| In recent years,with the continuous development of economy and technology,China has made a series of remarkable achievements in the fields of automobile,urban rail transit,industry and commerce.The scale of production and use of new energy vehicles,urban metro,trams,elevators and heavy machinery excavators and cranes has been expanding,even ranking in the world's leading level.These mechanical equipment will produce a lot of braking energy in the process of operation.For example,the braking energy generated by vehicles in urban areas is about 30% to 50% of the total driving energy,and the braking energy generated by traction track trains is about 30% of the power supply energy of traction network.In industrial areas,for example,only 20% of the output energy of generators is used for actuators in the operation of hydraulic excavators,and the energy utilization rate is extremely low.At present,these energy are consumed in the form of heat energy,which not only seriously damages the service life of machinery,but also causes a great waste of energy.If this part of braking energy is reasonably recycled,it will greatly improve the energy utilization rate and produce considerable economic and social benefits.This paper takes the recovery and reuse of braking energy as the research background,combines the characteristics of braking energy,and through the comparative study of various energy storage methods,determines the research goal of energy storage control system design with supercapacitor as energy storage unit.Firstly,the working principle and characteristics of supercapacitor energy storage elements are introduced,several mathematical models of supercapacitor are analyzed,and the series-parallel and charge-discharge characteristics of supercapacitor are analyzed based on a simple model,which provides a theoretical basis for the scheme design of supercapacitor module and the control strategy design of energy storage system.According to the overall design of energy storage system,the main circuit design is completed.The working principle and waveform of bidirectional DC/DC converter are analyzed in detail.The topology of the converter is determined and the parameters of the main circuit device are designed according to the design requirements.According to the relevant data and requirements of the system,the parameters of the supercapacitor module are calculated and the voltage equalizing circuit is designed to complete the design of the energy storage unit.On the basis of the main circuit design,the general scheme design schematic diagram of the control system is given.The basic control idea is determined according to the operation requirement of AC motor energy recovery and reuse system.The controller design of bidirectional DC/DC converter is completed by establishing small signal model,and the automatic coordinated control system is designed by setting up logic control table to realize the automatic control of energy storage system.Based on the main circuit and control circuit,the supercapacitor energy storage system is modeled and analyzed.Based on the model built by MATLAB/Simulink,simulation analysis of control strategy,steady-state experiment simulation of boost and buck of energy storage system and automatic control experiment simulation of energy storage system are completed respectively.The rationality of main circuit parameters and control circuit is verified by simulation.The prototype of 2kW bidirectional DC/DC converter is completed,and the experimental platform of energy storage system is built.Open-circuit and on-load experiments were conducted to verify the stability of the designed energy storage system,and impact experiments were conducted to verify the impact of the energy storage system on the main operating system.Finally,the energy-saving effect of the designed supercapacitor energy storage control system is verified by the comparative experiments of braking energy recovery and and reuse of braking resistance and supercapacitor. |
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