Patent ID: 7602136
Filing Date: 2009-10-13
Classification: H02P

Abstract:
1. A power controller system for controlling the amount of electrical power supplied to the windings of an AC induction motor that is coupled to a mechanical load, the AC induction motor having at least one motor phase winding, and the controller system including supply input terminals for receiving AC voltage at a fundamental power distribution frequency from one or more selected phases of an AC power source, and supply output terminals for applying AC voltage to one or more motor phase windings of the AC induction motor, comprising in combination: an electronic controller including AC power input terminals for receiving AC voltage at a fundamental power distribution frequency from one or more selected phases of the AC power source, and power output terminals connected to the supply output terminals, and switching means coupled between the power input terminals and power output terminals for controlling the conduction of AC current through each phase; a primary low pass filter connected in series between the AC power source and the electronic controller, the primary low pass filter including an input terminal for receiving AC supply voltage from the AC power source and an output terminal for delivering filtered AC supply voltage to one of the controller power input terminals; and reactive capacitor impedance means connected in shunt from phase to neutral across one or more output terminals of the electronic controller terminal, wherein the capacitance value of each reactive capacitor means is selected and coordinated with the inductance values of the stator phase windings to provide a secondary low pass filter between the output terminals of the power controller and the stator phase windings.