Control Strategy And Battery Management System Research Of Series Hybrid Electric Bus

Transportation energy shortage and environmental pollution are the crux of restricting the automobile development in the world, for the two big problems, countries highly focus on energy saving and begin to develop the field of new energy vehicles. Now the hybrid technology is more mature than any other new energy vehicles, a nd have a good effect of energy saving and environmental protection. Compared with pure electric bus, hybrid electric bus has low price because it dosen’t rely on new facilities. Besides, compared with the traditional fuel bus it can achieve the goals that saving fuel and reducing emissions. So it is the most common in the system of urban public transport.In this paper, we take a traditional city bus as the research object and convert it into the hybrid city bus to achieve the goals that improving fuel eco nomy and reducing emissions without affecting its power performance.To achieve the goals, firstly it introduces the driver structure and type of hybrid electric bus, then determine its drive system according to the working condition of the city and the bus’ s characteristics; secondly completes the parameters matching about the transmission system according to the vehicle parameters and performance goals; on this basis,establishing the new control strategy which in order to restrict the engine’s running regional in the best efficiency and emissions, eventually determining to join the thermostat control mode to power following type control mode; finally simulate the control strategy in UDDS city conditions by ADVISOR2002 software, compared with the traditiona l bus, it eases the problems of the fuel economy and emissions.Battery charged state is the key parameter of battery management system, its correct estimation is the premise and foundation of vehicle dynamic allocation, so improving the accuracy of the estimation is the important direction of battery research. This paper proposes a new method for estimating the SOC which based on the most common method which called Ah accumulation and the open circuit voltage method, then determine the method that compensate the open circuit voltage method into the Ah accumulation method. This paper takes the lead-acid battery as the research object, establishes Rint battery model, then forms table of the model parameters based on model parameter identification; secondly, analyses the defects of Ah method, Ah method will join Ah charge-discharge efficiency compensation method of calculation, then forms a new method of Ah; In the end, the SOC estimation model and the code can be established according to the new estimation met hod. Then simulates the method of SOC estimation on the basis of ADVISOR2002, draws the conclusion by comparing with discharge experiment curve: The calculation precision of the new SOC estimation method is in the range of allowable hybrid electric bus, and the precision is higher than it in the traditional Ah method, therefore, this method can be widely used in hybrid electric bus.