Investigation of a fuel cell hybrid system with a new modular test bench approach for all electric hybrid power train systems

Graf, Tobias; Fonk, Robin; Schröter, Jonas; Hoenicke, Pia; Bauer, Christiane; Kallo, Josef; Willich, Caroline

doi:10.1016/j.est.2022.105999

Cited by 15 publications

(14 citation statements)

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“…The efficiency achieved by Hoenicke et al [14] was above 99% during cruise and take-off which is higher than the usual efficiencies of DC/DC, which usually has efficiencies somewhere between 85% and 98%. Graf et al examine the influence of the battery SOC [25] and the influence of the low ambient pressure [26] at high altitudes on the direct hybrid system and the resulting implications for dimensioning of a fuel cell and a battery [27] is investigated. A power unit combining a fuel cell and a battery in a direct hybrid can be used flexibly with the help of a power management system (PMS) as proposed by Hoenicke et al [14] and already used in the previously described test-airplane HY4 [28].…”

Section: Direct Hybrid Powertrain Of a Fuel Cell And A Batterymentioning

confidence: 99%

“…To verify the defined switching procedures, the mode transitions were performed in a previously described laboratory setup [25]. The setup emulates the behavior of the fuel cell and the battery using two electronic sources.…”

Section: Experimental Verificationmentioning

confidence: 99%

“…The sum of the fuel cell (blue) and the battery (yellow) current results in the inverter (red) current. The deviations seen between the inverter, fuel cell and battery voltage can be traced to losses in the experimental setup (wires, switches, diodes) [25]. In order to switch from Hybrid Mode to Fuel Cell Mode, the power is reduced to fulfill the above described switching criteria.…”

Section: Experimental Verificationmentioning

confidence: 99%

“…The necessary power reduction when changing from Hybrid Mode into Fuel Cell Mode for an exemplary hybrid system based on the voltage-power curves of a 10 kW PEM fuel cell stack (HD10; Power: 10 kW; Cummins Inc. USA; prior Hydrogenics) and a high-energy battery module (SLPB120255255; Kokam Co., Ltd., Republic of Korea) was examined with the help of a Matlab simulation. For the simulation, data from a previous study [25] were linearized and an example system consisting of one motor, one fuel cell stack and one battery module was considered. Figure 7a shows the resulting voltage-power curve of the fuel cell-battery hybrid system.…”

Section: Power Reduction During Switchingmentioning

confidence: 99%

“…The defined switching procedures for operation mode changes were implemented in the control of a previously described experimental setup [25] of a power train consisting of two DC sources representing the fuel cell and the battery, the power management system and a load. The results of the test and validation of the mode transitions with the switching procedures in the experimental setup are shown.…”

Section: Introductionmentioning

confidence: 99%

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Switching Logic for a Direct Hybrid Electric Powertrain

Fonk,

Graf,

Paeßler

et al. 2024

Aerospace

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Hybrid electric aircraft with a powertrain based on fuel cells and batteries can reduce climate-active emissions in aviation. In a direct hybrid powertrain, the fuel cell and the battery are connected in parallel, without a DC/DC converter balancing their voltage levels. Switches make it possible to select different operational modes (fuel cell only, hybrid or battery charging) depending on the power demand during different flight phases. To exploit the high specific energy of hydrogen, the system should change from Hybrid Mode during take-off to Fuel Cell Mode in cruise. During descent, the battery can be charged if Charging Mode is selected. To avoid voltage and current peaks and consequent damage to components when switching between modes, certain conditions must be fulfilled. Those switching conditions were defined, and switching procedures for changing from one mode to the other during flight were developed and tested in a lab system. In a direct hybrid, the system voltage depends on the required power. When switching from Hybrid Mode to Fuel Cell Mode, a short reduction in power of 65% is necessary for the examined system to meet the switching requirements. It is also shown how this power loss can be reduced to 25% by distributed propulsion with a second powertrain or even eliminated by a change in the hybrid ratio.

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