DC Motor Speed Control - Ideas & Circuits

AI Thread Summary
The discussion focuses on designing a speed control circuit for a 24V DC permanent magnet motor, specifically for a car park barrier application. Key suggestions include using H-bridges for bidirectional control and implementing PWM for speed regulation, with a recommendation to utilize a 555 timer for simplicity. The user emphasizes the need for the motor to operate at two speeds in both directions and to hold position when limits are reached, without requiring precise position control. Participants highlight the importance of understanding control systems and suggest that microcontrollers can simplify the design process. Overall, the thread provides valuable insights and resources for building an effective motor control circuit.
levoeg
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dear members
i want to design speed control circuit for 24v dc permanat magnet motor in both direction if anyone have ideas or circuits please post here. it may be great help to me. Thanx in advance
 
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Look into H-Bridges.
 
Unless you have a reasonable knowledge of control systems, this is difficult task. Basically you should install a tachometer in the output of the motor, compare the output of the tachometer with a reference voltage and feed the difference to a power amplifier which will drive the motor windings.
 
SGT said:
Unless you have a reasonable knowledge of control systems, this is difficult task. Basically you should install a tachometer in the output of the motor, compare the output of the tachometer with a reference voltage and feed the difference to a power amplifier which will drive the motor windings.

Wow, that's somewhat complex
:biggrin:

A simple H can be made with as few at 4 transistors and 4 resistors. A more reliable solution would use 6 or so. An optimal solution would use a few mosfets. You can use PWM (a 555 timer would actually work here) to control the speed. Controlling a motor is not that hard:

http://www.bobblick.com/techref/projects/hbridge/hbridge.html
http://www.mcmanis.com/chuck/robotics/tutorial/h-bridge/
http://www.dprg.org/tutorials/1998-04a/

You can make things more difficult if you want to or need to; however, microcontrollers do simplify the entire design process.

levoeg, what exactly do you need from your controller? Current requirement, means of control, size of controller, cost requirement, intended use...
 
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dear members
thanx for the posts here. actually i want to use this for car park barrier.the existing one having problem very often so i am trying to replace that with this circuit. the rest of the control circuit no prob for me i mean power source, sensors, and limit swtches etc.. i want the motor should run in two speeds in both direction and hold when the limit is reached(less power to ensure it is not free fall). here is no need of encoders or tachos as it doesn't need precise position control
 

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