A 20 kW, 20 kHz unity power factor boost converter for three-phase motor drive applications from an unregulated single-phase supply

A three-phase, medium-power standard ac motor can be operated from a single-phase, highly-distorted and unregulated ac source by the use of a diode bridge rectifier / boost chopper / inverter cascade. The integration of a boost chopper unit employing an inductor made of amorphous metal (Metglas) into the system results in unity pf at the ac supply side, low harmonic content line currents, high -efficiencies and -power densities. Laboratory and field test results have shown that this system constitutes a reliable, cost-competitive and almost maintenance-free alternative to other drive options, especially for auxiliary systems in electric locomotives where squirrel-cage induction motors are chosen as auxiliary driving machines.