Abstarct: This thesis presents a novel control method baxsed on sliding mode control for permanent magnet synchronous motors which differs from the conventional sliding mode approach. The proposed sliding mode control takes the dynamics of the system to the sliding surface by a variable weighted average without using the sign function in the control approach. As a result, the chattering phenomenon does not occur. The proposed velocity control approach is baxsed on the voltage control strategy and is categorized as the field oriented control. The proposed control method is robust against uncertainties, external load disturbance and external disturbances imposed to a motor's electrical circuit. Stability of the proposed control approach is proved by the direct method of Lyapunov. First, the variable weights are determined by proportional-integral controller. This method simplifies implementation of proposed control scheme. The performance of the conventional sliding mode control and proposed sliding mode control for PMSMs are simulated and compared in terms of the chattering problem and accuracy of responses. The simulation results show the superiority of the proposed scheme over the conventional method. Then, variable weights are determined by fuzzy system for improvement of performance in the proposed sliding mode control under different conditions. This scheme (proposed fuzzy sliding mode control) is simulated and also compared with the previous proposed scheme in terms of chattering phenomenon. The simulation results show the superiority of the proposed sliding mode control's performance in reducing chattering phenomenon under different operational conditions of PMSM.