Battery is the key technology to the development of electric vehicles, and most battery models are based on the electric vehicle simulation. In order to accurately study the performance of LiFePO 4 batteries, an improved equivalent circuit model was established by analyzing the dynamic characteristics and contrasting different-order models of the battery. Compared to the traditional model, the impact of hysteresis voltage was considered, and the third-order resistance-capacitance (RC) network was introduced to better simulate internal battery polarization. The electromotive force, resistance, capacitance and other parameters were calibrated through battery charge and discharge experiments. This model was built by using Modelica, a modeling language for object-oriented multidomain physical systems. MWorks was used to implement the cycle conditions and vehicle simulation. The results show that the third-order RC battery model with hysteretic voltage well reflects the dynamics of a LiFePO 4 battery. The difference between the simulated and measured voltages is small, with a maximum error of 1.78%, average error of 0.23%. The validity and feasibility of the model are verified. It can be used in unified modeling and simulation of subsequent multi-domain systems of electric vehicles.

With the increase in car ownership and the increasing pressure of energy conservation and emission reduction, the lightweighting of cars has become an important development direction for traditional cars to reduce emissions and increase the endurance of electric vehicles. Aiming at the lightweight design of automobile crash safety structure, this paper proposes a variable section and multiple materials vehicle lightweight design framework based on collision safety. Taking a certain type of racing car frame as the research object, the lightweight design is carried out, and the optimal design scheme of racing car frame with good collision safety performance is obtained. Taking the lightest frame mass as the design goal, the optimal latin square design and response surface model are used to optimize the thickness of each pipe frame, and the lightweight frame optimization scheme based on the improvement of collision safety performance is obtained. Finally, under the premise that the peak acceleration of the cockpit is reduced by 20.02% and the amount of intrusion at the brake pedal is reduced by 25.31%, weight reduction of 14.38% is achieved. Based on the actual engineering situation, this paper constructs a lightweight design framework for automobiles based on collision safety, and provides an efficient optimization process for lightweight design of automobiles.

As one of the important components of intelligent warehousing logistics, Automated Guided Vehicles (AGVs) have greatly improved the efficiency of warehousing operations. AGVs are responsible for the delivery of goods in warehousing and logistics, and it is extremely important to maintain a stable running state. In this paper, an AGV in-situ steering dynamic model is established according to the actual size, and the center deviation phenomenon during AGV steering is theoretically analyzed to obtain the parameters that affect the AGV’s in-situ steering stability. Secondly, the dynamic simulation method is used to analyze the law of the stability of the AGV in-situ steering parameters to verify the correctness of the theoretical derivation equation. According to the analysis results, the motion parameters related to AGV in-situ steering are analyzed, and a reasonable design scheme is given. Based on the optimized fork-type AGV, the AGV in-situ steering control strategy is studied, and the adaptive fuzzy PID control algorithm is used to construct the fork-type AGV steering control system. Then the software and hardware design of the AGV steering control system is carried out. The optimized fork-type AGV has been turned to work stably after commissioning, meeting the actual work requirements.

Batteries are widely used in our lives, but the inevitable inconsistencies in series-connected battery packs will seriously impact their energy utilization, cycle life and even jeopardize their safety in use. This paper proposes a balancing topology structure combining Buck-Boost circuit and switch array to reduce this inconsistency. This structure can realize multi-cell-to-multi-cell (MC2MC) battery balancing by controlling the switch array and having a fast balancing speed, easy expansion and few magnetic components. Then, the operation principle of the proposed balancing topology is analyzed, and the simulation model is verified. In addition, the effects of switching frequency and voltage difference on the equalization effect are further analyzed. The results show that the higher the switching frequency, the lower the time efficiency, but the higher the energy efficiency. The voltage difference significantly impacts the duty cycle, so it is absolutely necessary to introduce a variable duty cycle in the multi-cell-to-multi-cell equalization. Finally, eight series batteries are selected for simulation verification. The simulation results show that, compared with any-cell-to-any-cell (AC2AC) equalization, the time efficiency of multi-cell-to-multi-cell equalization is improved considerably, the energy efficiency is improved slightly, and the variance of the completed equalization is reduced, demonstrating the excellent performance of multi-cell-to-multi-cell equalization.

Based on multi-body system dynamics, the model of Yutong high-speed bus was built by ADAMS/Car software to analyse the influence of crosswind on the high-speed bus' handing stability. Seven discrete wind pressure centers effects on the chasis were taken into account, so the crosswind model with a shifting pressure center was achieved. After improving the standard of the crosswind sensitivity test that is prescribed by American ESV (Experimental safety vehicle), the crosswind simulation tests with pressure center's shift and the immobile pressure center were carried out. The high-speed straight-line simulation test without the crosswind was also completed. By comparing the results of the three tests, the test data in consideration of wind pressure center's shift was more reasonable and provided the reference data for improving the crosswind stability of the bus.