DC/DC Conversion Systems Consisting of Multiple Converter Modules: Stability, Control, and Experimental Verifications

This paper investigates DC/DC conversion systems constructed from connecting multiple converter modules in series and/or parallel at both the input and output sides. Control strategies aiming at achieving proper sharing of the voltage and/or current at the input or output sides are studied in detail. The relationship between sharing of input voltages/currents and that of output voltages/currents is studied. In particular, the inherent stability of control operations applied at the input side and the output side is analyzed. Based on the analysis, a general control strategy for series-parallel systems, which decouples the output voltage control loop and the sharing control loop, is proposed. Furthermore, three modularization architectures are proposed for input-series-output-parallel (ISOP), input-parallel-output-series (IPOS), and input-series-output-series (ISOS) connected systems. These architectures enjoy full advantages of modularization and no external controller is needed to coordinate the sharing control for the individual modules. Experimental prototypes are built and tested to validate the general control strategy and the proposed modularization architectures.