Driving a permanent magnet synchronous motor requires
the rotor position information to control the motor torque
which is generally detected by mechanical position sensors
such as an encoder or a resolver. Many papers about position
sensorless drive of PMSM have been published, [3, 4] as for
examples. Flux estimation can be applied to detect the rotor
position and is considered as an important task in
implementing high-performance motor drives [5]. The
methodology of vector control is normally developed based
on estimation of pole position of surface permanent magnet
synchronous motor. The estimators are designed using
current or voltage models of the motor. Integration or low
pass filter-based flux estimators introduce error due to dc
offset value. To solve the problem notch filter is introduced
in [6]. The same methodology is applied through adaptive
integration ANN estimators for induction motors [7]. A flux
estimator for induction motor proposed in [8] is reported to
be almost insensitive to parameter variations