Abstract: In order to improve the control performance of permanent magnet synchronous motor（PMSM）servo

system，weaken the influence of uncertainty in the system，and solve the chattering problem in traditional SMC

technology，a dynamic sliding mode control（DSMC）method was proposed. Firstly，based on the PMSM

mathematical model，the traditional PID type SMC method was designed. At the same time，the DSMC method was designed to weaken the chattering phenomenon and further improve the robustness of the system. DSMC can obtain a hierarchical sliding surface by adding an additional dynamic variable，so as to ensure that the system still has fast and accurate speed tracking performance in the presence of parameter changes，external disturbances and other uncertainties. Finally，the validity of the proposed method was verified by the MC56F8346 DSP control core. The experimental results show that the proposed DSMC method can track the given signal faster and better than the

traditional SMC，and has stronger robustness.

      Key words: permanent magnet synchronous motor（PMSM）；uncertainty；dynamic sliding mode control

（DSMC）；speed control