Sharif Digital Repository

Torque ripple is a major difficulty in direct torque controlled induction motors. The reference value of the motor flux greatly influences the torque ripple. On the other hand, many motors work in an operating cycle, which includes load intervals of less than their nominal power. In these situations, it is not necessary to set their flux value as the nominal value. In this paper, the effect of the reference value of the motor flux on the motor torque ripple is investigated. A new control algorithm is proposed to determine the reference value of the flux according to the value of the motor torque. Simulation and experimental results justify the validity of the proposed method to reduce the... 

Torque ripple is a major difficulty in direct torque control of induction motors. The reference value of the motor flux greatly influences the torque ripple. On the other hand, many motors work in an operating cycle, which includes load intervals of less than their nominal power. In these situations, it is not necessary to set their flux value as the nominal value. In this paper, the effect of the reference value of the motor flux on the motor torque ripple is investigated. The effect of the flux reference variation on the motor power factor as well as torque dynamics is also presented. Simulation results as well as experimental results justify the validity of the proposed method on the... 

Flux spectrum is greatly influenced by flux and torque controller hysteresis loops (dead bands) in direct torque control of AC motors. On the other hand iron loss in induction motor is closely related to flux harmonics. Hence flux spectrum must be observed in control process to minimize the motor losses. In this paper the relation between the magnetic-flux spectrum and electromagnetic-torque and magnetic-flux controller hysteresis loops (dead bands) as well as machine parameters is investigated. Simulation results are presented to justify the results  

A flux search controller is proposed to achieve the best efficiency in a direct torque controlled induction motor with light load. The reference flux value is determined through a minimization algorithm with stator current as objective function. Experimental results show that using motor current instead of motor input power as the objective function causes better performance. © 2004 IEEE  

A new switching table is proposed for decreasing the torque ripple in DTC especially in low speed. Each sector is divided to two half sector and a proper vector set is defined for each. Through this new switching table, the torque response is smooth even in the beginning of each sector and it leads to the reduction of torque ripple. None of motor parameters are used in this switching strategy and there is no need to shorten the sampling period. Simulation and experimental results confirm the ability of this method in reducing the torque ripple. ©2004 IEEE  

This paper deals with the efficiency optimization of Field Oriented Control (FOC) of a six-Phase Induction Motor (6PIM) by adaptive flux search control. The six-phase induction motor is supplied by Space Vector PWM (SVPWM) and voltage source inverter. Adaptive flux search controller is fast than ordinary search control technique and easy to implement. Adaptive flux Search Control (SC) technique decreases the convergence time by proper change of flux variation steps and increases accuracy of the SC technique. A proper loss model of 6PIM in conjunction with the proposed method is used. The six-phase induction machine has large zero sequence harmonic currents that can be reduced by SVPWM... 

In this paper, a linear piezoelectric stepper (LPS) motor drive using a resonant converter is proposed. The mechanism of operation of the LPS motor is first described. Then, a single-phase equivalent model of the LPS motor is introduced. In addition, design theory of the driving circuit using a current source inverter for the LPS motor is explained in detail. At the end, simulation and experimental results based on the resonant converter are presented and analyzed to verify the validity of the proposed system  

A linear piezoelectric step motor (LPS) driver using current source inverter is proposed in this study. The mechanism of operation of an LPS motor is first described. Then, a single-phase equivalent model of the LPS motor is introduced. A detailed theory of driving circuit design using current source inverter for the LPS motor is explained. At the end the simulation and experimental results are presented and compared  

This paper presents a high performance direct torque control (DTC) theme for the induction motor (IM). To solve those problems associated with conventional DTC, such as flux and torque ripple, variable switching frequency, inaccuracy in motor model and other parts of system. The Active Learning Method (ALM) is implemented on the DTC. In the Active Learning Method for information modeling, a method known as Ink Drop Spread (IDS) is used. The simulation results of DTC system based on ALM and the comparison of motor performance under the proposed control system with respect to those obtained under conventional DTC confirms its effectiveness and accuracy  

The development of energy regeneration capability in electric vehicles can extend their driving range making them a competent alternative for conventional internal combustion engine vehicles. In this study, a novel energy regeneration technique, called a two-boost method, for electric vehicles driven by a brushless DC (BLDC) motor, a widely used motor in vehicular technology, is proposed. Based on this technique, the BLDC motor driver, which is selected to be a three-phase inverter, is converted into two simultaneous boost converters during energy regeneration periods in order to transfer energy from the BLDC motor into the battery and provide the braking force. Also, this method is compared... 

Switched reluctance motors (SRM) are one of the most reliable and cost effective motors and their applications are increasing in industry. However, it suffers from high level of torque ripple. In this paper, a new configuration for stator and rotor of SRM is presented. In the proposed method, a new saliency is developed to remove negative torque and therefore decrease torque ripple and acoustic noise, increase efficiency and as a result, expand speed range. The simulation results demonstrate that the new motor structure has a smooth torque profile with possibility to work at higher speed lower acoustic noise  

This paper presents a comprehensive design procedure of a brushless DC limited angle torque motor (LATM) based on magnetic equivalent circuit analysis which predicts its performance and magnetic characteristics. Design of toroidally wounded armature and rotor with two pole tip segments are developed using selected ferromagnetic material and rare earth permanent magnets. Derivation of airgap and other motor dimensions and design parameters with their expressions are given. A finite element analysis verification of designed LATM using a 2D modeling and simulating package is presented. Performance characteristic of analytical model and FEA model of designed LATM is compared which validates the... 

A precise and compact tubular ultrasonic motor driven by a single-phase source is proposed and tested in this study. The motor is designed by modeling a motor stator in FEM software. The motor fabricated according to the design is tested experimentally and its working characteristics including speed and torque are measured and presented. The maximum speed and torque of the motor are 59 rpm and 0.28 mN m at 80 Vpp of applied voltage. The proposed motor possesses advantages such as a simple and compact structure with application in the fields of robotics, space, medical devices and high-resolution stages, among others. The proposed motor is a good candidate for applications where accurate... 

The main objective of this a paper is to improve the efficiency of permanent magnet synchronous motors (PMSMs) by using an improved direct torque control (DTC) strategy. The basic idea behind the proposed strategy is to predict the impact of a small change in the stator flux amplitude at each sampling period to decrease electrical loss before the change is applied. Accordingly, at every sampling time, a voltage vector is predicted and applied to the machine to fulfill the flux change. The motor drive simulations confirm a significant improvement in efficiency as well as a very fast and smooth response under the proposed strategy  

Numerous disciplines are engaged in studies involving motor control. In this study, we have used a single link system with a pair of muscles that are excited with alpha and gamma signals to achieve an oscillatory movement with variable amplitude and frequency. The system is highly nonlinear in all its physical and physiological attributes. The major physiological characteristics of this system are simultaneous activation of a pair of nonlinear muscle-like-actuators for control purposes, existence of nonlinear spindle-like sensors and Golgi tendon organ-like sensor, actions of gravity and external loading. Transmission delays are included in the afferent and efferent neural paths to account... 

In this study, we have used a single link system with a pair of muscles that are excited with alpha and gamma signals to achieve an oscillatory movement with variable amplitude and frequency. This paper proposes a reinforcement learning method with an Actor-Critic architecture instead of middle and low level of central nervous system (CNS). The Actor in this structure is a two layer feedforward neural network and the Critic is a model of the cerebellum. The Critic is trained by State-Action-Reward-State-Action (SARSA) method. The system showed excellent tracking capability and after 280 epochs the RMS error for position and velocity profiles were 0.02, 0.04 radian and radian/sec,... 

A new control law for direct yaw moment control of an electric vehicle is developed. Although this study is considered as part of a global control system for the traction control of a four motorized wheel electric vehicle, but the results of this study is quite general and can be applied to other types of vehicles. The dynamic model of the system has been analyzed and, in accordance with the optimal control theory, an optimal controller is designed. Two different versions of the control law have been considered and the performance of each version has been separately studied and compared with each other. Finally, the numerical simulation of the vehicle-handling model with and without the use... 

Objectives: This study aimed to investigate the effect of upper extremity coordination exercises based on fatigue prediction on fine and gross manual dexterity, upper limb motor function, shoulder and elbow proprioception, occupational performance, and activities of daily living in chronic stroke survivors. Methods: In this pilot double-blind randomized clinical trial, 24 chronic strokes were enrolled using the non-probability sampling method. Participants were randomly allocated to the control (received routine occupational therapy) and intervention (received upper extremity coordination exercises based on fatigue prediction using the Kinect) groups. Before and after the interventions (six... 

In this paper, an algorithm for fault diagnosis of permanent magnet DC electromotors.has been investigated, based on vibration and electrical current monitoring. Several permanent magnet DC electromotors.with previously determined faults have been prepared and the vibration, current and speed data have been measured. The relationship between certain related measured data and faults has been determined. A fault diagnosis algorithm has been developed in this research based on these relationships. This algorithm can be used in mass production lines for quality control