Importance

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Abstract

A machine includes a rotor with a magnetic field produced therein that is fixedly oriented with respect to the rotor. The rotor is rotatably mounted within a stator which has a plurality of windings. Means are provided for applying voltage pulses to the stator windings. When voltage pulses are applied to the stator windings, there is a torque due to the interaction of a magnetic field produced in the stator windings and the rotor magnetic field that causes the rotor to rotate. A control system responds to voltage induced across unpowered stator windings by the rotating rotor magnetic field and controls application of the voltage pulses to the stator windings. The voltage pulse sequence, frequency, and duration are determined by the control system. The control system may also adjust the voltage pulse amplitude. The voltage pulses are applied to the stator windings in such a way that the machine operates at optimum efficiency and at a selectable speed over a wide range of loads and/or line voltages. The control system includes means for plugging the stator windings in the event that the selectable speed is exceeded. This assures synchronous operation of the machine at the selectable speed. In the case of a machine with three or more phases, the control system additionally includes means for distinguishing between voltage induced across unpowered stator windings by the rotating rotor magnetic field and voltage due to switching transients and transformer action among the stator windings.

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First Claim