Optimized Interleaved Ultra-High Gain DC-DC Power Converter With Low Ripple Input Current and Voltage Stress for Fuel Cell Systems

Abstract

This paper presents an ultra-high voltage gain power converter designed to address the challenges posed by the inherently low output voltage and high output current of fuel cell systems. The proposed converter features a two-stage integrated design, comprising a two-phase interleaved boost converter and a high-gain switched capacitor coupled inductor boost converter. The interleaved design divides the current equally between two phase legs, minimising conduction losses and enhancing efficiency. Additionally, this technique significantly reduces input current ripple, leading to lower fuel cell degradation and improved performance. The switched capacitors and coupled inductor in the high gain boost converter enhance the voltage gain while minimising voltage stress on the active switches and diodes. This approach enables the utilisation of low voltage rated switches and diodes, reducing costs and minimising conduction and switching losses. Additionally, the converter features a common input and output ground to mitigate electromagnetic interference and uses low-side switches to simplify gate circuitry and reduce costs. To validate the proposed design, a 500W prototype is developed and tested in a laboratory environment. The prototype achieves a peak efficiency of 95.52%, a peak-to-peak input current ripple of less than 1.5%, and a voltage gain of 27.8 at a 50% duty cycle.

Keywords

• DC-DC boost converter
• coupled inductor
• switched capacitor
• ultra-high voltage gain
• fuel cell
• low input ripple current