具備連續性內阻偵測機制與自動能量傳遞控制之切換式快充充電器研究設計

Abstract

近十年來由於科技的進步，可攜式電子產品如：智慧型手機、PDA、數位相機以及平板電腦…等，儼然成為市場上的主流性產品。在諸如此類的可攜式產品應用中，電池的效能主宰了此類商品的銷售量。然而，為了配合可攜式產品，可充電電池大量的被使用，如何有效管理電池能量以延長其使用時間以及如何針對電池安全並且快速的充電成為了重要的議題。 對於電池能量的管理本篇論文提出了自動能量傳遞(AEDC)的控制方法來達成，此控制方法主要分為四個階段：單純充電階段、電源直接供電階段、電池供電階段以及電源供電與充電階段，藉由此控制方法，充電器可操作在不同的能量供給模式，使可攜式產品可以在不同電池狀態下正常的操作使用。 此外，鋰電池皆採用定電流-定電壓(CC-CV)充電方法。充電階段如下：當充電器對一顆放電至一個較低電壓時，會先以小電流對電池充電使電池遠離物理性的傷害；當電池電壓上升至一個較高的位準時，充電器將會轉換至一個較大電流的儲能階段；當電池充至一個預先的額定電壓位準時，便進入了定電壓模式，確定電池真正達到預定目標。然而，因為電池本身以及充電器模組(包含PCB板)上的寄生電阻，將會造成定電流與定電壓階段轉換時的不穩定，同時會減短定電流充電的時數進而延長整體電池充電的時間，為了改善此兩項缺點，本篇論文提出一個包含連續性內阻偵測機制的充電器。不僅令充電器能平順的切換操作模式，同時加速了充電週期。本論文使用了Vanguard 0.25μm製程，而實驗結果亦顯示了出AEDC和CBIRD的成效。

The switching-based charger system with the automatic energy deliver control (AEDC) technique is proposed in this thesis. To satisfy power requirements during different power charging conditions, the AEDC includes four states, pure charge, direct supply, plug off, and charge and supply (CAS). The AEDC manages the charging current according to the system’s load and supply condition to achieve high efficiency charging. For the purpose to charge the battery by the AEDC, the switching-based charger is proposed to fulfill the charging process. Moreover, in order to achieve fast charging, the continuously built-in resistance detection (CBIRD) is also implemented in the charger system. Due to the unexpected variation of the built-in resistance (BIR) in Li-Ion battery and charging current, the CBIRD monitors charging current and BIR to dynamically adjust the compensated value for getting a suitable transition battery voltage. Proper and dynamic adjusting transition battery voltage, the transition from the constant-current (CC) mode to the constant-voltage (CV) mode can be extended. Through large charging current in the CC mode, the charging time can be effectively reduced. The frequency response is carefully analyzed and the compensation network is added to ensure the stability among all operations. The proposed AEDC in the switching-based charger system was fabricated in 0.25μm CMOS technology and occupies 0.32 mm2 silicon area. Owing to the CBIRD, the charger system can save up to 30% of charging time. With the AEDC technique, it also can arrange adequate power paths and regulate charging current. The AEDC technique can achieve 82% of power efficiency at a rated 2A charging current.