應用於初次側調整控制器之高效率及低成本 膝點電壓追蹤調整技術

Abstract

在現今社會，可攜式產品已經成為人人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。因此，如何以最理想且安全的方式將能量傳遞到電池，對電池進行最快速也最有效率的充電是一個重要的課題。基於通用串行總線充電變成一種趨勢，從交流市電直接對電子產品充電是現在大部分可攜式產品的充電方式。初次側調整控制器是一種高效率而且低成本的充電器，同時也是一種能容忍市電的高輸入電壓隔離式充電器。為了確保充電器在定電流充電模式與定電壓充電模式皆能保持穩定且平穩切換，本切換式充電器將定電流充電迴路與定電壓充電迴路並聯，且同時達到兩者的穩定性。但是初次側調整控制器與一般控制器最大的分別就是它並沒有直接的迴授路徑來獲取輸出資訊，因此如何準確從輔助繞組中去取得膝點電壓進而去控制整個系統變成一個重要問題。 本篇論文完成一具有膝點電壓偵測電路，同時針對偵測的時間做自我的調整來避免發生偵測錯誤。不同於以往的方式，這次提出的偵測電路不僅能準確的偵測膝點電壓，並不需要外部原件來做修正，同時也使所有的控制路徑在定電流充電模式與定電壓充電模式皆能保持穩定且平穩切換。為了使效率更進一步提升，波谷切換以及動態頻率切換被應用在定電壓充電模式。

Nowadays portable devices have been considered a necessity by a lot of people and have become an essential part of everyday life. With the rapid growth in the consumer electronics, rechargeable mobile battery bank has proved to be the most compatible and satisfactory solution for portable devices. Therefore, it will be an important task for us to create a fast and efficient battery charging method with safe delivery of energy to the battery. Since universal serial bus (USB) charging method is a common trend now, most of the portable devices are charged via alternating current (AC) supply combine with USB. Primary-side regulator (PSR) is a high efficiency and low cost solution for power applications. It is a high-input voltage isolated charger compatible with the AC supply. To stabilize and to smoothly transit between the constant voltage and the constant current modes, the constant voltage and constant current loops are connected in parallel in the proposed PSR charger. However, the prominent difference between the PSR and conventional regulators is that the PSR does not have direct feedback loop to obtain the output information. Hence, it is a major challenge to precisely detect knee voltage from the auxiliary winding and thus to accurately control the entire system. This thesis introduces the PSR with self-calibration knee voltage detection (KVD) technique, which it can perform self-calibration based on the detection period for error checking and correction. Moreover, the new detection method not only can precisely get the knee voltage without any external components, but also can have all control paths stabilized. The transition smoothly changes between the constant voltage and the constant current modes. Valley switching with a dynamic frequency switching is applied in the constant voltage mode in order to enhance its efficiency and performance.