Control of rubber tyred gantry crane with energy storage based on supercapacitor bank

This paper proposes a hybrid energy system, which consists of a diesel-engine generator and a supercapacitor, for improving performance of a rubber tyred gantry crane (RTGQ. 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. Moreover, the large engine generator is replaced by the much smaller one, because the supercapacitor reduces high power demands away from it. For the power conversion between the supercapacitor and the dc link, a three-leg bidirectional dc-dc converter, which has the same structure as the commercially available three-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. The proposed system can cut down the fuel consumption by 35% and the emission of engine by more than 40%.