可應用於太陽能微型動力車輛之高效率鋰鐵電池充電系統研製

A HIGH-EFFICIENCY WIDE-VOLTAGE RANGE BATTERY CHARGER FOR SOLAR-POWERED MICRO ELECTRIC VEHICLES

"本文旨在提出一個可應用於太陽能微型電動車輛（Solar-Powered MEV）之高效率鋰鐵電池充電系統。為了適應太陽能板以及鋰鐵動力電池的寬廣操作電壓範圍，此充電系統採用四開關升降壓轉換器（FSBBC）作為電力級，其架構簡單、並且具有相同極性的輸入／輸出端電壓。所研製之四開關升降壓轉換器搭配集成控制器（LT8490）不僅可以完成太陽能板最大功率點追蹤控制(Maximum Power Point Tracking, MPPT)，也能夠對鋰鐵動力電池進行定電流-定電壓（CC-CV）充電。再者，一般的電動車輛系統，其鋰鐵動力電池組是經由電磁接觸器提供馬達電力，為了能夠延長電磁接觸器與電池組的壽命，本文導入一種低成本的太陽能電力檢測電路，藉此與車輛電子控制單元（ECU）進行溝通、進而決定電磁開關啟動與否。為進一步驗證可行性，本文實際研製一台150W鋰鐵電池充電系統；在太陽能板直流輸入15~25V的實作條件下，不僅最大功率點追蹤控制得以實現，輸出充電規格最高達到定電流2.5A與定電壓60V。"

The objective of this project is to propose a high-efficiency wide-voltage range battery charger with integrated controller (LT8490) for solar-powered micro electric vehicles (MEVs). Due to its simplicity and identical input/ output voltage polarity, the four-switch buck-boost converter (FSBBC) with solar maximum power point tracking (MPPT) control and constant-current constant-voltage (CC-CV) charge strategy is developed as a charger module for LiFePO4 battery packs. In this paper, the energy of MEV is mainly supplied by a LiFePO4 battery bank through a magnetic actuator. A cost-effective power sensing circuit is also built in the battery charger module to reduce the contact bouncing problem of magnetic actuators. Beside, a 150W charger module is remotely controlled with an electric control unit (ECU) to convert the solar energy for compensating the lost charges of battery. To verify the performance of the proposed system, the battery charger prototype with 15~25V input and 60V / 2.5A output is constructed. Experimental results show that a safe CC-CV charging curve, high power conversion efficiency and high maximum power point tracking accuracy of the constructed battery charge module can be successfully achieved.