Abstract: A novel ultrahigh step-up dc–dc converter, which utilizes the features of modularity, multilevel and electrical isolation is proposed in this paper. To achieve an ultrahigh step-up ratio a novel dc–dc converter topology while maintaining a high conversion efficiency. It adopts a three degree of freedom approach in the circuit design. New control strategies including the two-section output voltage control and cell idle control are also developed to improve the converter performance. To a wide range of high voltage and high power distributed generation and dc power transmission the step-up conversion ratio can reach 1:14 with a peak efficiency of 94% and the proposed techniques can be applied. By using the simulation results we can analyse the proposed method. To improve the performance, a novel control strategy using Fuzzy Logic Controller (FLC) is proposed it will eliminates the drawback of using fixed gain in conventional PI controller.
Keywords: Boost converter, control strategy, dc–dc power conversion, degrees of freedom (DoF), high step-up converter, and modularization.