Enhancing Low-Throttle-Operation Robustness of ICE-Based APU by Supercapacitor-Realized Virtual Inertia

Low throttle operation of internal combustion engine-based auxiliary power units is desirable under light load to decrease specific fuel consumption. Unfortunately, sudden load increase may lead to voltage collapse and consequent stability lost due to limited total inertia and slow prime mover dynamics. This letter demonstrates that connecting a supercapacitor across auxiliary power unit output terminals is equivalent to increasing total inertia and may enhance low throttle operational robustness. Proposed findings are validated by experimental results.