EUROPEAN TRANSACTIONS ON ELECTRICAL POWER Euro. Trans. Electr. Power 2005; 15:245–256 Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/etep.56 Design, modelling and test results of the AWS PM linear generator H. Polinder 1, * ,y M. E. C. Damen 2 and F. Gardner 2 1 Delft University of Technology, Electrical Engineering, Electrical Power Processing, Mekelweg 4, 2628 CD Delft, The Netherlands 2 Teamwork Technology B.V., De Weel 20, 1736 KB Zijdewind, The Netherlands SUMMARY The Archimedes Wave Swing (AWS) is a system that convertsocean wave energy into electrical energy. A pilot plant of this system has been built. This paper describes the design of the permanent-magnet (PM) linear synchronous generator applied in the AWS. Based on a magnetic circuit model, it is concluded that saturation does not play an important role. The correlation between measured and calculated generator parameters and no-load voltage is reasonable, which indicates that the generator is adequate. Copyright # 2005 John Wiley & Sons, Ltd. key words: Archimedes Wave Swing (AWS); wave energy; permanent-magnet linear generator 1. INTRODUCTION There are various ways of converting ocean wave energy into electric energy, as shown in References [1–6]. The Archimedes Wave Swing (AWS) concept is unique because it is completely submerged. This is important, because it makes the system less vulnerable in storms; and it is not visible, so that public acceptance is not as much of a problem as it is, for example, with offshore wind farms. The AWS basically is a cylindrical air-filled chamber as shown in Figure 1. The lid of this chamber, called the floater, can move in a vertical direction with respect to the bottom part, which is fixed to the sea-bottom. When a wave is above the AWS, the volume of the AWS is reduced by the high pressure of the water. When a trough is above the AWS, the volume increases because of the air pressure inside the AWS. From this linear motion, energy can be extracted. By tuning the system frequency to the wave frequency, the stroke of the linear motion can be made much higher than the wave height. The system frequency can be changed by changing the air pressure and the volume inside the AWS. It is possible to convert the linear motion to rotating motion and thus use a rotating generator. However, it appears to be extremely difficult to build a robust and maintenance-free gear; therefore, a linear generator is used. The generator terminals are connected to a 6 km long cable, which brings the power to the shore. An inverter on the shore is used for the utility grid connection. Copyright # 2005 John Wiley & Sons, Ltd. *Correspondence to: H. Polinder, Delft University of Technology, Electrical Engineering, Electrical Power Processing, Mekelweg 4, 2628 CD Delft, The Netherlands. y E-mail: H.Polinder@EWI.TuDelft.nl