An Improved Quadratic Boost Converter with Lower Input Current Ripple and Reduced Power Components for Fuel Cell Systems

This paper presents an improved quadratic boost converter designed to achieve lower input current ripple and reduce the number of power components, specifically for fuel cell systems. The proposed converter is derived from a cascaded circuit that combines a conventional boost converter with a quasi Z-source boost converter. This configuration allows for higher voltage gain, a reduced number of power components, and the elimination of current spikes. In the proposed design, the rear-end boost inductor is connected to the input side of the front-end circuit. Additionally, two switches with the same duty cycle, but a phase difference of 180 degrees, are used. This interleaved structure significantly reduces input current ripple and doubles the equivalent switching frequency, thereby reducing the required input capacitance. Compared to a conventional quadratic boost converter, the proposed design decreases the voltage stress on power components and increases the voltage gain by a factor of (4 D - D 2 -1) through the introduction of a quasi-Z-source network. The working principle, steady-state characteristics, small signal model, and parameter designs of the proposed converter are discussed in detail. The theoretical analysis of the proposed converter is validated through comprehensive experimentation with a 300 W/50 kHz prototype. The maximum and minimum measured efficiencies are approximately 95.9% and 95.4%, respectively, at an output voltage of 400 V under full load conditions, with input voltages ranging from 40 V to 80 V.