Ukukhanya kwe-LED PWM
Ukufiphaza kwe-PWM bubuchwephesha bobumnyama obuqhelekileyo obusetyenziswa kwiimveliso zamandla ombane eziluzizi. Kwisekethe yesignali ye-analog, ukukhanya kwe-luminaire yokulawula kukhutshwe ngedijithali. Le ndlela yobumnyama ineenzuzo ezininzi xa kuthelekiswa nokuncipha komqondiso we-analog yemveli. Kakade ke, kukho iziphene ezithile kwezinye iinkalo. Ziziphi izinto eziluncedo nezingeloncedo?
Masiqale sijonge umgaqo osisiseko we-pwm dimming. Enyanisweni, ekusebenziseni okusebenzayo kwemveliso, kunokuqondwa ukuba ityhubhu yokutshintsha kweMOS ixhunyiwe kumthwalo we-LED. I-anode yomtya inikwe amandla ngumthombo wangoku oqhubekayo. Umqondiso we-PWM usetyenziswa kwisango le-MOS transistor ukuze utshintshe ngokukhawuleza umtya wee-LED ukuze umnyama.
Uncedo lwe-pwm dimming:
Okokuqala, i-pwm dimming kukufiphala okuchanekileyo.
Ukuchaneka kokuncipha kokukhanya luphawu olumangalisayo lokukhanya kwedijithali okuqhelekileyo, kuba i-pwm dimming isebenzisa imiqondiso ye-pulse waveform ngokuchaneka okuphezulu.
Okwesibini, pwm dimming, akukho mahluko umbala.
Kulo lonke uluhlu lwe-dimming, ekubeni i-LED yangoku ikwixabiso eliphezulu okanye icinyiwe, umyinge wangoku we-LED utshintshwa ngokulungelelanisa umlinganiselo we-pulse duty, ngoko ke iskimu sinokuphepha ukuhluka kombala ngexesha lokutshintsha kwangoku.
Okwesithathu, i-pwm dimming, uluhlu oluhlengahlengiswayo.
I-PWM dimming frequency ngokuqhelekileyo yi-200 Hz (i-low frequency dimming) ukuya kuma-20 kHz okanye ngaphezulu (i-high frequency dimming).
Okwesine, pwm dimming, akukho strobe.
Okoko nje i-PWM dimming frequency iphezulu kune-100 Hz, akukho kuqhwanyaza kwe-LED kubonwa. Ayitshintshi iimeko zokusebenza zomthombo wangoku oqhubekayo (i-boost ratio okanye i-step-down ratio), kwaye akunakwenzeka ukugqithisa. Nangona kunjalo, ukufiphala kwe-PWM pulse wide kuneengxaki ekufuneka uziqaphele. Eyokuqala kukhetho lwe-pulse frequency: kuba i-LED ikwimeko yokutshintsha ngokukhawuleza, ukuba i-frequency yokusebenza iphantsi kakhulu, iliso lomntu liya kuziva lincinci. Ukuze kusetyenziswe ngokupheleleyo into eshiyekileyo ebonakalayo yeliso lomntu, i-frequency yokusebenza kwayo kufuneka ibe phezulu kune-100 Hz, ngokukhethekileyo i-200 Hz.
Zeziphi izinto ezingeloncedo nge-pwm dimming?
Ingxolo ebangelwa kukufiphala yenye. Nangona ingabonakali ngeliso lomntu ngaphezu kwe-200 Hz, luhlobo lokuva kwabantu ukuya kuma-20 kHz. Ngeli xesha, kunokwenzeka ukuva isandi sesilika. Zimbini iindlela zokusombulula le ngxaki. Enye kukunyusa isantya sokutshintshela ngaphezulu kwe-20 kHz kwaye utsibe ngaphandle kwendlebe yomntu. Nangona kunjalo, i-frequency ephezulu kakhulu inokubangela iingxaki ezithile, kuba impembelelo yeeparamitha ezahlukeneyo zeparasitic iya kubangela ukuba i-pulse waveform (imida yangaphambili nangasemva) igqwetheke. Oku kunciphisa ukuchaneka kobumnyama. Enye indlela kukufumanisa isixhobo sokukhala uze usiphathe. Enyanisweni, esona sixhobo sivakalayo sisixhobo se-ceramic capacitor ekuphumeni, kuba ii-ceramic capacitors zihlala zenziwe ngee-ceramics ze-dielectric rhoqo, ezineempawu ze-piezoelectric. Ukungcangcazela komatshini kwenzeka phantsi kwesenzo se-pulse ye-200 Hz. Isisombululo kukusebenzisa i-tantalum capacitor endaweni yoko. Nangona kunjalo, i-high-voltage tantalum capacitors kunzima ukuyifumana, kwaye ixabiso libiza kakhulu, eliya kwandisa iindleko ezithile.
Ukushwankathela, iingenelo ze-pwm dimming zezi: usetyenziso olulula, ukusebenza kakuhle okuphezulu, ukuchaneka okuphezulu, kunye nesiphumo esihle sokufiphala. Ukungalungi kukuba ekubeni umqhubi we-LED jikelele esekelwe kumgaqo wokutshintsha unikezelo lwamandla, ukuba i-PWM dimming frequency iphakathi kwe-200 kunye ne-20 kHz, i-inductance kunye ne-output capacitance ejikeleze umbane wokukhanya kwe-LED ithandwa kwingxolo evakalayo. indlebe yomntu. Ukongeza, xa usenza i-PWM dimming, ngokusondeleyo ukuphindaphinda kwesignali yohlengahlengiso kukuphindaphinda kwe-chip yomqhubi we-LED kwisignali yokulawula isango, isiphumo sibi kakhulu.