An Efficient Solar-Hydrogen DC-DC Buck Converter System with Sliding Mode Control

Abstract

This paper focuses on two different scenarios to benefit from solar energy more efficiently. One of them is photovoltaic houses and storing their energy as hydrogen, the other one is photovoltaic cars and storing their energy as hydrogen. The common point in these two photovoltaic sourced scenarios is convert and storage of the hydrogen energy more efficiently. The direct current (DC) photovoltaic energy is converted to the desired voltage level using the DC-DC buck converter for generating hydrogen with electrolysis process. The electrolysis load for hydrogen production needs low voltage and high currents especially. To supply these conditions the converter must be designed and controlled sensitively. For this aim, the sliding mode controller is proposed as a solution in this study. This controller is used the inductance current in the inner loop and supply a strong control for the converter under normal and abnormal conditions. The photovoltaic powered DC-DC buck converter for electrolysis load was simulated in MATLAB/ Simulink software more detailed using the sliding mode controller.

Proton exchange membrane water electrolysis: Modeling for hydrogen flow rate control

“…For this reason, the activation phenomena in PEMEL are mainly dominated by the anode reaction. Therefore, this analysis is in agreement with the model in (14) which exhibits a dominant time constant in the behavior of the PEMEL.…”

“…In the literature, different models of PEMEL have been developed. In [14,15,16,18,19,20,32,38,39], the electrolyzer can be modeled as a simple resistor; whereas in [40,41,42,43], it is modeled by an equivalent circuit composed of a resistance series connected to a voltage generator representing the reversible voltage. In the major part of these papers and articles, too few information is provided regarding the determination of the parameters of the model.…”

“…Usually, a DC-DC converter is required to couple the PEMEL to the RES. Given that the PEMEL requires a low rated voltage (roughly equal to 8 V [13]) to maximize the production of hydrogen from water electrolysis, DC-DC buck converters are commonly used for this purpose [14,15,16]. However, depending on the electrical grid and the feature of the PEMEL, different DC-DC converter topologies can be employed [13,17].…”

“…A detailed literature review that has been carried out in [17] shows that the classic buck converter topology does not meet several requirements, especially in terms of reliability (one single switch fault), efficiency and voltage ratio. Most articles dealing with DC-DC converters and their controls for electrolyzer applications include only simulation results [14,15,16,29]. Therefore, new contributions including experiments with electrolyzers are required to assess the performance of developed DC-DC converters and their control.…”

“…The damping factor ζ and the natural frequency ω n associated to the complex poles p Since T 1 T 2 T > T 3 , it can be noted that the transient behaviour of the two step responses depends almost exclusively on the time constant T 1 with a settling time given by t s ≈ 3T 1 = 1.7268 s. The interleaved buck converter has influenced the dynamics of the step responses since the time constant of the model of the PEMEL in Figure 6 is R a C a = 0.80479 s (see (14)) and is higher than T 1 .…”