Abahlinzeki bemishini yempendulo yamandla yeziguquli zefrikhwensi bakukhumbuza ukuthi ezinhlelweni zendabuko zokulawula imvamisa ezakhiwe iziguquli zefrikhwensi, ama-asynchronous motors, kanye nemithwalo yemishini, lapho umthwalo ongase udluliselwe injini wehliswa, injini ingase ibe sesimweni sokubhuleka kabusha; Noma lapho injini yehla isuka ejubaneni elikhulu iye kwisivinini esiphansi (kuhlanganise nokupaka), imvamisa ingase yehle ngokuzumayo, kodwa ngenxa ye-inertia yomshini wenjini, ingase ibe sesimweni sokukhiqiza amandla kabusha. Kunezindlela ezimbili zokuphatha amandla okuvuselela we-converter frequency: enye iyindlela yokukhishwa kwamandla okumelana; Enye indlela yindlela yempendulo ephambene. Indlela yempendulo ephambene iyisakhiwo "se-PWM embaxambili" esakhiwe izinto ezishintshayo ezilawulwa ngokugcwele, kodwa izindleko zayo eziphezulu zikhawulela ukusetshenziswa kwayo okusabalele. Ngezansi yisingeniso sendlela entsha yempendulo yokuvuselela amandla kusiguquli sefrikhwensi.
Umgomo wokusebenza wempendulo yamandla
Impendulo yamandla azivuselelayo iwukubuyisela amandla kagesi anqwabelene kuzo zombili iziphetho ze-capacitor yokuhlunga ekhiqizwe injini esesimweni sokubhuleka sokuvuselela kugridi yamandla. Njengomjikelezo wempendulo, imibandela emibili kufanele ihlangatshezwe:
(1) Uma isiguquli sefrikhwensi sisebenza ngokujwayelekile, idivayisi yempendulo ayisebenzi. Idivayisi yempendulo isebenza kuphela uma i-voltage yebhasi ye-DC ingaphezu kwenani elithile. Lapho i-voltage yebhasi ye-DC yehla ibuyela kokujwayelekile, idivayisi yempendulo kufanele ivalwe ngesikhathi, ngaphandle kwalokho izokwandisa umthwalo kusekethe yokulungisa kabusha.
(2) Impendulo yamanje ye-inverter kufanele ilawuleke.
Isigaba se-inverter
I-V1-V6 thyristors yakha isifunda se-inverter yesigaba sesithathu. I-Thyristors inezinzuzo zezindleko eziphansi, ukulawula okulula, ukusebenza okuthembekile, nobuchwepheshe obuvuthiwe. Kodwa ama-thyristors ayizingxenye ezilawulwa kancane, futhi isifunda se-inverter esakhiwa ama-thyristors kumele siqinisekise ukuthi i-angle encane ye-inverter inkulu kuno-30 °, ngaphandle kwalokho kulula ukubangela ukwehluleka kwe-inverter, kodwa lokhu kwenza i-voltage evamile yebhasi le-DC ibe phezulu kune-voltage ye-inverter. Isekhethi ye-inverter eyakhiwe ngama-thyristors ingaqala i-inverter ngokukhipha i-trigger pulse, kodwa ayikwazi ukumisa i-inverter ngokukhansela i-trigger pulse. Uma i-trigger pulse ikhanseliwe ngesikhathi sokuguqulwa, kuzoholela emiphumeleni enzima yokuhluleka kokuguqulwa. Ngakho-ke, kuyadingeka ukusebenzisa indlela yokusika isifunda se-DC ukumisa inverter.
Umsebenzi we-VT ukabili: enye iwukulawula ukuqala noma ukuma kwesekethe ye-inverter. Uma i-VT ivuliwe, i-voltage ye-DC isetshenziswa ebhulohweni le-inverter ukuqala inverter; Uma i-VT icishiwe, isifunda se-DC siyanqanyulwa futhi i-inverter iyama (ngalesi sikhathi, i-trigger pulse iyakhethwa). Amandla kagesi ajwayelekile ebhasi le-DC acishe abe i-DC600V (kucatshangelwa ukushintshashintsha okungu-± 10% kugesi wegridi). Ukuma kokuqala kwe-inverter kuncike kubukhulu be-voltage yebhasi ye-DC futhi kwamukela ukulawula kwe-hysteresis. Lapho i-voltage yebhasi ye-DC iphakeme kune-1.2 × 600V, i-inverter iyaqalwa, futhi uma ingaphansi kuka-1.1 × 600V, i-inverter ivaliwe. Omunye umsebenzi we-VT ukulawula ubukhulu be-inverter yamanje.
Ukulawulwa kwe-inverter yamanje
Lapho uhlehla, i-voltage yebhasi ye-DC kanye ne-inverter voltage ixhunywe ngokuhambisana ne-polarity efanayo, futhi i-voltage yebhasi iphakeme kune-inverter voltage. I-Inductance L isetshenziselwa ukulinganisa umehluko we-voltage. Ukulawulwa kwe-VT kungathatha indlela ye-PWM yamanje yokulawula i-hysteresis, futhi indlela yamanje ye-hysteresis isetshenziswa lapha.
Uma iL<I Α L-IL, i-VT iqhuba; I-voltage yamanje eqondile isetshenziswa ku-inductor L kanye nebhuloho le-inverter, lenza i-current in path ①, futhi i-il yamanje iqala ukuphakama; Uma i-iL iphakama ngaphezu kwe-I3 L+IL, i-VT iyacishwa futhi i-inductor iyaqhubeka nokugeleza nge-diode D. I-iL yamanje iqala ukuncipha. Uma i-iL yehlela ku-I3 L-IL, i-VT iqhuba futhi futhi i-iL iqala ukuphakama futhi. Ngokushintsha kokuvula/ukuvala kwe-VT, i-iL yamanje ye-inverter igcinwa ngenani elimisiwe le-I3, futhi kungakhathaliseki ukuthi inani eliphakeme le-voltage ye-inverter lishintsha kanjani, ngenxa yokusetshenziswa kokulawula ukuguqulwa kwe-high-frequency, i-inductance L ingagcinwa encane kakhulu.
Kafushane, ukuqhutshwa kwe-VT kufanele kuhlangabezane nezimo ezimbili ngesikhathi esisodwa: (1) i-DC voltage Uc iphakeme kunomkhawulo ongaphezulu obekiwe; (2) Uma i-inverter yamanje i-il ingaphansi komkhawulo obekiwe ophansi wamanje.
Ukuvalwa kwe-VT kufanele kuhlangabezane nenye yalezi zimo ezimbili ezilandelayo: (1) i-DC voltage Uc ingaphansi komkhawulo ophansi kagesi obekiwe; (2) Uma i-inverter yamanje i-il yeqa umkhawulo ongaphezulu obekiwe.
Ukuze ugweme ukushintshwa kwe-VT okuvamile, ukulawulwa kwe-hysteresis kusetshenziselwa i-voltage Uc kanye ne-il yamanje, futhi ububanzi be-loop buwumehluko phakathi kwemingcele ebekiwe ephezulu nephansi.
Ukubalwa kwe-inductance
Ukwenza ukubala kube lula futhi kuziba ukuhluka okukhona ngokushesha kwe-voltage ye-inverter Vd Β, ethathwa njengenani elingashintshi, isibalo esilandelayo singatholakala: L diL dt=Uc Ud Β Ukuxazulula isibalo kukhiqiza t1=2ILL Uc Ud Β, lapho i-IL - ububanzi be-hysteresis yamanje;
Uc - DC voltage; Ud Β - isilinganiso senani le-voltage ye-inverter.
Esikhathini se-t2, i-VT ivaliwe futhi i-voltage iyaqhubeka nokugeleza ku-D.
Kukhona isibalo esilandelayo: L diL dt=- Ud Β Isixazululo: t2=2ILL Ud Β Isikhathi sokunquma: T=t1+t2=2ILLUc Ud Β (Uc Ud Β) Ukunqunywa kwamafrikhwensi: f=Ud Β (Uc Ud Β) IILLUc inductance: L=Uc UdΒ2 Ud. Isibalo esingenhla sibonisa ukuthi uma u-f ephezulu kakhulu, u-L mncane kakhulu. Lokhu kuhlukile kumasekhethi ajwayelekile we-thyristor inverter. Ifomula engenhla ingasetshenziswa njengesisekelo sokukhetha i-inductance.
Ukubalwa kwe-capacitor discharge current
Kuphela uma i-VT iqhuba, kungaba khona ukukhishwa kwamanje okuphuma ku-capacitor. Ngakho-ke, inani elimaphakathi lamanje lokukhipha lithi: Ic=t1 TI 3 L. Ukushintsha ifomula engenhla kufomula yomjikelezo wokusika, umphumela uthi: Ic=Ud Β Uc I 3 L.