Electromagnetic Vibration-Prediction Process in Interior Permanent Magnet Synchronous Motors Using an Air Gap Relative Permeance Formula

Seung-Hyeon Lee,Ik-Sang Jang,In-Jun Yang,Won-Ho Kim

doi:10.1109/access.2021.3055864

Abstract

Interior permanent magnet synchronous motors have the advantage of being applicable to various fields owing to their high torque density and wide operating range but have the disadvantage of large electromagnetic vibrations. To calculate the electromagnetic vibration, analysis of the magnetic flux density of the air gap using the finite element method (FEM) is essential. This process requires a significant amount of time because of the use of many analysis models. The radial force, which is the source of vibration, is expressed as the square of the air gap magnetic flux density, the vibration can be predicted in advance by calculating the waveform of the air gap magnetic flux density using a formula. In this paper, a new air gap relative permeance formula is proposed when an offset is applied to the outer diameter of the rotor to reduce electromagnetic vibration. By calculating the waveform of the air gap magnetic flux density using the proposed air gap relative permeance formula, a model with a minimum total harmonic distortion is selected. The validity of the formula was confirmed by comparing the FEM result with the waveform of the air gap magnetic flux density calculated using the proposed formula. The proposed model minimized the vibration and was confirmed using FEM. Using the proposed formula, vibration can be easily and quickly predicted in analytic way. The prototype of the final model was developed and compared using FEM, and the validity of the analysis result was confirmed.

Highlights

Electric motors are applied in various industries such as automotive, home appliances, defense, and aerospace, and they account for more than 45% of the world’s electricity consumption
AIR GAP LENGTH SELECTION USING total harmonic distortion (THD) ANALYSIS In the case of the model to which the offset is applied, the air gap magnetic flux density can be obtained by substituting the relative permeance (10) with the (14) representing the effective air gap length reflecting the air gap length that varies depending on the rotor position
AIR GAP LENGTH SELECTION USING THD ANALYSIS Similar to the case of a model with one offset applied, for a model that has two offsets applied, the air gap magnetic flux density can be obtained by substituting the relative permeance in (10) with (14), which represents the effective air gap length, thereby reflecting the air gap length that varies depending on the rotor position

Summary

INTRODUCTION

Electric motors are applied in various industries such as automotive, home appliances, defense, and aerospace, and they account for more than 45% of the world’s electricity consumption. An interior permanent magnet synchronous motor (IPMSM) uses both magnetic torque and reluctance torque, and designers can create various rotor shapes since permanent magnets have a high degree of freedom in terms of arrangement and shape They have wide operating ranges in field-weakening control applications, and the demand continues to increase in many industrial applications. Lee et al.: Electromagnetic Vibration-Prediction Process in IPMSMs Using an Air Gap Relative Permeance Formula that require high torque density and efficiency [11]–[14]. To obtain the electromagnetic vibration, the magnetic flux density in the air gap must be stored as a field value over time. Through the proposed air gap relative permeance formula, depending on the number of offsets per pole, the waveform of the magnetic flux density with respect to the rotor position can be obtained.

FORMULA OF THE AIR GAP MAGNETIC FLUX DENSITY

TEST AND VERIFICATION

Findings

CONCLUSION