General Derivation Law of Nonisolated High-Step-Up Interleaved Converters With Built-In Transformer

First, the limitations of the conventional interleaved boost converters in high-step-up and high-output-voltage applications are addressed in this paper. Then, a general derivation law of the nonisolated converters from their isolated counterparts is proposed and studied to give a universal solution for high-performance topology deduction. By employing the direct energy transfer concept, a family of nonisolated high-step-up interleaved boost converters is originated to make the turns ratio of a built-in transformer as another design freedom for the voltage gain extension. The derived converters have the advantages of large voltage conversion ratio, low power switch voltage stress, small input current ripple, and zero-voltage-switching soft-switching performance. The steady-state operation of the derived converter is analyzed, and the circuit performance is summarized to explore its advantages in the high-step-up, high-output-voltage, and large-current conversion systems. Finally, a 1-kW prototype with 40-V input and 380-V output voltages is implemented and tested to show the effectiveness of the derived converters. One of the main contributions of this paper is that a clear picture is made on the universal derivation law to generate high-step-up and high-performance dc/dc converters.