Conference Agenda

This paper proposes a framework for the optimization of electric vehicle (EV) powertrains utilizing physics-based electromagnetic models for the estimation of traction electric machine (EM) performance. Specifically, the framework employs finite element modeling to parameterize the electric motor, the output of which is utilized in a quasi-static vehicle model to holistically optimize the EV powertrain for efficiency. The framework minimizes computation time of of each optimization iteration. This framework enables investigation of EM design parameters from a system-level perspective, providing relations between vehicle performance and EM design parameters. The proposed framework is to be applied with a selection of optimization parameter sets, investigating the impact of EM design parameter inclusion.

With recent advancements in analysis and manufacturing technologies, interest in axial flux permanent magnet motors (AFPMMs) has been increasing. Accurate analysis of AFPMMs requires 3-dimensional finite element analysis (3-D FEA). While 3-D FEA offers high accuracy, it demands significant computational time and resources. To address these limitations, this paper proposes an equivalent 2-dimensional finite element analysis (2-D FEA) model. The proposed model improves the accuracy of 2-D analysis by considering the radial end effect. By dividing the 3-D model radially to construct the 2-D equivalent model, the analysis accuracy is enhanced by considering the leakage flux in the innermost and outermost radial regions. The precision of the equivalent 2-D FEA model will be validated through comparisons with 3-D FEA results and experimental data.

This paper proposes a cogging torque calculation model that considers stator inner diameter tolerances using an analytical method. The purpose of this study is to present a faster calculation method that maintains sufficient accuracy compared to traditional finite element method (FEM) analyses when performing electromagnetic analysis with tolerances. First, the motor is equivalently modeled as a smooth core, and the air-gap flux density is calculated based on governing equations. Subsequently, the effects of slots and tolerances are incorporated using Complex Relative Permeance (CRP) to compute the air-gap flux density that reflects the influence of tolerances. Finally, the cogging torque is calculated, completing the proposed process. The validity of the proposed model is verified through comparisons with experimental data obtained from an actual prototype.

The Interior Permanent Magnet Synchronous Motor (IPMSM) offers advantages such as preventing magnet detaching without increasing the air gap length and utilizing additional torque through flux-weakening control, enabling a wide operating range. However, it also has drawbacks, including 2D leakage flux through the ribs that bypasses the stator coils and 3D axial leakage flux through the upper and lower rotor core air gaps, which are magnetically isolated by the saturated ribs and permanent magnets(PM). This study addresses the impact of 3D axial leakage flux, which has not been considered in previous research, by introducing a Correction coefficient expressed as a closed-form function of key design parameters and incorporating it into 2D Finite Element Analysis (FEA).

The interior permanent magnet synchronous motor (IPMSM) is widely used in various industrial products due to its high torque density and efficiency. Vibration and noise generated from the motor can cause user discomfort and shortened life of the product. After designing the distributed winding model with full-pitch and short-pitch winding methods and the concentrated winding model, the excitation force generated on one tooth was evaluated through two-dimensional(2-D) finite element analysis (FEA). In addition, the spatial-time harmonic analysis of the air-gap flux density was performed to derive the spectrum of the air gap flux density and pressure. Finally, the electromagnetic characteristics derived through the 2-D FEA were mapped to the three-dimentional mechanical frequency analysis to comprehensively evaluate the displacement and acceleration outside the stator.

The linear oscillating actuator (LOA) operates as the driving mechanism for linear compressor, which shows high power density and efficiency. To ensure the high efficiency of linear compressor, it is important to accurately calculate the loss of LOA. Due to the complex structure of LOA with segmented outer core and permanent magnet, 3D finite element analysis (FEA) was executed to analyze the loss of LOA. Conventional loss calculation method includes DC copper loss and iron loss. This paper proposes a loss calculation method containing additional effect, core anisotropy and AC copper loss, on total loss of LOA. Methods to include effect in 3D FEA are introduced. Moreover, total loss error of conventional method and proposed method are compared to verify the effect.

In this paper, methods to reduce iron loss through same direction skew and halbach array by utilizing the shape freedom of 3D printing are proposed. Axial flux motors have a higher power density than radial flux motors and are advantageous in a multi-pole structure. However, in the case of an axial flux motor, it is difficult to manufacture through electrical steel sheet lamination for iron loss reduction. As a method for reducing iron loss in existing axial flux motors, manufacturing through core-loss type, armor force steel plate, and powder material rolling is mainly used. However, in the case of the armor force steel plate, there is a disadvantage in that it is difficult to manufacture, and in the case of manufacturing through rolling, high-cost mold manufacturing is essential. It is possible to overcome the disadvantages of the existing manufacturing method when manufacturing a motor by utilizing the shape freedom, which is an advantage of 3D printing technology. However, cores manufactured using 3D printing currently have high iron loss characteristics, which is a fatal disadvantage to motor output. To reduce iron loss, a combination of pole numbers and slots with a small number of poles can be selected, but a combination with a small number of poles opposes the characteristics of an axial flux motor. Through the same direction skew and Halbach array, the performance of an axial flux motor can be increased even in a combination with a small number of poles. The validity of the proposed model was reviewed through finite element analysis.

Recently, the need for collaborative robots is increasing as they can replace workers' repetitive manual work to improve work efficiency and solve labor shortage problems. The motor used for the joint of the collaborative robot must satisfy the limited axial length to ensure safety while having a large driving range in a limited space. Therefore, in the size of a thin structure with a short axial length, a design was performed to improve the output by replacing the existing radial permanent magnet motor (RFPM) with an axial flux permanent magnet motor (AFPM). In RFPM, the torque is proportional to the square of the diameter of the motor and the stacking length, so if the axial length is short, the performance is reduced in proportion to it. On the other hand, since the torque density of AFPM is proportional to the cube of the diameter of the motor and the permanent magnet can be used as much as possible as long as the core is not saturated, the output can be higher than that of RFPM in the same volume. In this paper, the design process for selecting the shape of AFPM that can increase the power density of the axial flux motor was proposed and the final model was selected. The combination of the number of pole slots was selected, detailed design for shape variables for various types was carried out, and the feasibility of the study was verified by performing finite element analysis (FEA).

Electric vertical take-off and landing (eVTOL) aircraft designed for urban environments rely on distributed electric propulsion systems to enhance safety and reliability. These systems necessitate electric propulsion solutions that combine high power density with superior efficiency. To address these demands, this study presents a novel axial flux wound rotor synchronous motor (AFWRSM) with an innovative design and operating principle, specifically developed for eVTOL propulsion. The proposed AFWRSM is a rare-earth-free motor that uses field windings on the rotor, eliminating the reliance on permanent magnets. To further improve power density and fault tolerance, the motor incorporates a dual-stator configuration. The design process is thoroughly detailed, with a focus on distinguishing the proposed motor from conventional designs in terms of structure and operation. Finally, the motor performance was validated using three-dimensional finite element analysis, demonstrating its suitability for eVTOL applications.