A Novel Control Strategy For Input-Series Output-Paralleled Converter

Power Electronics System Integration has drawn more and more attention recently. The series/parallelled connection of standard modules becomes one subject of the vigorous research field. The input-series output-paralleled (ISOP) converter, which consists of multiple DC-DC modules connected in series at the input and in parallel at the output, is very suitable for high input voltage and high power applications. Input voltage sharing and output current sharing among the modules of the ISOP converter should be ensured.This paper firstly reveals the relationship between the input voltage sharing and the output current sharing of the modules in ISOP converter, and indicates that input voltage sharing among the standard modules could guarantee output current sharing automatically, traditional control strategy of output current sharing does not lead to input voltage sharing, which eventually fails to realize output current sharing. A novel input voltage sharing control strategy is proposed in this paper, it features that the input voltage sharing close-loop is independent to the output voltage close-loop, which makes it easier to optimize the compensation network of the input voltage closed-loop and output voltage closed-loop. Phase-shifted PWM DC-DC full-bridge (FB) converter is chosen as the standard module and the small-signal model of the ISOP converter is derived. Then the small-signal model of the FB-ISOP system with the proposed input voltage sharing control strategy is derived. It is verified by mathematical method that the system is decoupled from the multi-input/multi-output nonlinear system into multiple single-input/ single-output systems based on the proposed control strategy.A 3kW ISOP prototype consisting of two full-bridge DC-DC modules is built in lab. Simulation and Experimental results are given to verify the effectiveness of the propose control strategy.