Analysis of electromagnetic and thermal characteristics of magnetic bearings in flywheel energy storage systems

doi:10.19799/j.cnki.2095-4239.2025.0523

Abstract

Abstract:

The flywheel energy storage system converts electrical energy into kinetic energy by accelerating the flywheel through a motor, storing the energy, decelerating and braking the flywheel to generate electricity, and releasing kinetic energy. The system relies on power electronic devices to control the acceleration or deceleration of the motor to achieve energy conversion. Characterized by a fast response, high charging and discharging frequency, high conversion efficiency, and long service life, flywheel energy storage systems are widely used in fields such as power frequency regulation, energy recovery, and uninterrupted power supply. In this study, a scheme for the magnetic bearing of a high-power flywheel energy storage system is designed by utilizing a support method combining radial and axial heavy-load electromagnetic bearings. The finite element method is used to complete the analysis of the electromagnetic performance of the system through simulation. Furthermore, a multi-physics coupled model is established for analysis of the bidirectional coupling between the electromagnetic and thermal fields, enabling comprehensive evaluation of the temperature distribution of the magnetic bearings under different current conditions. The performance of the designed heavy-duty electromagnetic bearing meets the design requirements, and the natural air-cooling method can ensure the safe operation of the system. Although reducing the coil current contributes to improving the thermal safety, it also leads to a decrease in the electromagnetic force. Therefore, the design of magnetic bearings for flywheel energy storage systems must achieve a proper trade-off between thermal management and the electromagnetic performance.

Key words: flywheel energy storage, electromagnetic bearing, finite element analysis, electromagnetic performance, thermal field

CLC Number:

TK 02

Xiankui WEN, Bowen LI, Zhengjun SHI, Huayang YE, Lingrong PANG, Xiaoyin ZHANG. Analysis of electromagnetic and thermal characteristics of magnetic bearings in flywheel energy storage systems[J]. Energy Storage Science and Technology, 2025, 14(8): 2932-2941.

Figures/Tables 19

Fig. 1

Fig. 2

Table 1

Design parameters of axial electromagnetic bearings"

序号	符号	名称	数值	单位
1	d_z0	转子内径	200	mm
2	d_z	转子外径	300	mm
3	D_z0	定子内径	220.5	mm
4	D_z	定子外径	257.5	mm
5	h	磁极高度	23	mm
6	A_z	内外环面积	18891.3	mm²
7	c₁	内环宽度	47.5	mm
8	c₂	外环宽度	35.85	mm
9	b	推力盘厚度	86.3	mm
10	$N z$	线圈匝数	191	—

Table 1

Fig. 3

Table 2

Fig. 4

Fig. 5

Fig. 6

Fig. 7

Fig. 8

Fig. 9

Fig. 10

Fig. 11

Fig. 12

Table 3

Convective heat transfer coefficients of different surfaces"

散热面位置	对流换热系数/[W/(m² $⋅$ K)]
轴向定子表面	16.7
径向定子表面	19.3
线圈绕组表面	13.3
定子磁极内圆面转子的端面	85.4 61.3

Table 3

Table 4

Physical properties of materials"

部件

导热系数/[W/(m

⋅

K)]

密度/(kg/m³)

比热容/[J/(kg

⋅

K)]

DT4C

7872

448

硅钢叠片

$λ x = λ y =$ 39.7

$λ z =$ 5.5

7600

460

线圈绕组

398

8933

390

Table 4

Fig. 13

Fig. 14

Fig. 15

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