Study On The Safety Performance Of HEB On High Voltage

For using electricity as the power, hybrid electric vehicles (HEV) generally use high voltage battery pack as one source of the power supply. Especially for the hybrid electric bus (HEB), for fitting the high-power motor, the battery pack always has a high voltage value which is much higher than safety voltage. Once there is a crash or a rolling over accident, the high voltage system may shock the occupant and the rescuer. Although most of the HEV have a circuit breaker to shut off the main circuit when it is in the crisis, but the high voltage of the inner battery pack also can threaten people. So it is of great significance to design an ideal high voltage protection system to promote the commercialization of HEV.In this paper, with the analyzing of the safety regulation correlated with the electric and hybrid electric vehicles safety,, the safety countermeasures in Toyota Prius and Ford Guide-Escape is studied, some analyzing of conceivable trouble about HEV is done and the countermeasure is given. An innovative high voltage electrical protection system is brought forward which is based on a step by step circuit breaking technology that aiming at HEB's special high voltage electrical problem, it is required that, this system must cut the high voltage circuit below the safety level in short order, but just cost a little. So a hazard detecting system is designed which using a mechanical universal angular sensor and a banding switch as the sense organ; Contriving a step by step breaking system, which can cut the inner circuit of the battery pack after the breaking of the main circuit, so the relays in the inner circuit don't need the function of electrical arc extinguishing, it can help to cut down the cost. It's proved by experiment this system can work as anticipation. After Constructing and validating a FE Bus model, Ls-dyna is used to do the simulation of the process of the HEB in frontal and lateral crash. The simulation results are used as the input data in the simulating of the response of the mechanical universal angular sensor witch designed by ourselves in Adams software. After Combining with the test results of the relays'working time, the system response time in different crash situations was obtained., and then its influence to the whole system is analyzed.Study shows that the high voltage protection system can successfully break inner circuit of the battery pack after breaking the main circuit. Simulation results also show that, the sensor can work properly in frontal impact, but may be ineffective in the lateral crash, so the system needs a banding switch to substitute the function of the sensor in latter crash situation. In addition, the function time of the relays and the structure of the battery cabin as well as the position of the battery should be reasonably redesigned to make the system perform better in lateral crash.