電動公車減速行為與能源效率關係之探討：以高雄市區公車為例

Investigating the Relationship between Decelerating Behavior and Energy Efficiency in Electric Buses: A Case Study of Kaohsiung City Buses

相對內燃機引擎，電動車減速動能回收再生制動系統為其特性，本研究蒐集2020~2021年高雄市3台電動公車5個月行駛數據，輔以運輸與環境政府開放資料集進行資料擬合，總計樣本含4條路線19位駕駛2,842趟次。選用多層次迴歸模型處理路線與駕駛人的趟次巢狀結構，解析耗電量影響因子及影響度，有助掌握公車營運路線所需電量與剩餘里程，為未來預估耗電量及續航里程基礎。結果顯示，動能回充比例與市區平均速度(不含惰轉)增加，能源效率也隨之增加，且動能回充比例為影響能源效率之最大程度預測變數。另動能回充比例隨減速度5 (m/s2)以下行駛時間占比增加而提高，且1~2 (m/s2)影響程度最大；若駕駛減少急踩剎車比例並緩和減速，有助動能轉為電能，增加電動公車能源效率。

Regenerating braking system (RBS) is unique to electric vehicles. To examine the influence of RBS on energy efficiency of city electric buses, a panel data set consisting of three buses, four bus routes, and 19 drivers, following five months (from July 2020 to January 2021) and consequently 2842 trips was collected. The data set was then expanded with roadway and ridership open-source data. Considering the trip-bus route and trip-driver nesting structures, the data were examined with multilevel models. The analysis results showed that the energy efficiency was enhanced with the increase of the ratio of RBS and the average driving speed (excluding idle time). Moreover, RBS appeared to be the most influential factor to the energy efficiency of city buses. The ratio of regenerated electricity was enhanced when the deceleration was maintained at 5 m/s2 or below and was the highest when the deceleration range was between 1 and 2 m/s2. The energy efficiency of city bus operations could be largely improved if the drivers maintained their driving behaviors within the recommended thresholds.