Automatic Input Voltage Sharing of ISOP Converter Using Duty Ratio Feedforward Control Without Interconnection and Input Voltage Monitor

The input-series–output-parallel (ISOP) dc/dc converter is ideal for applications requiring high input voltage and large output current. Ensuring proper input voltage sharing across the different submodules on the series side is crucial for practical implementation in ISOP systems. This article proposes a novel duty ratio feedforward control scheme that automatically balances the input voltage amongst the modules in the ISOP conversion system. In this method, each module operates independently without the need for interconnections to facilitate information exchange, and input voltage monitoring is unnecessary. Instead, only output voltage and filter inductor current need to be sampled, eliminating the requirement for high voltage isolation in conditioning circuits. Therefore, a fully modular design is achievable in the ISOP converter, improving metrics such as complexity, cost and reliability. This article presents a detailed discussion of the principle, small-signal model-based stability analysis and control system design. Experimental results are presented to validate the effectiveness of the proposed control strategy.