## 3 Performance Comparison of the Proposed and Other Models
Consequently, the magnetic permeability is greater, and the inductance of the \(q\)-axis is greater than the inductance of the \(d\)-axis. The \(d\)-axis and \(q\)-axis are always rotated with an angle of 90\({}^{\circ}\) to the electrical angle. Figure 8: Comparison of the harmonic order of the surface permanent magnet (SPM) vernier motor, double half permanent magnet (DHPM) motor, and motor with salient poles. Figure 9: Magnetic flux flow in the model with salient poles. Figure 10 depicts the comparison results for the inductance of the \(d\)-axis and \(q\)-axis at the SPM vernier motor, the predecessor, and the proposed model. Moreover, \(Ld\) is smaller than \(Lq\) in the \(Ld\)-axis and \(Lq\)-axis, whereas \(Lq\) is larger in the proposed model than in the predecessor. The proposed model has higher torque than the predecessor model because \(Ld\) is also larger in the proposed model than in the predecessor. Figure 11 reveals that the magnetic flux flow when the inclination angle is between the stator core's internal circumference surface and the rotational axis is \(7.5^{\circ}\) in the presence of a salient pole of teeth. The figure indicates that the magnetic flux density significantly increased. Figure 12 depicts the flux density of (a) the DHPM vernier motor with a salient pole with a peak value of 0.7 and (b) the proposed model with a higher peak value (>0.8). Figure 10: Comparison of the inductance \(Ld\), \(Lq\) of the surface permanent magnet (SPM) vernier motor, typical double half permanent magnet (DHPM) motor, and proposed DHPM motor. Therefore, we discovered that the proposed model creates a strong magnetic field by combining the salient poles and saddle types. The coils for both the predecessor and proposed model have the same conditions, such as the direction, shape, and number of turns. Therefore, the resistance value of the winding coil is the same. In the proposed DHPM model, the space occupied by the motor is small, and the surface area of the circumference is small, which reduces the magnetic resistance. As a result that the slot space inside the stator limits the number of coil windings and the space factor, the inclination angle should be designed carefully with optimum values. The proposed model with a saddle coil achieves high torque because the interlinkage magnetic flux in the air gap is increased by the rate of the magnetic strength of the coil electromagnet. The density of interlinkage magnetic flux by the salient pole is also increased. Therefore, we increase the slope angle. The simulation result reveals that the proposed model generates a higher magnetic flux density and space utilization than the predecessor model. In the proposed model, the space volume ratio is 89% of the predecessor model at an inclination angle of 7.5\({}^{\circ}\). The volume decreased by 11%. Thus, the space utilization efficiency increased significantly. This simulation result demonstrates that increasing the inclination angle improves motor performance and space utilization efficiency. Consequently, the energy density per unit volume and weight have improved significantly. In general, motor designs replacing PMs and increasing PMs instead of coils in the stator and rotor to miniaturize motors and improve motor performance are common [13; 14; 15; 16]. A dual structure that increases the number of rotors and stators to improve performance has also been attempted [16; 17; 18; 19]. However, the proposed model increases the slope angle by applying saddle coils and salient poles, improving performance and space utilization efficiency. Figure 12: Comparison magnetic flux density in an air gap between the proposed and predecessor models. (**a**) Double half permanent magnet (DHPM) vernier motor with salient poles. (**b**) Proposed double half permanent magnet (DHPM) vernier motor. Figure 13 compares the \(N\)-\(T\) and \(N\)-\(I\) characteristics of the predecessor and proposed models. Each model is connected using a Y connection with 12 V and a coil resistance of 1.09 ohms.