Using Simulink to simulate FOC of a PMSM motor
In order to have a stable design you must have good feedback and model all physics of motor+load+driver +sensors.  Since it is nonlinear, to have position control you need PID feedback from multiple sensors to achieve good phase margin.

Current is proportional to acceleration thus position is unstable as it 2nd integral. 

Velocity feedback is V backEMF between active pulses. 

Thus FOC design must use more than simple current feedback.  Expand your research in this area.