Comprehensive sharing control strategy for input-series output-parallel connected modular DC-DC converters

The systems consisting of multiple DC-DC converters with input-series output-parallel (ISOP) connection are widely used in high-power applications. In the ISOP connection, the total input voltage and output current should be divided equally between the converters. However, in order to achieve this purpose, a proper control scheme should be used. This study proposes two control schemes: (i) output current feedback (OCF) and (ii) input voltage feedback (IVF). Based on the power balance, in the IVF scheme, the total output current, and in the OCF scheme, the total input voltage are divided automatically between the converters, and there is no need to use an extra control loop. The IVF and the OCF control schemes consist of two control loops: a common output voltage regulator (OVR) loop and individual input voltage sharing loops in the IVF scheme or individual output current sharing loops in the OCF scheme. The proposed control scheme can effectively improve the stability and dynamic characteristics of system. Finally, both the results of the simulation and laboratory prototype of an ISOP system consisting two forward converters have verified the performance of the IVF and OCF control schemes.