周美兰 冯继峰 张宇

Abstract：The composite energy storage system composed of battery， super capacitor and bi-directional DC-DC converter was studied to solve the problem of insufficient mileage and short battery life in electric vehicles. In order to realize rational power allocation of battery and super capacitor， the logic threshold and fuzzy control strategy were established respectively. The vehicle model was constructed based on the electric vehicle simulation software.Through simulation study，the characteristic curves of the current and SOC of battery and the current curves of super capacitor were got， and the results were compared with the single battery power supply. For verifying the feasibility and effectiveness of the control strategy， the experimental platform was built to study electric vehicles during driving and braking. Simulation and the experimental results show the composite energy storage system and its control strategies successfully reduce the charge and discharge current of battery， regenerate the braking energy and improve the mileage of electric vehicles.

Keywords：electric vehicles; composite energy storage; logic threshold; fuzzy control

0 引 言

近年来，随着我国汽车保有量的急剧增加，石油资源逐渐匮乏、环境日益恶劣等问题也接踵而至，传统燃油汽车造成的负面影响已无法满足人们对可持续发展的要求，纯电动汽车已成为今后的主要发展方向[1]。纯电动汽车蓄电池的发展较为滞后，其功率密度较低、充放电次数有限、寿命较短，很难满足人们的日常需求[2-3]。

为解决这一技术难题，在纯电动汽车电源系统中安装了超级电容和双向DC-DC变换器，从而组成了复合储能系统[4]。由于超级电容具有功率密度高、寿命长、能承受瞬时大电流充放电等优点，由此组成的复合储能系统能够提升原有电源系统的性能，从而提高纯电动汽车的动力性能和续驶里程[5-7]。

随着技术的不断发展，复合储能系统逐渐走进研究人员的视野，并已取得一些可喜的成就[8-9]。Chugoku电力公司和丰田公司对蓄电池和超级电容构成的复合储能系统实验研究，实验结果显示，相比单一蓄电池电源的电动汽车，具有复合储能系统的电动汽车具有更好的动力性能[10]。Arani S K等人利用遗传算法优化电动汽车模糊控制器并进行实验，结果表明，所开发的模糊控制器在降低功耗等方面优于标准模糊控制器[11]。我国也开始对复合储能系统进行各项研究[12]。如王斌等人提出了一种新型复合储能系统结构，并设计了7种工作方案，有效提高了复合储能系统工作效率并保证蓄电池的充放电安全[13]。Chen Jian等人提出了一种电动汽车用模糊逻辑参数调整的自适应控制方法，仿真和实验结果证明了所提出方法的有效性[14]。……