Hyeon‑Seop Yi1, Sukwon Cha
Recently, petrol engines have been removed and replaced with fuel cells, batteries, and super capacitors as alternative power sources, in vehicles and construction machinery. Electric vehicles driven by batteries have been the only mass-produced vehicle with an alternative power source, while fuel cell vehicles have been developed in which the fuel cell and the battery are hybridized. For excavators, research and development are being done in a similar direction. Some excavators are equipped with a super-capacitor, which regenerates the upper braking energy to increase the efficiency of the engine. This paper deals with the energy management of environmentally friendly electric excavators using super capacitors. The power distribution profile of the fuel cell, battery, and super capacitor was examined with the optimal control theory of the required power profile of an existing engine excavator. The optimal control theory is based on dynamic programming. It was confirmed that the fuel cell efficiency of an excavator with a super capacitor was-higher than the fuel cell efficiency of a fuel cell-battery electric excavator. The simulation method used in this and its conclusions provide basic research that will help to mass-produce electric excavators in the future.