Abstract: Aiming at the disadvantages of lower speed accuracy, show dynamic response and complexity on
parameters selecting of vector control system of rail refrigerator used PMSM ( Permanent Magnet Synchronous
Motor), the traditional controller of speed loop and current loop is optimized by bacterial foraging algorithms.
The specific innovation is the combining of bacterial foraging algorithm with gravitational search mechanism to
form GS-BF(Gravitational Search-Bacterial Foraging) algorithm, so bacterial individual swimming action will be
endowed better target performance to speed up the efficiency of swimming. The bacterial foraging algorithm has
better performance on global optimal solution and convergence speed. Finally, the superiority of GS-BF algorithm
is verified by Matlab. The simulation results show that the optimized PID ( Proportional Integral Derivative)
controller has smaller ultra-tuning, faster response speed. The performances on static error and dynamic response
speed of the vector control system are effectively improved. This method has good universality and can be applied
to the speed control system for other motors.

Key words: permanent magnet synchronous motor ( PMSM);  , speed control,  , bacterial foraging algorithm;  , gravitational search