• Energy Research
• Problems of the Regional Energetics close

This study aims at determination the maximum power point parameters for the constant current source with nonlinear parasitic elements. The aim has been achieved by analyzing the differential resistance and equivalent parameters of a circuit with a constant current source. As a result, the buck-boost converter circuit is considered with the equivalent current source, which is formed with a photovoltaic module. The problem of the maximum photovoltaic module of energy harvesting is related to the research of its nonlinearity, which determines operating points at the current-voltage curves under different irradiances and temperatures. Thus, the differential resistance of photovoltaic module is examined to determine the parameters of the maximum power point mode. The main result of the research is the model, which differs from the known models by the description of the dependence between the buck-boost converter duty cycle and input equivalent current source parameters in the maximum power point mode. The results of modelling are supported by experimental research of the laboratory layout. The presented circuit ensures the operating point close to the maximum power point of the solar panel equivalent current source. The duty cycle of the buck-boost converter is determined directly from the equivalent current source model with the parameters estimated analytically from the irradiance and temperature of the solar cells. The presented approach allows developing the maximum power point tracking algorithms based on the estimation of the equivalent current source parameters that provide improvement of the energy harvesting efficiency.

 Two-coordinate platforms equipped with orientation systems are 40-45% more effective than stationary installations. However, there are other factors affecting the efficiency of solar installations. In particular, the shading on the panels’ surfaces when panels, located in rows, are casting shadows on each other. This negatively affects the efficiency of photovoltaic installations. Previous experience in the design of photovoltaic systems shows that neither stationary platforms nor two-coordinate installations completely eliminate energy losses due to shadow formation. The only way to mitigate this negative impact is to increase the distance between the panels. At the same time, and the density ratio (the ratio of the panel area to the area of the land) does not exceed 0.2. Our goal is to develop kinematic schemes and software control systems for three coordinate platforms that can avoid shadow formation on panels placed in constrained spaces. The result of our work is a numerical method that solves the optimization problem for controlling the motion of a set of platforms and a rational kinematic scheme for three coordinate platforms. This problem is especially relevant for solar photovoltaic systems located on space stations. In space, the changes in temperature between shaded and shadow-free sections of panels is enormous, due to temperature stress, the panels get destroyed and require expensive repairs. Three-coordinate tracking can reduce the surface occupied by solar panels by about 3 times compared to the currently used solutions and increased module placement densities from 0.2 to 0.6.