## 1 Introduction  
Transverse flux permanent magnet machine (TFPMM) produces high power and high torque, which bring about less constraints of structure on electric load and magnetic load [1; 2; 3; 4; 5]. This has made TFPMM desirable for direct drive applications where a high torque is required at a low rotational speed, such as traction applications, free piston energy converter applications, wind turbines, and wave energy converters [4; 6; 7]. TFPMMs are also recognized as modulated pole machines [8; 9]. The TFPMM usually has a toroidal armature winding, where the current runs parallel to the direction of rotation [10]. In other words, the plane of the magnetic flux path of a transverse flux machine is perpendicular to the moving direction [11]. Since the overall winding can link the Permanent Magnet (PM) fluxes from all the magnetic poles of the machine, TFPMM can reach higher torque when compared with the radial flux and axial flux machines [2; 3; 4; 12; 13]. Another advantage of the TFPMM is that the electrical and magnetic circuits of the machine are excellently decoupled [9]. The performance of the magnetic circuit is defined by the teeth and core-back of the machine. The number, size, and circumferential position of the teeth can be fixed individually based on the size of the coil, which specifies the electrical performance of the machine for a certain thermal limit. Moreover, as the magneto-motive force of the coil is distributed across all the teeth of the machine, an increase in the tooth number (effectively, a decrease in the pole pitch) results in an increase in the electrical loading of the machine [8; 9; 14]. TFPMMs suffer from a common set of drawbacks, namely a high cogging torque (and consequently a high torque ripple) [15], and a low power factor [16; 17]. For most electric machines, the magnetic field analysis is often performed in the machine's 2-D cross-sectional plane. However, the TFPMM has complicated 3-D flux components [6; 18; 19], and the machine's cross-sectional plane encloses a current loop. Thus, modeling a TFPMM using a two-dimensional finite (2D-FE) model in the cross-sectional plane is not a valid decision. Design becomes more difficult and time-consuming for TFPMMs than for other electrical machines, because three-dimensional finite element (3D-FE) may be the only design method which can produce reliable results [20; 21]. Another problem with TFPMMs is that it is difficult to make them with electrical laminated steels, due to their three-dimensional flux paths. In these machines, soft magnetic composite (SMC) materials are used to make the magnetic cores. SMC is composed of a surface with electrically insulated iron powder spots, which results in low eddy current losses, and magnetic and thermal isotropy. At a higher frequency, e.g., over 300 Hz, the eddy current losses of the SMC are much lower than that of laminated steels. Mechanically, this material can be used to produce magnetic cores by the highly matured powder metallurgic technology, which results in structures with extremely high productivity and low manufacturing costs. Thus, it is believed that SMC is appropriate for higher frequency applications, such as the high speed electrical machines and electrical machines with large numbers of pole pairs [22; 23; 24]. TFPMMs exist in the literature by a number of patents and scientific articles. The topologies of TFPMMs differ by structure, but the principles of their performance are the same [13; 25]. The present paper proposes a novel transverse flux permanent magnet disk-rotor generator with E and I core (TFPMDEIG). Moreover, the rotor is of disk shape, because a cylindrical rotor increases the inductance of armature winding and decreases the machine's power factor [26]. Among other advantages of the rotor-disk, it can be noted that this allows for high rotational speeds. On the other hand, employing this kind of generator in wind turbines is preferable, due to their compact structure.