PV system fuzzy logic MPPT method and PI control as a charge controller


This paper puts forward to Fuzzy Logic MPPT (Maximum Power Point Tracking) method applied photovoltaic panel sourced boost converter, under variable temperature (25–60 °C) and irradiance (700–1000 W/m2) after that the PI control was applied buck converter to behave as a charge controller. The voltage and current of PV panels are nonlinear and they depend on environmental conditions such as temperature and irradiance. Variable environmental conditions cause to change voltage, current and also cause to change maximum available power of PV panels. To increase efficiency and decrease payback period of the system, it needs to operate PV panels at maximum power point (MPP). Under any environment conditions there is unique MPP. To operate PV panels at that point (MPP) there are many MPPT method in literature, FLC MPPT method was preferred in this study because, its rapid response to changing environmental conditions and not affecting by change of circuit parameters. The accuracy of FLC MPPT method used in this system to find MPP changes, from 94.8% to 99.4%. To charge a battery there are two traditional methods which are constant current (CC), and constant voltage (CV) methods. For fast charging with low loss constant current and voltage source is a need. One of the methods providing constant is PI control which used in this study. PI control is not only well developed and a simple technique but also it provides satisfactory results. The goal of this study is operating PV panel at maximum power point under variable environment conditions to increase efficiency and reduce cost and also provide appropriate current and voltage for charging battery to charge quickly, reduce losses and also increase life cycle of battery. This system was established and analyzed in MATLAB/Simulink.


  1. PV systems
  2. MPPT methods
  3. DC-DC converters
  4. PI control
  5. Charge controllers



Fig. 1. PV system MPPT algorithm and PI control charge circuit.


 Fig. 2. The Power of PV panel.

Fig. 3. The Voltage of PV panel and load of boost converter.

Fig. 4. The duty cycle regulated by FLC MPPT.

Fig. 5. The load voltage of buck converter.

Fig. 6. The load current of buck converter

Fig. 7. The power regulated by PI control.


The proposed system has been studied under four different conditions. Responses of system under varying radiation and temperature was observed. The accuracy of the MPPT algorithm to find MPP varied from 94.8% to 99.4%. The load current and voltage of buck converter remained constant level until end time of system (2.39 A, 15.03 V respectively shown in Table 3). The efficiency we wanted to get from the system has been reached to a great extent. In some cases the efficiency of buck converter can be low but the desired point to be reached in this system is getting the maximum yield from the PV panel to reduce cost and to charge the battery with constant current and appropriate voltage to reduce losses, fast charge and increase life cycle of battery. If there is a meaningful support to the material, the system will be realized in real life.


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