalulekile: inani lokumelana namandla amandla. Izinhlobo ezimbili ezivame ukusetshenziswa eziphikisanayo kwezobunjiniyela ziyi-resistors eziboshiwe kanye ne-aluminium alloy resistors: izinto eziphikisayo eziboshiwe zisebenzisa ukubola okungaphezulu ukuze kube lula ukuchithwa kokushisa nokunciphisa inductance ye-parasitic, kanye nezingubo ze-inorganic retardant high flame zikhethwa ukuze zivikele ngokuphumelelayo izintambo zokumelana nokuguga futhi zandise impilo yazo yenkonzo; Ama-resistors e-aluminium alloy anokumelana kangcono nesimo sezulu kanye nokumelana nokudlidliza kunezinqamuleli zefreyimu ye-porcelain yendabuko, futhi asetshenziswa kabanzi ezindaweni ezinokhahlo ezinezidingo eziphezulu. Kulula ukuzifaka ngokuqinile, kulula ukunamathisela osinki bokushisa, futhi abe nokubukeka okuhle.
Inqubo ye-braking yokusetshenziswa kwamandla kanje: lapho i-motor kagesi inciphisa noma ihlehla ngaphansi kwamandla angaphandle (kuhlanganise nokuhudulwa), i-motor kagesi igijima esimweni sokukhiqiza, futhi amandla anikezwa emuva kumjikelezo we-DC, okwenza ukuba i-voltage yebhasi ikhuphuke; Iyunithi yokubhuleka isampula ugesi webhasi. Lapho i-voltage ye-DC ifinyelela inani le-conduction elibekwe iyunithi yokubhuleka, ishubhu yokushintsha amandla yeyunithi yokubhuleka, futhi yamanje igeleza ku-resistor yokubhuleka; I-resistor yokubhuleka iguqula amandla kagesi ibe amandla ashisayo, inciphisa ijubane lemoto futhi yehlise i-voltage yebhasi ye-DC; Lapho i-voltage yebhasi yehla enanini elinqanyuliwe elibekwe iyunithi yokubhuleka, i-transistor yamandla eshintshayo yeyunithi yokubhuleka iyanqanyulwa, futhi akukho okwamanje okugeleza ku-resistor yokubhuleka.
Ibanga lezintambo phakathi kweyunithi yokubhuleka kanye nesiguquli se-frequency, kanye naphakathi kweyunithi yokubhuleka kanye nesinqanda ukubhuleka, kufanele libe lifushane ngangokunokwenzeka (nobude bentambo obungaphansi kuka-2m), futhi ingxenye enqamulayo yocingo kufanele ihlangabezane nezidingo zokukhishwa kwamandla kwesinqanda ukubhuleka. Lapho iyunithi yokubhuleka isebenza, isixhasi sokubhuleka sizokhiqiza inani elikhulu lokushisa. I-resistor yokubhuleka kufanele ibe nezimo ezinhle zokulahla ukushisa, futhi izintambo ezikwazi ukumelana nokushisa kufanele zisetshenziselwe ukuxhuma i-resistor yokubhuleka. Izintambo akufanele zithinte i-resistor yokubhuleka. I-resistor ye-braking kufanele iqiniswe ngokuqinile ngamaphedi okufakelwa, futhi indawo yokufaka kufanele iqinisekise ukuchithwa okuhle kokushisa. Lapho ufaka i-resistor ye-braking ekhabhinethi, kufanele ifakwe phezulu kwekhabhinethi yokuguqula imvamisa.
2. Ukukhethwa kweyunithi yokubhuleka
Ngokuvamile, lapho ubhuleka i-motor kagesi, kukhona inani elithile lokulahlekelwa ngaphakathi kwe-motor, okungaba ngu-18% kuya ku-22% we-torque elinganiselwe. Ngakho-ke, uma i-torque ye-braking edingekayo ibalwa ukuthi ingaphansi kuka-18% kuya ku-22% we-torque elinganiselwe ye-motor, asikho isidingo sokuxhuma idivayisi yokubhuleka.
Lapho ukhetha iyunithi yokubhuleka, umthamo omkhulu wamanje wokusebenza weyunithi yokubhuleka uwukuphela kwesisekelo sokukhetha.
3. Ukukhethwa kokuthuthukisa i-braking resistor
Ngesikhathi sokusebenza kweyunithi yokubhuleka, ukukhuphuka nokuwa kwe-voltage yebhasi ye-DC kuncike ku-RC engashintshi, lapho u-R eyinani lokumelana le-resistor yokubhuleka kanye no-C amandla e-capacitor yangaphakathi yesiguquli sefrikhwensi.
Inani lokumelana le-resistor yokubhuleka liphezulu kakhulu, libangela ukubhuleka okunensayo. Uma incane kakhulu, izingxenye ze-braking switch zilimala kalula. Ngokuvamile, lapho inertia yomthwalo ingenkulu kakhulu, kukholelwa ukuthi kuze kufike ku-70% wamandla asetshenziswa injini ngesikhathi sokubhuleka adliwe yi-resistor braking, kanti amandla angama-30% asetshenziswa ukulahlekelwa okuhlukahlukene kwemoto ngokwayo kanye nomthwalo.
Amandla ahlakaziwe we-resistor yokubhuleka we-low-frequency braking ngokuvamile angu-1/4 kuya ku-1/5 wamandla enjini, futhi amandla ahlakaziwe adinga ukunyuswa ngesikhathi sokubhuleka njalo. Ezinye iziguquli zefrikhwensi yomthamo omncane zifakwe izinto zokuphikisa amabhuleki ngaphakathi, kodwa uma zibhuleka kumafrikhwensi aphezulu noma imithwalo yamandla adonsela phansi, izimbangi zangaphakathi zamabhuleki azikwazi ukulahla ukushisa okwanele futhi zivame ukulimala. Kulokhu, ama-resistors ama-braking angaphandle anamandla aphezulu kufanele asetshenziswe esikhundleni salokho. Zonke izinhlobo ze-braking resistors kufanele zisebenzise ama-resistors anezakhiwo eziphansi ze-inductance; Intambo yokuxhuma kufanele ibe mfushane futhi ipheya esontekile noma ucingo oluhambisanayo kufanele lusetshenziswe. Izinyathelo eziphansi zokudonsa kufanele zithathwe ukuze kuvinjwe futhi kuncishiswe amandla e-inductance ukuthi angangezwe kushubhu lokushintsha amabhuleki, okubangela ukulimala kweshubhu lokushintsha amabhuleki. Uma i-inductance yesifunda inkulu futhi ukumelana kuncane, kuzodala umonakalo kushubhu lokushintsha amabhuleki.
Ukumelana ne-braking kuhlobene eduze ne-flywheel torque ye-motor kagesi, futhi i-torque ye-flywheel ye-motor kagesi iyahlukahluka ngesikhathi sokusebenza. Ngakho-ke, kunzima ukubala ngokunembile ukumelana namabhuleki, futhi inani elilinganiselwe livame ukutholwa kusetshenziswa amafomula e-empirical.
RZ>=(2 × UD)/Kufomula: Okungukuthi isilinganiso samanje se-converter frequency; UD frequency converter DC ibhasi voltage
Ngenxa yemodi yokusebenza yesikhathi esifushane yesixhasi sokubhuleka, ngokusekelwe ezicini nasekucacisweni kobuchwepheshe kwesiphikisayo, amandla okuzisholo esiphikisayo sokubhuleka kusistimu yokulawula isivinini esishintshashintshayo ngokuvamile angabalwa kusetshenziswa ifomula elandelayo:
I-PB=K × Pav × η%, lapho i-PB ingamandla okuzisholo okumelana namabhuleki; I-K yi-coefficient enciphayo yesixhasi sokubhuleka; I-Pav isilinganiso sokusetshenziswa kwamandla ngesikhathi sokubhuleka; η izinga lokusebenzisa amabhuleki.
Ukuze kuncishiswe izinga lokumelana lama-resistors ama-braking, abakhiqizi abahlukahlukene be-frequency converter bavame ukuhlinzeka ngama-resistors okubhuleka anenani elifanayo lokumelana kumakhono amaningana ahlukene wamamotho. Ngakho-ke, umehluko we-torque ye-braking etholakala ngesikhathi senqubo yokubhuleka ubalulekile. Isibonelo, isiguquli sefrikhwensi yochungechunge lwe-Emerson TD3000 sinikeza isicaciso se-braking resistor engu-3kW no-20 Ω yeziguquli zefrikhwensi enamandla angu-22kW, 30kW, kanye no-37kW. Uma iyunithi yokubhuleka iqhuba ku-DC voltage engu-700V, i-braking current ithi:
IB=700/20=35A
Amandla we-resistor yokubhuleka yilawa:
PB0=(700)2/20=24.5kW
Iyunithi yokubhuleka kanye ne-braking resistor esetshenziswa kusistimu yokulawula isivinini esishintshashintshayo kuwukucushwa okubalulekile kokusebenza okuphephile nokuthembekile kwesistimu yokulawula isivinini esishintshashintshayo esinamandla okuvuselela kanye nezidingo ezinembile zokupaka. Ngakho-ke, lapho kukhethwa isistimu yokulawula isivinini esishintshashintshayo esilungile, ukukhethwa kweyunithi yokubhuleka kanye ne-resistor yokubhuleka kufanele kuthuthukiswe. Lokhu akunciphisi nje kuphela ithuba lamaphutha ohlelweni lokulawula isivinini esishintshashintshayo, kodwa futhi kuvumela isistimu yokulawula isivinini esishintshashintshayo ukuthi ibe nezinkomba zokusebenza ezinamandla aphezulu.