Simulating the Dynamic Characteristics of Spacecraft Solar Panels

Abstract

The paper discusses the development of a mathematical model of the solar battery as an object of control being an integral part of the spacecraft power supply system. The paper analyses the internal structure of a photocell and its equivalent circuit taking into account the photo element distributed capacity and overall inductance of the internal connections. Complete nonlinear mathematical model of the solar battery in its analytical form has been construed considering the p-n junction inverse current and photocells impedance. The ratios obtained allow the immediate visualization of voltage changes at the solar battery output depending on the loading current, light stream intensity and photocells temperature as a result of the solution of the system of implicit equations. A total complex impedance of photovoltaic cells is entered into the simulation model to reflect the solar battery dynamic properties. Basing on the actual technical parameters of photocells and the solar battery the volt-ampere characteristics have been drawn and the analysis of frequency characteristics of photo-electric converters has been made confirming the adequacy to the proposed model. Recommendations have been received concerning the choice of frequency of the pulse width converters interfaced to solar batteries in the spacecrafts onboard power supply systems, together with the equivalent circuits convenient for the imitating simulation of these systems.