Analysis and application of seismic battery rack
Abstract: In order to ensure the smooth process of energy in China, it is necessary to strengthen the safety of energy supply equipment. The battery rack is particularly important as a support device for the battery pack. This paper analyzes the material and performance of the seismic battery rack to promote the safety of energy supply.
Keywords: battery rack; seismic resistance; performance
Battery pack is a facility for providing energy, and the battery rack is the carrying device of the battery pack. The battery rack is equipped with a large battery pack, and its structural strength affects the safety and stability of the battery pack operation. Therefore, finite element analysis of the battery rack is necessary.
2 Seismic Analysis Reference Standards
(1) IEEE 693-2005: Recommended Practice for Seismic Design of Substations;
(2) International Building Code -2002;
(3) California Building Code -2013.
3 Battery rack structure and material performance
The following model R22 (2 layer 2 ladder) battery rack is used as an example. This battery rack is suitable for seismic zone 4.
R22 battery rack is a two-layer two-story steel bracket with 24 batteries of size 186*398*570, each weighing 65kg, as shown in Figure 1. The steel bracket is made of angle steel and square steel by bolt connection. The calculation of the battery frame structure under seismic load is based on the finite element commercial software ANSYS15.0.
4.1 Fixed load
Fixed load=Battery quality+Battery rack quality, where the battery quality is 65kg each.
4.2 Seismic Load
Structural calculations are based on high-level seismic levels, applying 0.5g in both horizontal directions and 0.4g seismic acceleration in the vertical direction. Figure 2 shows the standard seismic response spectrum used.
5 Calculation of the natural frequency of the battery rack
To calculate the natural frequency of the battery frame structure, the commercial software ANSYS15.0 is used to establish the finite element model of the structure. The cross-section of the members and the material parameters were selected according to Table 1, and the mass density was 7800 kg/m3. The nodes at the bottom of the bracket apply fixed boundary conditions to constrain their translational and rotational displacement, as shown in Figure 3.
6 Component Stress Calculation under Earthquake Load
Since the base frequency of the battery frame structure is greater than 33 Hz, the equivalent static analysis method can be used to evaluate the seismic capacity of the structure. The seismic force acting on the battery rack is obtained by multiplying the battery mass and the component mass by the seismic acceleration in the main direction.
6.1 Earthquake action x direction
The seismic load is obtained by multiplying the mass of the battery by 0.5g, and processing it into a uniform wiring load on one of the diagonal supports, the direction is along the horizontal x direction. The seismic load of the component is applied to the ANSYS by the inertial force (see Figure 4).
6.2 Earthquake action in y direction
Since the battery frame does not have symmetry in the other direction, the seismic acceleration is input in the horizontal +y direction and the -y direction respectively, and the seismic load acts on the bottom steel base of the battery (see Figure 4).
6.3 Seismic action in vertical z direction
Input according to IEEE693 vertical direction seismic action with an acceleration of 0.4g. Since the battery frame's own weight is also vertical, the total acceleration applied in the vertical direction of the member is 1.4g (see Figure 4).
7 Summary of Calculation Results
7.1 Maximum Stress of Components, MPa
7.2 Maximum Internal Force of Bolts
The bottom of the bracket is fixed with two M6 (4.8 class) bolts, the position of which is shown in Figure 5. Table 3 shows the maximum tensile force and maximum shear force of the fulcrum calculated by the root mean square of the three-direction input seismic acceleration.
This article analyzes the performance of the seismic rack by detailed data and calculations to ensure the safety of the battery rack.
LIANG Feifei,QIAN Jiang.Analysis of Seismic Performance of Battery Bracket Structures[J].Journal of Jiamusi University(Natural Science Edition),2013,31(5):651-654.
( Author unit: Sichuan Changhong Power Supply Co., Ltd.)