Design and analysis of modified single switch AC-DC bridgeless Cuk converter

Abstract

The Cuk converter is widely used in power electronics due to its ability to provide both step-up and step-down voltage conversion with low ripple characteristics. However, conventional designs suffer from increased component count, higher losses, and significant voltage stress on switching devices. In this paper, an improved single-switch bridgeless AC-DC Ćuk converter is proposed for power factor correction (PFC) and loss reduction. The proposed topology employs a two-stage integrated structure with two low-value coupling capacitors (1 µF each). These capacitors effectively reduce voltage stress across the main switch and enhance switching performance. The operating principles of the proposed converter are analyzed under different switching conditions, highlighting its improved dynamic behavior and reduced component stress. Simulations using MATLAB/Simulink show that the proposed design achieves high efficiency, very low output voltage ripple (less than 1%), and a near-unity power factor of 0.9988. This performance, particularly the fast dynamic response, was achieved using a specially designed proportional-integral (PI) controller for output voltage regulation. The converter demonstrates fast dynamic response with a settling time of less than 0.23 s and a maximum overshoot of 7.5% under sudden load and input variations. Compared to conventional two-switch topologies, the proposed design significantly reduces switch voltage stress while maintaining a simpler structure, leading to lower cost and compact size. These results confirm that the proposed converter is a promising solution for high power quality applications.