Naggar H. Saad

Comparison of state space vector PWM schemes for a voltage source inverter

This paper presents different schemes of state space vector pulse width modulation (PWM) for three-leg voltage source inverter. The analysis is performed with respect to switching losses and total harmonic distortion. Matlab /simulink programs are derived to illustrate the switching pattern for different schemes of space vector modulation (SVM). They are used afterwards to calculate harmonic values and total harmonic distortion (THD).Besides, the pulse modulation indices (reference signal / carrier signal) for different schemes are set as basis of comparison. The simulation programs are then applied on different types of loads and results are presented.

Sensorless Field Oriented Control based on improved MRAS speed observer for Permanent Magnet Synchronous Motor drive

Sensorless speed control of Permanent Magnet Synchronous Motor (PMSM) is still in development to eliminate the existing drawbacks such as speed ripples, torque ripples and slow response. This paper proposes Field Oriented Control (FOC) based on improved Model Reference Adaptive System (MRAS) to control the motor speed and minimize both the speed and torque ripples for the PMSM. The improved MRAS strategy is used for speed estimation. A regulator is added to the proposed MRAS to reduce the torque and speed ripples. Feed forward signal from reference speed has used with the PMSM dynamic equations to enhance the overall performance of the system. Cascaded Multi-Level Inverter (MLI), with special switching strategy and different DC sources, is used as PMSM drive. The switching and design of the cascaded MLI are based on getting more voltage levels with less number of components. The system is simulated using Matlab / Simulink package. The proposed controller success in minimizing the speed and torque ripples and provide faster system response. The simulation results of the proposed control system prove the capability of the controller for enhancing the performance of the system in both steady and dynamic states.