A novel Controller for Grid-interfacing Solar Arrays through Five-level Diode-clamped Converters

Abstract

This paper presents an approach to control a grid-connected, five-level, diode-clamped converter (DCC) with solar arrays directly connected to each capacitor of the dc-link, On one hand, the control of such converters is challenging as the voltage imbalance among the capacitor may affect the power controller. On the other hand, when dealing with solar arrays, the dc voltage is a key point considering that the efficiency of the array highly depends on it. This article presents a solution where both aims are fulfilled: the desired capacitor voltages, set by the maximum power point tracking (MPPT) algorithm, are reached at the same time that these values are taken into account in the power controller. This is an unusual approach for five-level DCC that avoids the use of DC-DC stages, therefore it makes the system more affordable and avoids extra losses. Thanks to the capacitor voltage controller, proper power extraction from each solar array is achieved. The theoretical presentation of this approach is shown along with simulation results that validates its effectiveness.