International Journal of Electrical and Computer Engineering (IJECE) Vol. 12, No. 2, April 2022, pp. 1251~1264 ISSN: 2088-8708, DOI: 10.11591/ijece.v12i2.pp1251-1264  1251 Journal homepage: http://ijece.iaescore.com Sliding-mode controller for a step up-down battery charger with a single current sensor Juan Pablo Villegas-Ceballos 1 , Carlos Andrés Ramos-Paja 2 , Elkin Edilberto Henao-Bravo 3 1 Departamento de Electrónica y Telecomunicaciones, Instituto Tecnológico Metropolitano, Medellín, Colombia 2 Facultad de Minas, Universidad Nacional de Colombia, Medellín, Colombia 3 Departamento de Mecatrónica y Electromecánica, Instituto Tecnológico Metropolitano, Medellín, Colombia Article Info ABSTRACT Article history: Received Oct 26, 2020 Revised Aug 12, 2021 Accepted Aug 25, 2021 This paper proposes a battery charger solution based on the Zeta DC/DC converter to provide a general interface between batteries and microgrid direct current (DC) buses. This solution enables to interface batteries and DC buses with voltage conversion ratios lower, equal, and higher than one using the same components and without redesigning the control system, thus ensuring global stability. The converter controller is designed to require only the measurement of a single inductor current, instead of both inductors currents, without reducing the system flexibility and stability. The controller stability is demonstrated using the sliding-mode theory, and a design procedure for the parameters is developed to ensure a desired bus performance. Finally, simulations and experiments validate the performance of the proposed solution under realistic operation conditions. Keywords: Battery charger Bus voltage regulation DC/DC converter Sliding-mode control This is an open access article under the CC BY-SA license. Corresponding Author: Juan Pablo Villegas-Ceballos Departamento de Electrónica y Telecomunicaciones, Instituto Tecnológico Metropolitano-ITM Calle 73 No. 76A-354, Vía al Volador, Medellín 050034, Colombia Email: juanvillegas@itm.edu.co 1. INTRODUCTION Direct curent (DC) microgrids are one of the most adopted structures to distribute power generated with renewable energy sources [1], [2]. Those microgrids require energy storage devices, usually batteries, to store energy when the sources production is higher than the load consumption; similarly, the batteries provide energy when the load consumption is higher than the sources production [3], [4]. Moreover, DC microgrids have a common bus in which both sources and loads are connected, hence the stability of such a bus is required to guarantee the safe operation of both sources and loads [1], [2]. Therefore, the batteries in DC microgrids can be interfaced using DC/DC converters, which are controlled to regulate the DC bus: When the sources produce higher power with respect to the load request, the bus voltage increases, hence the DC/DC converter must to charge the battery to ensure a regulated DC bus; similarly, when the requested load power is higher than the power produced by the sources, the bus voltage decreases and the DC/DC converter must to discharge the battery to ensure a regulated DC bus [5], [6]. In this way, the DC/DC converter ensures both the voltage stability and the power balance of the DC bus. Battery chargers are formed by DC/DC converters and controllers. Those DC/DC converters must to support the voltage difference between the battery and the DC bus; therefore, the battery chargers are designed with step-down topologies when the battery voltage is lower than DC bus voltage [7]–[9]. Similarly, step-up converters are used to design battery chargers to interface a DC bus with a higher voltage battery bank [2], [10]–[12]. In addition, buck-boost topologies have been used to interface DC buses and battery banks with similar voltages [13]–[16]. Concerning the controllers, battery chargers require control