高精準度電池電壓偵測技術應用於初級側控制反馳式電池充電器

Abstract

在日常生活中的許多電器用品中，可攜式產品已經成為人們不可或缺的必備工具。隨著電子產品的蓬勃發展，可充電電池也成為目前最適合可攜式產品使用的行動電源，而隔絕式的電源轉換器更是必備的充電系統。因此，如何對電池進行快速且有效率的充電是一個重要的課題。此外，在電池到充電器之間所產生寄生電阻和隔絕式的電源轉換器中的光耦合器中的非理想效應會對充電器判斷輸出電壓大小造成影響，可能減少對於電池的可用時間，更嚴重的是，過量的充電電壓會使得後端的設備損壞或減少設備的壽命。因此，準確的電池充電電壓是非常重要的。在充電器的架構中，特別是反馳式轉換器，因為其基本電路架構及控制電路簡單以及外部元件使用數較少，經常被選用在較低瓦數的電源應用。但在控制器中，因為排除了光耦合器的非理想效應，因此在電池電壓偵測電路中，需要依靠輔助側來擷取電池電壓資訊。本篇論文完成了定電流迴路及定電壓迴路的充電系統，達到快速充電及穩定電壓，並排除非理想效應造成的影響的電池電壓精準偵測電路。此晶片使用0.5微米的700伏高壓製程所實現，面積為4.25平方毫米。在輸出為3.5瓦的時候整體效率的峰值可以達到90.5%，輕載效率可達到76%。

For many electrical devices in our day life, especially portable devices become indispensable tools for people. With the rapid growth in the consumer electronics, rechargeable mobile battery bank has proved to be the most fit for portable devices, and electrical isolation power converter is necessary charging system. Therefore, high efficiency and fast charging are important issues if the charger carefully considers parasitic resistance from battery to charger system and non-ideal effect of photo-coupler in electrical isolation power converter. More seriously, excess charging voltage will cause damage or reduce the life time of the devices. Thus, accurate battery charging voltage is very important. Especially in low output power applications, the flyback converter is one of best candidates. Because architecture and control circuit are simple, it uses fewer external components. Without any opto-couplers, the controller needs an auxiliary winding to get the battery information in battery voltage detection circuit. This thesis developed both constant current loop and constant voltage loop in the charger system Fast charge and constant voltage in high accurate battery voltage detection circuit can be achieved without any feedback paths. Test chip was fabricated by 0.5μm 700V UHV process with an active silicon area of 4.25 mm2. Peak efficiency is 90.5% at the load of 3.5W and 76% efficiency at light loads.