適應性PFC/PWM整合控制IC之設計與模擬

Abstract

兩級式PFC AC/DC轉換器包含一個前級升壓型AC/DC轉換器與後級降壓型DC/DC轉換器，主要應用於需要高品質電源與快速動態響應的個人電腦與伺服器電源系統。本文針對兩級式PFC AC/DC轉換器提出一種以類比電路方式實現、具有負載變化適應控制能力的新型整合式PFC/PWM控制器IC電路架構，可應用於前級採用單相無橋式升壓轉換器，後級採用隔離式半橋DC/DC轉換器。所提出的整合式PFC/PWM控制架構，包含一個採用單週控制器來控制PWM波之PFC控制器的設計與分析，以減少線電壓之變動及穩定線電流。單週控制之架構可以實現對電感電壓直接且快速的控制，以達到電感電流之線性控制，且相較於使用乘法器控制，單週控制可以用較為簡單的類比電路實現。然而，實現電路所需的重置積分器有最小輸入補偏電流及感測電壓雜訊的問題，在實際應用上必須謹慎設計。在適應性PWM控制器設計中，提出一個使用感測平均電感電流之被動式適應性控制器的直流對直流轉換器之設計，藉由感測開關電流與使用一個電壓控制電阻，可以用來對直流對直流轉換器做適應性控制。非線性載波控制可以根據輸入電壓做調整，以減少輸入端的干擾。模擬結果顯示提出的適應性控制架構在負載電流劇烈變動下，能達到強健性電壓穩定、快速且動態調整的暫態響應。

A two-stage PFC AC/DC converter includes the pre-stage which is a boost AC/DC converter and the post-stage which is a buck DC/DC converter. Its primary application is used in the power supplies of PCs and servers which need high quality power and fast dynamic response. For two-stage PFC AC/DC converter, this thesis proposes a IC structure of combo PFC/PWM controller which is realized by analog circuits and has the ability of current adaptive control. It can be used in the pre-stage used a single phase bridgeless boost converter and the post-stage used an isolated half-bridge DC/DC converter. The proposed structure of combo PFC/PWM controller includes the design and analysis of a PFC controller which uses a one-cycle controller for PWM control to decouple the line voltage variation in regulation of a proportional line current. The OCC scheme can realize a direct voltage-second control of the boost inductance to achieve linear control of the inductance current control with input voltage decoupling and can be implemented by simple analog circuit compared with the conventional multiplier based approach. However, the implementation of the rest integrator with minimum offset current and sensing voltage noises requires a careful design in practical applications. In the adaptive PWM controller design, the design of a DC/DC converter with on-chip passive adaptive controller with the sensed average inductor current is presented. The sensed switched current and a voltage-controlled floating resistor can be used for the adaptive control of a DC/DC converter. The nonlinear carrier control can adjust carrier according to input voltage to reduce the input disturbance. Simulation results show the proposed adaptive control scheme can achieve a fast dynamic power on transient response as well as a robust voltage regulation against large loading current variation.