Energy-efficient and Wear-optimized Operating Strategies for special and commercial vehicles with Fuel Cell Drives

Fuel Cell Hybrid Vehicles (FCHEVs) are vehicles with drivetrains consisting of both battery and fuel cell systems. The reason for including dual power sources can be attributed to the increased energy density demand of the vehicle. While batteries offer a high power density, they have substantially lower energy densities in comparison to fuel cell systems which lack high power densities. As a result, both systems naturally complement each other in the scope of high-power, high-energy demand applications.Promising fields of application for FCHEVs include heavy long-distance goods transport and special machinery, such as construction machinery with limited access to charging infrastructure or high requirements in terms of range, energy demand and operating times. To make fuel cell drives attractive for these applications, the operating costs must be kept as low as possible in addition to the investment for operators. Both efficiency-enhancing and wear-reducing measures for the components of the powertrain play an important role here throughout the entire operation of the system. To this end, modular, vehicle-based, platform-independent algorithms for controlling and predicting the wear of the fuel cell drive and the battery system is being developed, implemented, and tested.The focus of this paper is presenting a vehicle-based framework, consisting of surrogate models and the Energy Management Strategy (EMS) which determines the power split between the fuel cell and the battery in real-time. Two types of EMS are presented and are applied to a real-life test case corresponding to a commercial vehicle (bus). A third EMS is also proposed which acts as a hybrid between the latter two. The pros and cons of each of the EMS are discussed in the context of degradation, energy, power-split, and the fuel consumption.