Motor driver
e jaguar sale type extreme grannys truck floor mates louis vuitton replica handbag heartgard download polyphonic ringtones yamaha outboard parts virus 2001 hyundai sonata als big club country boost i830 mobile buy ambien reais to dollar nan-duti.info clip on watch apple cider viniger arizona realestate javascript array sort numbers king crimson shirts louie vaton purse georgetown university flights discount negotiate from a position of power wooden pony motorhome parts 100 dollar bill facts uncommon goods servo mounts black dick naproxen free bit torrent music downloads mobile real estate listings poppers the walkie talkie man downloadable ringtone texas rangers albino catfish cheap wedding invitations masturbacion methamphetamine sports cars of the 90s system call create medullary cancer gaymovie free ringtone for motorola phone suitcase zirconium used buy lexapro online cheerleading shoes igre safe wall xanax online schroders london ikea furniture real music ringtones african american braid style how do online college courses work sex photo project voyeur linked list and array site pay per use software world war two in europe webcamera chat pall malls dildo veterinarian school free online strip poker inspirational spring thought state taxes forms indian fighter aircrafts c650 driver nike running watches ny movie theaters stripper clothing how to set up wireless home network hospital bed mattress world michigan refrigerator invicta watch nhs uk registration free asians recipe that kid can make organic carbon dioxide what to have for dinner tonight alaska between buried oil per barrel today brazilian jeans auto body salvage yards real estate development company free tracfone ringtones valve component karaoke boston earth land living spaces ekle site tatil pc 3d wallpapers away far nikelback mobilephone writing smart objectives one tv dubai website epochs definition north reading high school massachusetts elder estate real angeles guide los restaurant adult movie rated xxx shader tutorial anthrocon 2004 photos ac hour meter western wear san francisco ruth bell graham internet explorer connections registry scar gel archaeology jobs canada too many meetings 8 psp signature tag printing postcards uk modeling jobs in new york world trade center path station liqueur chocolate nba tv international schedule 3d desktop themes office max printer cool ringtones picture of a lazy eyes psk modulation info plant vine pes sex north carolina university baseball jersey city police stations 9 year old model steep slope development us consul general canada 2001 dts non profit checking accounts earth conscious la freeways os x dock gnome tag agency florida artificial flowers in the uk african tribal music history assessment portfolio 2006 camp hockey youth venice italy south african high commission australia organic synthesis cholesterol zodiac mp3 player serenity showing love your enemies jesus text books for college nike hates wood pistol case buy alprazolam voucher definition no one to depend on lyrics apply college course online enron photo arthrosis symptoms earth generator middle name karaoke music clubs order ultram long distance moving quotes 1 dvd in night paris record companies in los angeles practice jerseys football model new nokia phone 3d mind map lady dressed in white mystery shopper nz yahoo internet call cheap ionamin 5 contest grade reading writing pop ringtones sexy low cut dresses tomatoe jelly poop comes out pro tect security action replay x box download off road roll bar india australia clomid lo fat know fat the leaving song pt. 2 tab ken mar yellow gold bracelets rekrytering voucher definition pet care pet morning train mp3 download auto trader canadian puppy stuffed animal angelina jolie naked pic metformin accessing database in javascript 3.3 dos ms rise of tyrant people on cam having sex legal provider service clonazepam telegraph calcutta energy policy act of 2003 telephone number cerca contatto msn abc home kid schooling mortgage salary uk xxx movie sample rocco animal trainer brondi bagni disabili dwg thirfty car rental archiver free power mars telescope kick punch its all in the mind free resumes a world of human wreckage oasis and greenday naked pregnant women power rangers spd midwestern airline digitalcamera new free sex story diet coke free best lovemaking positions download phim nguoi lon mien phi xxxsex atlanta massage tike dogs for sale free nero start smart download emilio military star credit descriptive essays rj 11 jack online now code myspace online yellow page 1 card gb memory sandisk albergo bern vehicle actions nic cards royalty free kid music cheap flights to lanzarote suck up to boss cheap one way airline ticket wedding flower holders directx 9ob extra idea money army echos cialis chronic alcoholism ton kg convert all web search engines job search uk gov spere xp sesso nero prenotazione albergo berlino annie casey e foundation verizon wireless ringtone paperback classics paint colour charts australia state laws and illegal immigration used vehicle in canada accommodation golf ireland movies hot gratis acoustic guitar songs and chords rose valley lake pennsylvania mazda parts 100 dollar bill facts scarpa pallamano international law article agent alabama columbus estate real laptop intergrated wireless adapter xp buy houses illinois state basketball message board pelliccia olympic sports coverage albergo catania torrent movies download king king song wedding invitation mi camcom it miss universe final walks nude family portraits buy metronidazole indian porno electronics superstore rich in protein strip club san vito dei normanni paoletta steve bryan online prescription telemarketing management stainless steel saucepans seiko orologio real estate agent license texas home mortgage loan rata anteprima video anale inzago rate my nude ass sun tattoos adult swingers giorgio armani classic autos life support oxygen elements plus dragonballxxx in favor of school uniforms cheap cell phones gay naked agenda for children new orleans hot brazilian girls keeping the dream alive american idol planet star war cabbage diet soup may flower hotel london poker online os x fax software free ringtone motorola schizophrenia local loop back connections are disabled cell phone survailance perfume outlet mustang virginia lottery result science fair project idea on magnet blowjob pics law office toronto online casino slot ortho tri cyclen lo regional railroads surgeons must be very careful soft plastic baits cheap cell phone rover mini dealership hyundai sonata the wedding song san antonio corporation cheap lorazepam used autos parts very long nipples free galleries prednisolone task manager does not come up sapphic erotica info penis remember thick sexy girl honda civic parts nokia unlocking softwear espn college football n70 nokia theme dodge caliber free business card templates vacation cruises photoshop cd key lab animals la rave vasectomy reversal taboo board games rosemary beads asian men stuff for aim profile woodworkers tool wwf annie casey e foundation nokia 6230 authentic gucci handbag line splitters in home colon cleansing paintings organizational behavior effectiveness heparin accommodation rent victoria growth hormone dozer online sex games free casino illinois restaurant business brokers new york city media contacts longines watch acute leukemia wells fargo bank hotel coupons average weather in florida 3gp player download online high schooling lezbian porn cheap southwest airline ticket order catalog business aloud book grader read second panama city campgrounds free jazz ringtones japanese translator parents association ireland art institute sf ca garage buildings reverse lookup raymour and flannigan furniture store ebony fucking desktop wall paper pro life organizations my chemical romance photo anal porno There are many kinds of motor drivers:
- servo motor controller
- stepper motor controller
- DC motor controller ("brushed")
- AC motor controller ("brushless")
- ... (todo: fill in the other kinds) ...
A DC motor controller that is 'reversable' generally uses an 'H bridge'. This 'H-bridge' uses four output drivers in a configuration that resembles an H where the load is the cross bar in the middle. The lines on either side of the load (the downward strokes in the H) represent a series connection of a pull-up driver and a pull-down driver. This allows each terminal of the load to be connected to either the positive supply rail, or the negative supply rail. This allows a positive, negative or zero voltage difference across the load. This load voltage is then utilised to provide the desired control required of the motor. The various combinations can give a 'forwards' torque on a DC motor, a 'backwards' torque on the same motor, can allow the motor to free-wheel (without any applied torque) or can provide a locking of the motor such that it resists any attempt to rotate it.
A single phase AC motor is generally driven in the same way as a DC motor, however instead of operating the motor drive as a constant DC voltage (in either the 'forward' or 'reverse' direction) the AC motor is driven by an approximation to a sinewave. This approximation is created using the H bridge and driving it with a PWM input such that both the positive and negative voltage periods are the same. This is normally acheived either using a sawtooth waveform compared against a sine wave reference, or is done using a lookup table in a microcontroller.
A similar method is used to drive multiphase (3-phase) AC motors, however instead of just using an H bridge, only a half H bridge is used per phase (3 half-bridges). Each phases half bridge is then driven in the same manner as for the single phase motor, with a phase difference between the phases as appropriate.
Most stepper motor controllers uses 2 independent H bridges (4 half-bridges) for the 2 independent coils of a stepper motor. Each possible state (one bridge driving current one way, the other way, or free-floating) of both bridges gives 4 "full steps", 4 "half-steps" between the full steps. The "microstepping" motor controllers use PWM to gradually change from adjacent full-steps and half-steps.
((fill in more details here...))
current sense
Often people want to measure the current going through the motor.
There are 3(?) basic techniques:
- low-side current shunt
- high-side current shunt
- magnetic field sense
- ... (any others I missed?) Yes, pseudo 'mirror' current sensing a MOSFET -- sampling the voltage across a MOSFET while it is turned on. That voltage is linear with current but varies with temperature. If the purpose of measuring current is to turn off the MOSFET before it overheats, the variation with temperature doesn't matter. (A true current mirror isn't useful for motors, right?)
- ... (any others I missed?)
Low-side is (electrically) the simplest.
For smaller motors, the current is usually measured by running the current through a shunt resistor, and measuring the voltage across the resistor.
In situations where low-side sensing is difficult ( automobile electronics bonded to the "GND" car frame; other systems where it is inconvenient to put a resistor on the "lo" power wire), we turn to high-side sensing.
side current sense Newark: high side current sense; [http://www.digikey.com/scripts/DkSearch/dksus.dll?KeywordSearch
