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DC motor control with fixed ground

libertador_23

Jun 15, 2010
4
Joined
Jun 15, 2010
Messages
4
Hello everyone!
A new user here.
Thank you for sharing and helping!

Well, the thing is I am designing a DC motor (12V-2A) control but with a special characteristic, this motor has one terminal always fixed to ground so a full bridge is not possible.
This motor has to turn only in one direction but for inertia reasons I must design a braking system, and in this case I would use the "plug" method, which I think is the fastest one.
To use the "plug" brake I must reverse the voltage but I can't use any batteries or any external source. If I need a source it must be taken from the motor main source.
So I thought I could use an inverting switching regulator (5A) to obtain a negative voltage so I use three MOSFET for operation:
1- Connects the free terminal of the motor to the main source (12V)
2- Connects the free terminal of the motor to the negative source (-6V)
3- Connects the free terminal of the motor to ground so I can sense back EMF to prevent reversing the movement.

What do you think about that system?
What other options do I have?

Well thank you for your help!
Best regards,
libertador_23
 

Laplace

Apr 4, 2010
1,252
Joined
Apr 4, 2010
Messages
1,252
I had never heard of plug braking so I looked up the Alltrax document explaining what is plug braking.

http://www.alltraxinc.com/files/Doc120-044-A_TN008-What-Is-Plug-Braking.pdf

That document has the following passage. "Plug braking commonly found on electric forklifts, walk behind pallet stackers and other applications where the operator is constantly changing direction. Plug braking not used during normal braking operations. It only comes into play when the motor direction is reversed."

Yet your motor will only turn in one direction. I am confused.
 
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