This paper proposes a hybrid energy system, whichconsists of a diesel-engine generator and a supercapacitor, for improving performance of a Rubber Tyred Gantry Crane (RTGC). The supercapacitor contributes to the energy recovery associated with regenerative braking in 'Hoist-Down' braking operation and to the rapid energy consumption related with acceleration in 'Hoist-Up' operation of the RTGC. Hence it does save energy, which is conventionally wasted by a braking resistor. In addition, the large engine generator is replaced by the much smaller one, for the supercapacitor reduces high power demands away from it. For power conversion between the supercapacitor and the DC link, a 3 legs bidirectional DC-DC converter, which has the same structure as the commercially available 3-phase inverter, is used. Two kinds of simulations are performed to study the behaviors of the proposed system under the worst operating conditions. The performance of the proposed hybrid energy system is evaluated through several experiments with a real RTGC.
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