Amélioration de la durée de vie du condensateur sur le bus CC de l'onduleur pour l'application photovoltaïque

Abstract

The solar panel has a lifetime of about 25 years, but the inverter lifetime is on average only 5 years. This short life span of the inverter is due to its component that is both the most important and most vulnerable: it is the capacitor placed on the DC bus. This paper presents a topology which contributes to improve the lifetime of the capacitor placed on the DC bus of the inverter. The proposed typology uses an additional circuit of power decoupling which is mounted in parallel with the capacitor on the DC bus of the inverter. This power decoupling circuit behaves like a buck-boost circuit and thus eases the task of the DC bus capacitor in the power decoupling. With this topology, it is possible to use a long-life film capacitor on the DC bus of the inverter. The proposed circuit allows using, for 3kW photovoltaic power, only a 15μF capacitor on the DC bus, which greatly reduces losses because this kind of capacitor has a low equivalent series resistance compared to the high capacity chemical capacitor. Regarding the control of this power decoupling circuit, it uses the ripple current produced by the inverter as a reference current to provide the necessary power for the decoupling. This paper investigates the operating principle of the proposed circuit as well as the novelty of the control of the additional power decoupling circuit. All MATLAB simulations of circuit provide results that show the viability of the proposed topology. This improvement in the lifetime of the DC link capacitor and consequently that of the inverter and the entire system is achieved in a minimal cost through the proposed topology.

Date	25 Sept 2015
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Ambrish Chandra (Supervisor)