Research On Voltage Equalization Control Technology Of Energy Transfer Supercapacitor

Due to the inconsistency of the supercapacitor parameters,the phenomenon of voltage imbalance often occurs when used in series and parallel.It will not only limit the utilization rate of the whole series supercapacitor module,but even lead to the overcharge of individual cells.The voltage equalization control technology of supercapacitor is studied in this paper.Different voltage equalization topologies are analyzed and compared,and the distributed voltage equalization topology of Buck-Boost converter with energy transfer is chosen as the main research object.Firstly,the working principle of supercapacitor is analyzed from the structure of supercapacitor.The physical model and electrical model of the supercapacitor are established.By analyzing the electrical model,the factors affecting the voltage imbalance of the supercapacitor are obtained.Secondly,according to the dispersion of the capacitor parameters of the supercapacitor,the working principle of the selected voltage equalization circuit topology is analyzed,the mathematical model of the voltage equalization circuit of the supercapacitor is established,and the waveform of the inductance current and the supercapacitor voltage are analyzed when the switching frequency and the resonant frequency are different.Under the control of complementary pulse,the circuit is in continuous working state.Due to the existence of resonance,the voltage fluctuation of supercapacitor is large,which is not conducive to the energy storage of supercapacitor.To solve this problem,the pulse control strategy of the voltage equalization of the supercapacitor is proposed in the paper.In one switching cycle,because only the pulse of one switching tube is controlled,the circuit works in a discontinuous state,so that the inductance current can be controlled,and then the voltage equalization control of the supercapacitor is realized.Based on the voltage equalization model,the parameters of the voltage equalization circuit of the supercapacitor are designed.The inductance current is related to the duty ratio of the pulse,and the equalization speed of the voltage equalization circuit is affected by the inductance current.Therefore,the voltage equalization speed of the supercapacitor can be adjusted by changing the duty ratio of the pulse.Based on the PSIM simulation software,the simulation of the voltage equalization control strategy is completed,which verifies the feasibility and rationality of the control method and parameter design in this paper.Finally,the main circuit and control circuit of Buck-Boost converter are designed.The control circuit is composed of sampling circuit,pulse control circuit and driving circuit.The pulse control circuit based on DSP and TL494 are designed in this paper.The experimental results show that the proposed design can realize the voltage equalization function of the supercapacitor,and the equalization speed can be effectively adjusted by changing the duty ratio.The proposed method is feasible and the design is reasonable.