Abstract: To improve the characterization of blood flows, we propose a method which makes it possible to use the spectral analysis
of the Doppler signals. Our calculation induces a reasonable approximation, the error made on estimated speed reflects the fact
that speed depends on the flow conditions as well as on measurement parameters like the bore and the volume flow rate. The estimate of the Doppler signal frequency enables us to determine the maximum Doppler frequencie Fd max as well as the maximum flow speed. The
results show that the difference between the estimated frequencies
( Fde ) and the Doppler frequencies ( Fd ) is small, this variation tends to zero for important θ angles and it is proportional to the diameter D. The description of the speed of friction and the
coefficient of friction justify the error rate obtained.
Abstract: This paper presents a speed sensorless direct torque
control scheme using space vector modulation (DTC-SVM) for
permanent magnet synchronous motor (PMSM) drive based a Model
Reference Adaptive System (MRAS) algorithm and stator resistance
estimator. The MRAS is utilized to estimate speed and stator
resistance and compensate the effects of parameter variation on stator
resistance, which makes flux and torque estimation more accurate
and insensitive to parameter variation. In other hand the use of SVM
method reduces the torque ripple while achieving a good dynamic
response. Simulation results are presented and show the effectiveness
of the proposed method.