A Study on a Linear Magnetic-Geared Interior Permanent Magnet Generator for Direct-Drive Wave Energy Conversion

In this paper, an effective low-speed oscillating wave power generator and its energy storage system have been proposed. A vertical flux-switching permanent magnet (PM) machine is designed as the generator while supercapacitors and batteries are used to store the energy. First, the overall power generation system is established and principles of the machine are introduced. Second, three modes are proposed for the energy storage system and sliding mode control (SMC) is employed to regulate the voltage of the direct current (DC) bus, observe the mechanical input, and feedback the status of the storage system. Finally, experiments with load and sinusoidal mechanical inputs are carried out to validate the effectiveness and stability of power generation for wave energy. The results show that the proposed power generation system can be employed in low-speed environment around 1 m/s to absorb random wave power, achieving over 60% power efficiency. The power generation approach can be used to capture wave energy in the future.

Section: Introductionmentioning

confidence: 99%

A Vertical Flux-Switching Permanent Magnet Based Oscillating Wave Power Generator with Energy Storage

Zou¹,

Cheng²

2017

“…In recent years, magnetically geared (MG) machines have attracted much attention [6][7][8][9][10][11][12][13][14][15][16][17][18][19]. MG machines incorporate a PM brushless machine and a magnetic gear into one volume.…”

Section: Introductionmentioning

confidence: 99%

A Novel Flux Focusing Magnetically Geared Machine with Reduced Eddy Current Loss

Liu

Zhao

et al. 2016

This paper proposes a novel flux focusing magnetically geared (MG) machine for wind power generation, considering the permanent magnets (PMs) eddy current loss and the balance between the pull-out torque of MG machine and the back-electromotive force (EMF)of the PM brushless machine. The PM eddy current loss in the two rotors of the conventional surface-mounted MG machine is calculated and analyzed by using finite-element method. By adopting serial-spoke structure in the inner rotor, a novel rotor structure for a MG machine is proposed to reduce the PM eddy current loss. Moreover, in order to balance the pull-out torque and the back-EMF, several serial-spoke structures and the main design parameters are investigated. Then, a quantitative comparison between the proposed topology and the conventional surface-mounted MG machine is performed. The analysis results indicate that the PM eddy current loss of the proposed MG machine can be significantly reduced and its pull-out torque and back-EMF can be balanced well.

“…Its computational process is described in Section 3.5. P W is the input power of the wave and calculated by Expression (14).…”

Section: Conversion Efficiency Of D-dwecmentioning

confidence: 99%

“…Reference [13] presented a flux-switching linear generator for D-DWECs to improve efficiency. Reference [14] presented a linear magnetic-geared interior PM generator that aims to achieve high power density, high efficiency, and reduced costs in WECs. However, wave power density is low, and certain problems are encountered with the generators adopted in present WEC systems, such as high volume, low conversion efficiency, and the need for special mechanical structures to match the energy conversion systems.…”

Section: Introductionmentioning

confidence: 99%

Design and Experiment Analysis of a Direct-Drive Wave Energy Converter with a Linear Generator

Zhang

2018

Self Cite

Abstract:Coastal waves are an abundant nonpolluting and renewable energy source. A wave energy converter (WEC) must be designed for efficient and steady operation in highly energetic ocean environments. A direct-drive wave energy conversion (D-DWEC) system with a tubular permanent magnet linear generator (TPMLG) on a wind and solar photovoltaic complementary energy generation platform is proposed to improve the conversion efficiency and reduce the complexity and device volume of WECs. The operating principle of D-DWECs is introduced, and detailed analyses of the proposed D-DWEC's floater system, wave force characteristics, and conversion efficiency conducted using computational fluid dynamics are presented. A TPMLG with an asymmetric slot structure is designed to increase the output electric power, and detailed analyses of the magnetic field distribution, detent force characteristics, and no-load and load performances conducted using finite element analysis are discussed. The TPMLG with an asymmetric slot, which produces the same power as the TPMLG with a symmetric slot, has one fifth detent force of the latter. An experiment system with a prototype of the TPMLG with a symmetric slot is used to test the simulation results. The experiment and analysis results agree well. Therefore, the proposed D-DWEC fulfills the requirements of WEC systems.