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Topic: ESC + L293 + Brushless motor (Read 717 times) previous topic - next topic

So, i've been having some trouble lately and I can't seem to find a solution on the web. I've managed to controll a brushless motor through and ESC and arduino with PWM. Nothing too dificult. What I need now is a way to controll an inversion of the motor. Like you know, changing two of the wires from the motor makes it turn the other way around. I have an L293 that I know can be used to invert a brushed motor, but i've got no clue on how to use it to switch two wires when given a logic input (while controlling the speed of it through the ESC). Basically what i'm searching is if it's possible to build a circuit to change the two wires at a given signal:

Basic state, input 0:
-ESC wire 1 ==> motor wire 1
-ESC wire 2 ==> motor wire 2

Input 1:
-ESC wire 1 ==> motor wire 2
-ESC wire 2 ==> motor wire 1

Would it be possible with a single L293 or is there any other way to do it?


DuaneB


I guess you are trying to add a reverse function to an ESC That doesn't support Reverse ? First off, are you sure there is not way to enable reverse from the ESC Setup ?

Duane B

rcarduino.blogspot.com
Read this
http://rcarduino.blogspot.com/2012/04/servo-problems-with-arduino-part-1.html
then watch this
http://rcarduino.blogspot.com/2012/04/servo-problems-part-2-demonstration.html

Rcarduino.blogspot.com

yes, that's what I need to do, and no, my ESC hasn't got a reverse function.

DuaneB

I know that when you initially set up a 'sensorless' brushless motor the instructions mention that you can swap any two of the wires if it runs backwards I am not sure if this applies 'in project' meaning at high RPM and under load - its possible it does, I have no idea.

As for using an l293 its a very low current device compared to most ESCs so its almost certainly too weak for what you intend.

To cut a long story short, it is possible some how after all ESCs are still just electronics, you might try letsmakerobots.com

Duane B

rcarduino.blogspot.com
Read this
http://rcarduino.blogspot.com/2012/04/servo-problems-with-arduino-part-1.html
then watch this
http://rcarduino.blogspot.com/2012/04/servo-problems-part-2-demonstration.html

Rcarduino.blogspot.com

MarkT

Can't swap the connections under load.  RC brushless motors are sensorless so there's no reversing under load possible - backEMF is needed to maintain commutation under load, backEMF drops to zero are zero speed.  (Actually there are tricks to sense position using reluctance, but not in a cheap RC ESC)

A hall-sensor BLDC and controller will do the job, these are mostly engineering grade and very expensive (designed for decades of operation in harsh environments).  But with hall sensors the commutation at low speeds works.

For light duties the BLDC from an old disk-drive spindle will do the job as it has sensors, but you are very limited in speed and power.

A brushed DC motor will do the job with an H-bridge controller.
[ I won't respond to messages, use the forum please ]

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