Improvement Of Fuel Cell Bus Power System

The global automotive industry has been looking for more efficient and cleaner vehicle energy technologies. Fuel cell vehicle technology is undoubtedly one of the ideal technical routes. Because of its high efficiency, zero emissions, energy saving and other advantages, is widely regarded as the future development direction of new energy vehicles and the focus of research and development.In recent years, with the country issued a series of policies to encourage the development of new energy, new energy automobile showing explosive growth, at the same time, in addition to the fuel cell, the implementation of subsidy policy back slope. This series of initiatives to promote the fuel cell technology has been more and more attention, the major research institutes and automobile manufacturers for fuel cells were a lot of research. Fuel cell performance continues to improve, the cost is further reduced, so that the fuel cell vehicles from people’s life is getting closer and closer.Domestic research mostly focused on theoretical methods, the market for fuel cell vehicles less information.In this paper, the market research and development of 12 meters of pure fuel cell bus as the research object, aiming at the problem of poor dynamic performance, high cost, and can not recover the braking energy and other issues, the following research:First, the driving mode of the fuel cell vehicle power system is compared and analyzed.1, the pure fuel cell model has the advantages of light weight, simple structure, and easy to control etc.. At the same time, there is a large fuel cell power, high cost, does not have the energy recovery function, the dynamic response is slow, the reliability is poor, the cold start time is long and so on.2, fuel cell and power battery hybrid drive mode: can effectively cover the power demand fluctuations, to extend the life of the fuel cell. And the power battery responds quickly and can recover the braking energy. But the structure is somewhat complex.3, fuel cell and super capacitor hybrid drive mode: high capacitance charging and discharging efficiency, long cycle life, high power, can provide instantaneous high power. Disadvantages are also very prominent, than the energy is much lower than the power battery.4, fuel cell, super capacitor, power battery hybrid drive mode: both the power of the battery and the advantages of capacitance, but the control and structural complexity.Based on the feasibility of the improved target and scheme of the power system, the configuration scheme of the combination of the fuel cell and the power cell is selected.Second, according to the vehicle performance objectives, determine the main parameters of the power system.Including: motor maximum speed, motor rated power, motor peak power, peak torque of the motor, fuel cell power rating, power battery rated power and rated energy. To meet the performance objectives, combined with the performance of the domestic level, the completion of the total selection.Third, analysis and comparison of the mainstream control strategy, determine the car with the power to follow the control mode, and the vehicle in the driving conditions and braking conditions of the control strategy are described in detail.Selection of working mode and power allocation is the key problem of hybrid power system control strategy. The formulation of this vehicle control strategy includes two aspects: first, the opening conditions of different working modes are set up; second, the principle of energy distribution in different working modes is determined. In recent years, some intelligent algorithms(such as adaptive control, fuzzy control) have been applied in the control strategy of electric vehicle, but it is difficult to be widely used in practical vehicles because of the complexity of the algorithm.Fourth, based on the Cruise software to build the vehicle model, through the simulation of the vehicle’s dynamic performance, economic performance to verify. And carried out the vehicle trial and test, to further verify the rationality of this study. By improving the driving mode of the power system, the dynamic and economic indexes of the initial design are realized.With the formation of the new energy automobile market, the demand of the user needs to transform from the original functional requirements to the higher performance requirements. This study not only through the improvement of power system improves the fuel cell vehicle dynamic performance and economic performance, and established the simulation model of a vehicle, provides a strong support for future design work.