An Improved Single-Switch Quadratic Boost Converter With Lower Voltage Stress and Ultrahigh Voltage Gain With Switched Capacitor–Inductor Network for Solar Photovoltaic Systems

Abstract

This article proposes an improved single-switch quadratic boost converter (AISSQBC) for solar photovoltaic applications, offering an ultrahigh voltage gain with reduced voltage stress. The proposed converter is derived from the conventional quadratic boost converter (QBC), which is also a biquadratic boost converter (BQBC). It incorporates an additional capacitor and two diodes, achieving an ultrahigh voltage gain at the lower duty ratio (nearly 24 at the duty cycle of 50%) using a switched capacitor–inductor network. The proposed converter is able to produce six times higher voltage gain than QBC and 1.5 times higher voltage gain than BQBC. The proposed converter has 3.0% improvement in efficiency at a full load of 200 W, with the same input voltage of 24 V as compared with the conventional QBC. A single switch with a series-connected capacitor reduces the normalized voltage stress on the switch, enabling the use of lower rated, cost-effective switches. Presented comprehensive steady-state analysis under CCM, DCM, and BCM conditions, as well as small-signal AC modeling, power loss calculation, and cost evaluation for a 200-W power capacity. The voltage gain is derived for both ideal and nonideal conditions. The dynamic response under voltage-control mode is validated using a proportional-integral controller with step load variations. The maximum efficiency of the proposed converter is reported 96% for 180 W and 93.02% for 200 W of full load. A 200-W, 50-kHz prototype is developed and experimentally tested in the laboratory.