基于超级电容辅能的电动微耕机复合电源系统研究与试验

Research and Experiment on Composite Power Supply System of Micro-tiller Based on Supercapacitor Auxiliary Energy

锂电池组为单一动力源的电动微耕机在丘陵山地复杂多变的作业工况中,锂电池频繁瞬时大电流波动放电,严重影响锂电池的能效及寿命,本文将超级电容应用在电动微耕机上构成复合电源,并对该复合电源的参数匹配及能量分配策略进行了研究.结合电动微耕机实际作业情况,设计了逻辑门限控制策略,控制系统以主控芯片STM32F103为核心,使用C语言编程,对单一锂电池电源和复合电源两种工作模式下磷酸铁锂电池的工作电流、功率、温度、容量衰退速率等进行了试验与分析.田间试验表明,在一定土壤条件下,复合电源工作模式与单一锂电池电源相比,针对电机不同转速和不同地块,磷酸铁锂电池电流平均波动范围分别缩减14.37,13.07,14.3,15.23,13.77A,平均峰值功率分别下降43.6%,75.2%,77.4%,76.4%,60.3%.由于超出阈值的部分大电流由超级电容补充,磷酸铁锂电池输出电流变平缓,使磷酸铁锂电池组免受突变大电流的冲击;复合电源中磷酸铁锂电池组平均温升相较于单一电源锂电池组分别下降0.13,1.48,1.67,2.26,3.45℃;在试验作业时间内,复合电源中磷酸铁锂电池组平均容量衰退速率分别下降2.1%,9.1%,9.7%,9.2%,4.4%,在长期频繁使用情况下,复合电源系统微耕机的经济性和安全性要高于单一锂电池系统.该研究可为复合电源在农机装备上应用提供理论基础和技术参考.

In view of the frequent instantaneous high current fluctuation discharge of the lithium battery in the complex and changeable operating conditions of the electric micro-tiller with the lithium battery pack as the single power source, which seriously affects the energy efficiency and service life of lithium battery, the supercapacitor was applied to the electric micro-tiller to form a composite power supply, and the parameter matching and energy distribution strategy of the composite power supply were studied. Combined with the actual operation of electric micro-tiller, the logic threshold control strategy was designed. The control system took the main control chip STM32 F103 as the core and was programmed with C language. The working current, power and temperature changes of lithium iron phosphate battery and capacity decline rate of lithium iron phosphate battery under two working modes of single lithium battery power supply and composite power supply were tested and analyzed. The field experiment showed that under certain soil conditions, for different moto speeds and different blocks, the average current fluctuation range of lithium iron phosphate battery was reduced by 14.37,13.07,14.3,15.23,13.77 A, respectively. The average peak power decreased by 43.6%, 75.2%, 77.4%, 76.4% and 60.3%, respectively. Because the high current exceeding the threshold was supplemented by the super capacitor, the output current of lithium iron phosphate battery became flat, so that the lithium iron phosphate battery pack was protected from the impact of sudden high current. The average temperature rise of lithium iron phosphate battery pack in composite power supply decreased by 0.13,1.48,1.67,2.26,3.45 ℃, respectively, compared with that of lithium battery pack in single power supply. During the period time of testing, the average capacity attenuation rate of lithium iron phosphate battery pack in the composite power supply decreased by 2.1%, 9.1%, 9.7%, 9.2% and 4.4%, respectively. Under the condition of long-term and frequent use, the economy and safety of the micro-tiller with the composite power system were higher than that of the single battery system. The research can provide theoretical basis and technical reference for the application of composite power supply in agricultural machinery and equipment.