Tuning PI /w ZieglerNichols Method for RFOC Induction Machine

[290178]

I try to tune a pi control for a rotor flux oriented in induction motor speed control. I try ziegler-nichols method, but i'd fail. Because the system had very small delay time.
So i need help to solve this problem.

ps: I need a method for tuning pi controller wothout knowing the mathematical transfer function of the system.

Thank you