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first_pagesettingsOrder Article Reprints Open AccessArticle Power Converter Resonant Control for an Unbalanced and Non-Constant Frequency Supply by Jaime Rohten 1,*ORCID,Felipe Villarroel 1,José Silva 2ORCID,Esteban Pulido 3ORCID,Fabián Pierart 4ORCID,Johan Guzmán 1ORCID andLuis García-Santander 5ORCID 1 Department of Electrical and Electronic Engineering, Universidad del Bío-Bío, Concepción 4030000, Chile 2 Department of Engineering Science, Universidad de Los Lagos, Puerto Montt 5480000, Chile 3 Department of Electrical Engineering, Universidad Técnica Federico Santa María, Valparaíso 2390136, Chile 4 Department of Mechanical Engineering, Universidad del Bío-Bío, Concepción 4030000, Chile 5 Department of Electrical Engineering, Universidad de Concepción, Concepción 4030000, Chile * Author to whom correspondence should be addressed. Sensors 2023, 23(10), 4884; https://doi.org/10.3390/s23104884 Received: 24 March 2023 / Revised: 25 April 2023 / Accepted: 11 May 2023 / Published: 19 May 2023 (This article belongs to the Special Issue New Algorithms of Sensing/Metering and Optimal Control in Electrical Networks and Grid-Connected Converters) Download Browse Figures Review Reports Versions Notes Abstract Distorted voltage supplied as unbalanced and/or non-constant frequency can be found in weak grids, such as microgrids, or systems working in islanding mode. These kinds of systems are more sensitive under load changes. Particularly, an unbalanced voltage supply may be produced for large, single-phase loads. On the other hand, the connection/disconnection of high current loads may lead to important frequency variation, especially in weak grids where the short circuit current capacity is reduced. These conditions make the control of the power converter a more difficult task, because of the variations in the frequency and unbalancing. To address these issues, this paper proposes a resonant control algorithm to deal with variations in the voltage amplitude as well as grid frequency when a distorted power supply is considered. The frequency variation is an important drawback for resonant control because the resonance must be tuned at the grid frequency. This issue is overcome by using a variable sampling frequency in order to avoid re-tuning the controller parameters. On the other hand, under unbalanced conditions, the proposed method relaxes the phase with lower voltage amplitude by taking more power from the other phases in order to help the stability of the grid supply. To corroborate the mathematical analysis and the proposed control, a stability study is performed, including experimental and simulated results.