The Research On Hybrid Power Crane System

As energy shortage and environment problem are increasing outstanding, energy saving and environment protection become the major development trend of lifting machinery.During the working process, rubber-tyred container gantry crane handle loads with heavy weight and high height, lifting and laying down frequently. At the same time, the gravitational potential energy of the loads is consumed by resistance and can not be recovered. Therefore we can conclude that energy consumption of rubber-tyred container gantry crane is huge and potential of energy saving is favorable.Hybrid power rubber-tyred container gantry crane system uses super capacitor to recover gravitational potential energy during the process of laying down loads, and provides energy when starting and the loads are heavy, which will greatly improves the system performance because the measure can not only realize the recovery of energy but also solve instantaneous power deficiency.The dissertation adopts the design scheme of hybrid power that is widely used in automotive field. According to the characteristics of crane system, we use super capacitor with huge capacity and can be charged and discharged quickly as energy recovering unit, which can overcome the slow charging and discharging and small capacity of traditional storage battery. DSP with high precision, good stability and quickly response is as well used to control charging and discharging, just to satisfy the needs of real-time.The dissertation analyses the basis characteristic, parameter, characteristic of charging and discharging period and parameter configuration of super capacitors at first. Then it analyzes the working process of phase-shifted full bridge isolation type DC-DC converter suitable to large power occasion, as well as the conditions of achieving soft switching. Thirdly the specific control strategy is introduced which is key part of the dissertation. In this part, energy flow and losses during lifting and laying down periods are analyzed, also the principle program and specific control strategy are introduced. To ensure the system working properly and super capacity safety, the current is kept at constant value in charging period as well as voltage is kept at constant value in discharging period. At the end of dissertation, simulation is proceeded and Waveform Graph is provided from which we can know that the DC-DC converter has steadily output and favorable switching capability that can satisfy the needs of Hybrid power rubber-tyred container gantry crane system.