MATHEMATICAL MODEL AND CONVERSION CHARACTERISTICS OF A 4-SWITCH NON-INVERTING BUCK-BOOST CONVERTER FOR COMPUTER EQUIPMENT

Abstract

In the article, the mathematical model of the 4-switch non-inverting buck-boost converter operation is obtained, and the four switching algorithms are considered. Particular attention is paid to the switching algorithms that provide both an increase and a decrease in the input voltage, since the 4-switch non-inverting buck-boost converters is usually used in applications that can be powered by a power supply that has a voltage that can be either lower or higher than the required voltage on the main power rail.

All possible states of the switches in the circuit are considered, it is shown that out of 16 possible states of the switches, only 3 states of the switches can be practically used for voltage conversion. The algorithms are considered, in which switching cycles can consist of two and three stages. It is shown that there are three two-stage switching algorithms that provide only a decrease, only an increase, and both a decrease and an increase in the output voltage. It is shown that there is the only one three-stage switching algorithms that provide both a decrease and an increase in the output voltage and can provide a more accurate adjustment of the output voltage by changing the duration of the second conversion stage. For each switching algorithm, the formulas are obtained that relate the input and output voltages of the converter to the duration of the conversion stages.

The resulting mathematical model and relationships can be used to obtain the regulation characteristics of the converter. The 4-switch non-inverting buck-boost converters can be used in telecommunications, computer equipment, smart systems and IoT powered by energy harvesting systems, solar and wind generators, and widely used lead-acid and lithium-ion batteries. The article may be useful to electronics developers, specialists involved in switching energy conversion, scientists and students.