偵測電感飽和與反飽和調控之策略

Detection of Inductor Saturation with Anti-Saturation Control Strategy Applied

許育勝(Yu-Sheng Hsu)

指導教授 ： 胡國英

國立臺北科技大學/電資學院/電機工程系所/碩士(2010年)

摘要

本論文提出偵測電感飽和與反飽和調控之控制策略，將其應用於12V±20%轉5V的直流-直流降壓型轉換器(Buck Converter)。由於電感需要處於飽和狀態，所以電路週邊的元件必須超額設計(Over Design)，於負載在150%時，偵測電感飽和現象。理論上，電感飽和時，電流斜率會變的陡峭，可藉由偵測電流斜率來判斷是否有飽和，但是受限於偵測斜率的速度和雜訊干擾的影響，無法偵測到電流的變化，所以改用偵測電感電流的振幅以作為飽和的判斷依據，並同時使用差動放大器和電流感測放大器來監控電感電流漣波和輸出電流。
而反飽和調控的原理是，藉由類比數位轉換器(Analog-to-Digital Converter, ADC)將電感電流漣波和輸出電流轉換成數位訊號，經由串列匯流排介面(Serial Peripheral Interface, SPI)送入微控制器(MCU)，以判斷電感是否飽和。當飽和發生時，微控制器透過串列匯流排介面來控制數位類比轉換器(Digital-to-Analog Converter, DAC)，經由電壓控制電流源(Voltage-Controlled Current Source, VCCS)電路，輸出一個電流源信號到電感補償繞組端以調控飽和現象。除此之外，由於負載變動或輸入電壓變動都會造成飽和點的偏移，因此，必須將這些變動的因素都加以考量。最後，採用Freescale公司所生產的微控制器晶片(MC9S08AW60)以做為整個系統的控制核心來實作驗證所提架構之有效性。

關鍵字

偵測電感飽和 ； 反飽和調控 ； 降壓型轉換器 ； 電壓控制電流源 ； 數位類比轉換器 ； MCU

並列摘要

In this thesis, detection of inductor saturation, together with anti-saturation control, is presented, which is applied to a DC-DC buck converter with the input voltage of 12V±20% and the rated output voltage of 5V. Since the inductor maybe work in a saturation situation, the components relevant to this circuit must be overdesigned. At a load of 150%, the inductor saturation will be detected. In theory, as the inductor is saturated, the corresponding current slope in the inductor will be increased, and such a phenomenon can be used to judge whether the inductor is saturated or not. However, as this phenomenon occurs, variations in current are not easy to obtain because of limitations of slope detection and effects of noise interruption. Therefore, the amplitude detection is used herein to judge whether the inductor is saturated or not. At the same time, the inductor current ripple and the output current are monitored via the differential amplifier and the current sensing amplifier.
The basic operating principles of the proposed anti-saturation control strategy are to be described as follows. First, the digital signals created from the inductor current ripple and output current are obtained via the analog-to-digital converters (ADCs). After this, these digital signals are sent to the microcontroller unit (MCU) so as to judge whether the inductor is saturated or not. When the inductor saturation occurs, the MCU creates a digital compensation signal, and such a signal is sent to the ADC after the series peripheral interface (SPI) to activate the voltage-controlled current source (VCCS) circuit. By this way, the inductance saturation can be reduced as minimal as possible. In addition, the saturation point will be offset due to variations in output current and input voltage, and this must be taken into account. Finally, the MCU integrated circuit (IC), named MC9S08AW60, is used as a control kernel to demonstrate the effectiveness of the proposed scheme.

並列關鍵字

Detection of Inductor Saturation ； Anti-Saturation Control ； Buck Converter ； Voltage-Controlled Current Source ； Digital-to-Analog Converter ； MCU

參考文獻

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