改良虛擬電感電流控制之四開關降壓/升壓轉換器建模與分析

Modeling and Analysis of Four-Switch Buck/Boost Converter with Improved Peak Virtual Inductor Current Control

吳家成(Jia-Cheng Wu)

指導教授 ： 陳景然

國立臺灣大學/電機資訊學院/電機工程學系/碩士(2022年)

https://doi.org/10.6342/NTU202202756

摘要

當提到物聯網(IoT)和智慧裝置時，它們的運算能力通常由微控制器(MCU)來驅動，由於微控制器經常會在工作模式和待機模式間切換，因此其電源轉換器需要快速的負載暫態響應。本論文分析的電路拓撲結構是一個四開關降壓/升壓轉換器，可以在降壓或升壓模式下運行，用於物聯網應用。控制方案為立錡科技公司提出的改良式峰值虛擬電感電流模式(Improved PVICM)控制方式，該控制方案通過輸出電壓反饋耦合產生虛擬電感電流，以改善暫態響應和負脈衝(Undershoot)。本論文旨在建立改良式峰值虛擬電感電流模式控制之降壓/升壓轉換器的小訊號模型，建模方法基於修正型平均模型，為R.B.Ridley為峰值電流模式(PCM)控制建模所使用的方法。改良式峰值虛擬電感電流模式控制之四開關降壓/升壓轉換器已用離散元件實現，建模中得出的轉移函數，包括控制到輸出的轉移函數和迴路增益，與Simplis模擬和實驗結果相匹配，這證實了該模型可以預測實際電路的小信號特性。

關鍵字

峰值虛擬電感電流模式控制 ； 四開關降壓/升壓型轉換器 ； 小訊號模型 ； 微控制器 ； 負載暫態響應

並列摘要

When it comes to the Internet of Things (IoT) and smart devices, their computational ability is usually driven by microcontrollers or MCUs. Since the microcontrollers often switch between work mode and sleep mode, their power converter requires a fast load transient response. The circuit topology analyzed in this thesis is a four-switch buck/boost converter that can operate in either buck or boost mode for IoT applications. The control scheme is the Improved Peak Virtual Inductor Current Mode (Improved PVICM) control proposed by Richtek Technology, which generates a virtual inductor current with the output voltage feedback coupling to improve the transient response and the undershoot. The thesis aims to develop a small-signal model of the Buck/Boost converter with Improved Peak Virtual Inductor Current Mode control. The small-signal modeling approach is based on the modified average modeling method, which is used to model the Peak Current Mode (PCM) control by R. B. Ridley [1]. A four-switch buck/boost converter with Improved PVICM control was implemented with discrete components. The derived transfer functions, including the control-to-output transfer function and loop gain, match with Simplis simulations and the experiment. This confirms that the model can predict the small-signal characteristics of the actual circuit.

並列關鍵字

Peak Virtual Inductor Current Mode Control ； Four-switch Buck/Boost Converter ； Small-Signal Model ； Microcontroller ； Load Transient Response

參考文獻

[1] R. B. Ridley, "A new, continuous-time model for current-mode control (power converters)," in IEEE Transactions on Power Electronics, vol. 6, no. 2, pp. 271-280, April 1991.

[2] N. Kondrath and M. K. Kazimierczuk, “Control-to-output transfer function of DC-DC PWM buck converter in CCM,” IET Proc. on Power Electron., vol. 5, no. 5, pp. 582-590, May 2012.

[3] G. C. Verghese, C. A. Bruzos and K. N. Mahabir, "Averaged and sampled-data models for current mode control: a re-examination," 20th Annual IEEE Power Electronics Specialists Conference, 1989, pp. 484-491 vol.1.

[4] A. R. Brown and R. D. Middlebrook, "Sampled-data modeling of switching regulators," 1981 IEEE Power Electronics Specialists Conference, 1981, pp. 349-369.

[5] V. Vorperian, "Simplified analysis of PWM converters using model of PWM switch. Continuous conduction mode," in IEEE Transactions on Aerospace and Electronic Systems, vol. 26, no. 3, pp. 490-496, May 1990