Yintoni i-PWM?

I-PWM imele i-Pulse Width Modulation. Ucima amandla ombane avule kwaye uwacime ngamaxesha amiselweyo, utshintsha umlinganiselo wexesha{1}}lokucima{2}}ukulawula unikezelo lwamandla oluphakathi. Yiyo leyo. Okunye kukujongana neziphumo nje.

Thatha unikezelo lwe-12V oluqhuba i-LED efuna i-3V. Ngokwesiqhelo ungasebenzisa isixhasi okanye isilawuli somgca, utshise i-9V njengobushushu. Inkunkuma yobudenge. Nge-PWM ucima i-12V epheleleyo kwaye uyicime ngokukhawuleza ngokwaneleyo ukuba ubunzima be-thermal ye-LED buyikhuphe. 25% umjikelo womsebenzi ukunika malunga ne-3V elinganayo. I-LED ibona i-12V → 0V → 12V → 0V mhlawumbi i-1kHz, kodwa ayikwazi ukupholisa kwaye ifudumale ngokukhawuleza, ngoko ke ukuqaqamba kuhlala kungatshintshi.

Imiba yokuphindaphinda. Ukucotha kakhulu (ngaphantsi kwe-100Hz) kwaye ufumana ukuqhwanyaza okubonakalayo. Abanye abantu babona isantya ukuya kuthi ga kwi-200Hz. Ndidla ngokuqhuba i-LED dimming kwi-20kHz ukuze ndikhuseleke-kwaye ndiyigcina ngaphandle koluhlu oluvakalayo ukuba kukho ukudibanisa koomatshini. Ukutshintsha isantya kuchaphazela ilahleko nako, kodwa siza kufika kuloo nto.

Izibalo: ukuba ixesha lakho ngu-T kwaye{0}}ixesha ngu-t, umjikelo womsebenzi D=t/T. Elula. Amandla anikezelweyo amalunga ne-D × V_spply × I_load, thabatha iilahleko. Ezo lahleko kulapho izinto ziba nomdla kuzo.

Isizathu sokuqala: ukusebenza kakuhle. I-MOSFET kwi-saturation yehla mhlawumbi i-0.1-0.2V kwimisinga efanelekileyo. I-MOSFET icinyiwe izoba ii-microamps. Ke mhlawumbi uyachitha (0.1V × yangoku) okanye akukho nto. Thelekisa oko kwisilawuli somgca esiwisa i-9V ngokuqhubekayo ngokuqhubekayo. Umahluko wobomi bebhetri yi-40-50x kwezinye iimeko, hayi ukubaxa.

Okwesibini: ungasebenzisa izixhobo zombane ezingabizi kakhulu. Ngaba ufuna ukuqhuba i-48V motor ngesantya esiguqukayo? Ngolawulo lwe-analog udinga i-0-48V yexabiso eliguquguqukayo. Nge-PWM usebenzisa unikezelo lwe-48V esisigxina (ixabiso eliphantsi) kunye ne-MOSFET (nexabiso eliphantsi). Ugqibile.

Isizathu sesithathu akukho mntu uthetha ngaso: ukuthenga. Zama ukufumana unikezelo oluguquguqukayo lwe-analog kwivolumu. Amaxesha okukhokela ziiveki ezingama-26 ubuncinci ukusuka kubavelisi abafanelekileyo. IiMOSFET? Yonke into ikwi-stock e-Digikey. Xa imveliso ikhwaza kuwe, oku kubaluleke ngaphezu kweendleko ze-BOM.

PWM

I-EMI izakukruqula. Okokuqala ndenza ibhodi ye-PWM ephezulu-yangoku (120A yemoto ye-DC), yabulala ibhasi ye-CAN kwisithuthi esinye. Iipakethi ezingonakaliswanga{4}}ezifile ngokupheleleyo. Kwajika ukukhala kwesango lam lokuqhuba kwakudityaniswa kumhlaba we-chassis, isenza i-40V spikes kwi-CAN differential pair. Kongezwa amaso e-ferrite, amabala ashukumiweyo, kusenemiba. Ekugqibeleni kuye kwafuneka ukuba kongezwe isihluzo se-pi kunikezelo lwemoto kwaye kwahlule iinqwelomoya ezisemhlabeni ngenqaku elinye{9}}loqhagamshelwano. Uthathe iirevs ezintathu zebhodi.

Isango lokuqhuba linzima kunokuba likhangeleka. Udinga uthintelo oluphantsi ukusuka kumqhubi wakho ukuya kwisango le-MOSFET{1}}lokulandela imiba ye-inductance kwi-high di/dt. Ndiyibonile i-10nH ye-trace inductance ebangela ukuba i-50V voltage spikes ngexesha lokutshintsha (V=L × di/dt). Oko kwanele ukugqobhoza nge60V ekale ye-MOSFET. Abantu bayaphikisana malunga nezibalo kodwa ndiyibonile kwi-scope: 3A / ns ukutshintsha okwangoku kwi-10nH kukunika i-30V spike. Yongeza amandla ombane kwaye ungaphaya kowona mlinganiselo mkhulu.

Kwaye kukho ukudubula{0}}ku-H{1}}iibhulorho. KUFUNEKA ube nexesha elibekiweyo phakathi kokucima icandelo elisezantsi{3}}leFET kwaye ujike kwicala eliphezulu{4}(kunye ngokuphendululekileyo). Ukuphelelwa lixesha kuthetha ukuba zombini ii-FETs ziqhuba ngaxeshanye-ngokufutshane ngqo ukusuka ekuboneleleni ukuya emhlabeni ngokusebenzisa ukuxhathisa kwetshaneli yeFET{7}}A ukuya ku-0.01Ω kabini iseyi-1000A kwiimicroseconds phambi kokuba izinto zigqabhuke. Imowudi yokungaphumeleli iyamangalisa: i-crater encinci kwi-silicon, i-FET ihamba mfutshane ngokusisigxina, ikhupha yonke enye into kwikhonkco.

Kodwa ixesha elininzi lokufa kunye ne-diode yomzimba iqhuba ngexesha lokufa. Iidiode zomzimba ziyoyikeka{1}phezulu ukuya phambili (1-2V), ukuchacha kade. Ulahlekelwa ukusebenza kakuhle kwaye uvelise ubushushu obuninzi. Urhwebo ludla ngokuba yi-100-500ns yexesha elimiselweyo ngokuxhomekeke kwiimpawu zokutshintsha kweFET.

Ithuku lokuqala lomntu wonke: isantya esiphezulu=ii-inductors/capacitors ezincinci=zitshiphu. Ngamanye amaxesha yinyani. Kodwa ilahleko yokutshintsha iyanda rhoqo-ulahlekelwa ngamandla ngalo lonke ixesha utshintsho lweFET. ESwitching ≈ 0.5 × Vsupply × Iload × (trise + tfall) × fsw. Phinda kabini ukuphindaphinda, kabini ilahleko yokutshintsha.

Kwiimoto zokuqhuba, i-20kHz ixhaphakile. Ngaphezulu okuvakalayo, izigxina zexesha zoomatshini azikhathali. Kodwa kwilaptop unikezelo lwamandla ubona 300kHz-1MHz. Ngoba? Iimagnethi ezincinci. I-inductor eyi-1MHz ngokwasemzimbeni yi-1/50 ubukhulu be-20kHz enye ene-inductance efanayo. Loo nto inkulu kwizixhobo eziphathwayo. Urhwebo lufuna iiFET ezikhawulezayo (i-Qg esezantsi), uyilo olungcono, uyilo lomqhubi olunononophelo ngakumbi.

I-Audio (Ii-amps zoKlasi D) kuqhuba i-250kHz-1MHz. Ngaphantsi kwe-200kHz kwaye unokuva i-frequency carrier njenge-whine ephezulu{9}. Ngaphezulu kwe-1MHz kwaye uqala ukulwa nokuphazamiseka kwerediyo ye-AM. Uninzi loyilo luhlala kwi-400-500kHz, isihluzo esisezantsi mhlawumbi nge-50kHz ukususa umthwali.

Umzekelo wokwenyani: wenze i-500kHz buck converter kanye, yazama ukuya kwi-1MHz ukucutha ibhodi. Ukusebenza kakuhle kwehle nge-4% (88% ukuya kuma-84%). Oko 8W ubushushu obongezelelweyo kubonelelo lwe-200W. Ifuna i-heatsink enkulu, iphulukene nalo lonke ugcino lwendawo kwi-inductor encinci. Yahlala ku-500kHz.

PWM

8 - bit PWM (256 amanyathelo) ivakala kakuhle de uzame ukufiphalisa i-LED ukusuka kwi-100% ukuya kwi-0%. Ngaphantsi kwe-10% yomjikelo womsebenzi ufumana amanyathelo abonakalayo ekukhanyeni. Iliso lomntu li-logarithmic-linovakalelo ngakumbi kutshintsho kumanqanaba okukhanya aphantsi. Ifuna i-12-bit (izinyuko ezingama-4096) ubuncinci bokukhanya okugudileyo kuluhlu olupheleleyo.

Kodwa nantsi into yokubambisa: i-12-bit ku-20kHz ithetha ukuba ufuna i-20kHz × 4096=81.92 iwotshi yesibali-xesha seMHz. Ayizizo zonke iimicros ezinokwenza oko. Kwaye ukuba ufuna itshaneli ezininzi ezizimeleyo ze-PWM kwi-12-bit, ujonge kwiiperipherals zesibali-xesha okanye iFPGA.

Indlela yokusebenza: sebenzisa i-8-bit PWM kodwa uhlengahlengise amaza omoya ngamandla. Ekukhanyeni okuphezulu sebenzisa i-20kHz, ekukhanyeni okuphantsi kwehla ukuya kwi-100Hz. Ikunika amanyathelo angcono apho uwadinga khona. Kodwa ngoku une-EMI eguquguqukayo yokujongana nayo. Akukho nto yasimahla.

I-Industrial VFDs (i-variable frequency drives) itshintshe amakhulu e-amps kwi-480VAC. Isicwangciso solawulo sintsokothile ngakumbi-uguqulo lwevektha yendawo,-ulawulo olujolise kwintsimi, nokuba yintoni na{4}}kodwa ngaphantsi kwayo isekhona i-PWM itshintsha ii-IGBT ezintandathu kwibhulorho yesigaba sesithathu{5}}.

Umahluko kwesi sikali:

Abaqhubi besango bafuna izixhobo ezizimeleyo ze-15V. Yiloo mpahla emi-6 eyodwa edadayo kwisakhono esahlukileyo ukuya kuthi ga kwi-680VDC (ilungisiwe 480VAC). Umqhubi ngamnye ufuna amandla akhe, i-resistor yayo yesango (0.5-2Ω eqhelekileyo), ukhuseleko lwalo olugqithisiweyo.

Ixesha lokufa liyenyuka ukuya kwi-2-5µs kuba ii-IGBT zicotha kune-MOSFETs

Izihluzi ze-dv/dt kwimveliso ngenxa yokuba umthamo wentambo yemoto kunye neekona ezitshintsha ngokukhawuleza zibangela{0}}imisinga yendlela eqhelekileyo. Ndilinganise i-20A eqhelekileyo-imo yendlela yangoku kwintambo yemoto eyi-5HP, yahluke ngokupheleleyo kumji wemoto. Yiyo loo nto ufuna iintambo ezikhuselekileyo kunye nesiseko esifanelekileyo.

Thermal: ne-2% ilahleko ku-50kW yi-1kW yobushushu. Ukupholisa amanzi kunye nokutshintsha ukuhamba kunye nobushushu obudibeneyo. Ukuba ukugeleza kwesipholisi kuhla ngaphantsi komqobo, isilawuli sivala iziphumo ngoko nangoko. Iinkqubo eziboniweyo zivutha ngenxa yokuba kukho umntu olibale ukujonga inqanaba lokupholisa.

Ukhetho lwamacandelo luba lungaqhelekanga. I-IGBT enikwe umlinganiselo we-100A eqhubekayo inokusingatha kuphela i-80A kwi-50℃ambient, 60A kwi-70 degree. Kodwa ukuqala i-motor enkulu idonsa i-6x yangoku elinganiselweyo kwimizuzwana emininzi. Ke ngoko ubungakanani bencopho, hayi imo{9}}engazinzanga, uze unciphise ubushushu. Ukugqiba nge-300A IGBT yesicelo se-"100A". Iindleko ze-BOM zenza ukuba ukuthenga kungonwabi kakhulu.

Izibali zexesha ze-STM32: uninzi lune-16-bit PWM, ezinye iimodeli ziya kwi-32-bit kodwa awufane uyifune. Okubaluleke ngakumbi linani lokuthelekisa amajelo kunye neziphumo ezihambelanayo. I-TIM1 kunye ne-TIM8 kuthotho lwe-F4 zineendlela ezine ezithelekisayo nganye eneziphumo ezihambelanayo kunye nokufakwa kwenkqubo ecwangcisekileyo. Igqibelele kulawulo lweemoto.

Ingxaki: zonke iitshaneli ze-PWM kwisibali-xesha esinye zilungelelaniswa kwikhawuntara enye. Ukuba ufuna iifrikhwensi ezizimeleyo, udinga izibali-xesha ezahlukileyo. Kwaye zininzi kuphela izibali-xesha ezineempawu eziphambili. Kwi-STM32F4 ufumana iTIM1, TIM8 yolawulo oluphambili. I-TIM2-5 ye-PWM esisiseko. I-TIM9-14 yi-16-bit ngaphandle kwesizukulwana esifileyo. Uphelelwa ngokukhawuleza ukuba isicelo sifuna imiqondiso emininzi ekwanti ye-PWM.

Bona uyilo apho baluma khona-i-bang PWM kwisoftware kuba iphelelwe zizitsha zesibali-xesha. Umbono owoyikekayo. IJitter, iCPU ngaphezulu, inversion ephambili xa enye iphazamisa umlilo. Vele uhlawule i-$2 eyongezelelweyo kwi-micro enezibali ezininzi okanye usebenzise i-PWM IC yangaphandle (njenge-PCA9685). Ikamva lakho liya kukubulela.

I-ESP32 ineendlela ezili-16 zePWM esebenzisa iperipheral ye-LED PWM. Isandi esihle, ngaphandle kokuba zonke zithathwe kwiwotshi enye ye-80MHz APB kunye nezahluli zokwabelana ngokwamaqela. Ngaba ufuna iifrikhwensi ezahlukeneyo? Ndiyathemba ukuba ziyinani elipheleleyo. Kwakhona isisombululo siyehla njengoko sikhula rhoqo kuba sisebenzisa iwotshi esisiseko esifanayo. Kwi-20kHz ufumana i-12-bit, kwi-40kHz wehla ukuya kwi-11-bit, njl. I-Datasheet ayikwenzi kucace oku.

Ukusasaza -i-PWM ye-spectrum: endaweni ye-frequency esisigxina, uyayixuba ± 10% ngokungacwangciswanga. Ukusasaza i-EMI kuluhlu olubanzi lwamaza, kunciphisa ukukhutshwa kwencopho. Inceda ukudlula uvavanyo lweFCC/CE ngaphandle kokucoca izixhobo ezininzi. Uninzi lweetshiphusi ze-SMPS zale mihla zinale nto yakhelwe ngaphakathi. I-Cypress PSoC ikuvumela ukuba ulawule ipateni ye-dithering{6}}i-sawtooth, i-triangular, i-pseudo{7}}ngokungaqhelekanga.

I-Interleaved PWM: sebenzisa iziguquli ezininzi ngaphandle kwesigaba. Abaguquleli ababini kwi-180℃phase shift kuthetha i-input capacitor ibona isiqingatha se-ripple current. Iziguquli ezine kwi-90℃phase shift{4}}ikota yeripple. Kodwa ngoku ufuna ungqamaniso lwesigaba esichanekileyo phakathi kwamajelo kunye nokulinganisa umthwalo ukuze babelane ngoku ngokulinganayo. Ngokuqhelekileyo ufuna umlawuli ozinikeleyo we-IC ngaphandle kokuba i-micro yakho inezixhobo ezaneleyo.

Ii-GaN FET zinokutshintshela ngaphantsi kwee-10ns. Ivula i-10MHz+ i-PWM frequencies-i-inductors ziba zincinci, phantse nje umkhondo we-PCB. Kodwa: uyilo lwebhodi lubalulekile, isango lokuqhuba lifuna ingqwalasela enzulu, nakuphi na ukuthotywa kubangela ukudutyulwa okukhulu. Ayinabaqalayo. Ubone i-GaN design ring ukuya kwi-2x VDD kuba umntu usebenzisa umqhubi wesango oqhelekileyo kunye ne-5cm yobude bokulandelela. I-FET ayizange isinde.

PWM

Kwizinto ezininzi: 20kHz, i-hardware timer PWM, 10{{5}isisombululo sebit. Ininzi yolawulo lweemoto kunye ne-LED dimming. Yongeza umqhubi wesango i-IC (incopho ye-2A esezantsi ekhoyo ngoku), iminqwazi yeceramic ephantsi ye-ESR kanye kumbhobho we-FET, inqwelomoya etyebileyo. Jonga iifomati zokutshintsha kunye nomda kwiprototype yokuqala, lindela ukuphinda kube kanye.

Kuyo nantoni na engaphezulu kwe-10A eqhubekayo, ukulinganisa okushushu phambi koyilo. Ndisebenzisa i-ANSYS kodwa ne-FEA esisiseko ibamba uninzi lweengxaki. Thumela ngaphandle umaleko wobhedu kunye neelahleko njengemithombo yobushushu, misela iimeko zomda, khangela ukuba kukho nantoni na ebetha i-125℃junction temp at max ambient. Ngokwesiqhelo kufuneka iheatsinks okanye umoya onyanzelweyo ukuba utshintsha ngaphezulu kwe-50W.

Kwaye yivavanye kwiqondo lobushushu. Uvavanyo lweTemp yegumbi lubamba mhlawumbi i-60% yemiba. Ishushu-ibhokisi ekwi-70℃ambient kangangeeyure ezisi-8 ifumana okushiyekileyo{6}}i-thermal runaway, i- gate threshold shift, capacitor ESR yanda. Ndidle iveki kanye xa uyilo lusebenze kakuhle kwi-25℃kodwa i-FET yabambelela kwi-65℃kuba andizange ndiphendule nge-voltage ye-voltage coefficient.

Yi-PWM leyo. Ingcamango elula, iinkcukacha ezingenasiphelo.

Into yokugqibela: ukuba wenza ibhetri{0}izinto ze-PWM ezinikwe amandla ebhetri, musa ukuphelelwa lixabiso kwiiseli. Izame ezinye-azibizi gama ipakethe ze-lithium kanye-ayikwazanga kubamba i-ripple current, i-voltage ethotyiweyo phantsi komthwalo, inkqubo yonke yenziwe mdaka ngaphandle. Tshintshela kwindawo efanelekileyoionic lithium ibhetriIimodyuli ezineC{0}}ezifanelekileyo, ingxaki iphelile. I-$ 15 eyongezelelweyo ngepakethi indisindise kwiifowuni ezintathu zenkxaso ngeveki.