IEEE TRANSACTIONS ON SUSTAINABLE ENERGY, VOL. 8,NO. 1, JANUARY 2017 279 Design and Hardware Implementation of FL-MPPT Control of PV Systems Based on GA and Small-Signal Analysis Ahmed A. S. Mohamed, Alberto Berzoy, Student Member, IEEE, and Osama A. Mohammed, Fellow, IEEE Abstract—This paper presents a cost effective control algorithm for standalone batteryless photovoltaic (PV) systems. The control is driven by a fuzzy-based maximum power point tracker which has the capabilities to maintain high-energy conversion efficiency under different weather and load conditions. General design con- siderations are presented based on the linearization of the dy- namic model of the entire system which consists of PV panel, Cuk converter, and motor load. For our particular fuzzy-MPPT con- troller, these design considerations are combined with an artificial intelligent technique to achieve the optimum control design. Fur- thermore, the developed control algorithm has voltage regulation capability to protect the load from overvoltage during light load conditions and a fast digital overload protection. The transient and steady-state performance of the entire system was modeled by a nonlinear state-space representation. The proposed control is simulated in MATLAB and experimentally tested under the fast variation of climatic conditions for verification purposes A very good agreement has been shown between theoretical, simulations, and experimental results Index Terms—Design, dynamic modeling, fuzzy logic control (FLC), genetic algorithms (GA), maximum power point tracker (MPPT), pumping system, small signal analysis, state-space model. I. INTRODUCTION P HOTOVOLTAIC (PV) utilizations are getting more atten- tion due to the increased progress in power electronics and semiconductor technologies. The PV power systems are broadly classified into utility-interactive and stand-alone sys- tems. Stand-alone PV systems are ideal for remote rural areas where other power sources are either impractical or unavailable [1]. Among the different applications of off-grid PV systems, is the PV water pumping system (PVPS). This system is widely used in domestic and livestock water supplies and small-scale irrigation systems, especially those employed for water and en- ergy conservation such as low head drip irrigation systems [2]. Typically, PVPS consists of PV array, drive system and stor- age element which can be a battery bank or/and a water tank. Manuscript received December 7, 2015; revised April 11, 2016 and June 2, 2016; accepted July 26, 2016. Date of publication August 4, 2016; date of current version December 14, 2016. This work was supported by the Office of Naval Research. The work of A. A. S. Mohamed was supported in part by the Cultural Affairs and Missions Sector, Ministry of Higher Education, Egypt. Paper no. TSTE-00949-2015. The authors are with the Energy System Research Laboratory, Depart- ment of Electrical and Computer Engineering, Florida International Univer- sity, Miami, FL 33174 USA (e-mail: amoha070@fiu.edu; aberz001@fiu.edu; mohammed@fiu.edu). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TSTE.2016.2598240 The drive system is composed of a motor-pump set and a power conditioning component to extract the maximum power from the PV panel and drive the motor. The most commonly utilized motor in stand-alone batteryless PVPS is the permanent mag- net (PM) DC motor, since it can perform well even under low irradiance level and it is simple in control [3]. In PM DC motor-based PVPS, one or more DC–DC convert- ers are required between the PV panel and the motor for control and drive purposes. Four different system topologies can be found in literature: (1) direct coupled: the PV panel is directly connected to the motor-pump set [4], (2) using MPPT converter: a DC–DC converter is introduced between the PV panel and the motor to perform MPPT [5], (3) using driver converter: in this case the DC–DC converter is used for motor control [6], and (4) using MPPT and driver converter: two DC–DC converters are used for MPPT and motor drive [7]. In the direct coupled and using driver PVPS, the operating point can be anywhere on the PV panel characteristic and it is seldom to be at MPP. This mismatch causes system over-sizing and reduction of energy utilization efficiency [8]. When the system has maximum power point tracker (MPPT) converter, the control algorithm extracts the MP from the PV array even if there is no load demand. This will cause motor overvoltage during some normal operations such as no or light load operation. Typically, this problem can be mitigated either by using a storage battery with a charger to regulate the motor voltage or by adding a second converter for motor control (4th topology identified above). In both cases, the entire system efficiency decreases with an increase in complexity and cost. The median solution that enables the system to work with MPPT converter safely and without adding extra converter or battery storage is not presented yet in literature, and this is one of the contributions in this paper. Several MPPT algorithms were presented, experimentally tested and compared in the literature [9], [10]. The most widely used in PVP applications is the perturb and observe (P&O) algorithm. Due to the simplicity, ease of implementation, and it does not require previous knowledge for the system charac- teristics [6]. In this technique, the perturbation action can be applied directly [6], [11] or indirectly [12]. The direct pertur- bation algorithm is preferred as it does not require PI controller and provides higher energy utilization efficiency and less noise and oscillations [4]. The main drawbacks of P&O algorithm in- clude its failure under fast variation in climatic conditions, the steady-state swinging around the MPP, and it does not consider the motor rating [13]. 1949-3029 © 2016 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications standards/publications/rights/index.html for more information.