Because of increasing joint speed and acceleration of complex mechanical structures such as rigid and flexible robotics manipulators, accurate models of joints with electric drives are needed to improve their simulation and their control. The authors proposed a new way to identify the electrical parameters of a robot driven by a synchronous machine. A closed loop identification of an inverse model which is linear in relation to the parameters is performed using least squares techniques and exciting trajectories of current. These current trajectories minimize a criterion which is function of the condition number of an observation matrix. Experimental results are given