Analysis and implementation of a single-phase AC-AC converter to compensate voltage sags and swells

A converter topology to compensate voltage sags and swells simultaneously for critical loads is proposed It consists in a single-phase AC-AC matrix converter, which keeps a continuous regulation in the output voltage and it is able to compensate up to 25% voltage sags and 50% voltage swells. Energy storage devices are not required and the converter is directly connected to the AC mains taking the necessary energy to compensate the load perturbations. The compensation voltage is injected through a coupling transformer The four step switching technique is used to drive the AC-AC converter switches, executing a snubber-less operation. An optimal operation sequence that improves the operation features of the AC-AC converter is analyzed and proposed The reference control signal is generated by using the single-phase dq theory, obtaining a fast time response to compensate voltage sags and swells and a high regulation. The switching pattern is obtained from a Digital Signal Processor (DSP), and a Field Programmable Gate Arrays (FPGA) is used to control the state of the switches and the respective dead time. Several simulation and experimental results of a 5 kVA-127 V, 60 Hz experimental setup is presented in order to validate the obtained analysis. Copyright (c) 2007 Praise Worthy Prize S.r.l. - All rights reserved.