Yang Hengzhao
Department of Electrical Engineering, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, NM 87801, USA.
J Energy Storage. 2020 Feb;27. doi: 10.1016/j.est.2019.101004. Epub 2020 Jan 16.
This paper presents a comprehensive study of the supercapacitor Peukert constant dependence on its terminal voltage. Recent studies show that the charge delivered by a supercapacitor during a constant current discharge process increases when the discharge current decreases if the discharge current is above a certain threshold, i.e., Peukert's law applies. This paper investigates the supercapacitor Peukert constant dependence on the initial voltage, cutoff voltage, and voltage difference of the constant current discharge process. Experimental results show that the Peukert constant is lower when the cutoff voltage is lower (the initial voltage is fixed) or the initial voltage is higher (the cutoff voltage or voltage difference is fixed). The physical mechanisms accounting for these observations are analyzed. When the voltage difference is larger (the initial voltage or cutoff voltage is fixed), more charge is released. For the same voltage difference, more charge is delivered when the initial voltage is higher due to the voltage dependence of the supercapacitor capacitance. In these scenarios, the discharge time is longer, the branch capacitors are more deeply discharged and their depths of discharge are higher, which makes them more responsive to the discharge current and ultimately leads to a smaller Peukert constant.
本文对超级电容器的佩克特常数对其端电压的依赖性进行了全面研究。最近的研究表明，如果放电电流高于某个阈值，即在恒流放电过程中，当放电电流减小时，超级电容器所输送的电荷量会增加，即佩克特定律适用。本文研究了超级电容器的佩克特常数对恒流放电过程的初始电压、截止电压和电压差的依赖性。实验结果表明，当截止电压较低（初始电压固定）或初始电压较高（截止电压或电压差固定）时，佩克特常数较低。分析了导致这些观察结果的物理机制。当电压差较大时（初始电压或截止电压固定），释放的电荷量更多。对于相同的电压差，由于超级电容器电容的电压依赖性，当初始电压较高时，输送的电荷量更多。在这些情况下，放电时间更长，分支电容器放电更深入且其放电深度更高，这使得它们对放电电流更敏感，最终导致佩克特常数更小。
