Current Amplifiers for 12V DC Motors

Jake Callaghan

I am currently working on a project to create a set of autonomous stage speakers. For this i have ordered 4, 12V DC motors, for which i need current amplifiers. I am planning on controlling these motors with an NI-Elvis breadboard using the LabVIEW environment. I was simply hoping for some consultation on which current amplifiers to use, the specs for the motors can be found at http://www.robotmarketplace.com/products/images/VEX-217-2000.pdf, also there are 4 of them so a 4 channel amplifier would be the most beneficial.

Many thanks.

over 12 years ago

0 John Caldwell over 12 years ago

TI__Genius 12325 points

Hi Jake,

Just to clarify, are you looking for a circuit to actually power the motors or rather amplifiers that allow you to view the current waveform that is being drawn by the motor?

0 Jake Callaghan over 12 years ago in reply to John Caldwell

Prodigy 30 points

Ideally what i'm doing is using the labview environment to control the motors, the problem is that the current on the labview outputs via the NI-Elvis breadboard isn't high enough to run the motors. So what i need is an op-amp that will amplify the current so that the labview environment can control the motors, i guess in response to your question i'm looking for a circuit to actually power the motors.

0 John Caldwell over 12 years ago in reply to Jake Callaghan

TI__Genius 12325 points

I had a feeling that's what you were getting at. Do you have any specifications for the motors and the waveform you're going to be driving them with? That might help us narrow down an opamp that meets your needs. Also, if they consume a large amount of current, the motor drive forum might be a better place to turn (pun?!) for advice on an IC specifically designed for driving motors rather than an opamp.

0 Neil Albaugh over 12 years ago in reply to Jake Callaghan

Genius 5430 points

Jake;

Those motors draw 69A at full load and 133A at stall. This is going to take a big MOSFET switching driver.

0 John Caldwell over 12 years ago in reply to Neil Albaugh

TI__Genius 12325 points

Jake,

My mistake, I missed the pdf in your first post! Neil is correct, an opamp is not the way to drive a motor of this size. The preferred solution for a motor of this size is a MOSFET bridge that is controlled by a PWM signal because it is much more efficient. Looking closely at the PDF I noticed that it says "First Robotics", if these are the First Robotics motors that I've personally seen I know that students in the competition use a motor driver based on a stellaris MCU and TI gate-drivers to power the MOSFET bridge.

0 Bruce Trump over 12 years ago in reply to John Caldwell

Guru 21975 points

Jake,

There is an E2E forum specifically for motor drivers...

http://e2e.ti.com/support/applications/motor_drivers/default.aspx

Regards, Bruce.

Because of the Thanksgiving holiday in the U.S., TI E2E™ design support forum responses may be delayed from November 25 through December 2. Thank you for your patience.

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Current Amplifiers for 12V DC Motors