In order to solve the adaptability problem of acceleration slip regulation for distributed drive electric vehicles, a slip ratio adaptive control strategy based on wheel angular velocity is proposed. The principle of road estimation algorithm based on the Burckhardt tire model is analyzed, and an improved estimation principle for optimal slip ratio is designed to improve the speed and accuracy of optimal slip ratio estimation. A slip ratio control strategy based on a conditional integral sliding mode control is designed, and its stability is proven. To make the slip ratio control strategy have better practicability, the slip ratio control strategy is combined with the road estimation algorithm, and the control variable of the slip ratio adaptive control strategy based on a conditional integral sliding mode control is redesigned to obtain a faster vehicle dynamic response. Finally, the effectiveness of the designed road estimation algorithm and the slip ratio adaptive control strategy is verified by simulation of acceleration on joint road and split road. Results show that the designed road estimator can obtain the road adhesion coefficient and optimal slip ratio quickly and accurately; the slip ratio adaptive controller, based on a conditional integral sliding mode control, can maintain the wheel slip ratio near the optimal slip ratio and reduce the steady-state error of the wheel slip ratio.

Quick-replacement battery technology has the advantages of eliminating mileage issues, extending battery life and reducing cost. The battery box plays an important role in carrying and protecting the on-board battery pack. However, fatigue life has not been well-established in changeable operating environments and driving conditions; hence, this knowledge gap is the focus of this paper. Here, SolidWorks (SolidWorks, Waltham, MA, USA) was used to establish a three-dimensional model of a quick-replacement battery box for electric vehicles, OptiStruct software (Altair, Detroit, MI, USA) was used for sweep frequency and random vibration analyses, and random vibration fatigue analysis was carried out using Ncode software (ANSYS, Pittsburgh, PA, USA). The quick-replacement battery box structure was then optimized according to the analysis results and lightweight targets. The results of sweep frequency and random vibration analyses showed that the maximum stress of a quick-replacement battery box is 39.058 Mpa. Compared with the allowable stress of the DC01 material at 150 Mpa, a significant margin is still present. The results of random vibration fatigue analysis showed that the minimum service life of a quick-replacement battery box is 5.740 × 10¹⁰, which meets the design requirements. Following optimization design, the maximum stress of a quick-replacement battery box was 71.197 Mpa, still meeting the allowable stress of the DC01 material at 150 Mpa and effectively alleviating the stress concentration. Furthermore, the optimized quick-replacement battery box was approximately 4 kg lighter. Therefore, optimization of the quick-replacement battery box is feasible and necessary. The results provide great theoretical and engineering significance for the design and optimization of quick-replacement battery boxes for electric vehicles.

In order to counter the problems of cracks and large area fractures in the welding points of quick-replacement battery boxes for electric vehicles (which may lead to the concentration of stress), in this study, a fatigue analysis of the welding points, based on a load spectrum, was used to predict welding points’ fatigue and improve the structural life of quick-replacement battery boxes. Firstly, a model of the quick-replacement battery box was established in SolidWorks software; secondly, the welding points’ fatigue was analyzed using the Optistruct module of HyperMesh software, and the topology of the quick-replacement battery box was optimized according to the results of the analysis; finally, for testing purposes and to achieve a lighter weight and an improved structural life, the fatigue of the welding points of the optimized battery box was analyzed. The results of the analysis showed that the force of the quick-replacement battery box was primarily concentrated at the connection between the middle bottom plate and the partition. Additionally, retaining the number of welding points at the hanging ear was shown to be beneficial for maintaining stiffness during electric vehicle operation; however, the number of welding points at the partition connection could be appropriately reduced. Before optimization, the maximum fatigue damage values of the welding points were 2.763 × 10⁻⁶, 3.833 × 10⁻⁶, and 6.728 × 10⁻⁶, respectively, satisfying the criteria of fatigue damage to the welding points. After optimization, the fatigue damage values of the welding points in the quick-replacement battery box were significantly reduced to 4.431 × 10⁻⁸, 4.562 × 10⁻⁸, and 8.885 × 10⁻⁸, respectively, compared with their pre-optimized levels. Consequently, the stress concentration was alleviated effectively, thereby meeting the conditions for fatigue damage. These results have important theoretical and engineering significance for the design and optimization of quick-replacement battery boxes for electric vehicles.