## 1 Introduction  
The permanent magnet synchronous motor (PMSM) is widely used in the electric vehicle and domestic appliance industries. The structure of the PMSM motor varies depending on the permanent magnet arrangement in the rotor structure; among them, the interior permanent magnet (IPM) PMSM motors made by inserting permanent magnets into rotors have advantages in applications requiring high output power and high efficiency at load condition [1; 2; 3; 4]. In particular, IPM type motors have saliency depending on rotor shape. Because of, reluctance torque components can be obtained in addition to magnetic torque components. Thus, the total torque of IPM PMSM motors is higher than that of surface permanent magnet (SPM) PMSM motors, which comprise only magnet torque [5; 6; 7; 8; 9]. Several advanced studies have been conducted to improve motor properties through proposed novel structure and topology for the motor, considering the advantages of this IPM type motor. In Reference [10], in order to increase the efficiency of the motor and achieve a wide operating range at the same time, an optimal design for a concentrated flux type interior permanent magnet (CFIPM) motor with a concentrated flux was proposed. In References [11; 12], a concentrated flux type ferrite magnet motor using a ferrite magnet was proposed to improve the efficiency of the motor. Since the concentrated flux type permanent magnet motor has a high torque density, there are various attempts to replace the performance of rare earth magnet motor with the concentrated flux type motor using ferrite magnet. In References [13; 14], a new structure was proposed for the concentrated flux type synchronous motor (CFSM) to improve torque density and vibration characteristics. To increase torque density, structures for improved motors were proposed using three different types of rotor core structures. In References [15; 16; 17; 18], studies were conducted to reduce torque ripple. When the cogging torque characteristic of the motor is large, accuracy of position and speed control is reduced, which can increase the torque ripple. Therefore, the effect of the main design parameters of the motor for the reduction of cogging torque were accurately predicted and analyzed. In Reference [19], a design method was explored to adopt the same topology with two rotors, with one inner coreless stator, to improve the mechanical and electromagnetic performance of the motor. In Reference [20], the magnetic field calculation and performance characteristics of a transverse flux machine (TFM) with permanent magnet excitation were studied. The composition, magnetic flux distribution, the back electro-motive force (EMF) and winding inductance characteristics of the TFM were analyzed, and the effectiveness of a simplified computational model was verified. In Reference [21], a type of transverse flux reluctance machine was studied. However, this design had the drawback of having a high fundamental frequency and high torque ripple, which complicate the control of the motor. To address this, a magnetic material study was conducted that could use a complex magnetic stator shape with a 3D magnetic flux path using a soft magnetic composite (SMC) in the magnetic circuit. In this study, we will compare the characteristics of the basic IPM model (the spoke structure) and the proposed flared type IPM model (the flared structure). In our previous study, two types of concentrated flux type IPM motors with the flared-shape magnets arrangement were examined. The flared type IPM model adopts a flared structure of C-shape ferrite magnets [22]. The proposed flared-shape structure can increase the useful magnetic flux, so the flared type IPM motor is also a form of the concentrated flux type IPM motor. The proposed flared-shape structure is optimized, and the validity is verified experimentally [23]. The study proposes a flared type rotor structure for replacing the basic spoke type IPM model, for performance enhancement.