motor controller

Hi.
any body know any way to controlling the speed of power dc motor (brushed )(power=1 KW ) by the microcontroller ?
Any help is appreciated .

i have builded a chopper for a DC mottor 48V mail me @ vat.ciprian(_at_)gmail.com for schematics and components.

hi . i don't understand . if you can please send that file to my email : abolfazlk873(_at_)yahoo.com
very thanks for your help .

Abolfazl,

The most efficient speed control is by using pulsed DC. Speed is controlled by varying the duty cycle of the DC pulse. A web site with DC motor control theory is: http://homepages.which.net/~paul.hills/SpeedControl/SpeedControllersBody.html .

There are lots of sources for DC controllers. An internet search for "DC motor controller" will give lots of sites with controllers and how-to information. One such site is http://www.robotshop.com/all-brushed-motor-controllers.html .

Jim.

...really the most efficient speed controller relies on the application. There are a few schemes through which a, specifically brushed DC, motor can be controlled. While one could use a H-bridge in order to switch the current direction through the motor, as given in your link (which I found to be pretty insightful), one could also use a dual supply and a variable voltage supplied to the motor allowing for a full voltage swing from the negative supply to the positive(disregarding losses, of course). Where the PWM method works and is my most used method, due to its simplicity and capability to be driven, however indirectly, by a digital device(Darlignton Pairs, MOSFET drivers, etc.), if positional accuracy is the main requirement, then the dual supply mode is a must.

What does the DaVinci Robot use? http://en.wikipedia.org/wiki/Da_Vinci_Surgical_System
Would the jerkiness(as described in your link), however minimal, be acceptable while operating on a human? In this instance where accuracy is required, a dual supply is essential to the efficiency of the robot, so as to not sever a limb or something.

-Tim

Tim,

An application like the DaVinci robot will not use brushed DC motors. It will use BLDC, and most likely PMSM motors with some form of Field Oriented Control which is in essence Alien Technology. What you get is a motion with so much quality, the Terminator looks like an Osterizer blender.

You can get better performance out of a brushed DC motor if you use an H Bridge with INx interface and apply center aligned PWM's at each input. This is the best algorithm I have seen so far. But in my experience, using a single PWM with a PHASE/ENABLE H Bridge gives good enough results. Like you said, it depends on the application.

Here is a link of a video I recorded some time ago detailing some of the aspects of brushed DC motor control. http://www.youtube.com/watch?v=wk90pkso-4w&feature=relmfu

Yes, the DaVinci robot would not be using a brushed DC motor, I was simply drawing a comparison between the control capabilities of an H-bridge and a full dual supply swing, where the H-bridge type control would be too unstable. Perhaps I should have clarified this in my previous response...

Simply from a control system standpoint, attempting to get a multiple-order system to approach a single output when only on or off states are allowed introduces a much more complex system to control, as opposed to continuous or discreet steps within fully-on and fully-off.

Stepper motors would be the way to go, I'd think, though the step resolution would have to be to spec.