This paper is about the performance and analysis of ZETA converter using FUZZY LOGIC CONTROLLER . Due to the increasing demand of electricity and limited conventional energy resources, solar photovoltaic energy becomes a favourable alternative as it is pollution free, freely available and has less maintenance cost. The ZETA converter is used as DC-DC converter which is designed, simulated and analyzed in solar energy system. The complete model of solar energy system is simulated in MATLAB 8.1 using simulink. This model has solar arrays, ZETA converter, inverter and single phase asynchronous motor which is used as a load in this system. The DC-DC ZETA converter used in solar pv system is same as BUCK-BOOST converter. The ZETA converter provides a constant dc bus voltage and its duty cycle is controlled by the FUZZY LOGIC CONTROLLER (FLC). A FLC is also used to generate the PWM signal for the ZETA converter.
Keywords – Solar panel, ZETA converter, MOSFET , Inverter, PWM generator, Fuzzy logic Controller, Load.
The non-renewable energy sources are depleting rapidly and the demand for power is increasing day by day. To overcome this problem, generation of electric power from renewable source of energy should be made effective and efficient. The energy source which the society can depend on is renewable energy since it is clean, pollution free, and endless. Photovoltaic (PV) system is one of power generations that utilize renewable energy. To reduce consumption of conventional energy, then the PV system must be connected to grid, either directly or through back-up battery bank. However, the PV system has low efficiency because of the power generated from PV systems depends on the irradiation and temperature variation. For the control of the PV systems, there are various types of DC-DC converters such as, Buck converter, Boost converter and Buck-Boost converter. The Buck conerter’s output is less than the input voltage whereas the boost converter output is greater than the input voltage. The polarity of buck-boost converter is inversed of input signal.
A solar panel (also solar module, photovoltaic module or photovoltaic panel ) is a packaged, connected assembly of solar cells. The solar panel can be used as the component of a larger photovoltaic system to generate and supply electricity in commercial and residential applications. The photovoltaic system typically includes and array of solar panel, an inverter, and sometimes a battery and interconnection wiring. The cells must be connected electrically to one another and to the rest of the system. Cells must also be protected from mechanical damage and moisture.
The power metal oxide semiconductor field effect transistor (MOSFET) evolved from the MOS integrated circuit technology. The new device promised extremely low input power level and no inherent limitation to the switching speed .The operating principle a MOSFET is a voltage controlled device. As the name suggests, movement of majority carriers in a MOSFET is controlled by the voltage applied on the control electrode (gate) which is insulated by a thin metal oxide layer from the bulk semiconductor body. The semiconductor material in the region between the main current carrying terminals called the Drain (D) and the Source (S).
A diode is a two terminal electronic component which conducts electric current in only one direction. The most common function of a diode is to allow an electric current to pass in one direction (called the diode’s forward direction) while blocking current in the opposite direction (reverse direction) the unidirectional behavior is called rectification, and is used to convert alternating current to direct current. The most diodes are made of silicon, but other semiconductors such as germanium are sometimes used.
A ZETA Converter is DC-DC Converter to increase or decrease the DC voltage from one level to another DC-DC Converter is used as a switch mode converter.PWM switching in MOSFET is controlled using PID Controller to regulate voltage at the load. ZETA Converter operates at continuous current conduction mode only. Here inductor current of DC-DC Converter and reference current from solar panel are compared to generate PWM switching signals. Line frequency ripple in the DC voltage is neglected.
Fuzzy Logic Controller
The term fuzzy refers to things which are not clear or are vague. In the real world many times we encounter a situation when we cant determine whether the state is true or false, their fuzzy logic provides a very valuable flexibility for reasoning. In this way, we can consider the inaccuracies and uncertainties of any situation. In Boolean system truth value, 1.0 represents absolute truth value and 0.0 represents absolute false value. But in the fuzzy system, there is no logic for absolute truth and absolute false value. But in fuzzy Logic, there is intermediate value too presents which is partially true and partially false.
There are four parts in the architecture.
It contains the set of rules and the IF-THEN conditions provided by the experts to govern the decision making system, on the basis of linguistic information. Most of these developments reduce the number of fuzzy rules.
It is used to convert inputs i.e. crisp numbers into fuzzy sets. Crisp inputs are basically the exact inputs measured by sensors and passed into the control system for processing such as temperature, pressure, rpm.
It is used to convert the fuzzy sets obtained by inference engine into a crisp value. There are several defuzzification method available and the best suited one is used with a specific expert system to minimize the error.
It determines the matching degree of the current fuzzy input with respect to each rule and decides which rules are to be fired according to the input field. Next , the fired rules are combined to form the control actions.
Thus the result of a fuzzy logic controller is used to control the output voltage of a photovoltaic system with a DC-DC converter, type single ended primary inductor ZETA converter. The ZETA converter provides a constant dc bus voltage and its duty cycle is controlled by the fuzzy logic controller which is needed to improve PV panels utilization efficiency. Efficiency can be increased by using fuzzy logic controller.
- Neha Adhikari, Bhim Singh, “Analysis and Design of isolated Solar PV Energy Generating System,” IEEE Ind. Appl. Soc. Annual Meeting, pp. 1-6, Oct. 2011.
- C. S. Chin, P. Neelakantan, H. P. Yoong, K. T. K. Teo, “Fuzzy Logic Based MPPT for Photovoltaic Modules Influenced by Solar Irradiation and Cell Temperature”, 2011 UK Sim 13th International Conference on Modelling and Simulation.
- N. Adhikari, B. Singh, A.L Vyas, “Design and Performance of Low Power Solar-PV Energy Generating System with Zeta Converter,”IEEE Conf. on Industrial and Information System, pp. 1-6, Aug.2012.
- A. F. Murtaza, H. A. Sher, M. Chiaberge, D. Boero, M. D. Giuseppe, and K. E. Addoweesh, “A novel hybrid mppt technique for solar pv applications using perturb amp; observe and fractional open circuit voltage techniques,” in 15th International Symposium MECHATRONIKA, 2012, Dec. 2012, pp.
- Hichem lab,Abd Elaziz Chaghi and Patrice WIra.: A New Learning and Fuzzy Strategy for Active Power Filtering, International Journal of Elec Eng & Informatics 2016, Vol.8, 518-527
- Bhim Singh, Shailendra Dwivedi, Utkarsh Sharma and Chinmay Jain.: Solar PV Array Fed Direct Torque Controlled Induction Motor Drive for Water Pumping, Annual IEEE India Conference (INDICON), 17-20 December 2015.
- Aswin A.K, Asokan O.V.: Advanced Single Sensor Zeta Converter fed Induction Motor Drive System. International Journal of Innovative Research in Science, Engineering and Technology, 2016, Vol.5, pp.224-231.
- Sivakumar.A, Muthu Selvan N.B.: Reduction of Source Current Harmonics in R and RL Load with Active Filter at Source End, Asian Journal of Research in Social Science & Humanities 2016, Vol.6, pp.298-310.
- Dipen.A, Mistry, et al.: Power Quality Improvement using PI and Fuzzy Logic Controller Based Shunt Active Filter. International Journal of Elec, Comp, Energetic, Electron & Commu Eng. 2014, Vol.8, pp.661-667