I implemented a Field Oriented Control (FOC) controller for a synchronous motor, which works already pretty good. Now the I-part of the PI controllers is necessary to achieve a good reference tracking, but slows down the dynamics drastically. I heard that a feed-forward term and prefiltering can be used to get rid of this problems, but I actually don't know how this could be achieved. The motor will mostly be driven at very slow speeds, but also here, a huge current seems to be difficult to track.
I heard that the plant of the BLDC motor for each phase can be simplified as follows:
$$\frac{1}{Ls + R}$$
Such that the output current is related to the Space Vector Modulation (SVM) voltages, but I don't see how to go from here.
How can prefiltering and feed-forward control be used to achieve better performance in Field Oriented Control (FOC)?
Edit: What I find is mostly the feed-forward part to compensate for the speed of the system, but this is not necessary in my application, since it is used for position control or slow speed only.
Is there a way to take feedforward terms into account to achieve better current control? Maybe I'm just bad at tuning my PI-controllers for current control, but it seems that the current is very sensitive to the P-part and so to get best current tracking mostly the I-part is used. So I'm interessted in how to achieve better and faster control of I_q and I_d.