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Losing torque and motor smooth operation when enabling "Traj ramp" and "speed PI" with instaspin-FOC

Hos
Prodigy 110 points

Hello Guys,

I am losing torque and motor starts shaking when i speed up the machine to fast.

I am trying to speed up the in a short amount of time, when i disable "Traj ramp" and "speed PI" as described by lab4 i have good torque, and good acceleration, but when i re enable the speed control and put the acceleration above 20krpms then the motor starts shaking and the current drawn shoots up.

What am i doing wrong here???

Edit: I came across something peculiar, in torque mode the motor spins 6500rpm (with the set current limitation), when i enable the speed control and set the speed goal to 6500rpm while the acceleration is set high the motor does not start shaking.

  • 0
    TI__Guru** 119510 points

    This sounds like a standard speed controller tuning problem to me. Can you lower the acceleration to make it work? Ex, if you see the instability at 25krpm/s do you also see it at 20? 15? 10? Loaded vs unloaded?

    I even create this scenario on purpose when demo'ing by setting the speed Kp high. This shows one of the challenges of typical speed loop tuning across speed and load, especially with unknown inertia. The best solution is to use InstaSPIN-MOTION with SpinTAC. For most applications you won't have to change your controller tuning across the range.