Rare-earth PM Research Articles

펌프용 소형 BLDC 모터의 원가절감을 고려한 회전자 최적화 설계

In the present study, a BLDC motor for a pump in which a neodymium PM is replaced with a Ferrite PM has been developed in preparation for the cost increase and to ensure the stability of the resource supply. One of the currently used motors for pumps is a BLDC motor having an interior PM wherein a rare-earth PM is adopted. However, a BLDC motor for a pump is designed to have large airgap because of the use of a waterproof insulator according to its structural characteristics, and therefore, a SPM structure is suitable. Hence, an SPM BLDC motor in which a Ferrite PM is used is designed. Nevertheless, the use of Ferrite instead of rare-earth materials causes a deterioration in the performance of the electric motor, such as a decrease in the BEMF and the maximum power of the motor and the irreversible demagnetization of the PM. In order to mitigate such disadvantages, an optimized design of the BLDC motor is developed by changing each design parameter and by improving the electromagnetism structure.

Fast Computation of the Performance of Lunar Rover Drive Motor with Skewed Stator Slots Based on 2D FEM

In order to study the performance of rare earth PM brushless DC motor with skewed stator slots for lunar rover driving wheel at extreme temperatures of lunar surface rapidly and accurately, a computational method based on 2D FEM was proposed. The skewed motor was equivalent to a certain number of straight slot motor units in series and the mathematical expression of calculation accuracy was deduced. In order to make the winding current of motor units in the same slot equal, a circuit with ideal current source was proposed to couple with the geometric model in 2D FEM. No-load back-EMF and electromagnetic torque were calculated for the prototype and the calculation accuracy was estimated according to the spectra of air-gap flux density at different relative positions of the stator and rotor in axial direction of the skewed motor. The proposed method is simpler and much more timesaving than 3D FEM. The calculated results closely match those of 3D FEM with the relative error less than 3.7%. The effectiveness of the method is verified by comparing with experimental results of multiple prototypes and the absolute error is less than 0.014Nm.

Analysis of Torque Pulsation Considering Interior Permanent Magnet Rotor Rib Shape Using Response Surface Methodology

This paper presents an analysis of torque pulsation with respect to the rotor rib shape in an interior permanent magnet motors (IPMs) and the type of magnet materials. The effects of three parameters, the angle and length of the flux barrier and the residual flux density of the PM, are studied using the response surface methodology. Finite element analysis is used to verify that torque ripple reduction affects the optimal rotor rib shape in rare earth and ferrite PMs. In addition, the optimal barrier shapes for each magnet material are identified and compared.

Modelling of saturation and cross-saturation effects in an interior PM automotive alternator

A rare-earth 6kW interior PM machine has been examined as a concept demonstrator for a high power automotive alternator. This machine has a high magnet flux density resulting in strong cross-saturation, and operates with high stator currents resulting in heavy saturation. It is desired to improve the machine design to reduce both saturation effects and hence increase the output power, particularly at low speeds. This paper examines the effect of saturation and cross-saturation on the output power, and uses finite-element analysis to model the machine flux-linkage curves. The finite-element results were verified against the experimental results.