Nikolaos M. Kimoulakis

Power Generation Optimization From Sea Waves by Using a Permanent Magnet Linear Generator Drive

This paper presents the design procedure and modeling methodology for a four sided linear permanent magnet generator used in sea wave energy extraction applications. Appropriate coupled magnetic-electric-mechanical models for the analysis of the linear permanent magnet (LPM) generator and the hydraulic system have been developed. The effects of permanent magnet configuration on the overall system performance have been investigated. The proposed models suitability has been checked through measurements in a 16 kW prototype power plant.

Cogging Force Minimization in a Coupled Permanent Magnet Linear Generator for Sea Wave Energy Extraction Applications

The paper analyzes permanent magnet geometry effects on cogging force of permanent magnet linear generators. The dynamic modeling of the generators performance is based on sensitivity analysis technique and finite-element representation. The generator is coupled to a particular mechanical system for sea wave energy extraction applications. The proposed methodology involves minimization of cogging force through parametric sensitivity analysis on alternative magnet profile configurations.

Hybrid technique for dynamic modelling of the performance of linear generators with skewed mounted permanent magnets

The paper presents a specific simulation model for the analysis of linear electrical machines with skewed mounted permanent magnets. Modelling implementation is based on a hybrid numerical technique incorporating standard finite elements combined with analytical solution of Laplace equation in the air gap area. The proposed model enables the simulation of generators overall performance under various load conditions, taking also into account the case of surface magnet skew on the translator of the linear generator.This paper proposes a specific hybrid 2-D simulation model of magnetic field distribution accounting for magnet skew in the case of a linear permanent magnet generator (LPMG). The proposed methodology is based on a hybrid numerical technique implementing standard finite elements for the analysis of stator and rotor parts combined with an analytical solution in the Cartesian coordinate system in the air-gap area specified for magnet skew consideration. The developed technique has been incorporated in a coupled field-circuit model for the overall simulation of the performance of an electrical generating unit for sea-wave energy extraction using LPMG. The derived model has been implemented in the control subsystem aiming to tune the movement of the wave energy absorber to the system resonance frequency enabling to optimize its performance. Simulation results have been validated by measurements on a sea-wave energy extraction demonstration plant.

Parameter Extraction of a PM Machine Employing 3D Finite Element Analysis Tools for Model Predictive Control Schemes

This paper introduces a permanent magnet (PM) machine model accounting for saturation effects and non-sinusoidal electromotive force (EMF) employed in model predictive control schemes. The procedure of the model parameters determination is based on the three dimensional finite element analysis (FEA) considering saturation and cross-coupling effects. The conventional equivalent circuit model is subject to modifications so as to incorporate data derived from FEA enabling the model predictive control strategies to obtain proper actions for the converter operation based on the accurate prediction of the machine performance. The regeneration of the n-order harmonic components of the non-sinusoidal EMF is attained by combining methods of superposition and approximation estimating the output voltage at the machine terminals for different loading and speed. Developed model simulation results have been validated by experiments performed on an inset PM machine prototype.

Overview of the Alternative Topologies of Linear Generators in Wave Energy Conversion Systems

Several operation principles and generator types have been developed because of the growing interest for the wave energy conversion systems (WECSs). A WECS is demanded to be more efficient so that the overview of the already developed systems is necessary. An overview of the different operation principles and the various linear generator types is presented analyzing the advantages and the disadvantages. Finally, a complete scheme gathering the most vital characteristics is introduced.

Time Variation of Operational Characteristics for a Linear Permanent Magnet Synchronous Generator under Various Load Conditions

The paper presents the simulated time variation of the operational parameters of a Linear Permanent Magnet Synchronous Generator (LPMSG). A hybrid specific simulation model, incorporating standard finite elements combined with analytical solution of Laplace equation in the air gap area, has been coupled with a dynamic simulation model for the external electrical circuit loading the LPMSG. The proposed model enables the simulation of generator’s overall performance under various load conditions, taking also into account the case of surface magnet skew on the translator of the linear generator.