## 1 Introduction  
It is very apparent that the interest in photovoltaic power generation has strongly increased in recent years. Numerous studies and works have been done on this thematic to improve their production [1]. A non-linear I = f(V) curve characterizes the photovoltaic generators (PVG) with different points of maximum power (see Figures 1 and 2), [1, 2].  
PV cells temperature (T) and solar radiation (G) influence this characteristic [3, 4, 5], which change the electrical power produced by such PVG. To remedy the latter problem, specific control techniques were proposed and developed from 1968 until now in such a manner that these PVG produce their maximum electrical power [1, 2, 3, 4, 5, 6, 7].  
This type of control is called Maximum Power Point Tracking (MPPT) where the main function provided by the designed control laws is to ensure to extract the maximum power point (MPP) all the time. This is generally assured by DC/DC converters [8, 9, 10, 11, 12, 13] (see Figure 1).  
Many MPPT strategies have been proposed in the literature to extract the maximum power for the PV systems [1; 2; 7] ranging from classical techniques like perturb and observe (P&O) and Incremental Conductance (IC) [3] to artificial and intelligent techniques [14].  
Generally, the DC/DC converters element sizing is made for a fixed and known power supply. The DC/DC power output and the DC/DC power efficiency are high only for a good sizing of these elements [8; 9; 10; 11; 12; 13; 14; 15; 16; 17; 18]. The main element hardly affecting these two parameters is the power loss due to core saturation of the inductor. The sizing of inductor value in a DC/DC converter becomes difficult for a variable power supply, as in the case of a PV system under different levels of radiation and temperature change [2; 8].  
Most of the proposed modifications and improvements are applicable for a converter with fixed nominal values. In practice another problem appears on the power efficiency of the converter in PV applications under varying conditions and this issue is not well addressed in the literature. To the best of our knowledge, the efficiency improvement of the DC/DC converter for PV applications in practice is strongly related to the structure and the size of the inductor of the converter. In [12] a micro-scale topology was applied for a MPPT DC/DC converter without using an inductor but it is applicable only for very low power systems.  
In this paper, the main purpose is to improve the efficiency of a boost converter for PV applications and to reduce core losses in the inductor. In particular, a new DC/DC Boost converter topology using a variable inductor is proposed and tested in a PV application in order to maximize the power efficiency and minimize power losses.  
In [16] a solution is proposed to improve the power efficiency for a buck converter with a suitable inductor using a coupled inductor. In the proposed topology, only simulation results were presented without carrying out experimental validation. The purpose of this paper is to experimentally validate the same idea and extend it for a boost converter in PV systems.  
The paper is structured as follows. In Section 2 we recall the PVG characteristics and how to connect it to a load through a DC/DC converter and the operation of a boost converter. The proposed topology and analysis of the coupled inductor is also  
Figure 1: Adaptation block as a power interface between a photovoltaic generator(PVG) and load, to transfer the maximum power.  
Figure 2: (**a**) Direct electrical connection between a PV generator and a load; (**b**) different operating points for two levels of radiation with different loads.  
presented. Simulation and experimental result of the proposed boost converter for PV applications compared to a conventional topology are detailed. Section 4 is devoted to analysis, discussions and comments of the proposed solution. Finally, Section 5 reports concluding remarks.