This paper presents an investigation on the undesirable vibration of an oblique-stud stator frame in a large hydropower generator by means of experimental and finite element (FE) analysis. First, field experimental tests were performed, and the results indicate that the main vibration component comes from electromagnetic factors. Then, a 2D-magnetic and 3D-mechanical FE model was developed to i...

In this paper, accelerated multi-factor aging tests in laboratory have been conducted on the stator ham of a large generator. During the period of aging, the temperature spectra of dielectric dissipation factor tan 6 of stator insulation were employed to investigate aging characteristics of insulation materials. Test results showed that the peak temperature T,,, of the tan 6 -T curve under 0.2U...

This paper presents a speed sensorless direct torque control scheme using space vector modulation (DTC-SVM) for permanent magnet synchronous motor (PMSM) drive based a Model Reference Adaptive System (MRAS) algorithm and stator resistance estimator. The MRAS is utilized to estimate speed and stator resistance and compensate the effects of parameter variation on stator resistance, which makes fl...

This project presents a method of improving the speed profile, torque and flux using stator estimation method. This discusses the problems associated with the error in stator Resistance and proposes an analytical approach to investigate its effect on the actual and estimated variables of a induction motor. Based on how this error affects the estimated angle between the stator flux and current v...

A new online identification methodology for estimation of the rotor flux components and the main electrical parameters of vector controlled induction motors is presented in this paper. The induction motor model is referred to the rotor reference frame for estimation of rotor flux and rotor parameters, and referred to the stator reference frame to estimate stator parameters. The stator parameter...

The present paper approaches the comparative design and analysis of 5 SRM topologies for an EPAS application. Different number of phases and different combination of stator and rotor pole number will be considered, keeping the same main dimensions (outer and inner stator diameter, airgap length, stack length, stator pole height, stator yoke width, rotor pole height) and the same winding per pha...

This paper presents the study of a variable speed wind energy conversion system based on a Doubly Fed Induction Generator (DFIG) based on a sliding mode control applied to achieve control of active and reactive powers exchanged between the stator of the DFIG and the grid to ensure a Maximum Power Point Tracking (MPPT) of a wind energy conversion system. The proposed control algorithm is applied...

single-phase squirrel cage and three-phase induction electromotors are the most popular electromotors used in industry from long ago. when an induction motor starts with direct connection method, it takes a lot of current from the power supply (several times the nominal current); so, several methods have been devised to start such electromotors. these methods either reduce the voltage of the st...

This paper gives an overview of various electric machines for application to renewable energy harvesting, and reveals the corresponding challenges and research opportunities. After introducing various renewable energies and electric machines, the concept of renewable energy machines is coined. Then, the existing machines, including the DC, induction and synchronous types, for renewable energy h...

A population of young blacktip sharks was monitored over three years to determine their mortality rates using a series of acoustic listening stations. Based on these data it was possible to use several mortality estimators, including indirect life -history based methods and direct methods such as the Kaplan-Meier and SURVIV methods, to estimate natural, fishing and total mortality. Kaplan-Meier...