Voltage-offset resistive control for dc-dc converters in photovoltaic applications

Abstract

Photovoltaic (PV) systems must be able to maintain stable operation near the maximum power point (MPP) regardless of environmental conditions. Voltage-offset resistive control (VRC) exhibits inherently low sensitivity to irradiance changes and supports effective inner-loop control to maintain MPP operation. Small- and large-signal analysis show that VRC employed with a boost converter is stable for PV applications. VRC is tested on an experimental setup using a digital controller, PV boost converter, and dc-link load. Irradiance and control parameter step responses are observed through simulated and experimental results. VRC exhibits stable and fast transient response. Traditional and VRC maximum power point tracking (MPPT) methods that utilize sample-and-hold operation are compared through simulation. The fractional open-circuit voltage VRC and MPP-current-based VRC methods are identified as effective, simple control solutions for PV systems that seek to maintain high efficiency under irradiance transients.