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High power Permanent Magnet Synchronous Generators for wind applications may be made of modular subsystems, connected to the same shaft. The paper mathematically analyses the DC-side current and the torque ripples of a particular configuration: the stator phase axes of the several modules are axially aligned while the rotors are reciprocally shifted by a suited angle. Moreover each module is connected...
This paper deals with the characterization and construction of a rotating brushless PM exciter intended for synchronous generator excitation purposes. Traditionally, PM exciters are used as pre-exciters in synchronous generator excitations systems. In order to reduce the number of components and to increase the step time response of the system, a PM exciter is designed as an outer pole PM machine,...
Induction motors are usually well modeled with 2D finite element method. Nevertheless the result is very sensitive to the end ring resistance value. The paper describes different methods to determine a squirrel cage end ring impedance of induction machine. Starting from analytic formula, through 2D axisymmetric computation until 3D computation with finite element software, the impedance is obtained...
In general, radial gap motors employing neodymium sintered permanent magnet (Nd sintered PM) are used to achieve high torque density in many applications. However, the motors are not suited to a flat, disk-like shape because the dead space, such as the coil ends, occupies most of the motor volume. Therefore, axial gap motors are frequently used for flat shape instead of radial gap motors. Nd sintered...
This paper deals with the effect of the combination of double and triple layer (DTL) winding configurations on axially laminated anisotropic (ALA) rotor synchronous reluctance motors. Three ALA rotor shapes are opted in this paper to evaluate the airgap flux density, torque average and torque ripple contents. The stator geometry of a 4-pole, 1.5 kW, conventional three-phase squirrel cage induction...
Thanks to their higher power density and efficiency, the interior permanent magnet (IPM) machines equipped with a fractional slot concentrated winding (FSCW) layout have shown potentials in electric vehicle applications. Literature has shown that the application of multilayer winding layout to three-phase machines is effective in reducing the effect of low order space harmonics and the induced eddy...
The paper presents the simulations of influence of a shaft of induction motors on the magnetic field distribution and the resultant magnetizing current. Motors are supplied from mains at 50 and 200 Hz. For that calculations, field-circuit and analytical methods are used, taking into account the nonlinear phenomena. The results show a significant increase in magnetizing current for two-pole motor concomitant...
This paper presents a novel and fast modelling approach of electrical machines, which is purely based on coenergy only and it is conceived for being directly implemented in the very powerful, yet economical, real-time control architectures of today. The approach does not use any form of time-varying and/or non-linear inductances. A new mathematical formulation of the coenergy is combined with the...
This paper realizes a study of the influence of specific rotor design parameters on the permanent magnet synchronous machine (PMSM) electromagnetic behavior. The study is carried out in a FEM analysis environment. Four permanent magnet synchronous machines with the same stator and different rotor topologies have been simulated and their electromagnetic characteristics are compared to each other. The...
The adoption of the best available estimate for the stator Leakage reactance is the first step in several equivalent circuit of synchronous machine parameter estimation. However, there is no specific test for its direct measurement. This paper presents a simple and riskless procedure to estimate the Leakage reactance using the information obtained from the Constant Excitation Test. The method theory...
Superconducting generators are being proposed and investigated for large offshore wind turbines because of their compactness and light weight. Cost of energy is the key performance indicator to evaluate the feasibility of commercially applying superconducting generators to wind energy. This paper models, estimates and evaluates the cost of energy of a 10 MW direct-drive wind turbine for three superconducting...
Uprating and refurbishment of large hydro generators presents opportunities for increase in power output, efficiency and life time of the machine. Several parts of the machine can be changed depending on the need and predicted performance outcome. For the generator unit in this paper, refurbishment of the stator winding is to be done while maintaining the same stator core design, therefore a new winding...
This paper examines a rapid calculation method (RCM) to determine transient flux linkages depending on both rotor angle and coil currents. It was originally developed for small permanent magnet DC brush motors. In this paper, the RCM is applied to machines with reluctance rotors. After a short summary of the machines' characteristics, the adapted RCM is presented. Initially, the characteristic of...
This paper simply investigates experimentally multiple “rotor” bar current waveforms at standstill, on a dedicated inside-out induction motor prototype as a basis to analyze the asymmetry of bar currents. A phasor calculus scheme based on primary MMF space harmonics is developed to explain this asymmetry of bar currents at standstill for a symmetrical cage. The results of the paper should be a strong...
Electronically commutated motors (EC-motors) produce a mechanical torque by switching the currents in their stator winding system according to the instantaneous rotor position during rotation. The rotor position is determined by Hall-sensors capturing the magnetic field of the rotor's permanent magnets. In operation the Hall-sensors are exposed not only to the rotor field but also to the field of...
This paper deals with the two-dimensional (2D) finite-element (FE) and magnetic-equivalent-circuit (MEC) modelling of an existing 10 kW brushed wound-field DC machine, taking magnetic cross-saturation into account. The 2D FE model allows to thoroughly investigate the demagnetizing effect of the armature current on the pole flux and the cross-saturation effect on the field and armature-winding flux...
The dovetailed spoke interior permanent magnet (IPM) electric machine rotor has gained popularity over the past few years. The first machine prototype of this type was a design with NdFeB magnets. This rotor topology limits the magnet leakage flux associated with IPM designs that use the lamination structure to mechanically support the magnets and rotor structure by eliminating the need for magnetic...
Over the last few decades, there has been serious effort to replace mechanical and hydraulic systems with electrical systems. This effort also includes replacing fixed-speed and old electrical drives with higher-performance variable-speed drives. This is mainly due to the higher reliability, efficiency and robustness of electrical systems. This trend of “more electric” systems could be seen across...
Brushless doubly-fed induction machines (DFIMs) can be potential variable-speed generators for off-shore wind turbine applications. This special machine has two stator windings with different pole-pairs. There is no direct magnetic coupling between two stator windings. A unique nested-loop rotor is designed to couple both stator windings. However, it results in lots of undesired space-harmonics in...
Future electric vehicles requires electric motors with excellent torque-speed characteristics, high efficiency, and low costs. Equipped with controllable rotor flux, electrically excited synchronous motors are able to provide high torque at low speed and high efficiency at high speed. However, brushes and slip rings for field windings need maintenance and may influence reliability. In this paper a...
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