Hello Friends,
I am using this motor driver to run this kind of motor.
Current is around 2,5Amp/h.
The description of the motordriver says:
If both inputs are LOW the driver acts as a brake.
Your motor has a wormgear. Most wrm gears are self-locking which means
If you try to turn the outgoing shaft it does not turn caused by the self-locking of the worm-gear.
So I would do some practical tests
giving full power to the motor and then go instantly into brake-mode
and
measure how long does it take until the motor stands still. And if it stands still after brake-mode you can switch to oposite direction.
If you have a lot of weight that is rotated by the shaft the big rotating-momentum of this weight might overload the worm-gear or will wear-out the wormgear faster than normal use.
It is always a good idea to post an overview about your project. If the others users here know what you want to do in the end and what the overall circumstances are much better suited suggestions can be made.
best regards Stefan
Shouldn't that be, Current is around 2.5Amp.
Not A/h
What is your application?
Thanks.. Tom.. 
Oh.. sorry, yes you are right! It will be fly-by-wire steering for lawn mower.
Thank you Stefan! As I mentioned before it will be fly-by-wire steering for a lawn mower.
To measure how long it takes to stop is little bit difficult, I need to put encoder on the motor shaft. It is difficult for me. And then a believe the time is depending on conditions. I thoughts maybe there is some golden rule or similar for the motor drivers. Like relays need +/-50ms to connect, so if you go with 100ms you are safe. I am looking for the same
starting point, but for the DC motor.
No, the time for the motor shaft to stop spinning depends on lots of factors (initial RPM, rotor inertia, load, bearing friction, etc.).
Either use some method to detect shaft rotation, or do some experiments to find a typical time to stop.
There will also be a whole lot of end thrust on the worm. Be sure the thrust bearings can handle the repeated thrust.
For estimating the time just hear the motor hum and when the humming ends the motor stands still.
Short Test-program
give full throttle for maybe 5 seconds than switch to brake-mode.
If you switch off the power-supply of a rotating DC_motor. The motor becomes a generator because the motor is still rotating. Of course friction will slow down the rotor pretty quick.
If you connect the two motor-wires together this maximises "power-consumption" from the "external circuit"
Brake-mode means the wires of the motor are shorted to each other which will slow down the motor fast.
If the motor stands still you don't hear any rotating sound. So what is so difficult about that?
best regards Stefan
when a motor turns, it also generate back EMF, same principle as a generator.
so while a voltage is applied to turn a motor, the BEMF is countering that voltage. the motor current is the difference in those voltages / winding resistance
load the motor down causing it to slow, the BEMF decreases, the difference between the applied voltage increases and the motor current increases along with torque, countering the extra load. similarly, when a load decreases
so when the drive voltage is removed prior to changing direction, the BEMF continues as long as the motor continues to turn. reversing the applied voltage with the motor turning in the opposite directions causes the applied V and BEMF to add resulting in even greater current than if the motor were not turning.
the current thru the motor windings results in heat that can damage the motor.
if you really want to avoid this condition, monitor the BEMF when the applied V is removed prior to reversing direction and wait for the BEMF to reach zero indicating that the motor has stopped turning
Many many thanks to all members! I set it to 200ms and it works just fine!
The last question is about soft start and soft stop. Does it better for the motor and driver if I go from 0 to 255 let say in 100ms?
This depends on the load that the motor must really turn compared to the maximum load the motor can take.
The driver is for 100A your motor pulls 2,5A in normal operation.
In the moment of the start motor stands still and then you switch on full-power for a short moment the current will be higher. Depending on the load it will take some time until the motor is on constant rpm. If you have an oscilloscope you can measure the current-spike in the moment of switching fully on.
If you put the motor into a test where the motor must turn the real-world load and then do
switch power fully on clockwise run motor 5 seconds,
switch to brake for 200 ms
switch full power on counter-clockwise run motor 5 seconds - repeat
As long as the motor gets only handwarm but not hot the electrical side is OK.
How long it takes until the mechanic = the worm-gear is worn out - nobody knows.
best regards Stefan
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