Research On Hybrid RTG Bidirectional DC-DC Converter

Hybrid Rubber Tyred Gantry Crane(RTG)takes energy storage system as its second power source.Due to the contradiction between the terminal voltage of energy storage system and the bus voltage of the high voltage side,and the consideration of braking energy recovery,the bidirectional DC-DC converter is promoted on the hybrid RTG.And the bidirectional DC-DC converter in hybrid RTG is mainly studied in this paper.Firstly,according to the company’s hybrid power system revamping requirements,the working modes of hybrid power system and bidirectional DC-DC converter were analyzed,and the buck-boost technical index of bidirectional DC-DC converter was proposed.By studying the topology of bidirectional DC-DC converter,the three-phase interleaved bidirectional DCDC converter was selected as the main circuit topology.And the three-phase interleaved bidirectional DC-DC converter was superior to the traditional bidirectional DC-DC converter which was verified by simulation.It was more suitable for the high-power,high-current buckboost change occasion studied in this paper.Secondly,the small signal model of bidirectional DC-DC converter was established by using state space analysis method,and its controller was designed.In Buck mode,a single closed-loop control strategy based on current feedback was adopted,and a double closed-loop control strategy based on current inner loop and voltage outer loop was adopted in Boost mode.Then,in order to improve the control effect in Boost mode,combined with the idea of extended state observer,a sliding mode variable structure controller based on dynamic feedback of voltage and current was designed.And the simulation results showed that the system has good steady-state performance and superior anti-interference ability.Finally,an experimental prototype of 60 W three-phase interleaved bidirectional DC-DC converter was built in the laboratory,and steady-state experiment,external interference experiment and dynamic switching experiment were carried out respectively.The results showed that the system has good steady-state performance,anti-interference performance and follow-up performance.At the same time,the whole machine test was carried out in RainbowCargotec Industries Co.,Ltd.The voltage and current control indicators all met the design requirements,which verified the correctness and effectiveness of the research content in this paper.