Gravity battery charging model and equivalent circuit design

This thesis focuses on modeling the charging process in gravity-based energy storage systems and the design of the equivalent electrical circuit for this process. In these systems, electrical energy is used to lift a heavy mass up and when needed, the potential energy is converted back into electrical energy by lowering this mass. First, the mechanical structure of the system was analyzed together with the effects of the motor, moving mass, gravitational force and friction and the equations of motion were obtained. These equations were solved analytically (with the Laplace transform method) and numerically (with the fourth-order Runge-Kutta method) and the dynamic behavior of the system during the charging phase (upward movement of the mass) was investigated. Then, the equivalent electrical circuit of the system was designed. In this circuit, the mechanical components (mass, friction, motor, etc.) were modeled with electrical elements (resistance, inductance, voltage source). This designed equivalent circuit was simulated and analyzed using software such as MATLAB / Simulink and Python. In addition, two different simulation models were created, one with linear friction (model a) and the other with nonlinear friction (model b), and the results obtained from these models were compared with the analytical and numerical solution results. The results confirm the accuracy and validity of the developed model. This study aims to contribute to the design and performance improvement of gravity-based energy storage systems that can be used especially in renewable energy applications.