This paper deals with the design of an observer for the estimation of rotor
position and velocity for switched reluctance motors (SRMs). We present a
reduced order, non-linear observer, driven by stator currents and voltages.
We derive sufficient conditions for the observer convergence, that lead to
a design procedure. An extended observer is also presented that handles an
unknown load torque or slow load torque variations. Closed loop operation
of the observer and the motor is shown to converge exponentially. Performan
ce is illustrated with simulations that show very good behaviour, even when
there are uncertainties in the model parameters and in the flux model.