Power Quality Improvement Using Active Ac/Dc Pfc Converters

Abstract

Most modern electrical and electronic apparatus called as nonlinear loads use AC/DC power supply within their architecture. These devices draw discontinuous current from the AC network. The discontinuous currents include harmonics and cause problems for the power distribution systems. In addition, the harmonic contents of the discontinuous current cause additional losses and dielectric stresses in capacitors and cables resulting in increasing currents in windings of rotating machinery, transformers and electromagnetic interference. With the steadily increasing use of equipments including nonlinear loads, line current harmonics have become a significant problem. So, several international standards such as EN 61000-3-2 now exist limiting the harmonic content due to line currents of equipment connected to AC networks. In this chapter, parallel to power factor correction (PFC) study, several passive and active topologies applied to single phase power factor correction are analyzed. The major advantages and disadvantages of the topologies are highlighted. In addition, the commonly used control methods for active power factor correction are discussed and compared. The switching losses and soft switching methods of the boost type active power factor correction circuits are also reviewed and discussed. In the several active power factor correction techniques used to reduce current harmonics and to satisfy the requirements given in international standards, the boost type converters operating in continuous conduction mode have been widely adopted as power factor correction pre-regulators. For this purpose, the boost type power factor correction circuit is simulated and the related waveforms are given to show the importance of active power factor correction methods. © 2011 Nova Science Publishers, Inc.