<p>This article deals with solving chattering problems and convergence speed in methods based on sliding mode control (SMC) to control the velocity of permanent magnet synchronous motors (PMSM). In many applications, the speed tracking accuracy in PMSM motors is very important, and the use of SMC control will cause a chattering phenomenon, which lowers the control accuracy. In this paper, a non-singular terminal SMC for PMSM motor speed is presented. In this controller, the used manifold is chosen as a fractional power to increase the convergence speed. In addition, the chattering phenomenon is completely eliminated in this controller, which increases control accuracy. In addition, during the design of this controller, the uncertainties caused by all the parameters of the motor model are considered separately so that the resistance of the controller against uncertainties is as high as possible. In contrast, the traditional SMC approach, the parameters of the scheme are considered in a general way and in a limited bound. This issue causes SMC performance to decrease if the uncertainties of model parameters increase. Through a battery of laboratory experiments conducted in two distinct scenarios, the efficacy of the recommended tactic has been examined and contrasted with that of the traditional sliding method. The results showed that with the increase of the uncertainty of the scheme, the performance of the tactic is still maintained in a good level and the tracking inaccuracy for this method is roughly 1 RPM, while the conventional sliding method has decreased accuracy due to the chattering phenomenon and increasing uncertainties.</p>