Design and Realization of a Stacked Interleaved DC–DC Step‐Down Converter for PEM Water Electrolysis with Improved Current Control

Abstract

In order to face the intermittent nature of renewable energy sources (RES), hydrogen production and storage are considered an attractive solution. Nowadays, RES (e.g., wind, photovoltaic), and fossil fuels (e.g., coal, natural gas) are the various resources available on the planet Earth to produce hydrogen. Water electrolysis is one of the most interesting ways of producing hydrogen from RES; this electrochemical reaction is realized through an electrolyzer. Usually, DC–DC step‐down converters are used in the hydrogen production systems since electrolyzers must be supplied with a very low DC voltage to generate hydrogen from deionized water. Although these converters are widely used, they have several drawbacks from output current ripples and energy efficiency point of view. In order to meet the requirements for electrolyzer applications, a stacked interleaved DC–DC step‐down converter has been used to carry out this work. The objective of this paper is to develop a control law of the studied converter based on the current flowing through in one of the phases. This control allows reducing phase current overshoot and oscillations, and consequently conduction losses. Finally, by an experimental investigation, the performance of the current controller from overshoot, stability and oscillation point of view has been assessed.

Self-Discharge of a Proton Exchange Membrane Electrolyzer: Investigation for Modeling Purposes

“…Like supercapacitors, self-discharge in PEM electrolyzers is a major concern given that gas crossover through the membrane and leakage currents may decrease the lifespan of the electrolyzer and lead to the degradation of the membrane (e.g., pinholes), as reported for PEM fuel cells [ 32 , 34 ]. Besides, when the electrolyzer is reconnected to a power supply with low OCV (as a result of a self-discharge), high overshoot may occur, likely causing deterioration of the PEM electrolyzer [ 44 ]. In Figure 11 , a voltage overshoot (around 9 V, 12.5% higher than the rated voltage of the electrolyzer (i.e., 8 V)) is shown from when reconnecting the DC power supply (current step from 0 to 20 A).…”

Control and control-oriented modeling of PEM water electrolyzers: A review

“…Current density is a critical system parameter for PEM WE operation. The hydrogen production rate of the stack is directly proportional to the current density and other key system variables like hydrogen crossover rate, Faradaic efficiency, and even voltage degradation depend on it, making it a widely studied control knob in literature [111,112,113,114,115,93]. As mentioned, the hydrogen in oxygen volume fraction in the anode should not exceed the lower flammability limit of 4% volume-in-volume.…”

Control of a Three-Phase Current Source Rectifier for H2 Storage Applications in AC Microgrids

“…The SVM technique consists of controlling the reference vector I re f in the αβ frame in which the converter generates only six active current vectors, with each vector being a combination of different active switches. With six switches, and two states for each switch (open or closed), we have 2 6 = 64 theoretical possibilities; however, due to the operating conditions stated above, there are six active vectors and four zero vectors. The zero-state vector will be performed here by the opening of all the switches, thanks to the freewheeling diode D f .…”

“…To compensate for the intermittency of these sources and the fact that their production cannot be controlled, ESSs are a true solution [4]. Among the different types of ESSs, it is possible to highlight two categories: those using batteries [5] and those using hydrogen production by water electrolysis [6]. In the following, we will consider the This solution allows for the maintenance of the grid frequency, even in the case of low power demand.…”