In view of the flaw that the control performance of permanent magnet synchronous motor (PMSM), which uses PI control or traditional model free sliding mode control (MFSMC), is degraded due to the perturbation of internal electromagnetic parameters, an improved model-free sliding mode control algorithm (IMFSMC) has thus been proposed. Firstly, a hyperlocal model of PMSM is established under the condition of parameter perturbation. Secondly, an improved double-power combinatorial approach law is designed to accelerate the system convergence rate in the stage of approaching the sliding surface. Then, an extended sliding mode disturbance observer (ESMDO) is desinged for a real-time observation of the unknown total disturbance system. Meanwhile, the stability of the designed controller and observer is demonstrated by using the second method of Lyapunov stability determination. Finally, a comparison is made between the simulation and experiments of IMFSMC, MFSMC, and PI control, with the results showing that the proposed method can effectively accelerate the speed response rate and enhance the robustness of the system.