Topology Optimization Design For Support Structure Of Power Battery Pack Under Temperature Constraints

As the energy storage device of electric vehicles(EV),the power battery's performance including discharge capacity,cycle life,and consistency are all affected by the operating temperature.On the one hand,the low temperature environment will reduce the discharge capacity and high temperature will permanently damage the internal structure of the battery and increase the risk of thermal runaway.On the other hand,since the battery pack follows the short board effect,poor temperature uniformity leads to inconsis tency in performance between batteries,which in turn deteriorates the overall performance of the power battery pack.For power battery pack of EV,structural safety is another important issue.The battery pack structure must possess excel ent strength,protecting battery pack from short circuit,liquid leakage,and even fire explosion in abused working conditions such as collision and extrusion.At present,the excel ent thermal management system of power battery pack can control the operating temperature of the battery pack within a suitable range and the battery temperature difference does not exceed ±2°C,but the thermal management system has a complex structure,at the same time,most of the power battery packs have weak structural strength.Therefore,the temperature control and structural strength of the power battery pack are issues that need to be solved urgently.Focusing on the design of the module support structure of power battery pack consisting cylindrical power battery in EV,we develop a temperature constrained topology optimiza t io n method of thermal mechanical coupling under transient temperature conditions based on the variable density method,which provides a new idea for the design of the module support structure of power battery,and is of great significance in improving the performance of EV.The main research work of this paper are as follows:(1)To address the issues of the traditional cooling systems such as poor heat dissipatio n capability,complicated structure,high cost and energy consumption,and poor mechanic a l performance of battery pack structure,we develop the temperature constrained topology optimization method of thermal mechanical coupling under transient conditions.To our knowledge,we didn't find out the published research with the similar contents.(2)According to the variable density method,a thermomechanical topology optimizat io n method with temperature constraints under steady state is also established using the interpolation model RAMP,and the temperature constrained equation sensitivity and the objective function sensitivity are deduced,then several classical examples are solved.Based o n the steady-state,a temperature constrained topology optimization method of thermal mechanical coupling under transient conditions is further developed.The global structural compliance and local temperature constraint equations are deduced,then the sensitivity analys is is performed.Using this transient method,we design the two-dimensional module support structure and reconstruct it,then the thermodynamic simulation analysis is made.(3)Compared with the topology optimization without temperature constraints,the proposed method can effectively reduce the temperature at the constrained region.A small change of temperature constraint value will have a significant impact on the optimal topology,when the applied temperature constraint is reduced,the material distribution will increase and the topology become complex near constraint region.(4)Under normal conditions,the optimized module support structure composed of aluminum al oy can control the temperature of the battery pack between 31°C and 33°C,and it also has excellent strength.