Abstract
The energy management strategy is the key to achieve fuel cell hybrid system operation with high-efficiency and low-energy cost. The widely used energy management strategies are established based on the fixed models of power sources energy consumption and efficiency. However, due to the gradual performance degradation of the fuel cell during the service period, some model parameters will change significantly and the fixed models will become increasingly inaccurate over time. Therefore, this paper established time-varying models of power sources energy consumption and efficiency by introducing the fuel cell degradation rate. On this basis, in order to reduce the energy consumption of the system, improve the fuel cell efficiency and relatively maintain the SOC level, a novel dual-mode energy management strategy, DMDEE, for hybrid vehicles was proposed. In order to improve the online operation speed of proposed energy management strategy, the optimal control rules were obtained by offline calculation first. Then through comparison experiments with other two energy management strategies, PMP and PF, it was verified that the proposed strategy can effectively reduce the system energy consumption and improve the efficiency of the fuel cell system, meanwhile could make the SOC regress after its deviating from ideal working area. In addition, the mode switching hysteresis control was also validated. Therefore, the effectiveness and superiority of the proposed energy management strategy in this paper has been verified.
Highlights
Nowadays, the hydrogen energy is undergoing dramatic development, and will be the ultimate energy source of human beings in future
A DUAL-MODE ENERGY MANAGEMENT STRATEGY CONSIDERING FUEL CELL DEGRADATION FOR ENERGY CONSUMPTION AND FUEL CELL EFFICIENCY COMPREHENSIVE OPTIMIZATION (DMDEE) This paper proposed a dual-mode energy management strategy, in which the hybrid system works at optimal performance mode (OPM) or state regression model (SRM) according to the battery state of charge (SOC) state
The overall hydrogen consumptions of the hybrid system under three strategies are shown in the Fig.19, and are 70g, 48.24g and 48.11g respectively under power following strategy (PF), DMDEE and Pontryagin minimum principle (PMP) strategy
Summary
The hydrogen energy is undergoing dramatic development, and will be the ultimate energy source of human beings in future. This paper considers and only considers the performance degradation of the fuel cell system with service time, and establishes the time-varying models of instantaneous hydrogen consumption and efficiency On this basis, this paper designs an energy consumption and efficiency comprehensive energy management strategy. A lot of energy management strategies pay much attention to the maintenance capability of the battery SOC, for example, the battery SOC is required to remain consistent in the beginning and the end of the working conditions, or fluctuate around the target value, just like PMP and PF strategies respectively In these ways, it is bound to sacrifice some other performance to ensure the maintenance capability of the battery SOC, for example, when the SOC is low, the fuel cell is usually required to output at a high level, which leads to the hydrogen consumption increasing and fuel cell system efficiency decreasing. Maintenance capability of the battery SOC, and let that SOC fluctuates freely in its ideal working area, in exchange for improving other overall performance of hybrid power system
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