以太陽能對電動腳踏車充電之可行性研究

Abstract

本研究之目的在於探討以太陽能電池輸出之直流電直接對電動腳踏車充電之可行性。研究過程使用兩組135W與205W之六吋單晶矽太陽能模組建立輸出功率340W之太陽能充電站，並搭配串聯穩壓電路限制充電過程之最大電壓，充電之電動腳踏車質量39.5kg，搭載電壓36V、容量15Ah之鉛酸電池。本研究以開路電壓法評估充、放電後鉛酸電池之電量，在多雲(平均日照量310W/m2)之天氣狀態下，經過深度放電之電動腳踏車經過7小時充電可回復至85%以上之電量狀態，並在平均速度17km/h附近之平地騎乘狀態下提供62km以上之續航力。為了解太陽能充電站是否能長時間提供電動腳踏車足夠電力，本研究進行連續五天之充電與騎乘實驗，每日騎乘電動腳踏車作為通勤工具，並在抵達台大後進行充電，儘管後三天午後雲層增厚或者下雨，在第五天充電後仍可維持鉛酸電池電量在90%以上，檢視充電數據並進行估算後發現即使陰天(平均日照量在200W/m2以上)太陽能充電站仍然能提供足夠電力，滿足大部分騎乘狀況之需求。

The feasibility of charging electric bicycle with solar cell directly has been investigated in the present study. A solar charging station was constructed with domestic made PV modules having output of 340 watts. In order to prevent the batteries from being overcharged, a regulator was used to limit the maximum charging voltage. The tested electric bicycle weights 39.5kg and was equipped with a 36V, 15Ah VRLA battery. The state of charge (SOC) of the battery was estimated by measuring its open circuit voltage. When the average solar irradiation is more than 310W/m2, the completely discharged battery of the electric bicycle can be recharged to over 85% SOC in 7 hours. With that condition, the bicycle could run over 62km at an average speed around 17km/h. In order to determine whether the solar PV charging station could supply enough energy for long time period of testing, the electric bicycle has been ridden and then charged for five testing days. The SOC of the battery could reach 90% after recharged at the fifth day although the weather was cloudy or rainy in the late afternoon at last three days. From the test, the solar charging station should be able to supply enough energy for most riding condition when the average solar irradiation is higher than 200W/m2.