應用在全載範圍高效率直流對直流升壓轉換器的電流模式合成控制技術

Abstract

可攜式電子產品如手機、膝上型電腦和不同的多媒體設備使用電池作為主要能源。為了要延長電池壽命，攜帶式的裝置在待機時會進入睡眠模式，因此需要快速喚醒時間。所以快速的暫態響應和全載範圍維持高效率是常被要求的規格。 近年來，合成波調變機制常被用來增加系統的噪音餘度，使系統近乎一個無雜訊的漣波且系統的負載穩壓也可以藉由誤差放大器加入而提升。但是他導致系統包含了兩個極點而需要較複雜的補償方式。所以，本論文提出一個包含電流資訊的技術來簡化補償方式。 本論文提出一個運用在升壓轉換器的電流模式合成控制技術(current-mode synthetic control technique)可以加速升壓轉換器的暫態響應速度並在全載範圍維持高的轉換效率。這個技術類似於電流模式控制可以達到高的負載穩壓而且簡化電路不需要額外斜率補償機制。除此之外，由於類似遲滯電流模式控制，系統暫態響應可以提升。輕載時，由於與負載相關的頻率可達到高轉換效率。實驗結果顯示，載變化在0A到400mA時，輸出電壓的漣波可以維持在小於50mV且在負載在10mA時效率可以達到90%以上。

Portable electronics products such as cellular phones, laptops and diverse multimedia equipments use battery as the main power source. To extend battery life, portable devices stay in sleep mode with a very low static current but require a fast wake-up to reach the normal mode with a much higher operational current. Therefore, the suitable converter for the portable devices needs fast transient response from the standby mode to the normal mode, meanwhile, high efficiency is guaranteed over a wide range. Recently, the synthetic-ripple modulator (SRM) is proposed to improve the noise immunity through the synthetic current ripple, which is a nearly noise-free ripple signal. The accuracy also can be enhanced by the error amplifier. But it causes the system contains two poles and needs a complex compensation network. Therefore, this paper presents a current-mode synthetic control (CSC) technique to include the current information to simplify the compensation network. The proposed current-mode synthetic control (CSC) technique in the design of boost converters can improve the transient response time and maintain high conversion efficiency over a wide load range. The CSC technique has high accuracy similar to the current-mode control and doesn’t need the slope compensation for simplicity. Besides, the transient response is also improved due to the current-mode hysteresis control. The load-dependent switching frequency at light loads results in high power conversion efficiency. Experimental results show that the output voltage ripple can be kept smaller than 50mV over a wide load current range from 0mA to 400mA with power conversion efficiency higher than 90% at load current of 10mA.