本論文主要以8051微控制器研製鋰離子電池充電器,應用Motorola快速充電法,期望縮短電池充電時間及提高電池之充電效率,並延長電池之使用壽命。由於針對單體鋰電池之設計,充電器輸出電壓大約介於3.6V至4.2V之間,輸出電壓相當低,為了提高充電器轉換效率,採用同步整流技術,降低對效率影響極大的傳導損失。至於電池充電技術則是採用Motorola快速充電法,此充電法則主要以定電流進行充電一段預設時間後,休息一段不充電且不放電之時間,接著再進行短時間的放電以及第二次的休息。由於此種充電樣態較為繁雜,因此採用微控制器來實現。本論文最後以8051微控制器以及同步整流之降壓型轉換器完成所研製之充電器,實際對鋰電池進行充電,並記錄充電波形以及觀測其充電過程,顯示確實能達成快速充電效果,且電池溫升最高僅1.3oC左右,驗證所研製之充電架構與方式,能夠確保電池充電過程之安全。再者,使用本論文所實現充電器之充電效率可達97.33%。
This thesis focuses on a Li-ion battery charger for rapid charging. The charger is structured with a synchronous rectified buck converter and controlled by the 8051 micro-controller in which Motorola charging method is applied to short the charging time duration, boost the charging efficiency and enlarge the life time of used battery. Generally, the output voltage of charger for one Li-ion cell is from 3.6V to 4.2V, a quite low voltage, so that the synchronous rectified technique is utilized to improve the charger efficiency. The Motorola charging method is implemented with the used micro-controller to form the desired charging/discharging pattern in which a charging duration, a rest duration and a discharging duration are included. Experimental results derived from a rapid charger for Li-ion batteries show the good conforms to the rapid charging specifications. The increase in temperature is recorded as only up to 1.3oC to ensure the cell safety and the charging efficiency is calculated high to 97.33% in the implemented rapid charger.