This study investigates the tapering rotor surface technique in an interior permanent magnet synchronous motor (IPMSM) for electric vehicle compressors. To achieve this, this article proposes a novel tapered rotor design with a nonuniform air gap, created by applying asymmetric shaping to the bridge region along the rotor radius. A conventional IPMSM with a uniform air gap produces a trapezoidal-shaped flux density, introducing high-order harmonics and causing certain drawbacks for the motor. This study selected the offset height of the eccentric center and the distance between the rotor radius and the magnet as improvement design variables. The proposed tapered rotor model, characterized by a nonuniform air gap, demonstrated better performance than the initial model. Subsequently, a stress analysis of the thinned barrier was conducted to validate the structural integrity of the proposed model. The key parameters, such as air-gap flux density, cogging torque, inductance, flux linkage, and efficiency maps, were compared between the initial and improved models using finite element method (FEM) and MATLAB simulations. The proposed tapering motor achieved a 36.36% reduction in cogging torque error rate and a 0.6% improvement in efficiency deviation at the primary operating point. A prototype of the conventional rotor model was manufactured, and its efficiency curve was verified, which showed good agreement with the FEM analysis results.

This paper presents both analytical calculations and empirical measurements of the magnetic force between the permanent magnet (PM) and rotor yoke in a large-scale permanent magnet synchronous generator (PMSG). The assembly of PMs in large-scale PMSGs is particularly challenging owing to the substantial magnetic forces involved. Therefore, accurately predicting the PM magnetic force during the assembly process is of paramount importance. The presented analytical solution is instrumental for designing PM assembly jigs across various machine sizes. A scaled-down experimental setup, incorporating a steel plate to neutralize magnetic forces, was employed. The experimental results and the analytical solutions are compared to validate the accuracy of the proposed calculations.

An interior permanent magnet synchronous motor (IPMSM) rotor equipped with a carbon-fiber-reinforced plastic (CFRP) sleeve, based on an electromagnetic–mechanical coupled analysis approach, was designed and analyzed. As the demand for high-speed traction motors increases, addressing the excessive rotor stress caused by higher rotational speeds has become critical. To mitigate this issue, a CFRP sleeve is used to enhance mechanical strength while minimizing the impact on electromagnetic performance. However, the introduction of the CFRP sleeve increases design complexity because of changes in air gap length and structural constraints. The crucial considerations required in the design and manufacturing processes, including tradeoffs between mechanical integrity and magnetic performance, are discussed. The proposed design methodology differentiates the rotor structure from conventional IPMSMs, offering a viable solution for high-speed, high-power-density motor applications.

This paper presents a method for deriving the inductance of an interior permanent-magnet synchronous motor (IPMSM) by considering magnetic saturation. To obtain accurate inductance values during the motor characteristic analysis, it is necessary to consider the influence of core saturation on the magnetic flux changes. First, two distinct inductance calculation methods are presented, which are used to derive an inductance map across all operational regions. The torque was calculated using the derived inductance values. Finally, the validity of the analysis was confirmed by comparing the measurement results of the manufactured IPMSM.