Article Study of a Synchronization System for Distributed Inverters Conceived for FPGA Devices Leonardo Saccenti 1,2, * , Valentina Bianchi 1, * and Ilaria De Munari 1   Citation: Saccenti, L.; Bianchi, V.; De Munari, I. Study of a Synchronization System for Distributed Inverters Conceived for FPGA Devices. Appl. Syst. Innov. 2021, 4, 5. https://doi.org/10.3390/asi4010005 Received: 1 December 2020 Accepted: 12 January 2021 Published: 15 January 2021 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional clai- ms in published maps and institutio- nal affiliations. Copyright: © 2021 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Department of Engineering and Architecture, University of Parma, Parco Area delle Scienze, 181/A, 43124 Parma, Italy; ilaria.demunari@unipr.it 2 Department of Industrial Engineering, Alma Mater Studiorum University of Bologna, Viale del Risorgimento 2, 40136 Bologna, Italy * Correspondence: leonardo.saccenti@unipr.it (L.S.); valentina.bianchi@unipr.it (V.B.) Abstract: In a multiple parallel-connected inverters system, limiting the circulating current phe- nomenon is mandatory since it may influence efficiency and reliability. In this paper, a new control method aimed at this purpose and conceived to be implemented on a Field Programmable Gate Array (FPGA) device is presented. Each of the inverters, connected in parallel, is conceived to be equipped with an FPGA that controls the Pulse-Width Modulation (PWM) waveform without intercommunication with the others. The hardware implemented is the same for every inverter; therefore, the addition of a new module does not require redesign, enhancing system modularity. The system has been simulated in a Simulink environment. To study its behavior and to improve the control method, simulations with two parallel-connected inverters have been firstly conducted, then additional simulations have been performed with increasing complexity to demonstrate the quality of the algorithm. The results prove the ability of the method proposed to limit the circulating currents to negligible values. Keywords: smart grid; FPGA; parallel inverters; circulating current 1. Introduction In recent years, smart grids have become a very important topic and are extensively debated in the literature [1]. A smart grid is a network that can efficaciously monitor and manage the transport of electricity produced by generators to meet the varying electricity demands of end-users [2,3]. To add intelligence to a smart grid, the network must integrate signal processing blocks and communication logic. Conventionally, methods such as the use of parallel capacitors, tap-changing transformers and SVC (Static Var Compensator) are adopted [4]. These power controls generally lack precision and do not work in real time; to overcome these limitations, different solutions relying on FPGA (Field Programmable Gate Array)-implemented algorithms can be exploited [5]. In the last few years, the application of FPGA devices has increased exponentially in a wide variety of fields, such as: digital signal processing [6–10], data processing [11,12], bioinformatics [13,14] and power elec- tronics [15–17]. Among the applications based on FPGAs that recently have been applied to the smart grid field, MPC (Model Predictive Control) has particular importance [18–20]. An MPC is a control strategy that allows predicting the output of a discrete-time model, combining the input data and the current state of the model to choose the optimal control action. Implementing the complicated and challenging algorithms on FPGA devices can help to minimize the real-time response. Moreover, exploiting FPGAs in this context can lead to a strong advantage in terms of flexibility, reliability and costs [1,20]. In [20], an example of FPGA application is presented and, specifically, the strategy of voltage control in a smart grid is proposed. The FPGAs are also used in converters and, in particular, in inverter-based applica- tions, such as switching control, voltage balance and fault detection [16]. An inverter is Appl. Syst. Innov. 2021, 4, 5. https://doi.org/10.3390/asi4010005 https://www.mdpi.com/journal/asi