Chii chinonzi PWM?

PWM inomirira Pulse Width Modulation. Uri kubatidza kana kudzima voltage panguva yakatarwa, uchichinja reshiyo ye-nguva kuenda kudzima{2}}kuti udzore avhareji yekutumira magetsi. Ndizvo. Zvimwe zvacho zviri kungotarisana nemigumisiro yacho.

Tora 12V wekupa uchityaira LED inoda 3V. Kazhinji iwe waizoshandisa resistor kana linear regulator, kupisa 9V sekupisa. Kurasa benzi. NePWM unobatidza nekudzima 12V izere nekukasira zvekuti thermal mass yeLED inoiisa pakati pe. 25% duty cycle inokupa inokwana 3V yakaenzana. Iyo LED inoona 12V → 0V → 12V → 0V pamwe 1kHz, asi haigone kutonhora pasi uye kupisa nekukurumidza kudaro, saka kupenya kunoramba kuripo.

Frequency inokosha. Kunyanya kunonoka (pasi pe100Hz) uye unowana kupenya kunooneka. Vamwe vanhu vanoona flicker kusvika ku200Hz. Ndinowanzo mhanyisa LED dimming pa20kHz kuti ndingochengetedzeka-zvinoita kuti ibude kunze kwerinonzwika kana paine machira ekubatanidza. Kuchinja kumhanya kunokanganisa kurasikirwa zvakare, asi isu tichasvika kune izvo.

Masvomhu: kana nguva yako iri T uye pa-nguva iri t, duty cycle D=t/T. Simple. Simba rinounzwa rinenge D × V_supply × I_load, kubvisa kurasikirwa. Kurasikirwa ikoko ndiko kunofadza zvinhu.

Chikonzero chekutanga: kushanda zvakanaka. MOSFET mune saturation inodonha pamwe 0.1-0.2V panguva inonzwisisika. MOSFET yabviswa inodhirowa mamicroamps. Saka unenge uchidzinga (0.1V × ikozvino) kana kuti hapana. Enzanisa izvozvo kune mutsara regulator inodonhedza 9V panguva yakazara ikozvino. Musiyano wehupenyu hwebhatiri ndeye 40-50x mune dzimwe nguva, kwete kuwedzeredza.

Chechipiri: unogona kushandisa magetsi akachipa. Unoda kutyaira mota ye48V pakumhanya kwakasiyana? Iine analog control iwe unoda inodhura chinja 0-48V yekupihwa. NePWM unoshandisa yakagadzika 48V kugovera (yakachipa) uye MOSFET (zvakare yakachipa). Ndapedza.

Chikonzero chechitatu hapana anotaura nezvazvo: kutenga. Edza kutsvaga yakanaka inosiyana analog supply muhuwandu. Nguva dzekutungamira imavhiki makumi maviri nematanhatu kubva kune vagadziri vane hunhu. MOSFETs? Zvese zviri mustock kuDigikey. Kana kugadzirwa kuri kupopota kwauri, izvi zvinonyanya kukosha kupfuura mutengo weBOM.

PWM

EMI ichakukuvadza. Pekutanga -pazvino PWM board (120A yeDC motor), yakauraya bhazi reCAN pamotokari imwe chete. Mapaketi asina kushatiswa-akafa zvachose. Yakaburitsa kurira kwegedhi rangu rekutyaira kwaibatanidza nepasi chechasi, ichisimudzira 40V spikes paCAN musiyano wepairi. Yakawedzerwa ferrite beads, yakafambiswa nhandare, ichine nyaya. Pakupedzisira ndaifanira kuwedzera pi sefa pamagetsi uye kupatsanura ndege dzepasi ne-poindi imwe chete yekubatanidza. Akatora matatu board revs.

Kutyaira kwegedhi kwakaoma kupfuura zvazvinoita. Unoda kukanganiswa kwakaderera kubva kumutyairi wako kuenda kugedhi reMOSFET-kutevera inductance nyaya pahigh di/dt. Ndakaona 10nH yetrace inductance inokonzeresa 50V voltage spikes panguva yekuchinja (V=L × di/dt). Izvo zvakakwana kubaya kuburikidza ne60V yakatemerwa MOSFET. Vanhu vanopokana nezve masvomhu asi ini ndazviona pachiyero: 3A/ns kushandura ikozvino mu10nH inokupa 30V spike. Wedzera iyo yekugovera voltage uye iwe uri pamusoro peiyo absolute yepamusoro rating.

Zvino pane kupfura{0}nemuH{{1}mabhiriji. UNOFANIRA kuva nenguva yekufa pakati pekudzima yakadzikira-side FET uye kubatidza divi repamusoro-(uye zvichipesana). Zero deadtime inoreva kuti maFET ese ari maviri anozviita panguva imwe chete-kunanga kupfupi kubva pakutengesa kuenda pasi kuburikidza neFET channel resistance. 50A kusvika 0.01Ω kaviri ichiri 1000A yemamicroseconds zvinhu zvisati zvaputika. Iyo yekutadza maitiro inoshamisa: diki crater musilicon, FET inoenda zvachose ipfupi, inoburitsa zvese zvimwe mucheni.

Asi nguva yakawandisa yekufa uye diode yemuviri inoitisa panguva yekufa. Madhidhiyo emuviri anotyisa{{1}kudonha kumberi kwepamusoro (1-2V), kunonoka kupora. Iwe unorasikirwa nekugona uye kuburitsa kwakawanda kupisa. Kutengeserana kunowanzo 100-500ns nguva yekufa zvichienderana nekuchinja kweFET yako.

Masikirwo emunhu wese ekutanga: yakakwirira frequency=madiki inductors/capacitor=zvakachipa. Dzimwe nguva chokwadi. Asi kurasikirwa nekuchinja kunowedzera nekuwanda-uri kupera simba pese panochinja FET. ESwitching ≈ 0.5 × Vsupply × Iload × (trise + tfall) × fsw. Kaviri iyo frequency, kaviri kurasikirwa kwekuchinja.

Pamadhiraivha emota, 20kHz yakajairika. Pamusoro zvinonzwika, michini nguva isingachinji haina basa. Asi mumagetsi elaptop unoona 300kHz-1MHz. Sei? Madiki magineti. Iyo 1MHz inductor ndeyemuviri 1/50th saizi ye20kHz imwe ine yakafanana inductance. Iyo yakakura kune inotakurika zvishandiso. Kutengeserana ndiko kuti unoda kukurumidza maFET (yakaderera Qg), dhizaini iri nani, kungwarira dhizaini dhizaini.

Audio (Kirasi D amps) inoita 250kHz-1MHz. Pazasi pe200kHz uye unokwanisa kunzwa mafambiro emutakuri semutsindo wepamusoro-wakakwidza. Pamusoro pe1MHz uye unotanga kurwisa nekukanganiswa kweredhiyo ye AM. Mazhinji magadzirirwo anogara pa400-500kHz, yakaderera-pass sefa pamwe 50kHz kubvisa mutakuri.

Muenzaniso chaiwo: yakaita 500kHz buck converter kamwe chete, yakaedza kuenda ku1MHz kudzikisa bhodhi. Kubudirira kwakadzikira 4% (88% kusvika 84%). Ndiyo 8W yekuwedzera kupisa mune 200W inopa. Inodiwa heatsink yakakura, yakarasa yese yekuchengetedza nzvimbo kubva kune diki inductor. Yakagara pa500kHz.

PWM

8-bit PWM (matanho 256) inonzwika zvakanaka kusvikira waedza kudzima LED zvakanaka kubva pa100% kusvika pa0%. Pazasi pe10% yebasa kutenderera unowana matanho anooneka mukupenya. Ziso remunhu ndiro logarithmic-yakanyanya kugadzikana kune shanduko pamazinga akaderera emwenje. Inoda 12-bit (4096 nhanho) shoma yekutsvedzerera dimming pazere rakazara.

Asi heino kubata: 12-bit pa20kHz zvinoreva kuti unoda 20kHz × 4096=81.92MHz timer wachi. Haasi ese mamicros anogona kuita izvozvo. Uye kana iwe uchida akawanda akazvimirira PWM chiteshi pa12-bit, uri kutarisa akazvitsaurira timer peripherals kana FPGA.

Workaround: shandisa 8-bit PWM asi gadzirisa frequency zvine simba. Pakupenya kwepamusoro mhanya 20kHz, pakupenya kwakaderera kudonha kusvika ku100Hz. Inokupa nhanho dzakanaka paunoda. Asi ikozvino une shanduko-frequency EMI yekubata nayo. Hapana chemahara.

Industrial VFDs (variable frequency drives) chinja mazana emaamps pa480VAC. Nzira yekudzora yakanyanya kuomarara-muchadenga vector modulation, nzvimbo-yakatarisana nekutonga, chero-asi pasi payo pachine PWM ichichinja maIGBT matanhatu muchikamu chetatu-bhiriji.

Misiyano pachikero ichi:

Vatyairi vemagedhi vanoda 15V ega zvekushandisa. Ndiwo matanhatu ega ekushandisa anoyangarara pane akasiyana mikana anosvika 680VDC (yakagadziridzwa 480VAC). Mutyairi wega wega anoda simba rayo, rayo gedhi resistor (0.5-2Ω yakajairika), yaro yekudzivirira yakawandisa.

Nguva yekufa inowedzera kusvika ku2-5µs nekuti IGBTs inononoka kupfuura MOSFETs

dv/dt mafirita pane zvinobuda nekuti tambo yemotor capacitance pamwe nekuchimbidza maedges inokonzeresa-mode currents makuru. Ndayera 20A yezvakajairwa-modhi yezvino patambo yemota ye5HP, yakaparadzana zvachose nemotor current. Ndicho chikonzero iwe uchida tambo dzakavharidzirwa uye grounding yakakodzera.

Kupisa: kunyangwe 2% kurasikirwa pa50kW i1kW yekupisa. Kutonhodza kwemvura nemagetsi ekuyerera uye tembiricha inopindirana. Kana inotonhorera inoyerera ikadzika pasi pechikumbaridzo, controller inodzima zvinobuda nekukasika. Akaona masisitimu achitsva nekuti mumwe munhu akanganwa kutarisa iyo inotonhorera level.

Kusarudzwa kwechikamu kunowedzera kushamisa. IGBT yakarongerwa 100A inoenderera inogona kungobata 80A pa50℃ambient, 60A pa70 degree. Asi kutanga mota hombe inodhonza 6x yakayerwa ikozvino kwemasekonzi akati wandei. Saka iwe saizi yepeak, kwete kugadzikana-state, wobva waita tembiricha. Pedzisa ne300A IGBT ye "100A" application. Mutengo weBOM unoita kuti kutenga kusafadze.

STM32 timers: mazhinji ane 16-bit PWM, mamwe mamodheru anoenda ku32-bit asi iwe hauwanzo kuida. Chinonyanya kukosha ihuwandu hwekuenzanisa machaneti uye zvinopindirana zvinobuda. TIM1 neTIM8 paF4 nhevedzano ine mana anoenzanisa chiteshi imwe neimwe ine inopindirana mabudiro uye programmable deadtime kuisa. Yakakwana yekudzora mota.

Dambudziko: ese maPWM chiteshi pane imwe nguva anowiriraniswa kune imwechete counter. Kana iwe uchida yakazvimirira ma frequency, iwe unoda akaparadzana nguva. Uye kune chete akawanda ma timer ane epamberi maficha. Pa STM32F4 unowana TIM1, TIM8 yekutonga kwepamusoro. TIM2-5 yePWM yakakosha. TIM9-14 ndeye 16-bit pasina chizvarwa chekupedzisira. Iwe unobuda nekukurumidza kana application ichida akawanda ega ega PWM masaini.

Vakaona magadzirirwo avakaita{{0}bang PWM mumasofterth nekuti ashaya machanera enguva. Pfungwa dzinotyisa. Jitter, CPU pamusoro, inotungamira inversion kana imwe ichikanganisa moto. Ingobhadhara imwe madhora maviri kune micro ine yakawanda nguva kana kushandisa yekunze PWM IC (sePCA9685). Ramangwana rako richakutendai.

ESP32 ine 16 PWM chiteshi uchishandisa iyo LED PWM peripheral. Inonzwika zvakanaka, kunze kwekunge zvese zvakatorwa kubva kune imwe 80MHz APB wachi uye kugovana kupatsanura mumapoka. Unoda ma frequency akasiyana? Ndinovimba iwo ari integer ratios. Zvakare resolution inodzikira sezvo frequency inowedzera nekuti iri kushandisa imwechete base wachi. Pa 20kHz unowana 12-bit, pa40kHz uri pasi kusvika ku11-bit, nezvimwewo. Datasheet haiiti izvi pachena.

Kuparadzira-spectrum PWM: pachinzvimbo chenguva yakatarwa, unoikanganisa ±10% zvisina tsarukano. Inoparadzira iyo EMI kune yakafara frequency renji, inoderedza kuburitswa kwepamusoro. Inobatsira kupfuudza FCC/CE kuyedzwa pasina kuwanda kusefa Hardware. Machipisi mazhinji emazuva ano eSMPS ane izvi zvakavakwa mukati. Cypress PSoC inotokuita kuti udzore maitiro ekuita dithering-sawtooth, triangular, pseudo{7}}zvisina kurongeka.

Interleaved PWM: mhanyisa akawanda anoshandura kunze kwechikamu. Maconverter maviri pa180℃phase shift zvinoreva kuti inopinza capacitor inoona hafu yeripple current. Ma converter mana pa90℃phase shift-quater the ripple. Asi ikozvino iwe unoda chaiyo chikamu kuwiriranisa pakati pezviteshi uye mutoro wekuenzanisa kuti vagovane zvazvino zvakaenzana. Kazhinji inoda yakazvitsaurira controller IC kunze kwekunge micro yako iine zviwanikwa zvakakwana.

MaGaN FET anogona kushandura mukati me10ns. Inovhura 10MHz+ PWM frequencies-mainductors anova madiki, angangoita PCB traces. Asi: bhodhi dhizaini yakakosha, gedhi drive inoda kutariswa zvakanyanya, chero inductance inokonzeresa overshoot. Kwete kune vanotanga. Wakaona GaN dhizaini mhete ku2x VDD nekuti mumwe munhu akashandisa yakajairwa gedhi mutyairi ane 5cm yekutevera kureba. Iyo FET haina kurarama.

PWM

Pazvinhu zvakawanda: 20kHz, hardware timer PWM, 10{{5}bit resolution. Yakawanda yekudzora mota uye LED dimming. Wedzera mutyairi wegedhi IC (2A peak ikozvino shoma), yakaderera-ESR ceramic caps chaipo paFET drain, mafuta pasi ndege. Tarisa iyo switching waveforms ine chiyero pane yekutanga prototype, tarisira kudzokorora kamwe.

Kune chero chinhu chiri pamusoro pe10A inoenderera, yekupisa simulation isati yarongwa. Ini ndinoshandisa ANSYS asi kunyangwe yakakosha FEA inobata matambudziko mazhinji. Tumira kunze kwemhangura maseru pamwe nekurasikirwa sezvinobva mukupisa, isa muganhu mamiriro, tarisa kana paine chinorova 125℃junction temp at max ambient. Kazhinji inoda heatsinks kana kumanikidzwa mweya kana iwe uchichinja kupfuura 50W.

Uye zviedze patembiricha. Kuedza kwemukamuri kunobata pamwe 60% yenyaya. Kupisa-bhokisi rine 70 degrees ambient kwe8 maawa rinowana zvasara-thermal runaway, gate threshold shift, capacitor ESR inowedzera. Ndidyire vhiki kamwe chete apo dhizaini yakashanda zvakanaka pa 25 dhigirii asi iyo FET yakamira pa65 dhigirii nekuti ini handina kuverengera pachikumbaridzo voltage tembiricha coefficient.

Ndiyo PWM. Pfungwa iri nyore, mashoko asingaperi.

Chekupedzisira: kana uri kuita{{0}powered PWM zvinhu zvebhatiri, usadhure pamaseru. Wakamboedza-zita rekuti lithium packs kamwe-yatadza kubata ripple current, voltage yakaremerwa, system yese yakaita brown out. Kuchinjira kune kwayoionic lithium bhatirima modules ane C-rating yakanaka, dambudziko ranyangarika. Iyo yekuwedzera $15 pakiti yakandiponesa kubva kunhare nhatu dzekutsigira pasvondo.