COMPARATIVE ANALYSIS OF CONTROL TECHNIQUES FOR ACTIVE POWER CONVERTER

Abstract

The AC-DC conversion is used increasingly in a wide diversity of applications: power supply for microelectronics, household-electric appliances, electronic ballast, battery charging, DC-motor drives, power conversion, etc. Previously, in most of the cases, the ac-dc power conversion was extensively carried out using passive techniques. These include diode bridge rectifiers and phase-controlled thyristor rectifiers with suitable passive filters at the output. Though passive rectifiers are simple, these present themselves as nonlinear loads to the utility. The input currents of these rectifiers contain considerable lower order harmonics; this distortion in input current can distort even the line voltage waveform. This can increase the losses in the equipment connected to them. PWM Converters or Active Power Converters has advantage of high power factor, less THD, nearly sinusoidal input current and regeneration. The thesis aims at comparing various control strategies for Voltage source AC to DC Converters such as Hysteresis Current Control, Sinusoidal Pulse width modulation, Space Vector Modulation, Four wire control strategies and for Current Source Converter. Simulation models are developed in MATLAB for different control strategies to compare the results and obtain a performance evaluation. The performance of the converter under various conditions of load and switching frequency has been evaluated and tabulated. Its dynamic performance is checked by varying supply, reference or changing mode from generation to regenerative. Finally all results has been tabulated and plotted.