Abstract: A discrete-time, closed loop power factor corrector system controls the coupling of a delta-connected switched capacitor array to a 3- or 4-wire power line which may have time-varying, unbalanced, inductive loads. For inductive loads that cannot be exactly compensated with a delta-connected capacitance, the corrector system minimizes the total RMS reactive current drawn from the power line.

Abstract: Sinusoidal excitation currents are supplied to the three terminals of a "wye" or "delta" connected three phase motor by an improved multiphase motor energizing drive system. For each terminal associated with a different phase, an individual feedback signal representing the current flowing into that respective terminal is sensed and subtracted from its corresponding controllable sine wave reference command to produce a current error signal for each terminal. The error signal for each of these currents is preferably converted to a two-state signal by means of an associated pulse width modulator. The modulator outputs are used to control power semiconductor switches which connect the corresponding motor terminal to either the positive or negative dc voltage. In the preferred system, for one of the terminals, the associated current feedback loop and reference command are omitted, and the associated pulse width modulator is driven by the inverted sum of the error signals from the other two phases.

Abstract: A back EMF controlled, synchronous, permanent magnet motor capable of extremely high rotation speeds at high efficiency. The motor includes a permanent magnet flux source and excitation coils for producing a rotating magnetic field mounted on an iron free form to substantially eliminate core loss and resulting rotor drag. Back EMF is determined directly from the excitation and controls the excitation to produce a torque angle of substantially 90.degree. between the magnet and coil fluxes. Coil excitation is used at maximum efficiency and hunting is avoided. The permanent magnet provides a high flux density that also allows a low current in the motor coils and thus reduces coil copper losses to further improve efficiency.