小型引擎動力式噴霧機之電動化

Abstract

本研究分別使用額定功率為148 W及370 W之直流無刷馬達替代40 c.c.二行程引擎，並將動力來源改以電動之形式以達節能減碳之目的。首先將引擎拆除後根據鎖點位置與離心式葉輪轉軸之關係設計一組引擎與馬達之間的通用替換板，使凡於體積限制內的馬達皆可快速替換，以助於引擎噴霧機之電動化。電源方面，則主要選用24V 10Ah鋰電池作為提供電動噴霧機運轉之能量來源。為進一步提升電動噴霧機之使用效率，本研究設計一套快速充電電路以縮短充電所需之時間；此外我們也針對密度法、端電壓法及內阻法進行測試，期望可預估電池目前所剩餘的電量。 實驗結果所示，在引擎噴霧機與電動噴霧機輸出性能表現一致之條件下，電動噴霧機運轉時所產生的噪音已從原引擎噴霧機107 dB之噪音量降至92 dB。使用成本方面，引擎噴霧機使用每小時所花費成本約新台幣15.3元，電動噴霧機最高僅需花費新台幣0.6元的使用成本，最後在重量方面，引擎噴霧機總重約11.7 kg，電動噴霧機總重12.1 kg，僅相差0.4 kg。 充電電路方面，本研究選用2SA1941 PNP功率電晶體作為定電流充電之控制元件，並且採用定電流/定電壓充電法對電池進行充電。實驗結果發現雖然以大電流充電可縮短充電時間，但充電電流不宜過大，鉛酸電池以3 A為限；鋰電池應低於2 A，而鋰鐵電池則建議使用4A之充電電流。此外充電效率也會因充電電流的提高而降低。電量估測方面，端電壓法的準確度極高，但此量測方法無法預測電池老化的趨勢，須採用內阻法作為判斷電池老化之機制。

In this research, a 148W DC brushless motor and a 370W DC brushless motor were used to substitute the 40 c.c. two-cycle engine of a sprayer, and we dismounted the engine and designed a fixed board which is based on the location of screw holes for the replacement from engines to motors. If the motor does not exceed the restriction of space, it can be replaced quickly and it can help the engine sprayer electrification. We use 24V lithium battery as power source of the electrical sprayer. In order to increase the efficiency of electrical sprayer, we design a set of constant voltage / constant current mode charger to reduce the charging time and we also study density method、terminal voltage method and the internal resistance method in capacity estimation, expecting to estimate the residual capacity of batteries. The result of study, comparing with engine sprayer, the working noise of the electrical sprayer has dropped to 92 dB. The cost of the engine is NT$15.3 per hour, and the cost of the electrical sprayer is NT$0.6 per hour. The engine sprayer weight 11.7 kg, whilethe electric sprayer weight 12.1 kg. The difference of weight is about 0.4 kg. We used 2SA1941 PNP Power Amplifier as the control device of constant current charger and charged batteries with CC/CV mode. Charging batteries with high charging current can reduce the charging time, but charging efficiency decreased by increasing the charging current. In general, charging current for lead-acid batteries is 3A and lithium batteries is lower than 2A. The open-circuit-voltage method for residual capacity estimation was thought to be accurate, but the internal resistance method has to be used to determine the batteries ageing.