The recent increase in the use of permanent magnet rotor motors underlines the importance of designing a rotor with an interior permanent magnet (IPM) structure, high power, and high efficiency. This study analyzed the rotor shapes of IPM motors for electric vehicles. Five types of motor rotors for automobiles were analyzed, including two hybrid vehicles. In order to minimize the number of variables in the analysis, the size of the motor stators was fixed and only the rotor shapes were modified to compare torque, torque ripple, efficiency and back-electromotive voltage. When the motor properties were compared as a function of rotor shape, the rotor shape with the smallest magnet volume exhibited excellent results for torque, efficiency and torque ripple.

This paper proposes fuzzy gain scheduling of proportional differential control (FGS-PD) system for tracking mobile robot to moving sound sources. Given that the target positions of the real-time moving sound sources are dynamic, the mobile robots should be able to estimate the target points continuously. In such a case, the robots tend to slip owing to abnormal velocities and abrupt changes in the tracking path. The selection of an appropriate curvature along which the robot follows a sound source makes it possible to ensure that the robot reaches the target sound source precisely. For enabling the robot to recognize the sound sources in real time, three microphones are arranged in a straight formation. In addition, by applying the cross correlation algorithm to the time delay of arrival base, the received signals can be analyzed for estimating the relative positions and velocities of the mobile robot and the sound source. Even if the mobile robot is navigating along a curved path for tracking the sound source, there could be errors due to the inertial and centrifugal forces resulting from the motion of the mobile robot. Velocities of both robot wheels are controlled using FGS-PD control to compensate for slippage and to minimize tracking errors. For experimentally verifying the efficacy of the proposed the control system with sound source estimation, two mobile robots were fabricated. It was demonstrated that the proposed control method effectively reduces the tracking error of a mobile robot following a sound source.

Recently, various methods have been proposed to increase the output power density of a driving motor applied to an electric vehicle. One such method is to design a structure with two motor rotors. High output density can be obtained by applying the dual rotor to the motor. However, this increases the cogging torque, which can cause high noise and vibration. In this paper, we proposed a method for reducing the cogging torque by adjusting the angle between the magnet and the dual rotor, as well as a novel method for reducing the cogging torque by angular adjustment of the slot opening based on electromagnetic field analysis. In addition, the design was implemented by applying a split core to increase the ease of manufacturing and the dot rate in the motor. We believe that high cogging torque, which is a disadvantage of dual rotor motors, can be lowered by the methods proposed in this paper. The results of this study are expected to be applicable to electric vehicles that require high output power density.

In this study, a method to determine the optimal generator operating point is proposed to enhance the utilization of power resources in a range-extended electric vehicle (Re-EV). Currently, the Re-EV is being developed as one of the solutions to the short driving range and charge problem of electric vehicles (EVs). In particular, we present a method for flexibly determining the operating point of the generators mounted on Re-EVs based on the power consumption trends of the users. Our proposed method can address the problem in existing algorithms wherein all the available resources are not utilized, even though there is fuel remaining in the EV because the battery is not completely discharged. The proposed algorithm was developed based on data acquired through actual driving tests using an agricultural utility vehicle; these data can be applied to various power consumption patterns, including nonlinear consumption patterns. In addition, this algorithm can be applied to other types of Re-EV with different battery and generator specifications. We perform simulations and experiments to verify the proposed algorithm and the results demonstrate the effectiveness of the proposed approach compared with other existing methods.

In this paper, the densification mechanism of ultrasonic compaction was analyzed using a force balance model. Ultrasonic compaction is quite a promising way to solve the lower mechanical property problem of green compact in the compaction process, although it has some obstacles to overcome for its various applications. Our model proposes that the resultant density is achieved as the applied and resistance forces reach the equilibrium state. Based on the proposed model, the ultrasonic compaction increases the density of green compact by reducing the internal friction between the powder and compaction die, as well as the internal friction among particles themselves. It was also found that during the powder compaction, the ultrasonic vibration mostly contributes to slipping and the rearrangement of the particles.