Mitigation of Harmonic Currents and Conservation of Power in Non-Linear Load Systems

A power controller system including one or more supply input terminals for receiving AC voltage from one or more supply phases of an AC power source, and one or more supply output terminals for conducting AC current to one or more stator phase windings of an AC induction motor, comprising in combination:

• an electronic power controller including one or more power input terminals for receiving AC voltage from each of the power controller system supply input terminals, one or more power output terminals electrically connected for conducting AC current to each of the power controller system supply output terminals, and switching means coupled between the power input terminals and power output terminals for controlling the conduction of current to each of the power controller system supply output terminals;
• a primary low pass filter circuit including one or more input terminals coupled to each of the supply input terminals and one or more output terminals coupled to each power input terminals of the electronic power controller;
• and
• one or more shunt capacitors connected in shunt phase to neutral relation across each of the electronic power controller power output terminals,
• wherein the electronic power controller interrupts the AC current flow conducted to stator phase windings in each phase during an interval that is proportional to the measured phase difference between the voltage waveform and the current waveform zero crossings in the preceding half cycle,
• wherein the capacitance value of each shunt capacitor is selected and coordinated with the inductance value of one or more stator phase windings of the AC induction motor that is to be connected to the power controller system, connecting each of the shunt capacitors with each of the stator phase windings and thereby forming a secondary low pass filter circuit,
• wherein the primary low pass filter circuits transform the impedance of the AC power source to an effective source impedance, the secondary low pass filter circuits transform the impedance of the AC induction motor into an effective load impedance, and the effective load impedance is approximately equal to the power source impedance,
• the primary low pass filter circuit and the secondary low pass filter circuit have low attenuation from DC up through the fundamental power distribution of the AC power source to a cutoff frequency, and, attenuates current flow at frequencies above the cutoff frequency.