Improved self‐oscillating control of a quadratic buck converter for constant voltage applications

Abstract

AbstractA great number of switching power supplies are used to provide a variable voltage for resistive‐inductive loads. However, some applications in industry, require a regulated current with a constant voltage such as battery charging systems, LED drivers, and laboratory equipment for power converters connected to PV cells. Additionally, some constant voltage systems are intrinsically unstable, and therefore, they cannot be used without a closed‐loop compensatory circuit. Hence, this article describes a novel smooth starter system behaving as a current source for constant voltage applications. The proposed technology is implemented by a quadratic buck converter, and then, a self‐oscillating control technique is applied for performing the output current regulation of the converter, which is capable of aiding to improve the system performance, stabilize the overall system, protect the converter from transient current oscillations, and provide an acceptable control performance. In addition to practical aspects, soft starter methods and limitation of the constant voltage power converter are mentioned and described in this article. The designed structure has not only the advantages of smooth response and simplicity to construct but also performs a nearly zero steady‐state error regulation. The power stage, the control scheme, and the modulator are explained in detail and validated by experiments.