Unlike the existing bar-type permanent magnets, it is difficult to magnetize the Ferrite Spoke-type permanent magnet synchronous motor (PMSM), because the permanent magnet is placed deep inside the shaft. In order to magnetize permanent magnet, a high magnetic field intensity is required. However, the high magnetic field intensity may cause demagnetization of surrounding permanent magnets. It has a bad effect on the magnetization of the permanent magnet and the performance of the spoke-type PMSM. In this paper, we proposed magnetizer models for magnetization of spoke-type 10 pole rotor and the inter-pole winding to reduce the demagnetization of surrounding permanent magnets. Finally, the optimally designed model was manufactured and the performance of the magnetizer was verified.

This paper discusses a motor that was designed to satisfy the size constraints of system by using ferrite magnet and has the same performance as rare-earth magnet motor. In general, the size of the motor is increased in order to meet the same performance of motor using a ferrite magnet, because of its very low energy density compared to the rare-earth magnet. In order to compensate for these drawbacks, spoke structures capable of generating maximum magnetic flux at the same rotor size have been frequently studied. However, the spoke type motor structure has a drawback that demagnetization occurs in a magnet-specific portion. However, because it affects harmonics of the airgap flux density by demagnetization, it affects mechanical torque ripple and vibration. Therefore, in this paper, the changed air-gap flux density due to the demagnetization phenomenon and the changed mechanical vibration are analyzed by the finite-element method. In addition, we proposed an optimal rotor structure that can reduce the demagnetization phenomenon of magnets in spoke interior permanent magnet synchronous motor. Experiments were performed to evaluate the reliability of the optimized design.

Permanent magnet motor are used in various fields because of their relatively small size, high power and high efficiency. However, an electric machine performance using permanent magnet can be decreased as temperature, humidity, and magnetic field related demagnetization phenomenon. Therefore, the motor should be designed considering the demagnetization characteristics. In this paper, the demagnetization characteristics and eddy current loss of a BLDC motor generator are analyzed according to magnet segments. For the comparison of eddy current loss, 3D analysis is performed by dividing the magnet into Non segment, three seg-ments, five segments, and seven segments. The magnet demagnet-ization according to the change in eddy current is analyzed. The rotor temperature is measured to determine the difference in heating caused by the change in eddy current loss. The electro-magnetic characteristics are analyzed by ANSYS EM 19.0. The validity of the results is verified by comparing the simulation and experimental data.

In this paper, we analyze the vibration and noise characteristics of the basic and skewed models of permanent brushless direct current (BLDC) motor. The electromagnetic characteristics of the basic model are analyzed by the finite-element method. We analyzed the electromagnetic characteristics for skew angles from 15° to 25°. The skew angle was selected based on the analytical results of the electromagnetic characteristics. We analyzed the characteristics of radial force density for the basic model and the skewed model. The vibration and noise characteristics were analyzed through the mechanical harmonic analysis of the radial force and tangential force generated in the motor. We developed the basic and skewed models, and performed vibration and noise tests. The validity of this analysis is verified by comparing the simulation results with the actual test results of the model. Finally, for the optimal design of the BLDC motor considering vibration, the design variables such as teeth shoe length, yoke thickness, and teeth thickness were used. Based on the results of vibration analysis, the final model is derived and its performance is described.

Generally, brushless dc (BLDC) motor control uses a 120° conduction method that utilizes a low-cost Hall sensor as a position sensor. However, because of the mounting position error of the Hall sensor and the uneven magnetic flux density of the rotor, an erroneous position signal may be output, which will adversely affect the BLDC motor control. Therefore, this paper analyzes the abnormal electric current section that occurs due to the position error of the Hall sensor and the uneven magnetic flux density. Subsequently, the error is derived from the analyzed phenomenon as a formula. The compensation control algorithm to overcome the control problem due to this error is studied, and a method to maintain an accurate energization interval is suggested. Further, it is shown through experiments that the quantitative analysis of the error using the proposed compensation control algorithm is valid.