Hi,

I am new to motor PI controllers.

I am building a Field oriented control of a motor. There are two cascading loops. One for current controller and one for speed controller.
I know that inorder to have proper controlling, bandwidth of the inner controller should be 10 times higher than the outer control loop. However, we can select any bandwidth for the speed controller. I have few questions related to this. I would be glad if someone could help me to figure these out.

1. How can I select the most suitable bandwidth for the speed controller.
2. Does the operating speed range varies depending on the bandwidth or the PI gains of my speed controller?
3. If so,how can I determine the operating speed range mathematically before working experimentally?
4. Does at low speeds high torque conditions we need a higher bandwidth, If so, the reason for that?
5. How can I determine mathematically at a specific speed, how much torque can be handled by the given PI setting?

Thank you loads for helping me out
Kind regards
Sam

 

All those details are provided by the VFD and motor supplier

 

Hi Dave,

Thank you for your reply.
Any idea of doing those calculations analytically without using the details of the VFD?
Currently, I have only the motor parameters such as resistance, inductance etc. So I am trying to calculate the PI gains using an analytical method.

Thank you
Kind regards
Sam