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control DC motor speed and direction

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olof102

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Hi,
me and a classmate is coming with a schoolproject where we're supposed to control 2 100W 12v DC motors using a computer.

We're looking for suggestions, can we do this through the computers parallelport or COM-port?

Do you guys have any wiring diagrams for circuits that we will need?

All suggestions are appreciated!

PS! We will be writing a program ourselves.
 

haker_fox

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olof102 said:
All suggestions are appreciated!
Key words are: H-bridge, microcontroller, motion control, motor control and etc. Google it and have a lot of examples, books, papers.
This theme is very very large. And it's impossible to answer all your questions here.
Best regards!
 

elrayes

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i prefer parallel port, much easier in interfacing just remember if you working under win XP you will need program to low level access to access your parallel port like "User port", also don't forget to use buffers like 74244 and 74373, it is very important to buffer the parallel port outputs/inputs.
you can use H-bridge IC L298, it is a dual h-bridge IC which mean you can control two motors through it, you can generate PWM signal from the parallel port and connect it to the enable of the IC, you can use either C/C++ or Matlab to interface parallel port.
good luck
 

Naveed Ahmed

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Dear it is better to use Microcontroller.

1) Connect Microcontrollers serial port with COM port of PC.

2) Connect Motor through H-Bridge circuit with microcontroller.

3) Program your Microcontroller.

4) Using your defined commands, control the motor through PCs serial port.


Thanks

Regards
Naveed Khowaja
 

haker_fox

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elrayes said:
ou can use H-bridge IC L298, it is a dual h-bridge IC which mean
you can control two motors through it

I think 100W dc motor is too power for L298. Guys should to use MOSFETs.
 

elrayes

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then you can use two IC's of the L298 in parallel, or build you H-bridge using MOSFETs like "haker_fox" mentioned.
 

Peter Nachtwey

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If you are doing this in a serious way you should use PWM but if you are just supplying a DC voltage then look at this.
https://www.engin.umich.edu/group/ctm/examples/motor/motor.html
There are other useful links on the bottom of this page.

PWM requires that you have a very fast means of switching the pulses. I would use a micro controller or better yet a DSP for this.
 

hameeds01

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to vary the speed of DC motors u need PWM signal, it can be generated via software programming, in order to keep the hardware simple use parallel port + H-bridge Driver
 

haker_fox

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hameeds01 said:
to vary the speed of DC motors u need PWM signal, it can be generated via software programming, in order to keep the hardware simple use parallel port + H-bridge Driver
Also this IC needs the external drivers to drive the MOSFETS (especially the upper ones) and to have a dead-time. Fellows should pay attention to app notes on www.irf.com.
 

ali_aku_suka_telo

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I thing the most challengged in your project is about the current that drawn by DC motor, 100 W at 12V it mean almost 10 A for one motor ( in no load and not starting current);if your DC motor is series DC Motor its more worst, so you must make a sufficient driver for the motor , and you say that its at 12 V , if its held constan, you didnt need PWM , but if 12 V its maks voltage motor, and its can be varied , you need a chopper to make PWM pulse (ussualy chopper freq at 2o kHz, for minimlize filter)...so god bless for you... ali
 

olof102

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Hi,
it's been a while. We've been working on our project, the chassi is finished and we managed to get 12V 7,2Ah batteries.

We've got to that point where we need something to interface with the parallelport.
A H-bridge seems good.

Any examples of a H-bridge which can handle the current?
 

xxtigerxx

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haker_fox said:
hameeds01 said:
to vary the speed of DC motors u need PWM signal, it can be generated via software programming, in order to keep the hardware simple use parallel port + H-bridge Driver
Also this IC needs the external drivers to drive the MOSFETS (especially the upper ones) and to have a dead-time. Fellows should pay attention to app notes on www.irf.com.

do you know where is the application on irf site?
 

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