Abstract
Due to the progress of power semiconductor technologies and power electronics technologies, applications of power converters have increased significantly in recently years, such as adjustable speed drive and switching power supplies. Most of these applications require diode rectifiers or thyristor rectifies to convert electric power from AC to DC. The nonlinear nature of the front-end rectifiers draws serious harmonic current from the utility grid, which results in harmonic distortion of current and voltage in the power system.Several regulations have been passed at the commercial and industrial levels to reduce harmonic distortion, such as IEEE-519 of USA, and IEC-1000-3-2 of Europe. To meet these standards, the related technologies of harmonic filter have been proposed.When the diode and thyristor are used as the AC/DC front-end rectifiers in the inverter-fed motor drive systems, they can not pump the re-generation energy back to the utility grid as the motor brakes. Thus the DC bus voltage will increase and the surrounding circuits may be damaged by over-voltage.In this thesis, a re-generative front-end system based on the diode bridge rectifier and an auxiliary IGBT converter (abbreviated as DAXC) is presented. By utilizing the active filter control techniques, the auxiliary IGBT converter compensates the harmonic current of the diode rectifier load to reduce the harmonic current distortion. Besides, the IGBT converter provides the function of re-generation. This thesis includes the operation principles of the proposed DAXC system. Both simulation results and laboratory test results will be provided to validate the proposed system. Design example based on adjustable speed drive system is also provided.