PI parameter design of the flux weakening control for PMSM based on small signal and transfer function

In this paper, the transfer function of PMSM drives system with feed forward complete decoupling is developed based on the small signal model. According to the transfer function, the stable operation range of system and PI parameter of flux weakening control are analyzed by Routh Stability Criterion. According to the analysis results, the stable operation range of system is to reduce with the speed increasing when PI parameter of flux weakening control keeps invariant, and the system even becomes unstable. So the PI Parameter of flux weakening control should be designed to increase the stable operation range to keep the system stable. What is more, the system is always stable in some areas, and the PI parameter designed in this area just affect the dynamic performance of system, which is validated by experiment.