Abstract—This paper presents a single-phase AC-AC matrix converter which is able to compensate voltage harmonics and voltage regulation at critical loads terminals. The converter is composed with the minimum number of switching devices and is controlled using a non-linear law based on passivity achieving a high reliability and robustness during transient and steady state operation condition. The proposed scheme has the advantage that energy storage devices are not required. The converter is connected between the AC mains and the load through a series transformer. A DSP and a FPGA are used to program the passivity-based controller and to determine the state of the switches respectively. In this case, the converter is able to compensate up to 25% voltage sags and 50% voltage swells and to eliminate up to the fifteenth harmonic component. The tested system presents a fast time response and the stabilization time of the load voltage is less than 1ms. Analysis and modeling as well as simulation and experimental results of a 5kVA, 127V, 60Hz experimental setup are analyzed and presented. I. INTRODUCTION The proliferation of non-linear loads and voltage-sensitive equipments has made industrial processes more vulnerable to supply voltage deviations. Such voltage deviations can cause severe disruptions in the processes and result in a substantial production loss. The power quality problems include transients, sags, swells, surges, outages and harmonics that vary in quantity or voltage magnitude [1]. Because of these problems, the line conditioners have been developed to perform the role of regulating, conditioning, isolating, purifying and distributing incoming power with adequate power quality standard. Nowadays, the necessity of compensator equipment able to eliminate different disturbances at the same time has increased. The Dynamic Voltage Restorers (DVR) and Uninterrupted Power Supply systems (UPS) have been developed during last two decades and they are capable to compensate voltage harmonics, sags and swells maintaining a clean regulated voltage at critical loads during enough period of time. Nevertheless, they depend on devices to store energy, like large capacitors or batteries bank. The rated power operation is a function of the size and capacity of these devices; if the power is increased, the size of these devices will increase. This work was partially sponsored by Mexican Secretariat of Public Education (SEP), with the project UASLP PIFI 3.1 This paper demonstrates that it is possible to use an AC-AC converter instead of a power inverter in the topology of a Dynamic Voltage Restorer avoiding the storage energy devices. The three-phase matrix converter concept introduced by Venturini and Alessina in 1979 seems to be the most advanced concept for static energy conversion [2], [3], [4]. The characteristics of these circuits are satisfactory output waveforms, bidirectional energy flow, minimal energy storage elements and adjustable input power factor. Most of published papers dealt with three-phase converter topologies, their control and power switch protection. The main purpose of this paper is to show that a single-phase AC-AC matrix converter may be applied in DVR topologies. The proposed system uses the minimum number switching devices and is controlled by using a non-linear law based on passivity. Energy storage devices are not required. One of the advantages in the proposed structure is that the coupling transformer does not required taps to change the polarity of the compensated voltage; therefore the converter drives only a fraction of the load power. A four step switching technique is used to drive the converter semiconductors executing snubber-less operations. In this case, the converter is able to compensate up to 25% voltage sags and 50% voltage swells and to eliminate up to the fifteenth harmonic component. The tested system presents a fast time response and the stabilization time of the load voltage is less than 1ms. The proposed voltage compensation scheme is proved by simulation and through a 5kVA laboratory prototype. II. PRINCIPLE OF OPERATION The topology of the proposed scheme is shown in Fig. 1. The proposed scheme can be divided in three parts: the AC mains, the single-phase AC-AC matrix converter and the load. Single-Phase AC-AC Converter Operating as a Dynamic Voltage Restorer (DVR) Jorge Pérez * , Víctor Cárdenas * , Luis Morán & , Ciro Núñez * . * Centro de Investigación y Estudios de Posgrado CIEP-FI Universidad Autónoma de San Luis Potosí Manuel Nava #8, 78290, San Luis Potosí, MEXICO Phone / Fax: 52(444) 8-173381 e-mail: japerez@uaslp.mx, vcardena@uaslp.mx, calberto@uaslp.mx & Departamento de Ingeniería Eléctrica Universidad de Concepción Casilla 53-C, Concepción CHILE Phone 56(41) 205314 / Fax: 56(41) 246999 e-mail: lmoran@die.udec.cl Load v o v AC AC/AC Z AC v in v out 1 ¨ n . . v con i o Fig.1 Single-phase dynamic voltage restorer implemented with a single-phase matrix converter. 1938 1-4244-0136-4/06/$20.00 '2006 IEEE