Abstract:Pulse width modulation (PWM) is widely used in the field of automatic control. However, in the process of practical engineering application, the system including PWM is difficult to meet the requirements of high-precision speed index under the condition of low-speed drive. On the basis of engineering practice experience, this paper analyzes this problem in detail, puts forward the theory of fluctuation caused by PWM truncation effect and frequency shift effect, and completes the verification of simulation level by the simulation combined with the typical electromechanical servo system model. The simulation results show the phenomenon of speed fluctuation caused by PWM truncation effect of electromechanical servo system at low speed, which is consistent with the performance of the actual system, verifies the correctness of truncation effect and frequency shift effect, and provides a basis for improving the accuracy index of the system.