Analysis of grid interfaced power converter for uninterrupted hydrogen production using PEM electrolyzer

Abstract

Phase-shift full bridge (PSFB) converter is widely used for high-power applications in battery charging, and data centers. However, it also has a strong application for the electrolyzer system to produce hydrogen. But, in this condition, the supply power factor can be distorted due to the nonlinearity of the electrolyzer-interfaced power circuitry. Further, the electrolyzer operates relatively at a lower voltage and higher ripple-free current for its prolonged operation. Therefore, the PSFB converter can be integrated with the interleaved buck (IB) converter that has an almost steady current at its output terminal. In this study, a three-stage power converter is proposed to connect the electrolyzer with the single-phase utility grid. In the first stage, the Vienna rectifier is utilized to connect the single-phase utility grid to the electrolyzer via the cascaded PSFB-interleaved buck converter. The utility grid operates the electrolyzer and exhibits the unity power factor operation, therefore, better power quality can be ensured. Moreover, the modeling and control of the proposed configuration of the cascaded PSFB-IB power converter have been performed. As there are many active switches in the proposed converter circuit, they can be subjected to open-circuit/short-circuit faults. The faulty operation of the power converter can stop the hydrogen production leading to catastrophic failure of the complete system. Therefore, an analysis of the fault-tolerant operation of the studied cascaded converter configuration has also been performed. After the open circuit/short circuit fault occurs in any switch of the PSFB converter, the converter still operates in the symmetric half-bridge configuration, to guarantee the hydrogen as well as oxygen production. For two electrolyzer units of each rating 0.72 kW, the hydrogen and oxygen production rates are maintained at ≈ 354 L/h and ≈177 L/h, respectively under the no-fault as well as in faulty condition. The simulation of the proposed circuit is performed using the OPAL-RT OP4610 XG real-time simulator