Research On Control Strategy Of Energy Storage System Based On Ultracapacitor

In recent years,for the development of renewable energy and research has gradually become the focus of energy markets,this recycled,non-pollution clean energy is increasingly being applied.With the popularity of hybrid vehicles and electric cars,ultracapacitors are getting more and more widely used.Ultracapacitor has many advantages,such as large capacity,fast charge and discharge rate.At present,the research and development of energy storage system which is based on ultracapacitor has been an important choice of aspect in the energy utilizationIn this paper,first of all,it introduces the basic working principle of the ultracapacitor,its several commonly used mathematical model and charge and discharge characteristics.Single ultracapacitors pressure the lower voltage generally,so an ultracapacitor modules which is combination of several ultracapacitors in series parallel is commonly used in practice.On account of that parameters of each ultracapacitors is different,such as capacitance,equivalent series resistance(ESR),leakage current and so on.if voltage was not balanced or stable by some measure,it can leads difference of the pressure rise rate between each capacitance,thus affecting the energy storage system's work efficiency,and reducing the service life of the ultracapacitor.Therefore,in practical application,using the certain measures for ultracapacitor modules to keep voltage stable is commonly.Voltage equalizing strategy consists of the energy consumption model and feedback.,including switch resistance,voltage regulator tube and DC-DC converter method,etc.In the third chapter of this paper,firstly,it conducts simulation analysis and expounds the advantages and disadvantages of several methods mentioned above,and then based on the method of DC-DC converter circuit,an improved scheme is proposed and simulated.To eusure the energy is in the cycle and the voltage is balanced at the same time,comparing with several methods in front in these aspects:energy loss assessment,times and other fields.In normal work,the terminal voltage of ultracapacitor is will continue to change,for this kind of situation,we usually configurats bidirectional dc converter between the load and the super capacitor in order to achieve constant pressure discharge or constant power discharge,etc.In the fourth chapter of this article has established bidirectional dc converter topology mathematical model,analyzed several kinds of working mode and deduced the small signal transfer function.The plan of this idea has been verified the feasibility of the scheme and stability by using matlab simulation.Finally,with Infineon XC886 as main control chip,combining several super capacitor to set up a experimental platform for the energy storage system.throughing the three-phase controlled rectifier after LC filter,the ultracapacitor charging and discharging experiments,to verify the working characteristic of the ultracapacitor.The experiment has been ensured the reliability of the energy storage system.