This paper provides an overview of the design and analysis of high-speed PM motors by focusing on prominent issues such as motor losses, temperature rise, rotor strength and vibration. The design challenges of high-speed PM motors are briefly described, and the application of various stator and rotor structures and materials is presented in electromagnetic design. Combined with the temperature distribution of the motor, various heat dissipation measures to suppress the temperature rise are summarized. Strength and dynamics analysis of the rotor are outlined with respect to the safety of rotor operation. The current status of coupled multi-physics domain design used to improve the comprehensive design capability of high-speed PM motors is reviewed. Future directions of technologies related to the design of high-speed PM motors are pointed out.

This paper focuses on the electromagnetic vibration noise source of fractional-slot concentrated-windings (FSCWs) interior permanent magnet synchronous machines (PMSMs) and its optimal design for vibration noise reduction. First, the analytical model of the radial and tangential force waves of the interior PMSM is constructed, and the harmonic characteristics of the electromagnetic force waves under the action of the stator slotting effect and the rotor saliency effect are obtained. Second, an electromagnetic field finite element simulation model of a 36-slot/24-pole PMSM is established, and the harmonic sources of the main excitation forces are explored in combination with the analytical method. Then, the simulation analysis method of vibration noise with separately loaded radial and tangential concentrated forces is proposed to explore the contribution of different force wave components to the vibration noise. Finally, the main excitation force of the prototype is weakened by using an auxiliary groove, and the auxiliary groove parameters are optimized by sensitivity analysis and multi-objective genetic algorithm, and the effectiveness of the optimization method is verified by simulation and experiment. This study can provide a reference for the low-vibration and low-noise design of the same type of machine.

Addressing the thermal management challenges associated with the stator and rotor system of yokeless and segmented armature (YASA) motors, this article proposes an enhanced cooling strategy for the stator and rotor. Taking a dual-rotor single-stator YASA motor as the research subject, the volume of fluid (VOF) model is employed to evaluate the cooling performance of the existing advanced oil cooling technique. Subsequently, the stator bracket is perforated to enable cooling oil to flow into the air gap area for direct heat exchange with the stator and rotor system. By investigating the impact of the number of holes on both the motor’s cooling performance and oil friction loss, the optimal hole configuration is determined to be a direct cooling solution with hole of $1\times 1.5$ mm. Compared with the existing cooling scheme, the maximum temperatures of windings, stators, permanent magnets, and rotors under rated conditions are reduced by 29.14%, 28.53%, 51.67%, and 50.21%, respectively. Through the comparison of temperature rise experiments, the accuracy of thermal simulation modeling and the efficiency of the cooling system are further verified, which provides a new method for the design of efficient cooling system of YASA motor.

This article takes a dual-rotor single-stator yokeless and segmented armature (YASA) axial flux permanent magnet (AFPM) motor as the research object. To address the insufficient structural strength of the conventional spoke-type bracket, an improved stator design utilizing a crimping-type bracket is proposed. This proposed scheme effectively enhances the mechanical stability of the stator; however, the introduction of the crimped bracket extends the eddy current path, thereby giving rise to a new issue characterized by a significant increase in eddy current losses. To comprehensively assess the performance tradeoffs induced by this structural modification, the study first systematically compares two design schemes for stator teeth and brackets, conducting analyses across multiple dimensions including structural strength, harmonic distribution of the air-gap magnetic field, and loss characteristics. The results indicate that while the crimped bracket ensures mechanical reliability, its eddy current losses emerge as the primary factor constraining motor efficiency. Addressing this problem, this article further investigates strategies for suppressing eddy current losses and fabricates a prototype to carry out experimental verification. The experimental results demonstrated that the new structure maintained favorable mechanical stability while possessing superior electromagnetic performance, verifying the rationality and practical engineering value of the proposed scheme.