Abstract: This disclosure is concerned with a motor technique for generating speeds that are fractions of synchronous speeds, through novel time-staggered selected half-cycle energization of a plurality of magnetic poles by a controlled switching sequence, generating such a fractional motor speed that would otherwise have to be produced by a much larger number of magnetic poles.

Abstract: The quality of the output waveform of a cycloconverter is greatly improved by a feedback loop that compensates for the inherent nonlinearity of the converter forward gain. A feedback signal, preferably proportional to the current through the shunt capacitor of the converter output filter, is multiplied by a compensating signal generated by full wave rectification of the cycloconverter AC reference signal with the resultant signal summed in opposition with the reference signal before it is applied to the converter control circuit. Alternatively a more precise compensating signal can be generated through 90.degree. phase shifting and negative going full wave rectification of the sinusoidal cycloconverter reference signal.

Abstract: A motor drive apparatus includes a two-phase synchronous motor having two power windings. The motor is supplied with power from an alternating voltage network through a direct convertor. The converter has two controllable converter bridges that are supplied with power by the network. Each power winding of the motor is connected between a DC terminal of one bridge and a DC terminal of the other bridge. The power windings have center taps that are connected.

Abstract: The Solid State Step Transmitter converts a low level asymmetrical squareve voltage into a high level three-phase asymmetrical square-wave voltage, which is completely isolated from the input voltage and is one twenty-fourth of the input frequency. The output also has a positive and negative phase rotation selection.