A nonlinear observer has been developed in order to estimate the stator current of a wound rotor synchronous machine (WRSM) and get rid of the current sensors. The main difficulty with the phase current observation is the uncertainties on the model of the system. Indeed, the parametric values of the passive components may vary due to the temperature or the wear of the components. In this paper, a new nonlinear observer of the stator current and parameters will be introduced. This observer shows good results when the model is considered well known, and it is also robust to some parametric errors in the model.