A CMOS controller for submodule integrated converters in photovoltaic systems

Substring level differential power processing (DPP) in photovoltaic (PV) power systems is used to mitigate power loss due to mismatches in PV strings. This paper presents the design and implementation of a controller chip in a 0.18 μm CMOS process for a submodule integrated converter (subMIC) in the isolated-port DPP architecture. The presented controller design combines linear and non-linear PWM control for the subMIC MOSFETs while requiring only a few external components. Other features such as power limiting and system disable are included to improve converter and system efficiency. The controller opens the possibilities to minimize the converter footprint, reduce power consumption, and potentially reduce the cost. Experimental results are presented for a 72-cell PV module with three subMICs using the controller chip, demonstrating greater than 99% module-level efficiency at up to 50% mismatch.