Hybrid Buck-Boost Feedforward and Reduced Average Inductor Current Techniques in Fast Line Transient and High-Efficiency Buck-Boost Converter

Abstract

This paper presents a buck-boost converter with high efficiency and small output ripple to extend the battery life of portable devices. Besides, the hybrid buck-boost feedforward (HBBFF) technique is integrated in this converter to achieve fast line response. The new control topology minimizes the switching and conduction losses at the same time even when four switches are used. Therefore, over a wide input voltage range, the proposed buck-boost converter with minimum switching loss like the buck or boost converter can reduce the conduction loss through the use of the reduced average inductor current (RAIC) technique. Moreover, the HBBFF technique minimizes the voltage variation at the output of error amplifier. Consequently, a fast line transient response can be achieved with small dropout voltage at the output. Especially, the converter can offer good line and load regulations to ensure a regulated output voltage without being affected by the decreasing battery voltage. Experimental results show that the output voltage is regulated over a wide battery lifetime, and the output ripple is minimized during mode transition. The peak efficiency is 97% and the transient dropout voltage can be improved substantially.