We show that the gradient observer proposed in
Bernard & Praly, IFAC 2017 for PMSMs, can be used to estimate
the stator flux of SynRMs, using only electrical measurements
and the knowledge of the resistance. This sensorless observer
ensures global convergence of the flux estimate provided the
rotation speed and the current norm remains away from zero
and the current and voltages are bounded, without requiring the
knowledge of the magnetic model. Its robustness with respect to
resistance errors is shown, with explicit expression of the resulting
steady state error. This observer operates dynamically, in normal
conditions, without any constraint on the load, and without
any mechanical information. In a second step, we propose to
exploit the knowledge of a magnetic inductance model (containing
magnetic saturation) to estimate the rotor position from the flux
estimate. The performance of this estimation in open-loop are
illustrated on experimental data on a SynRM.