Research On Voltage Equalization Technology Of Supercapacitor Energy Storage Module

Supercapacitor is new kind of electrical energy storage device with performance between conventional capacitors and batteries,and has reversible process of energy storage.Supercapacitors are considered to be an option instead of the traditional battery.Compared with traditional capacitor,supercapacitors have the advantage of high energy density.Compared with conventional batteries,supercapacitors have advantages of high power density and long cycle service life and high safety factor.These advantages make supercapacitors having a wide application prospect in electric vehicle,rail transit,new energy grid system and so on.Due to the limitations of the current technology,the main drawback of supercapacitors in practical electrical energy storage applications is the low rated voltage.Therefore,in applications with higher voltage requirements,supercapacitors are used in series to form the module to meet the voltage requirements.Due to manufacturing process and other factors,there are differences in the parameters of the single supercapacitor device.Then,during the use of the module,the phenomenon of unbalanced voltage in the single device will lead to local over-voltage phenomenon in one or more devices.This phenomenon will also limit the lifespan and energy storage efficiency of the supercapacitor module.Therefore,it is very necessary to use voltage equalization technology for the supercapacitor module,which can greatly improve the service life and energy storage efficiency of the supercapacitor.This dissertation focuses on the problem of unbalanced voltage of supercapacitors.Based on the principle and characteristics of supercapacitors,the equivalent circuit model of supercapacitors and their charge/discharge characteristics are introduced and analyzed.After the in-depth analysis,discussion and simulation comparison of the existing voltage equalization technology solutions,the design of the supercapacitor module voltage equalization system was designed.The system includes voltage and current data acquisition module,switch network and its driving module,display module and serial port communication.In this system,a STM32 is used as the core controller,and an electrolytic capacitor is selected as the middle capacitor to achieve energy transfer,to achieve voltage equalization.Then,according to this design,the hardware platform was established,and the relevant functional circuit designing and implementation were investigated including the control strategy and software design.Finally,the completed system was test to evaluate as possible voltage-balance module.It has been found that,through analyzing the data obtained from the experiment,it can be seen that after this equalization system scheme is adopted,the single cell voltage of the supercapacitor module is effectively balanced during charge and discharge and standing processes,which also showed good consistency in these processes.Moreover,through these simulation and experimental tests,the correctness and feasibility of the system are verified.