A Variable Phase-Shift Control Scheme for Extended-Duty-Ratio Boost Converter With Automatic Current Sharing in High Step-up High Current Application

Abstract

Recently, an extended-duty-ratio (EDR) boost converter has attracted great attention of many scholars. However, the EDR boost converter with fix phase shifts is difficult to achieve phase-to-phase current sharing over a wide range of duty ratio. In this article, a variable phase-shift control strategy is proposed to further expand its current sharing range for the EDR boost converter. Under the proposed control strategy, the EDR boost converter can operate in wide range of duty ratio varying from 0.5 to 1 with automatic current sharing between phases since two adjacent phase shifts can be adjusted to guarantee that the energy stored in certain inductor is only transferred to the next phase capacitor step by step for generating high step-up output voltage. Next, the steady-state analysis of the EDR boost converter under the proposed control strategy is discussed thoroughly, and the switch voltage stresses and current stresses are also analyzed. Finally, a 300 W, 3.3 V to 38.9 V, four-phase EDR boost hardware prototype has been built. The effectiveness of the proposed control strategy is verified by the experimental results of the built prototype.