Research On High Voltage And Full-scale Impact Safety Of Hybrid Electric Vehicle

As a new type of vehicles in favor of energy saving and environmental protection, hybrid electric vehicles can utilize and convert the energy fully, and whereby reduce the pollution. Due to continuous and rapid growth of the economy, and the city scales take on an expanding trend, more and more major city governments will promote the use of clean-fuel vehicles as an important measure to clean air and improve the environment. China has become the world's second largest car consumer market only after the United States, which will also make hybrid vehicles flourish in China. Also, because the power-train voltage of hybrid electric vehicle is about 100 ~ 600 V, which is far more than the safety voltage of human body, short circuit or battery electrolyte leakage is likely to cause explosions and burning. In addition, the battery chemical reaction will cause potential harm to passengers and bring new security requirements, comparing with the traditional hybrid fuel vehicles, which will also affect the application of hybrid electric vehicle in the future. As a kind of transport tool, hybrid vehicles have the same security issues as traditional fuel vehicles, and hence they should meet the same safety request with traditional fuel vehicles, including active safety and passive safety. Therefor, the research on power systems and full-scale impact safety of hybrid electric vehicle is of great significance.In this paper, some key research work has been carried out and the following main results are obtained:1. In view of research hybrid car battery management system, it brings forward one centralization BMS structure of isolated switch matrix, and the hardware and software of battery management system are also designed, which can promote systematic safety, agility, reliability and anti-jamming power of date collecting.Based on a series of charge-discharge experiments of Ni-MH battery, the characteristics of charge-discharge, temperature and local action are analyzed in detail. In order to prevent the high electric voltage hurting passengers under dangerous working conditions such as collisions, overturn and etc, a simple and compact battery box structure with low cost is designed, which is adapted to the hybrid electric vehicle and can breake high-voltage off to safety voltage quickly when the battery box is deformed severely.2. The finite element model of one hybrid car is developed and validated by comparing with the experimental results of front impact, rear impact and side impact respectively. Through in-depth analysis of the root causes of side impact safety problems, the design principles of side structural improvement and comparison with similar side impact deformation results of other car, the primary improved measures were proposed. 3. The passenger restraint system of front impact is established by using MADYMO soft, which is based on the multi-rigid body theory, and in-depth analysis of passenger injury protection have been developed too. By choice of design variables and use of MADYMIZER as optimized method, it could optimize the system performance and improve front impact safety of hybrid car.4. Based on the analysis of the mechanical characteristics of the car during side impact, this paper proposed a new method to improve the side impact safety of the car by changing the side connection characteristics of the power cabin, passenger cabin and rear cabin. In order to verify the effectiveness of the method, by using the validated hybrid car finite element model, and with decreasing the number and reducing the lapse rule of weld point and decreasing the thickness of the plates in the connection area, the side impact safety performance of the car is investigated. The passenger injury parameters are calculated by using multibody PSM method. The results show that decreasing the strength and stiffness between power cabin and passenger cabin as well as passenger cabin and rear cabin can significantly reduce the intrusion of the door. So the passenger injury parameters of chest, abdomen, and pelvic can be decreased effectively.