Multiphase to single phase and frequency converter system

Abstract

A multiphase to single phase electrical energy converter wherein the frequency is converted from a relatively high frequency, in the order of 1,000 hertz, to a relatively low frequency, as for example, normal household frequency of 60 hertz. A three-phase alternator is driven by an internal combustion engine and in one form of the invention the output of the alternator is fed to a controllable, full-wave bridge circuit and finally to an inverter. The controllable bridge circuit is controlled by a resolver, the resolver, alternator rotor and internal combustion engine all operating at the same rotary speed. In the one form the resolver is utilized to control the conduction of a plurality of controlled semiconductor devices interconnected between the output windings of the alternator and the invertor to control the delivery of energy from the alternator to the inverter. In another form the controlled semiconductor devices are replaced by a modified resolver. In accomplishing the control, the controlled rectifiers or modified resolver are rendered conductive to provide an average current or power to the inverter which increases and decreases in a unipolar sinusoidal form at a frequency which is twice the desired output frequency. The bridge circuit then provides an output to an inverter device which is rotating at one-half the speed of the resolver, the inverter being utilized to invert every other cycle of the output from the resolver. Thus, the power from the inverter will take the form of an alternating sinusoid waveform insofar as the power output is concerned at 60 hertz.