應用數位控制方法於多相DC/DC轉換器暫態響應及輕載效率之改善

Abstract

這篇論文提出ㄧ數位控制方法來改善直流轉直流轉換器的輸出暫態響應以及輕載效率。所提出的數位控制方法是藉由增益排程控制策略以及極零點抵消方法來設計補償器的控制參數; 進而有效的改善轉換器的輸出暫態響應。增益排程控制策略是ㄧ個實際且實用的適應性控制方法;欲實現此方法，一些適當的資訊如受控體及輔助量測變數是需要的。這個方法主要優點為當輸出負載的變動時; 此控制器能有效且快速的反應來應付輸出的變化。 除此之外，ㄧ個相數切換功能也實現於數位控制器;所提出的相數切換功能是基於ㄧ個數值儲存切換原則下設計;並且將半導體溫度變化參數儲存於表格; 藉由查表法及相數結構選擇器來比較總電源消耗損失及預設的相數結構來決定是否執行切相動作。 所提出的數位控制方法不僅容易實現於直流轉直流轉換器，並且也可以應用於其他技術架構下的轉換器。 如所提出的控制方法，輸出暫態響不僅能有效的改善,且輸出電容數量也可以被減少。再者，所設計的相數切換功能不僅改善輕載效率亦能使轉換器的總消耗功率減至最低。提出的數位控制方法是實現在ㄧ個交錯式兩相直流轉直流轉換器;規格是定於輸入電壓為12 V，輸出電壓為1.2 V以及輸出負載電流為40 A。模擬和實驗結果驗證所提出的方法確實能有效的改善暫態響應和輕載效率。

In this dissertation, a digital control scheme is proposed to improve the transient response and light load efficiency of multiphase DC/DC converters. The proposed control scheme is based upon gain scheduling scheme which uses pole-zero cancellation method to adaptively auto-tune parameters of the compensator to efficiently improve the output transient response. The gain scheduling is a practical and useful adaptive control method. It requires some knowledge about the plant and some auxiliary measured variables. A great advantage of this method is that the controller adapts quickly to changing conditions. Moreover, a phase-shedding function is also designed in this control scheme. More specifically, the phase shedding is realized by a numerically stored power switch thermal characteristics look-up tables and a phase configuration selector for comparing the power loss of the present phase configuration with that of the assumed various phase configurations to determine whether the phase shedding should be operated or not. The design can be easily adapted to different technologies or modification to fulfill a new set of specifications with fast time-to-market. Having the improved transient response, then the output capacitance can be significantly reduced by the proposed control scheme. Furthermore, the phase shedding function makes a significant improvement in light load efficiency with minimum in overall power loss of DC/DC converter. The proposed digital control scheme is implemented on an interleaving two-phase DC/DC synchronous buck converter with 12 V input, 1.2 V output, and 40 A load current. Simulation and experimental results are presented to demonstrate the effectiveness of the proposed scheme.