Abstract—This article presents a performance comparison of an interior mounted permanent magnet synchronous generator (IPMSG) with a synchronous reluctance generator (SynRG) with the same size for a wind application. It is found that using the same geometrical dimensions, a SynRG can convert 74 % of the power that an IPMSG can convert, while it has 80% of the IPMSG weight. Moreover it is found that the efficieny for the IMPSG is 99% at rated power compared to 98.7% for the SynRG. Keywords—Interior mounted permanent magnet synchronous generator (IPMSG), synchronous reluctance generator (SynRG), wind energy, annual energy efficiency. I. INTRODUCTION HE synchronous reluctance machine (SynRM) has a long history. The first SynRM was introduced by Kostko in 1923 [1]. The synchronous reluctance motor was developed particularly in the 1960’s as a line-start synchronous AC motor [2]. During the 1990’s a substantial amount of work and research on the design and control of synchronous reluctance motors have been done [2]-[8]. Recently, the SynRM have been further improved [9]-[11]. Even though most of the researchers have explored the application of the reluctance machine as a motor, the field of the synchronous reluctance generator (SynRG) has also been brought to attention [12]-[14]. Several applications for synchronous reluctance machines are proposed in [15]. One of the interesting applications of the SynRG is for wind turbine generation systems [14], since SynRGs are robust, inexpensive and they have a simple rotor construction. In addition, a SynRG has no cogging torque. Moreover, they have low noise emission and are suitable for variable speed operation. Although synchronous permanent magnet motors often are a very good choice for many variable-speed drive applications, the advantages of using synchronous reluctance motors is that, the today very expensive magnets are not needed. In [14] a small wind turbine generation system with SynRG has been investigated. However, the system is not compared with any other generation systems. The purpose of this paper is to compare a modern wind turbine generator type, the IPMSG, with a generator using the Poopak Roshanfekr, Torbjörn Thiringer, and Sonja Lundmark are with the Chalmers University of Technology, Göteborg, Sweden (e-mail: poopak@ chalmers.se, torbjorn.thiringer @chalmers.se, sonja.lundmark@chalmers.se). Mikael Alatalo is with the Chalmers University of Technology and Aros electronics AB, Göteborg, Sweden (e-mail: alatalo@chalmers.se). synchronous reluctance principle. In order to perform this comparison 5MW IPMSG for wind applications is formed into a SynRG with the same size and design features. Moreover a target is to demonstrate how much power that can be converted from the SynRG with the same volume as the IPMSG. In addition; a goal is to compare the weights of the machines. Finally an objective is to determine and compare the losses and the annual energy efficiency for the generators. II. PERMANENT MAGNET SYNCHRONOUS MACHINE OPERATION The equations for the permanent magnet synchronous machine in the dq-component can be written as sq q el sd s sd i L i R u ω − = (1) and m el sd d el sq s sq i L i R u Ψ + + = ω ω (2) The torque is formed as; ( ) [ ] sd sq q d sq m i i L L i p T − + Ψ = 2 3 (3) where u sd and u sq are the stator voltage in d and q axis, R s is the armature phase resistance, el ω is the electrical speed ,L d is the d-axis inductance, L q is the q-axis inductance ,i sd and i sq are the stator current in d and q axis respectively and Ψ m is the flux linkage originating from the magnets. III. SYNCHRONOUS RELUCTANCE MACHINE OPERATION Equations (1) and (2) are also valid for the SynRM, with the remark that Ψ m is equal to zero in the SynRM. The SynRM torque in the dq-coordinate system can, therefore be simplified to ( ) ( ) θ 2 2 3 2 sin I L L p T q d − = (4) where p is the number of pole pairs,L d is the d-axis inductance ,L q is the q-axis inductance, I is the stator current and θis the current angle. More information about (4) can be found in [9]. The SynRM torque under constant current condition based on (4) is for a given current magnitude maximum when tanθ=1. Comparison of an Interior Mounted Permanent Magnet Synchronous Generator with a Synchronous Reluctance Generator for a Wind Application Poopak Roshanfekr, Torbjörn Thiringer, Sonja Lundmark, and Mikael Alatalo T World Academy of Science, Engineering and Technology International Journal of Electrical and Computer Engineering Vol:7, No:7, 2013 943 International Scholarly and Scientific Research & Innovation 7(7) 2013 scholar.waset.org/1307-6892/16541 International Science Index, Electrical and Computer Engineering Vol:7, No:7, 2013 waset.org/Publication/16541