Sensorless Control Strategies for Three - Phase PWM Rectifiers

support and help. His precious advice and numerous discussions enhanced my knowledge and scientific inspiration. preparation of the laboratory setup is especially appreciated. Finally, I am very grateful for my wife Ann's and son Kacper's love, patience and faith. I would also like to thank my whole family, particularly my parents for their care over the years. Introduction 2 1. INTRODUCTION Methods for limitation and elimination of disturbances and harmonic pollution in the power system have been widely investigated. This problem rapidly intensifies with the increasing amount of electronic equipment (computers, radio set, printers, TV sets etc.). This equipment, a nonlinear load, is a source of current harmonics, which produce increase of reactive power and power losses in transmission lines. The harmonics also cause electromagnetic interference and, sometimes, dangerous resonances. They have negative influence on the control and automatic equipment, protection systems, and other electrical loads, resulting in reduced reliability and availability. Moreover, nonlinear loads and non-sinusoidal currents produce non-sinusoidal voltage drops across the network impedance's, so that non-sinusoidal voltages appears at several points of the mains. It brings out overheating of line, transformers and generators due to the iron losses. Reduction of harmonic content in line current to a few percent allows avoiding most of the mentioned problems. Restrictions on current and voltage harmonics maintained in many countries through IEEE 519-1992 in the USA and IEC 61000-3-2/IEC 61000-3-4 in Europe standards, are associated with the popular idea of clean power. Many of harmonic reduction method exist. These technique based on passive components, mixing single and three-phase diode rectifiers, and power electronics techniques as: multipulse rectifiers, active filters and PWM rectifiers (Fig. 1.1). They can be generally divided as: A) harmonic reduction of already installed non-linear load; B) harmonic reduction through linear power electronics load installation;