A PCB stator axial flux permanent magnet (AFPM) motor is presented that overcomes the manufacturing challenges associated with the complex geometry of conventional stators by employing a PCB substrate. Traditionally, AFPM motors are produced by winding coils around the stator teeth, a process that requires specialized winding machinery and is both labor intensive and time consuming, ultimately incurring considerable manufacturing costs and delays. In contrast, PCB substrates offer significant advantages in manufacturability and mass production, effectively resolving these issues. Furthermore, the primary material used in PCB substrates, FR-4, exhibits a permeability similar to that of air, resulting in negligible electromagnetic cogging torque. Cogging torque arises from the attraction between permanent magnets and stator teeth, creating forces that interfere with motor rotation and generate unwanted vibration, noise, and potential mechanical collisions between the rotor and stator. In the PCB stator design, the conventional PCB circuit pattern is replaced by the motor’s coil configuration, and the absence of stator teeth eliminates these interference issues. Consequently, a slotless motor configuration with minimal vibration and noise is achieved. The PCB AFPM motor has been applied to a vehicle-mounted electric water pump (EWP), where mass production and space efficiency are critical. In an EWP, which integrates the impeller with the motor, it is essential that vibrations are minimized since excessive vibration could compromise impeller operation and, due to fluid resistance, require high power input. Moreover, the AFPM configuration facilitates higher torque generation compared to a conventional radial flux permanent magnet synchronous motor (RFPM). In a slotless AFPM motor, the absence of stator teeth prevents core flux saturation, thereby further enhancing torque performance. AC losses occur in the conductors as a result of the magnetic flux produced by the permanent magnets, and similar losses arise within the PCB circuits. Therefore, an optimized PCB circuit design is essential to reduce these losses. The Constant Trace Conductor (CTC) PCB circuit design process is proposed as a viable solution to mitigate AC losses. A 3D finite element analysis (3D FEA) model was developed, analyzed, fabricated, and validated to verify the proposed solution.

When a magnetic bearing is used in the design of a high-speed motor, no friction and wear occur because of the principle of magnetic levitation; however, the size of the entire system increases. An integrated magnetic bearing motor is a motor with a magnetic bearing inserted inside the rotor that can minimize the increase in the size of the entire system. In this study, a method to reduce the bearing force ripple and torque ripple of an integrated magnetic bearing motor through parameters for a Halbach array and permanent magnet tapering is proposed. When designing an integrated magnetic bearing motor, because the magnetic bearing is located inside the rotor, the influence of the magnetic flux of the rotor and stator on the magnetic flux of the magnetic bearing should be minimized. By combining the magnetic fluxes of the magnetic bearing, rotor, and stator at the rotor back yoke, magnetic saturation occurs, and the performance of the bearing force and torque ripples decreases. The bearing force and torque according to the Halbach array and permanent magnet tapering were analyzed using finite element analysis. The average bearing force and torque were maximized, and the ripple was minimized through the rotor parameters. Thus, the validity of the main design variables selected to improve the output characteristics was confirmed.

Axial flux motors have a large output density with a large outer diameter of the motor and a short axial length. Since it is advantageous in short axial length, the axial thickness of motor components becomes a very important parameter when designing axial flux motors. Among the components, the back yoke exists to serve as a path for magnetic flux and must have a certain thickness to prevent magnetic saturation. However, as the thickness of the back yoke increases within the axial size limit of the motor, the output of the motor may decrease. In this paper, same-direction skew that increases the cross-sectional area of the magnetic flux path without increasing the thickness of the back yoke is presented. Same-direction skew is a way to increase the cross-sectional area of the back yoke by skewing the rotor and stator in the same direction. The back yoke thickness that can be reduced by same-direction skew was calculated. Performance with same-direction skew designed using the equations was analyzed and compared, and the effectiveness of each type of rotor was verified. The validity of the proposed model was examined using the finite element analysis method.

Owing to the shortage of rare-earth magnetic materials, various methods are being examined to reduce the use of magnets. One of these is a consequent pole. The consequent pole model can reduce the use of magnets by 50% using only one pole of the magnet and replacing the other pole with iron. However, the consequent pole has the disadvantage of generating back EMF asymmetry and a high cogging torque. In this study, an intersect magnet consequent pole structure is proposed to overcome the disadvantages of the existing consequent pole. Two methods have been proposed to improve axial leakage magnetic flux caused by the intersect magnet consequent pole structure. Finally, we propose a method to reduce the cogging torque and minimize the use of magnets with the same performance standard. For motor design, two-dimensional and three-dimensional finite element analysis was used, and comparative analysis was performed via simulations for several models. The existing model and the final model were compared and verified.

Duct fan motors must provide high torque within limited space to maintain airflow while requiring low vibration characteristics to minimize fluid resistance caused by fan oscillation. Axial Flux Permanent Magnet Motor (AFPM) offers higher torque performance than Radial Flux Permanent Magnet Motor (RFPM) due to their large radial and short axial dimensions. In particular, the coreless AFPM structure enables superior low-vibration performance. Conventional AFPM typically employs a core-type stator, which presents manufacturing difficulties. In core-type AFPM, applying a multi-stator configuration linearly increases winding takt time in proportion to the number of stators. Conversely, a Printed Circuit Board (PCB) stator AFPM significantly reduces stator production time, making it favorable for implementing multi-stator topologies. The use of multi-stator structures enables various topological configurations depending on (1) stator placement, (2) magnetization pattern of permanent magnets, and (3) rotor arrangement—each offering specific advantages. This study evaluates and analyzes the performance of different topologies based on efficient arrangements of magnets and stators, aiming to identify the optimal structure for duct fan applications. The validity of the proposed approach and design was verified through three-dimensional finite element analysis (FEA).

Axial Flux Permanent Magnet Synchronous Motor (AFPMSM) offers high power density in structures with short axial lengths and large radial dimensions, making it attractive for applications that require thin structures, such as in-wheel motors. This study proposes an AFPMSM design process applicable under fixed inner/outer diameter and axial length constraints. The proposed process is presented as step-by-step procedures: selection of pole/slot combinations, adjustment of slot depth, determination of stator/rotor dimensional ratios, and slot structure design. It is universally applicable to both bobbin-type rectangular wire windings and shoe-type round wire windings. The validity of the proposed process was verified through finite element method (FEM) analysis, and the differences between the two winding structures were examined through post-processing of the results. By presenting an AFPMSM design methodology that can be consistently applied under constrained spatial conditions, this study provides practical design guidelines for the development of in-wheel motors for next-generation mobility applications.