Due to automotive industrial constraints, the number of sensors on the electric powertrain has to be reduced. Thus, the stator phase currents of the wound rotor synchronous machine are not directly available and they have to be estimated. In this paper, different solutions of estimation are proposed. The first one is based on the extended Kalman filter, and the second one is a non-linear estimator based on the convergence of a Lyapunov candidate function. A comparison between the two solutions will be conducted. Moreover, since the parameters in the system may not be well known, or may vary due to the change of temperature and the wear of the passive components, an estimation taking the parameter errors in account will also be introduced in order to determine the sensitivity of each parameter error.