Motor driver
sito ufficiale resident evil apocalipse aria givanni i due avventurieri paltrow sexy rintracciare cognome persona spartiti modena city ramblers yugioh duel monster juglans sorteggi champion league hotel augustus rimini ronnie wood far east man epl 6100l modelle di lusso fiat napoli abbigliamento uomo moschino laica accessori elettrostimolatori prodotti per parruchiere roberto lumia potter beatrix jennifer lopez j lo accessori dx 7630 qtek pocket pc montgomery clift cantone www ilmessaggero it hdd maxtor 300gb sata 7200 rpm 16mb telefoni double booble www games com se io se lei ram 72 www f c inter it www bianchi it awt9120 carlo 999 vaa pensiero immaggini per lutto mms cordless telecom webcam free live bikkemberg calzature uomo za za za grupo climax atlantis router a02 foto villa mare camera spoleto quark x press patch gallerie di foto porno gratuite roma kiev cavallino d oro casse 2 satelliti creative labs webcam nx pro che bella cosa sei batterie al litio nokia 3310 teddy reno video torture americane jeux de maths asciugatrice classe energetica a universal prayer tiziano ferro cd telemovil el salvador com piracicaba juegos atenas 2004 edoardo vianello frank elliott provini film porno hot chocolate lavoro crociere musica teenporn danym titoli hit mania dance 2004 ragazzo di strada mappa provincia di latina more free rimini eros nec 72vm francesco libero it lumberjack bari canon fax b 160 continente americano lets go val di canneto kingston memory card tempete cantantes italianos bubbin rappresentanti adidas plasma 42 pollici a parete tv televisori foto dalla a alla z toom raider muvee disco fisso free download mac video games gratis il volo dell angelo hd 2 5 5400 camera guidonia lourdes tarbes panasonic digital le dolcezze del peccato foto annunci coppie esibizioniste hp 4300 so called chaos 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 meas 1000 ure 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?)
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
