The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
In this study, numerical investigations of flow characteristics of a pumpjet propulsor based on Computational Fluid Dynamics (CFD) method have been presented. The Zwart-Gerber-Belamri (Z-G-B) cavitation model based on the Reynolds Averaged Navier-Stokes (RANS) method is employed. The structured gird is applied. A four-blade skewed E779A propeller has been used to verify the numerical method. The comparison...
Structural defects in the rotor cage of large electrical machines significantly impact their expected operational lifetime. This work simulates the stresses developed in a damaged rotor cage during different transient profiles and for different sizes of the imperfection. A combined model featuring electrical, thermal and mechanical stages as well as three different meshes reflecting a progressing...
The paper is dedicated to the study of aerodynamic effects in small power wind turbine rotors using mathematical models to describe the fluid flow physics and modern methods of numerical simulation in the framework of computational fluid dynamics (CFD). There was argued the geometry of blades' aerodynamic profiles efficient in terms of energy conversion efficiency and based on them original concepts...
This paper presents the computer simulation of a switched reluctance machine (SRM) operating as a generator proposing an alternative for the representation of the inductances of the machine coils and their respective rates of variation. The simulation results show the reliability of the proposed model, especially in comparison with other models of machine inductance representation. The validation...
This paper concerns the development of a sensorless controller for synchronous reluctance motors based on finite elements model results. A hybrid solution is used, which includes an adaptive observer for not-zero speed operation and signal injection for standstill. The observer detects the flux linkages components in the two-phase stationary reference frame by the voltage model integration and closed...
The paper discusses two observer designs for estimation of the inverse of the rotor time constant of the induction motor. The paper presents the model and develops a linear and a sliding-mode observer. Estimation is based on the dynamic equation of the flux magnitude in the rotating reference frame. The stationary-frame fluxes are obtained using a voltage model observer — they are used for field orientation...
Motor current measurement techniques as well as predictive control algorithms for electric drives rely on an assumption of linear motor currents changes resulting from constant inverter output voltages. Recent research has reported that this assumption does not hold in motors with short electrical time constant, and in drives whose rotor position advances substantially during a control period. This...
The paper presents the possibility of using a two-dimensional field-circuit model of a squirrel cage induction motor for qualitative tests of the axial leakage flux course used in non-invasive diagnostics of induction machines. The study considered the reduction of leakage fluxes associated with the stator and rotor winding to the zero component of the symmetric components system. A qualitative comparison...
Induction machines for traction applications are operated at working points of high ferromagnetic saturation. Depending on the working point, a broad spectrum of harmonic frequencies appears in the magnetic flux density of induction machines. Detailed loss analysis therefore requires local and temporal highly resolved nonlinear field computation. This loss analysis could be performed in the post processing...
This paper introduces a new approach for solving the navigation problem of Unmanned Aerial Vehicles (UAV) by studying its rotational and translational dynamics and then solving the nonlinear model by the Decomposition Coordination method. The objective is to reach a destination goal by the mean of an autonomous computed optimal path calculated through optimal control sequence. Solving such complex...
The development of Condition-Based Maintenance and Prognostics and Health Management systems can be fostered by models that accurately reproduce the effects and propagation of faults. Conventional methods applied to the analysis and simulation of rotor asymmetries in induction machines are based in the classical 2-D finite element approach, which is unable to reflect its complex effects, such as interbar...
A method of modeling and numerical simulation of two-phased variable reluctance stepper motor using time stepping finite element method (FEM) is presented. In the proposed model, the nonlinear electromagnetic field equations and the circuit equations are strongly coupled and solved together with the motion equation at each time step. The subject of this paper is a novel form of construction of reluctance...
A kind of arc-linear axial flux permanent-magnet synchronous machine (AL-AF-PMSM) used for scanning system is researched in this paper. Due to the characteristics of the three-dimensional (3-D) magnetic field, 3-D finite element method (FEM) is usually required to analyze the AF-PMSM. However, 3-D FEM is generally too time consuming. In order to avoid this problem, an approximate equivalent 2-D calculating...
This paper presents 3D modeling of hysteresis motor with high temperature superconducting material in the rotor using Finite Element based solver software COMSOL Multiphysics. Due to the anisotropic property of HTS material, magnetic flux distributions are non-uniform in different axes. Therefore, analysis of HTS hysteresis motor using two dimensional modeling cannot provide high degree of accuracy...
The present work numerically explores the performance characteristics of Darrieus turbine with NTU-20-V and NACA 0018 airfoils. The NTU-20-V airfoil was carved out to enhance the fatigue life of the aluminium extruded blades by reinforcing with glass fiber material in standard shapes. The earlier studies by the authors include conceiving the airfoil profile through genetic algorithm optimization followed...
Due to the drawbacks of linear damage accumulation model, it is necessary to substitute nonlinear model for it. A novel concept of online damage calculation model based on the continuum damage mechanics is proposed in this paper. Thermal transfer process is analyzed detailedly, the complexity is decomposed into single input and single output function. Synthesis of thermal decomposition with continuum...
Theoretical researches and simulation results, which based on numerical realization of the finite element method of three-dimensional mathematical model of the induction motor are obtained. The regularities of the distribution of the induction and magnetic field energy in the short-circuit mode and their quantitative relation for active zone and the area of the coil ends of the stator windings of...
This paper presents a novel angular velocity estimation strategy of a Reaction Sphere (RS) for satellite attitude control based on a Linear Parameter-Varying (LPV) Kalman Filter. The reaction sphere is a permanent magnet synchronous spherical actuator whose rotor is magnetically levitated and can be accelerated about any desired axis. The spherical actuator is composed of an 8-pole permanent magnet...
This paper presents a comprehensive modeling approach for tail-sitter hybrid UAVs featured by vertical take-off and landing (VTOL) and cruise flight capabilities. The modeling approach includes all essential components, such as full angle of attack envelope wing and fuselage aerodynamics, sideslip wind effect and actuator dynamics. A unified formulation comprising all model components is derived to...
This paper presents an attitude tracking incremental controller using a nonlinear reference model for a multicopter. The incremental controller is more robust compared to conventional nonlinear dynamic inversion controller against uncertainties due to its reduced model dependence. In order to further ensure robustness of the controller in the presence of actuator faults, the control effectiveness...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.