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Electric motors with a double air-gap structure offer increased power or torque density compared to their single air-gap counterparts, achievable through double-stator or double-rotor configurations. In a previous study, the authors proposed a double-stator permanent magnet synchronous motor (PMSM) with a magnetic screen placed in the middle of the rotor to isolate the outer and inner motors. However, the analysis of the magnetic screen was not provided in that study, as the design was arbitrarily chosen. This research focuses on the effects of the magnetic screen size and selects the appropriate dimensions for optimal motor performance. Finite element analysis (FEA) is employed to assess the electromagnetic characteristics of the screen. Subsequently, the motor is manufactured and tested. The results show that the chosen magnetic screen size contributes to significant efficiency improvements. In particular, the motor achieved an efficiency of 95.2% during the qualification test, surpassing the efficiency obtained in the previous study. [ABSTRACT FROM AUTHOR]

This paper introduces a novel dual-air-gap surface permanent magnet synchronous motor (DAG-SPMSM) and investigates its electromagnetic characteristics. The motor comprises two stators (inner and outer) and a single rotor with permanent magnets on both sides (inner and outer). The magnets are arranged in a zig-zag configuration to isolate the inner and outer stator and rotor magnets. Additionally, a magnetic shield is incorporated into the rotor to further isolate the rotor magnetic flux, which results in a localized short flux path that can reduce core loss. The insertion of the magnetic shield also affects the flux path, reducing torque ripple. The electromagnetic characteristics, such as flux path, flux density, and torque, are analyzed using finite element analysis. The effectiveness of using a magnetic screen is also evaluated, and simple experiments are conducted to validate the observed characteristics of the proposed motor. [ABSTRACT FROM AUTHOR]

This paper presents a characteristics analysis and performance comparison of high-speed two-phase 4/2 and hybrid single-phase 4/4 switched reluctance motors (SRMs). Although the motors are advantageous as high-speed drives, both conventional structures have high torque ripple as a result of the presence of the torque dead zone. In this paper, solutions to the torque dead zone problem for each motor are discussed. For the 4/2 SRM, a wide-rotor stepper-type is adopted, while for the 4/4 SRM, the structure is changed to a hybrid by adding permanent magnets (PMs). Both motors have a non-uniform air gap to modify their inductance profile, which leads to the elimination of the torque dead zone. A finite-element method was used to analyze the characteristics of each motor. Then, the manufactured motors were tested through experiments, and lastly, their performance was compared. [ABSTRACT FROM AUTHOR]