This paper introduces a nonlinear control scheme based on the differential flatness approach for controlling the speed/torque of a permanent magnet synchronous motor (PMSM) drive. The differential flatness estimation is a model based approach. Then, two state-observers are proposed to estimate a load torque disturbance and a stator resistance (represent losses in an inverter and PMSM) by means of its voltage drop. It can help to improve the PMSM drive system and the efficiency. Using the flatness property, we propose simple solutions to dynamics and stabilization problems. The design controller parameters are autonomous of the operating point; moreover, high dynamics in disturbance rejection is achieved. To validate the proposed method, a hardware system is realized in a laboratory, and digital estimation is accomplished with a dSPACE controller DSll04 platform. Simulation and experimental results with a small-scale PMSM of 1000 W, 3000 rpm in a laboratory corroborate the excellent control scheme during a motor-drive cycles.