Permanent magnet synchronous motors (PMSMs) are suitable options for high-performance applications due to their potential of high power density and torque smoothness. Nevertheless, there are some factors affecting this feature by producing unwanted pulsating torque. One of the causes of torque ripple is the presence of harmonic components in motor back EMF. This paper has presented a multiple reference frame (MRF) method improving torque characteristic in PMSM regarding nonsinusoidal back EMF. An adaptive notch filter (ANF) was used as a current estimator which can separate needed current components. Optimal current components, obtained from Lagrange multiplier method, were regulated through PI controllers which guaranteed the desired convergence. Cogging torque and rms current minimization were intended, too. Results were investigated through simulations in Matlab/Simulink environment.

In this paper, an optimal basic speed controller for switched reluctance motor (SRM) based on Elitist-Mutated Multi Objective Particle Swarm Optimization (EM-MOPSO) with good accuracies, and performances is presented. The control mechanism is composed of a Proportion-Integration (PI) speed controller and a hysteresis current controller. Because of nonlinear characteristics of a SRM, EM-MOPSO is used to tune coefficients of PI speed controller, turn on and turn off angles along with maximum value of the phase current by applying a multi-objective function, including both Integrals Squared Error (ISE) of speed and torque ripple. This EM-MOP SO based controller simulated in SIMULlNKlMA TLAB software for a four phases, 4-1cw SRM. The performances of the EM-MOPSO and PSO algorithm in tuning the controller parameters are compared with each other. Simulation results show that the EM-MOPSO based controller can better improve SRM performance such as torque ripple, dynamic response and copper losses.

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In saliency-based sensorless methods, the amplitude of the injected voltage cannot be reduced to levels below its specified value because of the reasonable signal required for the noise ratio. Increasing the injection signal amplitude increases not only the acoustic noise and high-frequency (HF) losses, but also the total harmonic distortion (THD) of the output voltage and current ripples. A new pulsating semi-impulse signal injection method based on the current sensing technique is proposed for the sensorless control of interior permanent magnet synchronous motors (IPMSMs). The proposed method aims to control the motor speed and reduce some problems due to the HF signal injection involving acoustic noise, HF losses and THD of the output voltage. Taking into account the premium injection angle, these problems are reduced significantly as compared to those in conventional square-wave methods. Hence, the proposed method increases the sensorless driver efficiency and its application scope. The effectiveness of the proposed method is then confirmed with computer simulation and experimental tests. Experimental comparisons at the same injection frequency and injection effective voltage show that the performance of the proposed method is beneficial. All experiments were performed on a IPMSM with V-shaped PMs which is used in a refrigerator compressor.