control DC motor speed and direction

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olof102

Joined: 19 Sep 2009
Posts: 6
Location: Sweden

22 Oct 2009 7:48 control DC motor speed and direction

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

Joined: 24 Jun 2009
Posts: 51
Helped: 4
Location: Russia, Irkutsk

26 Oct 2009 1:52 Re: control DC motor speed and direction

olof102 wrote:

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

Joined: 03 Jun 2008
Posts: 164
Helped: 8
Location: Egypt

31 Oct 2009 16:38 control DC motor speed and direction

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

Joined: 31 Aug 2008
Posts: 22
Location: Pakistan

31 Oct 2009 17:27 Re: control DC motor speed and direction

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

Joined: 24 Jun 2009
Posts: 51
Helped: 4
Location: Russia, Irkutsk

02 Nov 2009 1:44 Re: control DC motor speed and direction

elrayes wrote:

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

Joined: 03 Jun 2008
Posts: 164
Helped: 8
Location: Egypt

02 Nov 2009 11:18 control DC motor speed and direction

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

Joined: 10 Nov 2009
Posts: 3
Helped: 1
Location: Vancouver, WA

10 Nov 2009 16:12 Re: control DC motor speed and direction

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.
http://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.

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hameeds01

Joined: 23 Aug 2005
Posts: 308
Helped: 15
Location: NUST Islamabad

10 Nov 2009 17:28 Re: control DC motor speed and direction

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

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haker_fox

Joined: 24 Jun 2009
Posts: 51
Helped: 4
Location: Russia, Irkutsk

11 Nov 2009 3:57 Re: control DC motor speed and direction

hameeds01 wrote:

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.