Research On Control Strategy Of Full-power Fuel Cell Vehicle Based On Driving Condition Prediction

In this paper,the full-power fuel cell vehicle is taken as the research object.Considering the dynamic response characteristics of the fuel cell system,the control strategy of the fuel cell air supply system is studied,and the optimization of the vehicle energy management strategy is completed based on the driving condition prediction of the travel route.The result has proved that the economy of the whole vehicle has been improved.First,according to the working principle of the fuel cell,the core components of the fuel cell system was modeled,such as the stack model,the compressor model of the air supply system,etc.,and the model has been proved to simulate the stack output power and the power consumed by the compressor under different current requests correctly.At the same time,based on the established fuel cell model,the output characteristic curve of the fuel cell is obtained for subsequent research on the energy management strategy of the whole vehicle.Then,the control strategy of the air supply system has been studied.Under different load current requests,the compressor in the air supply system needs to provide a certain pressure and flow of air to the stack to ensure the smooth progress of the internal chemical reaction of the stack.The air flow provided by the compressor can be expressed by the index oxygen excess ratio.Considering the power consumption of accessories such as compressors,the optimal oxygen excess ratio is existed,and the net output power of the fuel cell can reach the maximum under the optimal oxygen excess ratio.Therefore,the optimal oxygen excess ratio at different currents is obtained as the control target of the air supply system,the three control algorithms of PID,MPC and ADRC are designed for the air supply system,and it is found that the ADRC control algorithm has a better control result which has the smaller overshot of oxygen excess ratio in the case of the step of the current request.Secondly,the compressor operating point may exceed the surge line when the current request changes significantly,which will cause damage to the compressor and the stack in the real fuel cell system,the compressor operating point was controlled in the safe area by regulating the relief valve opening.Then,the energy management strategy of the whole vehicle was studied based on the driving condition prediction of travel routes.First of all,the traditional energy management strategy has been improved,the fuel cell demand power is optimized when the vehicle drive power is divided,the interval between the opening and closing of the fuel cell is optimized,and the demand power change rate is limited.At the same time,in order to avoid the air supply system response lagging behind the change rate of load current,the vehicle demand power signal is divided into high frequency power signal and low frequency power signal,the low frequency demand power is provided by fuel cell,and the high frequency demand power is provided by battery.Finally,a route was selected and we will predict its traffic,the traffic on this route will be used to set the energy management strategy to improve the fuel economy of vehicle.The air supply system can supply gas in advance before the load current changes rapidly based on the driving condition prediction,which can reduce the overshot of oxygen excess ratio,optimize the distribution of compressor working point and improve the compressor work efficiency,the result shows that the energy management strategy based on the driving condition prediction in this paper can ensure the fuel cell system work in the high efficiency range.Compared with the traditional energy management strategy,the average working efficiency of the fuel cells has increased by 4.69% in the improved energy management strategy,the fuel economy of the vehicle was improved effectively.