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I am working on a Field Oriented Control ("FOC") based Brushless DC ("BLDC") Motor Controller. The controller takes speed as an input, I need to extend the control system to also control the DC Link Current in order to implements current constraints which ensure that the battery isn't overloaded.

The control should work in the following way: a speed reference and a DC current reference is given. The system should aim to run the motor at the reference speed. If the current reference constraints the system (due to the load) it should regulate after this reference-point instead.

The basic control system is depicted below. The most straight forward way to implement the DC Link Current Control would be in cascade with the speed PI-controller (arrow on picture).

enter image description here

This cascade implementation would require a lot of tuning (due to three cascade control loops) and require making the outer control-loop slow in order to make the system stable.

Do you have other suggestions to implement a DC Link Current Constraint?

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  • $\begingroup$ Get some realistic numbers for a sim and have a computer crunch away at tuning. I suspect that more degrees of freedom just allow for more acceptable solutions. $\endgroup$
    – Abel
    Mar 26 at 2:49
  • $\begingroup$ A good idea - unforturenately I do not have access to expensive commercial simulation tools like Simulink. Do you know a way to do it with open-source tools? $\endgroup$
    – Nikolaj TL
    Apr 4 at 6:13
  • $\begingroup$ Use free things like python to make your own sim. Simulink is a glorified time-stepping engine with a lot of premade drag and drop blocks. $\endgroup$
    – Abel
    Apr 4 at 7:28
  • $\begingroup$ I have setup a simulation in python, byt it isn't good enough yet to represent the complexities of the motor system. I haven't worked much with simulating motors before, but I will try and get it setup to be able to work on simulating a good tuning. Do you have an example of a python project (or know any resources) in order to see how to tune a electrical/mechanical control system in python? $\endgroup$
    – Nikolaj TL
    Apr 4 at 10:24

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