AMPS current limitation by script

5 years 3 months ago #29530863 by VRTECH
Dear all,
i am new user of roboteq FBL2360 for brushless motor.
I use this controleur for many brushless motor. Some of motor are low power (eg 2A nominal at 48V for 6000 rpm).
In this case i can not use the generic AMPS limitation of the controleur (the minimal value is 10 Amps).
So i want to control the amps by script.

The configuration of the controleur is in close loop speed and it work fine.
I have put an acceleration smooth and a deceleration strong to stop fast.
No problem for regenerative process for high current back to supply.

Actually it work fine when the motor has no load.
The motor go to the recheaded speed.
Then i apply a load to make the MOTOR AMPS growing.
In my script i read the motor amps and when it goes over a trigger level value, i send a M1command=0 to stop the motor.
Then when all analog input are center i enable new command on M1command motor.
All is working fine by this way.

My problem is when i start the motor with a load.

The PID correction put power higher to make the motor running.
So the AMPS go up to the trigger level and can make my script to put the motor off.
Those because of the physical caracteristic of a brushless motor (starting current can be up to 6 times the nominal current).

My request :
Is there any way to know when the motor is on acceleration phase ?
I want to put in the accelration phase a trigger amps level 1.5 higher than in continous running.

As any one already made such a script ??

Thank you in advance for your support.
Best regards,

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5 years 3 months ago #29530869 by TechSupport
If the motor starts with a load present, then the motor amps reading will be likely close to or at limit upon command start. Recommend that your settings should start for a higher current amps limit,and have your script make changes as needed once the motor is moving.

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5 years 3 months ago #29530870 by VRTECH
Dear thank you for your quick answer.
So i should put a higher Limit amps when command is set to 0 ( or motor is stopped)

Then with the feedback reading value and the maxmotor speed config set
I should change the limit amps value only when speed has reach 30% of max speed for example.
OK i go to try this.

Thanks

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5 years 3 months ago #29530871 by TechSupport
Yes. The motor amps is a calculated value, so at less than 100% pwm output, then motor amps will read higher, therefore will limit the amps output if the amps limit is reached.

You may want to have the script query the motor amps and then make your adjustments accordingly.

getvalue(_A, 1) ' queries the motor amps channel 1 motor.

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