Mehdi Shafiei

Brushless DC (BLDC) motors and their drives have been increasingly considered in a broad range of applications due to their significant features. The implementation of these motors is possible thanks to firstly, the progress of permanent-magnet (PM) technologies which provide high efficiency, power density, and torque for these motors. Secondly, the structure and special features of these motors have prepared a basis for simpler control and smaller size compared to those with the same power. In… Show more

Brushless DC (BLDC) motors and their drives have been increasingly considered in a broad range of applications due to their significant features. The implementation of these motors is possible thanks to firstly, the progress of permanent-magnet (PM) technologies which provide high efficiency, power density, and torque for these motors. Secondly, the structure and special features of these motors have prepared a basis for simpler control and smaller size compared to those with the same power. In this paper, the basic drives of BLDC motors have been reviewed in order to provide a useful reference for primary research in conventional methods of these types of motors. To present a proper insight to various drive techniques in these motors a systematic classification to control strategies with principles of these techniques has been made. In addition, computer simulations have been utilized in order to achieve a more accurate evaluation, provide the possibility of comparative analysis between various strategies, and place emphasis on the constraints and features of each method. Apart from the comparison of different methods of each strategy, a general comparison among the different methods of various strategies has been made based on the torque ripple, analysis of frequency, and losses of the BLDC motor drive as well as various applications of the different controlling methods. Moreover, considering the importance of electric vehicles (EVs) in industry, selection of the best controlling method for this type of applications together with energy regeneration has been discussed.
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Micro Grids (MGs) are clusters of the DER (Distributed Energy Resource) units and loads which can operate in both grid-connected and island modes. This paper addresses a probabilistic cost optimization scheme under uncertain environment for the MGs with several multiple Distributed Generation (DG) units. The purpose of the proposed approach is to make decisions regarding to optimizing the production of the DG units and power exchange with the upstream network for a Combined Heat and Power (CHP)… Show more

Micro Grids (MGs) are clusters of the DER (Distributed Energy Resource) units and loads which can operate in both grid-connected and island modes. This paper addresses a probabilistic cost optimization scheme under uncertain environment for the MGs with several multiple Distributed Generation (DG) units. The purpose of the proposed approach is to make decisions regarding to optimizing the production of the DG units and power exchange with the upstream network for a Combined Heat and Power (CHP) system. A PEMFCPP (Proton Exchange Membrane Fuel cell power plant) is considered as a prime mover of the CHP system. An electrochemical model for representation and performance of the PEMFC is applied. In order to best use of the FCPP, hydrogen production and storage management are carried out. An economic model is organized to calculate the operation cost of the MG based on the electrochemical model of the PEMFC and hydrogen storage. The proposed optimization scheme comprises a self-adaptive Charged System Search (CSS) linked to the 2m + 1 point estimate method. The 2m + 1 point estimate method is employed to cover the uncertainty in the following data: the hourly market tariffs, electrical and thermal load demands, available output power of the PhotoVoltaic (PV) and Wind Turbines (WT) units, fuel prices, hydrogen selling price, operation temperature of the FC and pressure of the reactant gases of FC. The Self-adaptive CSS (SCSS) is organized based on the CSS algorithm and is upgraded by some modification approaches, mainly a self-adaptive reformation approach. In the proposed reformation method, two updating approaches are considered. Each particle based on the ability of those approaches to find optimal solutions in the past iterations, chooses one of them to improve its solution. The effectiveness of the proposed approach is verified on a multiple-DG MG in the grid-connected mode. Show less

Damping of electro-mechanical oscillations in interconnected power systems is important to guarantee secure and stable operation of the system. Power system stabilizers (PSSs) are applied to damp these oscillations. To overcome flows associated with conventional algorithm of PSS design, a modified version of non-dominated sorting genetic algorithm is used to regulate the PSS parameters in this paper. Additionally, fuzzy logic principle is employed to develop PSS in order to improve the… Show more

Damping of electro-mechanical oscillations in interconnected power systems is important to guarantee secure and stable operation of the system. Power system stabilizers (PSSs) are applied to damp these oscillations. To overcome flows associated with conventional algorithm of PSS design, a modified version of non-dominated sorting genetic algorithm is used to regulate the PSS parameters in this paper. Additionally, fuzzy logic principle is employed to develop PSS in order to improve the stability and reliability of the power systems subjected to disturbances. Two-area (four-machine) power system is considered as the case study in this paper. PSS parameters are obtained for four PSS connected to four generators. The effectiveness of the proposed algorithm in damping the system oscillations during overall disturbances is evaluated. The simulation results illustrate this issue.
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This paper presents a direct torque control technique for brushless DC motors with non-sinusoidal back electromotive force. Direct torque control has some benefits such as faster torque response and reduced torque ripple for driving the brushless DC motors. Because of ignoring stator flux linkage of direct torque control in constant torque region, driving of brushless DC motors is not complicated. In order to solve the problems associated with conventional PI speed controller, a new speed… Show more

This paper presents a direct torque control technique for brushless DC motors with non-sinusoidal back electromotive force. Direct torque control has some benefits such as faster torque response and reduced torque ripple for driving the brushless DC motors. Because of ignoring stator flux linkage of direct torque control in constant torque region, driving of brushless DC motors is not complicated. In order to solve the problems associated with conventional PI speed controller, a new speed control based on adaptive-neuro fuzzy inference system is proposed to eliminate overshoot in the torque and speed responses, simplify designing and reduce complexity of math formulas. To reduce rising time, PD controller is used with adaptive-neuro-based Fuzzy Inference System. The effectiveness of proposed system has been validated by simulation results.
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This paper presents a direct torque control technique for brushless DC motors with non-sinusoidal back electromotive force. Direct torque control has some benefits such as faster torque response and reduced torque ripple for driving the brushless DC motors. In order to solve the problems associated with conventional PI speed controller, a speed control based on fuzzy logic controller is proposed to reduce starting current, eliminate overshoot in the torque and speed responses, simplify… Show more

This paper presents a direct torque control technique for brushless DC motors with non-sinusoidal back electromotive force. Direct torque control has some benefits such as faster torque response and reduced torque ripple for driving the brushless DC motors. In order to solve the problems associated with conventional PI speed controller, a speed control based on fuzzy logic controller is proposed to reduce starting current, eliminate overshoot in the torque and speed responses, simplify designing and eliminating complex math formulas. To reduce rising time PD controller used with fuzzy logic control. The effectiveness of proposed system has been validated by simulation results.
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This paper presents a direct torque control technique for Brushless DC motors with non-sinusoidal back electromotive force. Direct torque control has some benefits such as faster torque response and reduced torque ripple for driving the Brushless DC motors. The Sliding mode observer, which is robust to parameter uncertainties, can be used to estimate the back-EMF and generate the torque. It is employed to estimate the non-sinusoidal back-EMF waveform in a Brushless DC motor using only the… Show more

This paper presents a direct torque control technique for Brushless DC motors with non-sinusoidal back electromotive force. Direct torque control has some benefits such as faster torque response and reduced torque ripple for driving the Brushless DC motors. The Sliding mode observer, which is robust to parameter uncertainties, can be used to estimate the back-EMF and generate the torque. It is employed to estimate the non-sinusoidal back-EMF waveform in a Brushless DC motor using only the measurements of the stator currents. A modified version of Non-Dominated Sorting Genetic Algorithm (NSGA-II) is used as an effective optimization tool for regulating the PID controller parameters of speed controller and selection of four gains of sliding mode observer. The relation between PID controller and the sliding mode is also satisfied using NSGA-II. The effectiveness of proposed system has been validated by simulation results.
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This paper describes the optimal operation performance of a Brushless DC Motor (BLDC) fed by a z-source inverter accompanying with photovoltaic (PV) system, driving a water pumping system. The proposed system employs a Z-Source Inverter (ZSI) to extract the Maximum Power from a Photovoltaic array to supply the BLDC motor simultaneously. Utilizing the ZSI provides some advantages such as high efficiency and low cost. In order to achieve an accurate Maximum Power Point Tracking (MPPT) of the PV… Show more

This paper describes the optimal operation performance of a Brushless DC Motor (BLDC) fed by a z-source inverter accompanying with photovoltaic (PV) system, driving a water pumping system. The proposed system employs a Z-Source Inverter (ZSI) to extract the Maximum Power from a Photovoltaic array to supply the BLDC motor simultaneously. Utilizing the ZSI provides some advantages such as high efficiency and low cost. In order to achieve an accurate Maximum Power Point Tracking (MPPT) of the PV array, fuzzy logic controller(FLC) is applied to attain an appropriate variable step size in incremental conductance method. Direct torque control (DTC) has some benefits such as faster torque response and reduced torque ripple for driving the BLDC motor. Because of ignoring stator flux linkage of DTC in constant torque region, driving of BLDC motor is not complicated. The effectiveness of proposed system is evaluated by simulation results.
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