DC Motor Control

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Anonymous Poster	DC Motor Control 02/06/2006 10:14 AM
	RonG writes: Looking for a DC motor control. Here's the application: Trying to run a progressive cavity pump with a Baldor 1/2 hp motor (cat# CDP3430-V24?). The pump outputs fluid every time it makes a revolution. Currently controlling the revolutions on the pump with an custom-built (and expensive) Axiomatic controller that is not doing the job. Would prefer DC (24VDC), but the problem with some DC versions is that they don't have a wide enough range... (will be inputing anywhere from 9-36 volts, to get an output of 24V). The controller will need to output in milliamps... that will control the revolutions on the pump. As example, 4mA from the controller might make the pump not turn at all... while 20mA would make the pump go to 1800rpm. This needs to be linear. Also, the controller needs to be current-limiting, ie if the pump were to freeze, and the controller saw that it was pulling way to many amps, then the controller would shut down. Any suggestions certainly appreciated.
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shooter Power-User Join Date: May 2005 Posts: 161 Good Answers: 2	#1 dc speed controller 02/06/2006 3:11 PM
	Check out Mcmaster Carr,www.mcmaster.com, search for low voltage dc motor controller and one will show up for about $300, looks like what you said you needed.
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MD Active Contributor Join Date: Jan 2006 Posts: 18	#2 DC Controller 02/06/2006 4:57 PM
	A brushless DC motor would be best. You get more control and more torque for the current. Typically, motor speed is controlled with a constant voltage, but using PWM (pulse width modulated) signals. PWM allows more torque and the ability to operate at lower RPMs without a stall. Search the web for controller boards and learn the vocabulary. Brushless DC (BLDC) motors will be something to consider.
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Anonymous Poster	#3 In reply to #2 Re:DC Controller 02/06/2006 9:50 PM
	If a DC motor is preferred, a switched-mode regulator is the way to go. There a hundred of standard units available; or a custome one could be designed. Why is the voltage regulation range of the power so wide? Bob
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Bill Guru Join Date: Dec 2005 Location: Clemson, South Carolina Posts: 1722 Good Answers: 18	#4 Pump Control 02/07/2006 9:38 AM
	What determines that the pump needs to speed up or slow down, the operator, or the process? What kind of feedback is there? When you say progressive cavity pump, I assume you mean a helical rotor pump. Is that correct? What about the fluid you're pumping? Does it vary in viscosity or have solids in it? The only reason I'm asking so many questions is that you seemed to want to know how to do it economically and reliably. What you want to do is easy when money is not a factor. __________________ We have met the enemy and he is us . . . Walt Kelly
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Grant Commentator Join Date: Dec 2005 Location: Okanagan Valley, BC Posts: 69	#5 motor control 02/07/2006 11:49 PM
	Contact AC Motor Electric and ask for Dave, these guys are electric motor gurus. dave@acmotorelectric.com __________________ I love this site.Thanks to everyone that makes it possible.
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Anonymous Poster (1); Bill (1); Grant (1); MD (1); shooter (1)

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