A Decentralized Nonlinear Control Scheme for Modular Power Sharing in DC-DC Converters

Abstract

Modular power conversion systems can have a variety of potential advantages, including high thermal contact area, reliability, repairability, wide operating range, the use of devices with reduced voltage and/or current ratings and better Figure of merit, and overall small parasitics to enable high-frequency operation even at high power. In order to ensure power sharing among modules, most approaches adopt a centralized or distributed approach which require communication with a central controller or among modules, which increases the opportunity for global system failure and impedes modularity. In this paper, we present a truly decentralized control approach (one with no communication between modules) for power sharing in modular converters. Each module's controller implements a nonlinear 'selfish' control algorithm, wherein the increment or decrement in its power at any time instant is a function of its present contribution to the overall output power. That is, modules currently processing high power respond strongly when less power is required, but weakly when more power is required (and vice versa for modules currently processing low power). The successful operation of the proposed control strategy is first verified using simulation results which show its fast convergence and stable operation in IPOP, ISOP, IPOS and ISOS configurations without changing any physical or control parameters. Further validation is presented through the successful operation of a hardware prototype when arranged in different modular configurations, as well as its stable operation over load transients and in the event of module failure. © 2021 IEEE.