Increasing energy efficiency by developing a new adaptive mppt algorithm based on a two-legged interleaved DC-DC buck converter

Today, the importance of renewable energy sources is increasing day by day because of the expectation of depletion of fossil fuels in the near future, its negative impact on human health and the environment, the dependence on fossil fuels pose a political and economic risk to countries, etc.. It is expected that in the next decade, electrical energy will replace fossil fuels as an energy source in automobile technology, increasing this importance even more. Solar energy comes to the fore in renewable energy types in considering the factors as energy continuity, high and low power availability, ease of installation, operation and maintenance, low cost, environmental impact, etc. Photovoltaic (PV) systems in solar energy appear as grid-connected (on-grid) and off-grid solar power plant (SPP) applications. The need for methods that reduce losses and increase efficiency in power electronics products as inverters, charge regulators continues apart from the panels that make up the system components in SPPs. Today, with the widespread use of commercial and self-consumption-based PV systems, the issue of energy efficiency has gained importance and R&D studies have intensified. Even an efficiency increase of 0,1% is considered important in terms of the feasibility of investments and high efficiency is an important preference criterion in the selection of commercial products. Solar panels are the most important part of SPP investments. Currently, the most widely used PV panels in practice are silicon-based and their efficiency is 20% on average. This value shows that there is more distance to be covered in solar energy. New technologies and researches are needed for the development of high efficiency PV panels. Increasing the efficiency of PV panels means less space, less mechanical parts, less cable usage and higher energy efficiency. Today, mostly silicon-based (monocrystalline, polycrystalline) and chemically alloyed thin-film PV panels are produced. Commonly used thin film panels are amorphous-silicon (a-Si), cadmium-tellurry (Cd-Te) and copper indium gallium selenide (CIS/CIGS). Silicon-based panel types are monocrystalline and polycrystalline. While the module efficiency of thin film PV panels is 7-11%, the module efficiency of silicon panels is 15-23%. Since the efficiency of silicon panels is better than thin film panels and the investment cost is more economical, silicon panels are mainly used in the market. Solar panels produce variable power depending on the radiation falling on them and and temperature. Panel current and voltage values increase or decrease depending on the solar radiation in direct proportion. In a constant radiation environment, the panel voltage changes sharply and the panel current changes very little inversely proportional to the temperature, so the power value obtained from the panel decreases. In order to make maximum use of the instantaneous power, which can change with the effect of radiation and temperature, it is necessary to monitor the maximum power point and transfer the maximum power to the load at this point. The maximum power point tracking technique is called Maximum Power Point Tracking-MPPT. In solar energy applications, the most important criteria are to transfer the energy obtained from photovoltaic (PV) panels to the load with the least loss and to ensure high energy efficiency. DC-DC converter circuits consisting of traditional buck, boost or buck-boost combinations are used as hardware for MPPT control. However, in traditional circuits; the use of high-capacity capacitors, the use of high-current switching elements are required, and there are various disadvantages such as the high ripple rate of the circuit output voltage and current, the physical pressure on the output capacitors that affect the component life, the noise formation on the load side, the shortening effect of this on the life of the batteries, and the energy losses. In order to eliminate these negative effects to a large extent, it was decided to use a two-legged interleaved buck converter circuit and it was based on providing the highest energy efficiency with the least energy loss in terms of hardware. In order to ensure high system efficiency, MPPT (Maximum Power Point Tracking) algorithms with traditional, modified and/or adaptive traditional, artificial intelligence and biological structured methods are used as the inverter driving technique. In addition to traditional methods for MPPT control, fuzzy logic and artificial neural network from artificial intelligence applications, particle swarm optimization from biological structure methods, ant colony and particle swarm optimization etc. algorithms have been developed. In these MPPT algorithms used, one or both of the input parameters, which basically consist of the current and voltage data of the PV panel, are used, but other data input parameters are also used, and the maximum power calculation and monitoring are performed. However, the disadvantage of these MPPT algorithms; compared to traditional MPPT methods, medium and high level hardware is needed and hardware costs are high, system dependent and various input parameters such as PV panel power, number, string number, string open circuit voltage are needed, and therefore it is difficult to use for users with low technical level. The most important disadvantage of non-adaptive conventional MPPT algorithms is that they create high energy losses from the moment of sudden air change to the moment when the maximum power point (MPP) is reached. A new adaptive MPPT algorithm that captures maximum power point (MPP) fast in the rapid solar radiation change has been developed by adding the ambient illuminance data (lx, lux) as a third input parameter to the non-adaptive traditional Perturb&Observe-P&O MPPT Algorithm in order to minimize that energy loss and the new algorithm is named "Accelerated P&O MPPT Algorithm". Another most important feature of the new algorithm is that it is a completely system-independent algorithm that does not need external data inputs such as PV panel power, number, voltage, PV array number. In addition, expensive circuit components with high speed and memory, such as computers, are not needed for the new algorithm. In the Accelerated P&O MPPT Algorithm, the MPP capture speed is high at high radiation variation and low at low radiation variation. Therefore, in high radiation variation, the new algorithm achieves MPP with less number of cycles, thus providing higher energy efficiency. The higher the difference between the duty value of the PWM signal at the moment of sudden air change and the duty value of the target PWM signal that it will reach the MPP is, the higher the energy gain value is. The system energy efficiencies provided by adaptive and traditional P&O MPPT algorithms in different solar radiation simulations, conventional and two-legged interleaved buck converter circuit bases have been analyzed in detail in Matlab/Simulink and experimental setup. In the results of working; with the "Accelerated P&O MPPT Algorithm", it has been determined that the maximum power point is reached faster in sudden air changes and high energy efficiency is achieved by minimizing power loss.