Abstract: Supply interruption may occur during the operation of permanent magnet synchronous motor

（PMSM）in some special applications and it needs to be restarted in the rotating state which is called flying start，the accurate initial position/speed observation is the foundation of flying start. Aiming at the problem that the pulse

width and interval time cannot be adjusted automatically when the traditional zero-voltage vector（ZVV）pulse

method is used to observe the initial position/speed，the adaptive adjustment strategy of ZVV pulse was studied. The ZVV action time was adjusted adaptively through comparing the amplitude of short circuit current vector monitored in real time with the threshold value. The ZVV interval time was adjusted adaptively according to the speed prediction results of single ZVV pulse method. The experimental results show that the designed adaptive double ZVV pulse method can adjust appropriate pulse width and interval time of ZVV pulse for different initial speed，which is conducive to improving the performance of initial position/speed observation and flying start at high speed.

      Key words: permanent magnet synchronous motor（PMSM）；flying start；initial position/speed observation；

adaptive double zero voltage vector（ZVV）pulse method