使用精確合成漣波磁滯控制機制的降壓轉換器

A Buck Converter Using Accurate Synthetic Ripple Hysteresis Control Scheme

莊智鈞(Chih-Chun Chuang)

指導教授 ： 周懷樸

國立清華大學/原子科學院/工程與系統科學系/碩士(2011年)

摘要

本論文提出一個使用磁滯電流控制模式的直流對直流降壓型轉換器。合成漣波被提出用來偵測電感電壓並產生一個適合遲滯控制使用的三角波。本論文提出之感測電路具有低通濾波器特性和局部回饋可以降低切換雜訊的影響。因為固定的電感電壓使合成漣波具有固定的上升及下降斜率，確保在不同的負載條件下能保持固定的切換頻率。誤差放大器被用來補償直流導通電阻所產生的誤差項，全電路結果指出合成漣波精確度在不同的負載條件及±10%的直流導通電阻誤差範圍皆能保有99%以上的精確度；電壓操作範圍設計在2.7V~4.4V；輸出電壓回復時間為24微秒；最大轉換效率為89%；低雜訊設計適用於以鋰離子做為電池電源供應的可攜式產品。

關鍵字

降壓轉換器 ； 遲滯控制 ； 切換雜訊抑制 ； 電流模式控制

並列摘要

This thesis presents a dc-dc buck converter using hysteresis current control mode. A synthetic ripple voltage is proposed to sense the voltage across the inductor and to generate a saw tooth waveform for hysteresis band control. The proposed sensing circuit acts like a low-pass filter and has a local feedback loop to reduce the switching noise. The switching frequency in different load conditions is fixed because the fixed inductor voltage provide constant rising and falling slope of synthetic ripple. The error of the dc term of DCR multiply iL is compensated by an error amplifier to prevent saturation. Full chip simulation results of different load conditions and plus-minus a 10% error of DCR indicate that the synthetic ripple has accuracy about 99%. The range of the operation voltage of the proposed design is from 2.7 to 4.4V; the output voltage recovery time is 24μs under load current conditions between 100mA and 300mA; the maximum conversion efficiency is 89%; the low noise design is particularly suitable for portable device with a Li-ion battery power supply.

並列關鍵字

Buck Converter ； Hysteresis Control ； Switching Noise Rejection ； Current Mode Control

參考文獻

1.“Power Management Guide 2011,” Texas Instruments Incorporated, 2011.

2. P. Hazucha, T. Karnik, B.A. Bloechel, and C. Parsons, “Area-Efficient Linear Regulator with Ultra-Fast Load Regulation,” IEEE Journal of Solid-State Circuits, vol. 40, no. 4, pp. 930-940, April 2005.

3. P. Favrat, P. Deval, and M.J. Declercq, “A High-efficiency CMOS Voltage Doubler”, IEEE J. Solid-State Circuit, vol. 33, no. 3, pp. 410-416, Mar. 1998.

5. R. Redl and G. Reizik, “Switched Noise Filter for the Buck Converter Using the Output Ripple as the PWM Ramp,” in Proc. IEEE APEC’05, 2005, pp. 918-924.

6. J. H. Park and B. H. Cho, ”Small Signal Modeling of Hysteretic Current Mode Control Using the PWM Switch Model,” IEEE COMPEL, pp. 225-230, July 2006.