Architecture and control of PV modules with submodule integrated converters

Abstract

This paper describes a PV module architecture with submodule integrated converters (subMICs) that improve efficiency of energy capture in the presence of partial shading or other mismatch conditions. Replacing standard bypass diodes, the subMICs are bidirectional dc-dc converters capable of injecting or subtracting currents to balance the module substring voltages. When no mismatches are present, the subMICs are simply shut down, presenting no insertion losses. A simple distributed control approach is described that allows autonomous subMIC control without the need for a central controller or any communication among the subMICs. It is shown that this control approach is close to optimal. Besides, this distributed control approach allows to isolate the secondary port of subMICs from the module output. The isolated-port architecture has additional advantages in its implementation and integration within arrays of PV modules. Simulation and experimental results demonstrating effectiveness of the proposed architectures and the control approach are shown for a typical PV module with 3 substrings.