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Topic: motor controller burnout (Read 444 times) previous topic - next topic

aerobyrd

so i had this motor controller here, http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=221043792022&ssPageName=ADME:X:RTQ:US:1123#ht_12869wt_932 rated at 36V 68A. I plugged it up to a motor of 12v and around 12-15 amps. It ran fairly well. I then plugged in a second identical motor to the controller. It didn't drive the motor (which may have been a programming issue somehow, not sure). so i unplugged the signal and the motor controller immediately fried. what happened? and more importantly, how can I keep it from happening again?
Thanks,
Ryan

zoomkat

Maybe you did something like this by accident.

Quote
Attention: two channels PWM CAN NOT output at the same time, otherwise will burn the driver.  (when the PWM two channels output at same time, both LEDs for the motor will be on)
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aerobyrd

it's possible, but it happened when i unplugged the signal cable while it was still attached to power, it wasn't receiving input at the time. at least not from the computer

zoomkat

If the pwm inputs on the board don't have pull down resistors on them, they may have floated causing the the problem.
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CoolJ

Never unplug anything from a motor controller of any type while it is powered on. All sorts of bad things happen. One of those bad things is smoking motor controllers.

aerobyrd


If the pwm inputs on the board don't have pull down resistors on them, they may have floated causing the the problem.

You've gone a little over my head there. "floated"? also, i'm not sure what the resistors would be for

Chagrin



If the pwm inputs on the board don't have pull down resistors on them, they may have floated causing the the problem.

You've gone a little over my head there. "floated"? also, i'm not sure what the resistors would be for

http://www.thebox.myzen.co.uk/Tutorial/Inputs.html (notably the "Feeding").

MarkT

If you're used to USB cables etc you may think hot-plugging is normal, but the reverse is true - hot plugging of circuits is usually a no-no, and special protection circuitry is required to allow this for USB for instance.

For motor controllers unplugging the motor will probably blow it up (massive inductive spikes), unplugging the inputs _ought_ to be safe electrically if the controller is conservatively designed - here the controller was not designed to be safe unless the inputs conformed to a protocol - hence the warning in the documentation. 

With large motors hot-plugging the controller will not be safe mechanically - the motor could be out-of-control even if the electronics are safe...  Once we are in the 100's of W category of motor there is a real danger of harm if care isn't taken to make everything fail-safe (for instance RC airplane motor controllers shut-down for various reasons when abnormal conditions are detected.)
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