Patent ID: 6965212
Filing Date: 2005-11-15
Classification: H02P

Abstract:
1. A method of controlling a power converter of an AC motor drive system, said method comprising: generating a field current regulating signal to control a field current component flowing from said power converter to the AC motor, thereby achieving field current regulation; generating a torque current regulating signal to control a torque current component flowing from said power converter to the AC motor, thereby achieving torque current regulation, said torque current regulation having lower priority than said field current regulation; and executing a close-loop field weakening control scheme, which generates a field weakening control command as a function of the difference between a torque current regulation voltage demand and voltage available for torque current regulation, wherein said field current regulating signal is adjusted in accordance with said field weakening control signal to selectively reduce back EMF of said AC motor, thereby enabling said step of generating a toque current regulating signal to achieve a toque current component needed to drive the AC motor at a desired speed despite a limitation on DC voltage available to said power converter.