This paper presents the relationship between electric current fluctuation and energy efficiency of a laboratory scale alkaline electrolyzer, combined with a novel rectifier system. Electrochemical impedance spectroscopy of the electrolysis cell provides information on the ohmic resistances, the double layer capacity between electrodes and the electrolyte as well as the frequency dependency of these parameters. Thus, it enables the generation of specific current profiles in order to reduce ohmic resistance from polarization as well as bubble evolution. The measurement results show a connection of the energy efficiency on the provided current profiles as well as on the periodical pulse duration. A pulsed current profile, based on the results from the impedance spectroscopy, is able to reduce polarization and bubble resistance losses, while consuming additional electrical energy.
This paper presents the relationship between electric current fluctuation and energy efficiency of a laboratory scale alkaline electrolyzer, combined with a novel rectifier system. Electrochemical impedance spectroscopy of the electrolysis cell provides information on the ohmic resistances, the double layer capacity between electrodes and the electrolyte as well as the frequency dependency of these parameters. Thus, it enables the generation of specific current profiles in order to reduce ohmic resistance from polarization as well as bubble evolution. The measurement results show a connection of the energy efficiency on the provided current profiles as well as on the periodical pulse duration. A pulsed current profile, based on the results from the impedance spectroscopy, is able to reduce polarization and bubble resistance losses, while consuming additional electrical energy.
Z-source inverter (ZSI) combines the electrical function of a DC/DC converter and a three-phase inverter. This study deals with a three-level neutral-point-clamped (NPC) ZSI which brings an additional electrical potential. The benefit is the lower output current ripple of each phase. Due to the non-linear behaviour of the Z-source control path, designing an accurate and especially a dynamic control can be challenging. This study presents a design of an adaptive control for a three-level NPC ZSI to fulfil the previously mentioned goals. The correct functionality of the control system is underlined with measurements at different operating points. A possible application field for threelevel ZSIs are hybrid and electric vehicles.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.