A Bidirectional Buck-Boost Voltage Converter for near-Earth Satellites

The article is dedicated to the development and experimental study of a perspective highly efficient current converter designed for use in systems for powering spacecraft in a near-Earth orbit. The design consists of a four-switch uninsulated buck–boost converter that carries out critically important functions of controlling the charge and discharge of lithium-ion batteries and stabilizing bus voltage. The key characteristics of the development are the use of modern powerful wide-bandgap GaN transistors, which allow switching losses to be minimized and the total effectiveness of the system to be increased; operation under elevated bus voltage, which makes it possible to reduce the weight and size characteristics; and the use of a new control scheme. To guarantee smoothness of operation and maximum speed of operation of the system, a mixed mode of control is realized that allows sharp changes of current and electromagnetic interference upon switching between modes of voltage reduction and increase to be avoided, which is especially important in conditions of stringent requirements for electromagnetic compatibility in space technology. The average-current method of control provides high precision of the control parameters and significantly increases the resistance to interference of the system, as well as allowing high-accuracy sensors with a high level of inertia to be used in the power section of the converter, which increases the reliability of the construction. On the basis of the results of comprehensive testing, the experimental prototype of the converter showed an efficiency comparable with the calculated values of efficiency on the level of 96% and a high specific power of 2.5 kW/kg at a device mass of about 1 kg. A compact form factor corresponding to the strict demands of spacecraft construction, as well as a high reliability of operation in different modes, confirms the technological readiness of the development for immediate integration into systems for supplying power to spacecraft of different purposes.