Design of the power system for an autonomous hybrid Wing-In Ground effect vehicle

The shift towards more-electric and autonomous vehicles in eMobility applications demands innovative energy management strategies, especially for hybrid systems that integrate fuel cells, batteries, and supercapacitors. Wing In Ground (WIG) effect vehicles represent both a significant challenge and a promising opportunity for the development of future hybrid-electric vehicles. Their capability to achieve high speeds with low energy consumption by exploiting the ground effect meets mobility requirements while allowing functionality without the need for specialized infrastructure. The combination of the power-electronic components belonging to the hybrid system allow a variety of possible configurations that can be tailored to specific mission requirements, this aspect makes them versatile and efficient. Among these configurations, the most complex and studied is the one involving fuel cells, batteries, and supercapacitors. These energy sources are managed through Energy Management System (EMS) strategies, which differ based on how they distribute energy among the various sources under different operational scenarios. The study explores several EMS strategies, including the State Machine, Classical PI, Fuzzy Logic, Frequency Decoupling, Equivalent Consumption Minimization Strategy (ECMS), and External Energy Maximization Strategy (EEMS). A new strategy, the Modified PI, was developed to address some identified shortcomings in these strategies. To optimize the use of EMS strategies, it is essential to manage energy sources through converters, which inherently introduce inefficiencies. A balanced approach was identified in a topology that incorporates a DC/DC converter for fuel cells, a bidirectional DC/DC converter for the battery pack, and a necessary DC/AC converter to connect the load. The strategies mainly differ for the Fuel Cell Power computation, instead, the battery power is managed by a PI controller in order to keep the desired bus voltage. Field tests with scale models provided valuable data, particularly for the takeoff phase, which is one of the most demanding in terms of system response speed and power request. The most valuable result is the discover of a characteristic takeoff profile for WIG vehicles, marked by an initial power peak followed by stabilisation at approximately one-fifth of the peak power. This profile was used to simulate the takeoff manoeuvre one of the most challenging scenarios for the EMS. Simulations were conducted on Simulink, using the Simscape Power Systems add-on thanks to its wide power-electronic components library. All strategies have been tested using a typical takeoff and stabilization load pattern of about 10 minutes. The results were compared based on components’ wear and tear, fuel consumption, efficiency, and reaction slope. The ECMS strategy offers the best reaction time but results in the highest fuel consumption. On the other hand, the EEMS strategy achieved the lowest hydrogen usage while maintaining good reaction time and efficiency. However, this strategy had to be discarded due to fluctuations during steady-state operation, which caused stress and wear on the components. Among all the strategies tested, the Modified PI emerged as the best compromise, balancing the key parameters effectively and offering a promising solution for managing energy in WIG vehicles.