Sharif Digital Repository

Real-time linear robust control of a two phase hybrid stepper motor with Quantitative Feedback Theory method in micro-stepping operation is considered in this paper. Utilizing the phase currents as inputs, linear robust controller is derived for a Hybrid Stepper Motor that achieves robustness to parametric and dynamic uncertainties such as viscous friction, load torque, flux linkage and other uncertainties. Simulation and experimental studies are presented to show the efficiency of the control design approach  

The flux and torque hysteresis bands are the only gains to be adjusted in direct torque control (DTC). The torque ripple and harmonic loss of motor and switching loss of inverter greatly Influence them. Hence, these variables must be observed in the control process to maximize performance of the system. In this paper, the effects of flux and torque hysteresis bands on inverter switching loss, harmonic loss, and torque ripple of induction motor are investigated. In order to find their optimum values, a cost function consisting motor harmonic losses, torque ripples, and inverter switching losses is defined. Minimizing this cost function leads to the optimum value of the hysteresis bands of... 

A superconducting synchronous motor with an inductor containing bulk high temperature superconductor and BiSrCaCuo wires has been studied in this paper. The principle of operation is based on the interaction between the two spatial variable magnetic fields in the motor air gap. One of the two aforementioned magnetic fields is produced by the superconducting inductor based on magnetic shielding of high temperature superconductors. A procedure is developed to calculate the magnetic field produced by the inductor in the environment of the commercial finite element code ANSYS. The HTS motor is designed to develop 100 hp (the rated power). © 2008 Australasian Universities Power Engineering... 

Vector control induction motor drives are particularly sensitive to the variation of motor parameters. As a consequence, the field orientation is missed, leading to substantial degradation of performance. The performance of traction motors can be even more degraded by the substantial core loss due to their high supply frequency. In this paper, a flux observer using combined voltage and current model is presented. The influence of the core loss resistance is considered in motor models. This control system is robust against simultaneous variations of the stator resistance, rotor resistances, as well as the mismatch of the equivalent stator core-loss resistance, yielding a globally stable... 

The main purpose of this paper is to minimize the loss while reducing the flux and torque ripples in permanent magnet synchronous motors (PMSMs) under direct torque control (DTC). Offline method is used to minimize the loss and obtain the optimal flux. To reduce the amount of computation, the optimal flux table is produced according to the conditions in which the machine works. To reduce the flux and torque ripples and to control the switching frequency, SVM-DTC method is applied. Simulation results depict a noticeable increase in efficiency of the motor and a reduction in flux and torque ripples  

The vertebrate nervous system produces a wide range of movements flexibly and efficiently, in spite of high complexity and nonlinearity of their motor system. The existence of building blocks in motor system known as synergies can be a convincing solution to overcome the computational complexity. In mathematical perspective, optimal feedback control as a theory of motor coordination provides a coherent framework that leads to optimal synergies. Alternatively, some experiments in vertebrates have shown the involvement of spinal motor primitives in movement execution. The goal of this study is first extracting optimal synergies in nonlinear dynamics case and then investigating their biological... 

Permanent magnet synchronous motor (PMSM) drives have many advantages over other drives, e.g. high efficiency and high power density. Particularly, permanent magnet synchronous motors are epoch-making and are intensively studied among researchers, scientists and engineers. This paper deals with a novel high performance controller based on genetic algorithm. The scheme allows the motor to be driven with maximum torque per ampere characteristic. In this paper assuming an appropriate fitness function, the optimum values for d-axis current of motor set points at each time are found and then applied to the controller. Simulation results show the successful operation of the proposed controller. ©... 

The study reported in this paper deals with the problem of developing a controller with tolerance to current sensor faults. To achieve this goal, two control strategies are considered. In the first method, field oriented control and a developed observer are used in case of no fault. The second approach is concerned with fault tolerant strategy based on an observer for faulty conditions. Current sensors failures are detected and the current will be estimated successfully in order to allow continuous operation of the vector control. Based on the motor model, currents can be estimated using a nonlinear observer. A decoupling current vector control strategy is developed to ensure high... 

Although permanent magnet synchronous motors (PMSMs) are inherently of high efficiency, their efficiency is enormously dependent on their control strategy. The purpose of this paper is to improve the efficiency of PMSMs under a direct torque control (DTC) method. The main idea behind the proposed method is to predict a required small change of the statorflux amplitude at each sampling period to reduce the machine electrical loss before the change is applied. Accordingly, at every sampling time, a voltage vector is predicted and applied to the machine to change the flux amplitude in a xvay that the electrical loss decreases. The results of simulation show significant improvement in the... 

Permanent magnet synchronous motor (PMSM) drives have many advantages over other drives, i.e. high efficiency and high power density. Particularly, PMSMs are epoch-making and are intensively studied among researchers, scientists and engineers. This paper deals with a novel high performance controller based on genetic algorithm. The scheme allows the motor to be driven with maximum torque per ampere characteristic. In this paper assuming an appropriate fitness function, the optimum values for d-axis current of motor set points at each time are found and then applied to the controller. Simulation results show the successful operation of the proposed controller  

Standing-wave ultrasonic motors are a modern class of positioning systems, which are used to deliver a high precision linear or rotary motion with an unlimited stroke. The design process should be performed through an effective optimization algorithm in order to guaranty proper and efficient function of these motors. An optimization method of ultrasonic motors is proposed based on the combination of finite element method and factorial design as a design of experiments in this study. The results show the ability of this method in optimal design of ultrasonic motors especially those which have a complex structure and multi modes operation principle  

Interior permanent magnet (IPM) bearingless motors are becoming a good choice for high-speed applications. In these motors, reducing the thickness of the PM leads to the increase of the radial forces which affects the demagnetizing fields. Various types of PM motors have so far been recommended for enhancement of the radial forces and torque. In the proposed IPM motor the d-axis flux-linkage and the q-axis torque component are raised due to the armature reaction and this saturates the stator teeth. In addition, the magnetic attraction force generated by displacement force depends on the armature reaction. The mathematical model of IPM bearingless motor based on the dq transformation,... 

Modular linear doubly salient permanent magnet motors are well adapted to linear propulsion systems because of their distinct characteristics, such as high efficiency and power density, reduced maintenance and initial cost, low noise and permanent magnet (PM) leakage flux, and fault tolerance capability. However, such motors suffer from high cogging thrust. In this study, various techniques based on previously proposed methods for PM machines are applied on the studied motor and evaluated by using non-linear three-dimensional time-stepping finite element analysis; three novel, optimised techniques are then presented. The techniques presented are based on the minimisation of the variation in... 

A linear ultrasonic motor (LUSM) with an elliptical-shaped metallic stator and two orthogonal vibration modes is presented in this research. The driving tip's desired vibration is generated by the excitation of two piezoelectric actuators installed inside the stator by two sinusoidal voltages with ±[Formula presented] phase difference. The working principle of the motor is described and mathematically formulated. Furthermore, finite element analysis and parametric optimization are performed to finalize the motor design. A prototype of the motor is fabricated and evaluated by identification and operation tests. The experimental and numerical characteristic curves of the motor are presented... 

The performance of an HTPB/N2O hybrid motor was experimentally investigated. A hybrid motor was designed and manufactured in a laboratory with the purpose of studying the effects of various parameters on the motor's performance, including fuel regression rate and specific impulse. A series of tests were conducted to find a correlation between the fuel regression rate and the oxidizer's mass flux. The effects of chamber's pressure on the regression rate as well as other performance parameters were investigated. While the burning rate did not change dramatically, both the efficiency and ISP of the motor increased. The local fuel regression rate and the fuel port were also calculated. In... 

Stalling of residential air conditioners (RACs) following a transient fault can delay the voltage recovery ranging from 3 to 20 seconds. This phenomenon is referred to as fault-induced delayed voltage recovery (FIDVR). Several aggregated RAC models have been presented to replicate the actual FIDVR events. However, they usually have two main drawbacks as: i) considering independent stalling voltage and stalling time for all RACs, ii) resulting in only two ultimate modes; either 100% stalled or 100% normal running. This paper amends the abovementioned shortcomings by proposing a simple and effective performance-based RAC model. The proposed model utilizes a simple explicit relation between the... 

Switched Reluctance Motors (SRMs), which are simple and reliable motors, have attracted interest for electric vehicle propulsion systems. It is shown that an SRM offers a good performance at high acceleration and low speed driving conditions. Efficiency map of an electric motor is a very important characteristic specially when the motor is to be used in a wide range of speed and load variations, which is the case in electric propulsion systems. In this research, the efficiency map of an SRM is derived using a combination of the Finite Element Method (FEM) and a mathematical model. This efficiency map has been used for different driving cycles to test the SRM performance as a vehicle... 

Single-phase, outer-rotor squirrel cage induction motors are widely used in ceiling fan applications. Furthermore, they can be employed for pumps, and in-wheel hub drives. In this article, an analytical model based on magnetic equivalent circuit is proposed to evaluate the performance of the motor. The influence of rotor slots' skewing, stator end windings, slots' leakage inductance, and core saturation are included in the model. Furthermore, the windings' copper losses and the core's iron losses are calculated using the proposed model. The results of the presented model are compared with those of time variant finite element analysis (TVFEA) and experimental measurements close agreement...