Limit battery current in FOC of PMSM

I am trying to limit the DC current of a battery in an foc controlled drive.I implemented a DC Pi cascaded to the id iq pi and the iqref is controlled by this PI.However I am getting oscillations in the DC current with this implementation.Is there any way to limit DC Current within the FOC loop itself so that the dynamics of another PI doesnt cause disturbances in the drive and power is limited smoothly.What is the relation between id iq and idc?

[Shivam Gothi]

Hello @PRATHEESH S,

There might be many reason for getting oscillations in DC current. If possible, can you please share the simulink model file? It will be helpful in suggesting an appropriate workaround.

Answer 1

[MULI]

Hi @PRATHEESH S,

I understand that you are trying to limit the DC current of a battery in an FOC-controlled drive and are experiencing oscillations with your cascaded DC PI implementation.

Relation Between , and :

• The DC current is related to the stator currents in the d-q frame as:

If =0 (common in surface PMSM control), is primarily determined by .

Direct Current Limitation Within FOC:

To avoid oscillations and additional PI dynamics, you can limit directly within the FOC loop by:

• Calculate the maximum allowable based on :

• Limit the torque command to ensure stays within the desired range:

These methods provide smooth power limitation and avoid disturbances caused by an additional PI controller.