LQR Controlled, High Step-Up Interleaved DC-DC Converter with Voltage-Lift Capacitor and Voltage Multiplier Cell

Abstract

In recent years, the demand for high stepup DC-DC converters has increased due to their wide use in renewable energy systems, electric vehicles, and other low-voltage applications. However, conventional boost converters face certain limitations when high voltage gain is required, mainly due to increased switching losses and reduced efficiency at higher duty cycles. To address these issues, this work presents an LQR controlled high step-up interleaved DC-DC converter incorporating a voltage-lift capacitor and a voltage multiplier cell. The interleaved structure helps in reducing input current ripple and improves overall efficiency, while the voltage-lift and multiplier stages contribute to achieving higher voltage gain without pushing the duty cycle to extreme levels. The proposed system is designed to convert a low input voltage of $\mathbf{1 2 V}$ DC to an output of around $\mathbf{7 4}-\mathbf{7 5 V}$ DC. A Linear Quadratic Regulator (LQR) is used as the control strategy to ensure stable operation and better dynamic response. The controller adjusts the system in such a way that output voltage variations are minimized even under small disturbances. Simulation of the system is carried out to observe current and voltage characteristics, and the results show a steady output with manageable ripple. The hardware prototype is also developed and tested, where the output voltage is verified using a digital multimeter. he fact that the output voltage is sustained even when the supply is disconnected for some time suggests that energy is effectively stored because of the capacitors used in the circuit. In general, the voltage gain of the converter has been enhanced with low ripple content. Because of these features, it can be considered suitable for applications like DC microgrids and renewable energy-based systems.